International Review of Research in Mental Retardation: v. 1

International Review of RESEARCH IN MENTAL RETARDATION VOLUME 1

Contributors to this Volume JOHN M. BELMONT SIDNEY W. BIJOU HARVEY F. DINGMAN FREDERIC L. GIRARDEAU

H. CARL HAYWOOD C. EDWARD MEYERS RALPH M. REITAN LEONARD E. ROSS JOSEPH E. SPRADLIN JACK T. TAPP EDWARD ZIGLER

International Review of

RESEARCH IN MENTAL RETARDATION EDITED BY

N O R M A N R . ELLIS DEPARTMENT OF PSYCHOLOGY UNIVERSITY OF ALABAMA UNIVERSITY, ALABAMA

VOLUME 1

CONSULTING EDITORS FOR THIS V O L U M E

Sidney W. Bijou UNIVERSITY OF ILLINOIS URBANA, ILLINOIS

Neil O’Connor THE MAUDSLEY HOSPITAL LONDON, ENGLAND

Ivar Arnljot Bjorgen UNIVERSITY OF OSLO

OSLO, NORWAY

Richard L. Schiefelbusch UNIVERSITY OF KANSAS LAWRENCE. KANSAS

Edward Zigler YALE UNIVERSITY NEW HAVEN, CONNECTICUT

1966

ACADEMIC PRESS

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COPYRIGHT 0 1966, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM, BY PHOTOSTAT, MICROFILM, RETRIEVAL SYSTEM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION PROM THE PUBLISHERS.

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List of Contributors Numbers in parentheses indicate the pages on which the authors’ contributions begin.

M. BELMONT, Department of Psychology, University of Alabama, Tuscaloosa, Alabama (219)

JOHN

SIDNEYW . BIJOU, Department of Psychology, University of Illinois, Urbana, Illinois (1) HARVEY F. DINCMAN, Department of Mental Hygiene, Pacific State Hospital, Pomona, California (55) FREDERIC L. GIRARDEAU, Bureau of Child Research, University of Kansas, Lawrence, Kansas (257) H. CARLHAYWOOD,+ Department of Psychology, George Peabody College for Teachers, Nashville, Tennessee (109) C. EDWARD MEYERS,Department of Mental Hygiene, University of Southern California, Los Angeles, California (55)

RALPHM . REITAN,Neuropsychology Laboratory, Indiana University Medical Center, Indianapolis, Indiana (153) LEONARD E. Ross, Department of Psychology, University of Wisconsin, Madison, Wisconsin (21) JOSEPHE. SPRADLIN, Bureau of Child Research, University of Kansas, Lawrence, Kansas (257)

T. TAPP, Department of Psychology, Vanderbilt University, Nashville, Tennessee (109)

JACK

EDWARD ZIOLER, Department of Psychology, Yale University, New Haven, Connecticut (77) Present addrcsa: Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.

V

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Preface Behavioral research pertaining to mental retardation has suddenly burgeoned. Indeed, it seems reasonable to speculate that more research has occurred in this field in the past 10 years than in all previous years. A decade ago, an investigator could, with little effort, familiarize himself with all the research literature in the area; now, he can hardly keep abreast of a particular problem area within the field. His difficulty stems not only from increased productivity in the field of mental retardation but also from the need to be versed in research and theory as they relate to the normal human being as well as to lower organisms. Discriminda for promising avenues for further research and theorizing may come into view more sharply in interpretative collations of this plethora of research literature. The main purpose of this serial publication is to provide a ready source of current information on research and theory development in the field. Although this volume does not include contributions from outside the United States, future ones will be international in scope. The problem areas treated will vary widely within and among volumes. Although topics of primary interest to the behavioral sciences will be emphasized, some attention will also be given to biological and educational issues. Some chapters will consist of reviews of research, others will describe the more significant theoretical approaches, and still others will present the systematic research of a single investigator. Some overlap in content seems inevitable, although this may be a “mixed blessing” since interpretations of data may differ markedly. I wish to express appreciation to the consulting editors who graciously assisted in the preparation of the current volume. I am also grateful to Brendan A. Maher (University of Wisconsin), D. A. R. Peyman (Bryce Hospital, Tuscaloosa, Alabama), and H. C. Rickard and Paul S. Siege1 (University of Alabama) for critically reading manuscripts. University, Alabama December, 1965

NORMANR. ELLIS vii

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Contents .. . . , . . . , . . . . . . . . . . . . , . . . . . . , . . . . . ... . . . .. . . . . .. . . . . . . . . . Preface ..................................................................... List of Contributors

V

vii

A Functional Analysis of Retarded Development

SIDNEYW. BIJOU

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Physiological Functioning .. . .. . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . , . . 111. Retarded Development through Inadequate Reinforcement and Discrimination Histories . . . .. . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . IV. Retardation through Contingent Aversive Stimulation . . . . . . . . . . . . . . . . V. Retardation through the Reinforcement of Aversive Behavior . . . . . . . . . . I. Introduction

1

11. Retarded Development through Abnormal Anatomical Structure and

VI. Summary ........................................................... References

6

9 14 16

17

.........................................................

18

Classical Conditioning and Discrimination Learning Research with the Mentally Retarded

LEONARD E. Ross I. Introduction

.......................................................

11. Classical Conditioning and Discrimination Learning 111. Current Research Involving Classical Conditioning and

.

.. . . . . . . . . . . . . . . .

. ...

..

Discrimination Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Concluding Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

.

21 22

35 51 52

The Structure of Intellect in the Mental Retardate

HARVEY F. DINCMAN and C. EDWARD MEYERS I. Introduction

.......................................................

........

11. Identifying and Naming Factors ................. . .. ........ 111. Research Models for Use in Factorial Study of Abilities in the

Ketarded

......................................................... ix

56

57 59

Contents

X

IV . Problems of Applying Factor Study to Young and Retarded Children . . . . V . Factor Analytic Processes and the Availability of Computers . . . . . . . . . . . V I. Uses of Factor Analysis .......................................... .... VII Problems of Factorial Investigation of Subgroups of Retarded . . . . . . . . . . VIII Factorial Studies Using Preliterate Normal and Rctarded Children . . . . . . IX Factors Established at Preliterate Levels . . . . . . . . . . . . . . . . . . . . . . . . .... X . Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . .

61 64 64 68 70 71

73 74

Research on Personality Structure in the Retardate

EDWARD ZICLER

. . . . . . . . .

I Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..................... 77 The Lewin-Kounin Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 The Motivational Hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Social Deprivation and Institutionalization . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Positive- and Negative-Reaction Tendencies .......................... 90 The Reinforcer Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Expectancy of Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Outer-Directedness ..... ................................... 99 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

I1 111 IV V VI VII VIII IX

Experience and the Development of Adaptive Behavior

H . CARLHAYWOOD and

JACK

.

T TAPP

I . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1 The Behavioral Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 A Brief Synopsis of the Human Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Theories of the Effects of Early Experience . . . . . . . . . . . . . . . . . . . . . . . . . . V . Implications for Mental Retardation ................................ References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

.

109 111 129 135 143 145

A Research Program on the Psychological Effects of Brain lesions in Human Beings

.

RALPHM REITAN

. . .

I Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1 Selection of Tests for Neuropsychological Assessment . . . . . . . . . . . . . . . . . 111. Methodological Approach ........................................... IV Description of Psychological Test Battery ............................

154 160 162 164

Contents

xi

V. Research Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Interpretation of Results for Individual Patients ..................... VII. Concluding Comments .............................................. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

170 195 214 214

long-Term Memory in Mental Retardation JOHN

I. 11. 111. IV. V.

M. BELMONT

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Development of the Problem .............................. Methodological Considerations .......................... Retention Research with Retarde Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . ......................

221

263

The Behavior of Moderately and Severely Retarded Persons JOSEPH

I. 11. 111. IV.

E. SPRADLINand FREDERIC L. GIRARDEAU

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Respondent Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . Operant Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . 257 . . . . . . . . . 262

Author I n d e x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

299

Subject I n d e x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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A Functional Analysis of Retarded Developmentlo2 SIDNEY W. BIJOU DEPARTMENT OF PSYCHOLOGY,

UNIVERSITY OF ILLINOIS.

URBANA, ILLINOIS

I. Introduction .........................................

11. 111.

IV. V.

VI.

Diffculties of Conceptualizing Retardation in Hypothetical Terms ................................... B. Difficulties of Conceptualizing Retardation in Biological Terms .................................... Retarded Development through Abnormal Anatomical Structure and Physiological Functioning ................ Retarded Development through Inadequate Reinforcement and Discrimination Histories A. Circumstances in which Reinforcements May Be Infrequent and in Small Amounts B. Circumstances in which Reinforcements Are Withheld (Extinction) or Are on A Noncontingent Basis C. Circumstances in which Opportunities Are Restricted by Social or Economic Factors .................... Retardation through Contingent Aversive Stimulation Retardation through the Reinforcement of Aversive Behavior ............................................... Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

A.

.................... ..................

3 5

6 9

11 13

IS 14

16 17 18

1. INTRODUCTION

Current research on retardation is becoming bountiful, yet such increased efforts are not producing principles and techniques which substantially advance new ways of dealing with this problem. Although many complex conditions contribute to the slow, forward pace of this 1 This presentation

is a revision and extenaion of a theory of retardation by Bijou

(1963). 2 Much of this formulation has developed in the reaearch supported by Public Health Service grants MH-02232 and MH-01366, from the National Institute of Mental Health, and grant 32-57-0200-1003, from the U. S. Office of Education.

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Sidney W . Bijou

field, a prime factor is the present, widely accepted theory of psychological retardation. The objective of this paper is to criticize current theory and to present an alternative approach, one that is consistent with a natural science point of view. It is suggested that developmental retardations be treated as observable, objectively defined stimulus-response relationships without recourse to hypothetical mental concepts such as “defective intelligence” and hypothetical biological abnormalities such as “clinically inferred brain injury.” From this point of view a retarded individual is one who has a limited repertory of behavior shaped by events that constitute his history. Retardation is not conceived of as a symptom. A promising objective for behavioral research on retardation is an analysis of the observable conditions which produce retarded behavior, not retarded mentality. Pursuing this objective would require investigating the processes that prevent, reduce, or delay the formation of stimulus-response functions. “In such cases as have been traditionally called idiocy, imbecility and moronity, the basic principle is the failure of the individual to build up response equipment to certain things. There is failure to coordinate certain stimulus-response functions” (Kantor, 1959, p. 176). A study of the formation of stimulus-response functions in the retarded can be achieved within a theoretical framework in which the principles of development are the same for both normal and deviant individuals (Bijou & Baer, 1961; Bijou & Baer, 1965). Here, psychological development consists of progressive changes in interactions between the individual, as a total functioning biological system, and the environmental events. The individual as a total functioning biological system is conceptualized from an experimental analysis point of view (Skinner, 1964) as a set of responses and response systems and a source of environmental stimuli. Hence, the total environment is made up of eflective stimuli from social and physical events outside of the body wall and from biological events in the organism. For the so-called normal individual, the succession of effective environmental events in development are more or less typical for his culture. The opportunities for him to interact with social and physical events have been within normal limits; his biological structure and physiological functioning are adequate and are maturing at the usual rates. For the retarded individual social, physical, and biological conditions of development deviate in the direction of slowing down the pace of successive interactional changes-the more extreme the curtailment of opportunities, the more extreme the retardation. 3 The term “developmental retardation” is used in place of “mental retardation” and “mental deficiency.”

A FUNCTIONAL ANALYSIS OF RETARDED DEVELOPMENT

3

One might hastily conclude that there is nothing new in this formulation, for the literature on retardation abounds with discussions on the significance of social, physical, and biological factors. Yet there is a difference, a critical difference. I t lies in the way in which these variables are said to interact. I n our view, retarded behavior is a function of observable social, physical, and biological conditions, all w i t h the status of independent variables. I n the traditional view, retarded behavior is said to be caused by either hypothetical psychological concepts (e.g., “defective intelligence”) or hypothetical biological concepts (e.g., “constitutional defect”) which in turn is controlled basically by heredity and modifiable by social and physical interactions. A. Difficulties of Conceptualizing Retardation in Hypothetical Terms

It has been common practice in psychology and psychopathology to estimate level of mental retardation on the basis of either (1) the observed behavior alone or ( 2 ) the behavior observed and the context of stimulating conditions. Let us consider each in turn. T o judge the amount of mental ability on the basis of observed behavior alone, the usual practice is to conceptualize and measure a sequence of behavior, and then make a statement of the amount of intelligence necessary to account for the behavior. T h e behavior of concern is therefore given two names, one LO describe it (e.g., poor problem-solving behavior) and one to account for it (e.g., low level of mental ability). Skinner (1953, p. 202) succinctly describes the process of inferring causes from behavior as follows. ‘aggressive,’ “Trait-names usually begin as adjectives-‘intelligent,’ ‘disorganized,’ ‘angry,’ ‘introverted,’ and so on, but the almost inevitable linguistic result is that adjectives give birth to nouns. T h e things to which these nouns refer are then taken to be the active causes of the aspects. We begin with ‘intelligent behavior,’ pass first to ‘behavior which shows intelligence’ and then to ‘behavior which is the effect of intelligence.’ . . . But at no point in such a series do we make contact with any event outside of the behavior itself which justifies the claim of a causal connection.” Consider now the second practice of creating hypothetical conceptsin terms of both the conceptualized behavior and the context of stimulating conditions. This strategy is designed to avoid the pitfall of the procedure described in the process of accounting for presumed psychological events inside the organism. It is aimed at creating terms that will form a hypothetical set of terms to serve as a linkage between a behavior concept (such as distractibility) and genetic, biological, physical, and social conditions.

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Sidney W . Bijou

There are at least two limitations to this way of defining mental competence. The first is based on the assumption that environmental and behavioral concepts are “symptoms” or “surface terms,” and that “the more fundamental variables,” located inside the organism, are correlated with or are potentially correlated with physiological processes. I t stands to reason that such an orientation does now and has in the past discouraged a search for detailed and concretely observable biological, physical, and social events which might play a role in retarding psychological development, especially in the infancy and early childhood phases. Only recently, for example, has it been deemed profitable to analyze experimentally specific and subtle relationships between the infant and mother and the resultant effects of these relationships on the psychological behavior of the infant. Examples include the infancy studies on controlling the rate of smiling by Brackbill (1958), of vocalizations by Rheingold, Gewirtz, and Ross (1959), and of exploratory behavior by Rheingold, Stanley, and Cooley (1962). Conceiving of mental competence as something internal and inferred from behavior and stimulating conditions has a second limitation: such a procedure ordinarily contributes little or no new knowledge to the field of retardation as such. While it is true that much research on retarded children has evolved from investigators with this orientation, their interest has been on constructing hypothetical relationships among the internal hypothetical variables rather than on the specific observable conditions, both past and present, that might limit, curtail, depress, and restrict behavior development. Whether the hypothetical concept of defective intelligence is inferred from behavior alone or from behavior in combination with stimulating conditions, its level is said to be generated by built-in processes such as hereditary, familial, constitutional, intrinsic, or endogenous factors, and modified by detrimental environmental, extrinsic, or exogenous factors (Tredgold & Soddy, 1956). The first set of conditions determining the extent of mental defectiveness is said to evolve through genetic processes or some other transmissional mechanism not fully understood at present: the second set is thought to exist in those external events which impair or lower the level of mentality established by heredity. Therefore, according to this point of view, an individual “inherits” a level of intellect. If the environmental factors with which the individual interacts during development are disadvantageous (injuries, diseases, toxic conditions, and physical or social neglect), his “native ability” will not be fully expressed in his behavior. On the other hand, if environmental factors are advantageous

A FUNCTIONAL ANALYSIS OF RETARDED DEVELOPMENT

5

(good health, good physical and medical care, good social stimulation, and good intellectual experiences), his native level of intellectual ability will be fully or almost fully expressed by his behavior. This kind of theoretical analysis is untenable for several reasons. First, heredity and environment are not fixed, oppositional forces locked in struggle for domination but are terms referring to sources of specific variables which interact with each other (Dobzhanski, 1957). Second, the relationships between the behavior of the individual and environmental events are changing continuously by virtue of the unremittent interchanges between them. Sometimes the interactions result in dramatic changes; sometimes they maintain a rather even course of modification over the years (Sontag, Baker, & Nelson, 1958). Third, the amount of socalled innate mental ability at birth (or at any other times during development) can be known or measured only by an analysis of behavior, and the relationships between measures of intelligence in infancy and in later development are not significantly related (Bayley, 1958). Each of these three considerations should be developed in some detail; however, in the light of the purpose of this paper, the discussion of defective intelligence as a hypothetical variable ends at this point. 8. Difficulties of Conceptualizing Retardation in Biological Terms

Consider now briefly the theory that psychological retardation is an impairment of the brain. Kugelmass (1954) stated that “. . . amentia or mental deficiency is a symptom of cerebral dysfunction.” From this point of view, mental retardation is seen as a condition in which the brain is prevented from attaining full development, limiting the ability to learn and to apply what is learned. Were we to adopt this position, we would have to advocate that psychological research should concentrate on exploring brain processes and that efforts at a direct study of retarded behavior and the determining environmental conditions be set aside. Instead, we take the position that even under the conditions of the most advanced state of knowledge about physiological and biochemical processes stimulus-response relationships must be studied, presumably in accordance with a scientific analysis of behavior. There is no question that contributions from physiologists and biochemists increase our understanding of the conditions generating normal and deviant biological development. What is questioned is the wisdom of considering biological variables as the “real” determiners of psychological behavior and of believing that we must be content with the current array of psychological variables until the biological sciences can provide the science of psychology with the “true” causes of behavior. This view also carries the

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Sidney W . Bijou

dubious implication that the biological sciences will eventually yield all of the essential information on conditions and processes for both physiological and psychological pathology. A final word about the relationships between retarded development and biological variables. In many writings retardation is treated as if all mentally retarded individuals may be adequately classified on the basis of a clinical-medical diagnosis. I n some discussions attempts are made to relate medical categories to presumed causal conditions and to degree of retardation. Tredgold and Soddy (1956), for example, advocated classifying a retarded individual on the basis of etiology (hereditary, genetic or primary; exogenous, secondary or acquired; and mixed), level of retardation (idiot, imbecile, and moron) and medical type (familial, intracranial birth lesion, cretin, mongoloid, microcephaly, and the like). For individuals who do not currently show biological involvements, terms such as “simple,” “unknown,” or “undifferentiation” are suggested. According to a natural science point of view, medical categories like those above refer to anatomical and physiological characteristics of the individual. There is no need to assume that they also give an adequate account of reduced psychological development. Biological pathology may or may not be a condition contributing to slowing down the rate of developing behavior repertories (Garrard & Richmond, 1965a; Garrard & Richmond, 1965b) . The remainder of this chapter presents an analysis of the conditions which contribute to failures of development-failures of coordination of stimulus-response functions which make up behavior repertories. These conditions, derived from biological, social, and physical sources, are discussed in the light of the role of (1) abnormal anatomical structure and physiological functioning,‘ (2) inadequate reinforcement and discrimination histories, (3) consequences of contingent aversive stimulation, and (4)reinforcement of aversive behaviors. II. RETARDED DEVELOPMENT THROUGH ABNORMAL ANATOMICAL

STRUCTURE AND PHYSIOLOGICAL FUNCTIONING

An individual with biological irregularities may have altered response capabilities that could affect the nature and progression of stimulating conditions. Irregularities in anatomical structure and physiological functioning include defects in gross anatomy, the structure and functioning of the sense organs, the muscle-skeletal system, the neurological and endocrine systems, and other systems and glands of the body. Such flaws 4 Actually this topic should be integrated with the other three. It is separated for the purpose of emphasis.

A FUNCTIONAL ANALYSIS OF RETARDED DEVELOPMENT

7

may originate in genetic processes5or in injurious &emical and mechanical actions during the prenatal period, birth, or after birth. Since biological anomalies range from mild to severe, the effect of such conditions on psychological development extend from inconsequential to devastating. Obviously the response function of a stimulus-response relationship may be disadvantageously affected by impairments of the responding and coordinating systems of the individual. A physically impaired child cannot perform tasks involving response components which he cannot possibly execute. He does not have the necessary anatomical parts and/or physiological functioning to make the required response. If he cannot physically perform a task, no amount of stimulation, exposure, or training will enable him to do so. (He may, of course, learn other responses that produce the same results on the environment, i.e., serve the same response function. Whether or not he does learn compensating behavior depends to a large extent on the effectiveness of the guidance and instruction received.) The stimulus function of the stimulus-response relationship may also be adversely affected by biological impairment. The biologically atypical child develops a limited behavioral repertory because of restrictions in opportunities to interact with stimuli essential for normal development. If skills in body management are inadequately developed, the number and kind of physical and social stimuli available are curtailed. A child who is limited to lying on his back can have commerce only with stimuli above his body or with those brought into his line of vision, while the child who can roll from side to side and can remain in a sitting position can interact with stimuli over a greatly extended range. Similarly, a child who can reach, grasp, and retrieve an object can have infinitely more experiences than a child who has yet to develop such manual coordination and skill. The child who can move from place to place can become involved in all sorts of novel situations compared to one who must depend upon the goodwill of others for his locomotion. Depending on the locus and extent of organismic impairment, some stimuli will never be accessible to certain children; other stimuli will become available on a delayed time schedule. The physically impaired child may also suffer from restricted stimulation on the basis of the way he looks to others, i.e., on the basis of his social stimulational properties. His physical appearance could well 6 Hereditary processes participate in retarding psychological development in so far as these processes contribute to pathological anatomical structure and physiological functioning of the individual.

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Sidney W.Bijou

be either aversive or nonreinforcing to others, causing them to avoid him, to leave him as quickly as possible, or to behave toward him in an altogether indifferent manner. Zimmerman (1965, p. 182) commented on this relationship: “Children of grotesque physical appearance may be avoided by others, or others may react to the strange child, but in an abnormal and restrained manner. These results superimpose social deprivation upon physical defect.” Because our society disapproves of practices which suggest that a physically impaired child is not getting his full share of attention, avoidant behavior is often made to appear unavoidable. For example, a physically disabled youngster could be without positive social interactions for long periods because his parents are “too busy” looking after the other children and his siblings are too “bogged down” with homework to engage in extended play with him: the children in the neighborhood exclude him from their play because he cannot “keep up with them”; and the school principal bars him from attending school because he is not “ready.” Avoidant, abbreviated, and dutiful social relationships fail to provide the child, physically impaired or otherwise, with basic intellectual and social interactions which only people can provide. For example, complex behaviors in later childhood and beyond, such as conceptualizing, abstracting, and problem-solving behaviors, develop if there are people who arrange and rearrange cue-stimuli (pointing out similarities and differences, assisting in grouping stimuli on the basis of one criterion and then another, etc.) and to reinforce responses differentially (Skinner, 1953). Innumerable activities of this sort are a part of informal play and are incidental to everyday activities in the home, shopping district, neighborhood, and preschool. Likewise, advantageous emotional behaviors in adolescence and adulthood seem to require early social experiences with positive reinforcing consequences and social support under conditions of aversive stimulation (e.g., consolation following a nasty fall or an immunization shot). Since a number of children will always have structural and functional biological impairment through hereditary processes, diseases, injuries, or toxic conditions, it is expected that many of these individuals will have limited behavioral repertories or will be developmentally retarded. These children will continue to attract the attention of behavioral scientists interested in the relationship between actual measures of physiological deviations and corresponding behavioral changes as weli as those concerned with research on the preparation of effective educational environments.

A FUNCTIONAL ANALYSIS OF RETARDED DEVELOPMENT

9

111. RETARDED DEVELOPMENT THROUGH INADEQUATE REINFORCEMENT AND DISCRIMINATION HISTORIES

Reinforcement as used here refers to an interaction in which a response event is followed by a stimulus event that on similar subsequent occasions makes a response of the same class more probable, i.e., it occurs with increased frequency. Responses sensitive to such consequent stimulus events, called operants by Skinner (1937), include verbal, motor, social, and intellectual responses and large components of emotional behavior. T h e stimulus condition following operant behavior is designated as a “stimulus event” to emphasize that some identifiable change has occurred. Such a change may be either a presentation operation (nodding to a young child following his correct solution to an arithmetic problem) or a removal operation (taking off one’s coat in an overheated room). Stimulus events shown to strengthen operants in an individual through either operation are called reinforcing stimuli and are said to have a reinforcing function. T h e reinforcement interaction does not take place in isolation. I t takes place while other stimulus events and setting factors6 are occurring. These situational conditions can develop power to increase or decrease the probability of the occurrence of operant behavior. We are particularly interested here in one class of contextual stimulus events: those that occur immediately preceding the response. Such stimuli may come to indicate the occasion for making a response that is likely to be reinforced. When they do they are called discriminative stimuli (cues) and are said to have a discriminative function. Reinforcing and discriminative stimuli are therefore functionally interdependent. Reinforcing and discriminative stimuli are not only functionally interdependent; the same stimulus (identifiable in terms of its physical dimensions) may have both functions. A smile from a parent in response to a child’s good table manners may increase the probability of good table manners in future similar situations. A smile from the same parent in the living room may serve as a cue for the same child to approach and climb onto the parent’s lap. Likewise, receipt of a sweet cracker may be a reinforcing stimulus strengthening the preceding behavior such as saying “I wanna cookie.” T h e same cookie on a plate may be a discriminative stimulus for reaching, grasping, and bringing to the 6 A setting event or setting factor is a stimulus-response relationship that effects the probability of occurrence of a response. Examples are satiation and deprivation of the reinforcing stimulus controlling the response, and critical periods in the sleep and fatigue cycles.

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mouth. Because of the overlapping relationship between reinforcing and discriminating stimulus functions, we shall consider them together in this section as conditions retarding development. I n general a child’s progress in adding to and elaborating upon his repertory of discriminations (as well as motor acts and skills) depends to a large extent on the number and kinds of opportunities made available to him by the action of people (particularly parents), the properties of available physical things, the characteristics of his bodily structure and physiological functioning, and his maturational and health status. On one hand, interactions with environmental events which reinforce, discriminate, and interrelate varieties of culturally serviceable behaviors are expected to produce individuals with large repertories of socially, intellectually, and vocationally valuable (highly reinforcible) behaviors. Reports by Terman and his co-workers on the background and achievements of high-IQ children and their offspring support this contention (Cox,, 1926; Terman, 1925; Terman & Oden, 1947). On the other hand, environments with meager opportunities for reinforcement, discrimination, and the development of complex stimulus-response chains are expected to produce children with limited repertories of socially serviceable behaviors. Ferster (1958, p. 104) analyzes the role of inadequate stimulus support in these words: “Under this category belong individuals who are not making contact with important parts of their environment simply because their history did not include a set of experiences (educational) which could develop these performances during the normal maturation of the individual. Especially in the area of everyday social contacts, considerable skill is necessary for producing social reinforcements, and the absence of this skill either results in an individual without a social repertoire or one who achieves effects on his social environment by indirect means, as, for example, using aversive stimulation to gain attention.” From a functional point of view, the only way of knowing whether a limited repertory of behavior’ has in fact developed from an inadequate reinforcement and discriminative history is by experimental demonstration. Unfortunately there are only a few studies in the literature with data relating long-time histories with performances, and most of these were aimed at showing that a motor skill such as stair-climbing, cubestacking, and buttoning buttons was more influenced by maturation than by training (e.g., Gesell & Thompson, 1929; Hilgard, 1932; McGraw, 1935). I n the absence of clearly pertinent experimental data, it may be profitable to speculate on some of the circumstances under which such inadequate histories develop. They include conditions under which (1) reinforcements (particularly social) are infrequent and in small amounts,

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(2) reinforcements are withheld or are on a noncontingent basis, and (3) opportunities for the development of essential discriminations and skills are restricted. A. Circumstances in which Reinforcements May Be Infrequent and in Small Amounts

Child-care institutions with inadequate or marginal personnel may constitute one set of circumstances in which reinforcements are infrequent (on a thin intermittent schedule) and in small amounts. There is much literature on this subject (Sarason, 1959). Dennis and Najarian (1957), for example, observed children, ages 1 to 4, in the context of different child rearing practices in three Iranian institutions. I n two, the children were markedly retarded in motor skills; in the other, little retardation of this sort was evident. Dennis and Najarian (1957, pp. 5859) summarized their findings as follows: “The extreme retardation in Institutions I and I1 was probably due to the paucity of handling, including the failure of attendants to place the children in the sitting position and the prone position. T h e absence of experience in these positions is believed to have retarded the children in regard to sitting alone and also in regard to the onset of locomotion. T h e lack of experience in the prone positions seems in most cases to have prevented children from learning to creep; instead of ct-eeping. the majority of the children in Institutions I and 11, prior to walking, locomoted by scooting. In Institution 111, in which children were frequently handled, propped in the sitting position and placed prone, motor development resembled that of most home-reared children. T h e retardation of subjects in Institutions I and I1 is believed to be due to the restriction of specific kinds of learning opportunities.” A later study by Sayegh and Dennis (1965) was performed to see if additional stimulation given to infants in a comparable situation in Birut, Lebanon, would accelerate development. Sayegh and Dennis (1965, p. 81) concluded that “appropriate supplementary experiences can result in rapid increases in behavioral development on the part of environmentally retarded infants.” A similar relationship between inadequate reinforcement and retardation may generate from child-rearing practices in a home or a foster home in which the infant or child is left to his own resources, except for basic biological care, because the parents or parent surrogates are excessively preoccupied with outside activities or with serious physical health and adjustment problems. Ferster (1961, pp. 443-444) discussed how these processes may operate from a behavior theory point of view in child-rearing practices to contribute to behavior deficits in the early

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development of a grossly disturbed child. He wrote: “The most fundamental way to eliminate a kind of behavior from an organism’s repertoire is to discontinue the effect the behavior has on the environment (extinction). A performance may also be weakened if its maintaining effect on the environment occurs intermittently (intermittent reinforcement). Behaviors occurring because of their effects on the parent are especially likely to be weakened by intermittent reinforcement and extinction, because the parental reinforcements are a function of other variables and behavioral processes usually not directly under the control of the child.” He went on to point out that speech and other social behaviors are most likely to be adversely affected under these circumstances because at this early stage the parents‘ behaviors constitute the most important source of primary and acquired reinforcers for the development of such behaviors. One might question the relevance of these parent-child interactions to retarding development since Ferster alluded to them as mechanisms for the formation of behavior deficits in severely disturbed young children. The contention here is that an analysis of retardation should take into account the processes that fail to initiate new chains of behavior as well as those that fail to maintain behavior already established. Failure to perpetuate a class of behavior in strength not only eliminates it from the child’s repertory but also makes it almost impossible for him in later development to establish the behavior elaborations that are essential for adequate adjustment. This point is most obvious in the case of distorted verbal development. Because it is foundational as well as a part of so many other behaviors, failure of continued and adequate reinforcement of the beginnings of verbal behavior can result in deficits in intellectual, social, emotional, and even motor development. It follows that the conditions and processes that contribute to severe emotional disturbances or undesirable stimulus-response coordinations in children can also contribute to retarding development. Many retarded children are, of course, also emotionally disturbed (Beier, 1964) and practically all severely maladjusted children are also developmentally retarded (Kanner, 1957). We only make distinctions between the emotionally disturbed and the developmentally retarded for practical purposes. Still another set of circumstances which might produce mild amounts of social reinforcement on a sparse schedule is one in which the physical appearance of the child is considered repellent by the social community. As has been mentioned in the section on abnormal anatomical structure and physiological functioning, such atypical biological makeup can result in a paucity of constructive contacts depriving the child of an

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adequate frequency of social contacts and experiences with a wide variety of physical objects. The loss is in the development of new reinforcing and discriminative stimuli. B. Circumstances in which Reinforcements Are Withheld (Extinction) or Are on A Noncontingent Basis

As pointed out in the previous section, one of the ways in which behaviors, particularly the weaker response classes, are eliminated is by withholding reinforcement or extinction. One might say that the extreme case of intermittent reinforcement is extinction. Behaviors strengthened by widely scattered social interactions and by the mildly reinforcing consequences of self-stimulation (response-produced stimulation) or by feedback with physical objects may not be maintained by members of the family because of the continuing influence of poor health, adjustment difficulties, drug addiction, alcoholism, and the like. Behaviors may fail to develop or be weakened by noncontingent reinforcement-reinforcement delivered nondiscriminatively (Rheingold et al., 1962). This is likely to occur in family situations in which the child is considered chronically sick, disabled, or incapacitated, and the parents react by maintaining close supervision and respond almost continuously. Such a regime also usually restricts a great deal of the child’s exploratory behavior-a consequence which will be discussed in the next section. C. Circumstances in which Opportunities Are Restricted Economic Factors

by Social or

For a variety of reasons a child might be prevented from having opportunities which generate serviceable responses, e.g., basic skills in body management, locomotion, and manual manipulations; in transforming sounds into words, phrases, and sentences; and in relating words to things, representations of things, and other words. If he is not given occasions to make serviceable responses, it will not be possible for such responses to be strengthened and maintained as a part of his repertory and it is likely that he will remain grossly uncoordinated, unskilled, and uninformed in the social practices of his culture. There are several sets of circumstances in which serious restrictions in opportunities may be imposed. One, for example, is treating the child as if he were abnormal or chronically sick. I n one instance at the University of Washington a 9-month remedial guidance study of a 4-year-old girl showed that such restrictions can lead to incoordinated locomotion to the point of perpetual falling and stumbling and the complete absence of speech development.

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Restrictive circumstances may also evolve from peculiar, abnormal, or idiosyncratic practices of the parents. Davis (1947) provided an example of this sort, Because the child in his study was illegitimate she was kept in isolation by her deaf-mute mother. T h e child and her mother spent most of the time together in a dark room shut off from the rest of the family. When discovered, the child was 63 years old. She communicated with her mother by gestures and made only “strange croaking sounds.” At first it could not be determined whether she could hear; later it was established that she could. She showed fear and hostility toward others, especially men. Her reactions to objects were unusual. For example, when presented with a ball she used it to stroke the interviewer’s face. Her mental age on the Stanford-Binet was 1 year and 7 months and her social age on the Vineland was 2 years and 6 months. Restrictions in opportunities for the development of serviceable behaviors may, of course, come about because the environment is thinly populated with effective people and intriguing things. Just as a sparse social environment reduces the frequencies of social reinforcing stimuli, it also reduces the opportunities for the child to engage in activities that develop the kinds of discriminations that are normal for development in the culture. People are needed to arrange most of the intellectual (educational) situations for the child, hence people have to be in close proximity and have to be reinforced for contriving such discriminative activity; otherwise such opportunities would not materialize. Behavior of people and availability of things have to be a n effective part of the child’s environment. They actually have to enter into interactional relationships with him. Absence of the necessary physical and cultural components of the environment will, of course, also contribute to the lack of opportunities for essential behavior. T h e detrimental effects of economic deprivation on development are now recognized and are being given major emphasis in the programs designed to help children from underdeveloped geographical areas. Particular attention is given to involvement in the educational experiences needed to help these children attend public schools and to prepare them for effective vocational and community activities. IV. RETARDATION THROUGH CONTINGENT AVERSIVE STIMULATION

Another class of interactions which retards development pertains to contingent aversive stimulation. Reference here is to the practice of administering strong punishment to stop the preceding or ongoing behavior and to reduce its repetition, o r simply to aversive events that

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may occur as a part of medical treatment or in a serious accident. What punishment does and how it works are controversid subjects which for the most part do not involve the science of behavior. We shall therefore limit the discussion to some of the facts and principles derived from experimental studies. There are several consequences to following a response with an aversive stimulus (in many cases a negative reinforcer). First, such stimulation may modify a serviceable response, one that once produced positive reinforcers or removed negative reinforcers. A child is reprimanded by his parents for making derogatory remarks about his sister. After a few occurrences of this sort, he may begin to garble words about his sister so that what he utters avoids the parents’ disparaging remarks. Such a change in the form of his verbal behavior is not conducive to further growth in language behavior, at least with respect to siblings and possibly other children. Second, aversive stimulation may stop ongoing behavior. If the aversive stimulation is moderate or mild, it is likely that the behavior will be reinstituted. If, however, it is severe, it is likely that the suppressive effects will remain for some time. The action of intense aversive stimulation also has implications for changes in the functions of stimuli and responses in situations resembling those in which the aversive interaction occurred. Stimuli similar to those present at the time of aversive stimulation can acquire similar suppressive effects (stimulus generalization), and responses similar to or “chained in with” the punished sequence can also be curtailed. More than one clinical account has been given of a young child who stopped talking following a traumatic physical episode with an intoxicated or severely disturbed parent. Third, stimulus settings in which aversive stimulation occurs may acquire aversive properties; formerly positive or neutral conditions acquire through respondent (classical) conditioning, aversive properties. (Having been thrown from his favorite horse, the child now reacts to the animal in a fearful manner.) The removal of aversive stimuli and conditioned aversive stimuli is reinforcing, negatively reinforcing. Responses such as getting out of an aversive situation, getting away from it, avoiding getting in or near it, as well as being inactive while in it, will be strengthened. Exactly which classes of behavior will be strengthened by such negative reinforcement cannot be predicated beforehand. One thing is clear, however; excessive avoidant behavior can limit opportunities for interaction. Hence, such avoidant behavior is functionally like the other biological and social restrictive conditions described in this chapter. From these considerations it is apparent that severe aversive stimula-

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tion mediated by social or physical events contingent upon behavior may distort serviceable behavior (form and intensity) so as to reduce its functional effectiveness and its foundational value for further behavior elaboration. It may also terminate ongoing behavior-manual, locomotor, linguistic, social, and emotional-and set up stimulus situations that strengthen behaviors which keep “clear of them.” The behavior terminated may be pertinent to further behavior development (e.g., verbal behavior), and the situations evaded may include critical features of the normal child-rearing environment (e.g.. those which involve the father) and may effect other similar aspects of the environment (from the father to all male adults). Hence, stimuli and responses not directly involved in the aversive interaction may come to have effective aversive properties. Furthermore, aversive stimulation, conditioned and unconditioned, evokes responses controlled by antecedent stimulation (respondent type such as gastric reactions to fear stimuli) which may have detrimental effects on the biological functioning of the individual and through this route come to reduce his potential for serviceable interactions. The consequences of strong aversive stimulation are most frequently discussed in the literature of child psychopathology under the heading of severe emotional disturbances (e.g., psychoneurotic, psychotic, and autistic). These consequences are discussed here because it can be shown that they also retard development. I n other words, aversive interactions may lead to strong maladjusted behaviors as well as serve as critical conditions limiting the development of behavior repertories. In child therapy, it is the usual practice to engage the child in educational and reeducational procedures as he gains or regains more appropriate personal and social behaviors. Among other things, the therapeutic objective is to have the child “catch up” to his age group, at,tend school, and participate in other cultural activities. V. RETARDATION THROUGH THE REINFORCEMENT OF AVERSIVE BEHAVIOR

We now turn to a consideration of situations in which retardation may develop because reinforcement is made contingent upon “undesirable” behavior. Presumably no parent in “his right mind” would want to develop “bad’ behavior in a child. But such “bad” behaviors may evolve because they are aversive to the parent and attending to them reduces or eliminates them. Practices of this sort may strengthen the “bad” behavior of the child as well as the attending behavior of the adult. Under these circumstances the child is positively reinforced by the

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parent’s action and the parent is negatively reinforced by the termination of the child’s “bad” behavior. This analysis may give a plausible technical account of how a parent may strengthen undesirable behavior in a child and how some forms of maladjustment might develop, but how would it be relevant to retarded development? Probably on two counts: (1) Such behavior, because it is followed by highly effective primary and acquired reinforcers, may become so strong that it becomes the major way of responding (e.g., having temper tantrums, screaming, and crying). Under these circumstances, new learning (shaping) of socially and educationally desirable behavior would be slow or even static. Also, the occasions for setting up, refining, and elaborating stimulus discriminations would be reduced. Effective attention and work spans would be short and even minor nonreinforcement episodes might well set off strong and prolonged aversive behavior sequences. For example, correction of an error in color discrimination might produce a temper tantrum. The report by Wolf, Risley, and Mees (1964) on the behavioral treatment and rehabilitation of a preschool boy, diagnosed as autistic, retarded, and brain-injured, described many instances in which strong aversive behavior had to be weakened before effective retraining could be instituted. (2) Such aversive behavior may serve to discourage people from approaching and participating in prolonged educational and social interactions with the child, thereby limiting the development of discriminative and motor-skills repertories. In many instances such children are considered uneducatable or educatable to a limited degree, dependent on conditions which control the child’s aversive behavior. Many of their characteristics are attributed to hypothetical biological processes. This condition is similar to that in which the child is avoided because of his repellent physical appearance or functioning. VI. SUMMARY

This chapter presents a functional analysis of retarded development. From this point of view, ,the retarded individual is analyzed as one who has a limited repertory of behavior as a consequence of the organism-environment interaction that constitutes his history. Explanations of retardation in terms of hypothetical, internal determining factors and assumed biological processes are rejected. The conditions of development derived from biological, social, and physical sources and the behavior or learning principles that pertain to the way they enter into functional relationships are discussed in the light of the role of abnormal anatomical structure and functioning, inadequate reinforcement and discrimination histories, the consequences of contingent aversive stimulation, and rein-

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forcement of aversive behavior. These are not the only interrelations that result in retardation. There are others. For example, Garrard and Richmond (196513) discussed as a possibility the discontinuity in the interaction with a mother figure after an affectionate bond has been established. This process involved the weakening of strong behavior by the removal of the discriminative stimulus to which it is functionally related (Bijou & Baer, 1965). These conditions and principles are presented separately for expository purposes. They interact with each other in many complicated ways in the course of development. REFERENCES Bayley, Nancy. Value and limitation of infant testing. Children, 1958, 5 , 129-133. Beier, D. C. Behaviorial disturbances in the mentally retarded. I n H. A. Stevens & R. H e b a (Eds.), Mental retardation. Chicago: Univer. of Chicago Press, 1964. Bijou, S. W.Theory and research in mental (developmental) retardation. Psychol. Rec., 1963, 13, 95-110. Bijou, S. W., & Baer, D. M. Child development: A systematic and empirical theory. New York: Appleton, 1961. Bijou, S. W., & Baer, D. M. Child development: The universal stage of infancy. New York: Appleton, 1965. Brackbill, Yvonne. Extinction of the smiling response in infants as a function of reinforcement schedule. Child Dmelpm., 1958, 29, 115-124. Cox, Catherine M. Genetic studies of genius. Vol. 11. The early mental traits of three-hundred geniuses. Palo Alto, Calif.: Stanford Univer. Press, 1926. Davis, K. Final note on a case of extreme isolation. Amer. J . Sociol., 1947, 57, 432-457. Dennis, W., & Najarian, P. Infant development under environment handicap. Psychol. Monogr. 1957, 71, No. 7 (Whole No. 436). Dobrhanski, T. The biological concept of heredity as applied to man. In Milbank Memorial Fund, The nature and transmission of genetic and cultural characteristics of human populations. New York Milbank Memorial Fund, 1957. Ferster, C. B. Reinforcement and punishment in the control of human behavior by social agencies. Psychiat. res. Rep., 1958, 10, 101-118. Ferster, C. B. Positive reinforcement and behavior deficits of autistic children. Child Develpm., 1961, 32, 437-456. Garrard, S. D., & Richmond, J. B. Diagnosis in mental retardation. In C. H. Carter (Ed.), Medical aspects of mental retardation. Springfield, Ill.: Thomas, 1965. (a) Garrard, S. D., & Richmond, J. B. Mental retardation without biological manifestation. In C. H. Carter (Ed.), Medical aspects of mental retardation. Springfield, Ill.: Thomas, 1965. @) Gesell, A., & Thompson, Helen. Learning and growth in identical twins: An experimental study by the method of co-twin control. Genet. Psychol. Monogr.. 1929, 6 , 1-124. Hilgard, Josephine R. Learning and maturation in preschool children. J . genet. Pvchol., 1932, 41, 40-53. Kanner, L. Emotional disturbances simulating mental retardation. Publ. Hlth New, 1957, 38, 313-332.

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Kantor, J. R. Znterbehavorial psychology (rev. ed.) Bloomington, Ind.: Prindpia Press, 1959. Kugelmass, I. N. The managentent of mental deficiency in children. New York: Grune & Stratton, 1954. McGraw, Myrtle B. The growth: A study of Johnny and Jimmy. New York: Appleton, 1935. Rheingold, Harriet L., Gewirtz, J. L., & Ross, Helen W. Social conditioning of vocalizations in the infant. J. abnorm. SOC. Psychol., 1959, 52, 68-73. Rheingold, Harriet L., Stanley, W. C., & Cooley, J. A. Method for studying exploratory behavior in infants. Science, 1962, 136, 1054-1055. Sayegh, Yvonne, & Dennis, W. The effect of supplementary experiences upon the behaviorial development of infants in institutions. Child Deuelpm., 1965, 36, 81-90. Sarason, S. B. Psychological problems in mental deficiency. (3rd ed.) New York: Harper, 1959. Skinner, B. F. Two types of conditioned reflex: A reply to Konorski and Miller. J . gen. Psychol., 1937, 16, 272-279. Skinner, B. F. Science and human behavior. New York: Mamillan, 1953. Skinner, B. F. What is the experimental analysis of behavior? Address given at the 1964 meeting of the Amer. Psychol. Ass., Los Angela, Calif. Sontag, L. W., Baker, C. T., & Nelson, V. L. Mental growth and personality development: A longitudinal study. Monog. SOC. Res. Child Deuelpm., 1958, 23, No. 2. Terman, L. M. Genetic Studies of Genius. Vol. I. Palo Alto, Calif.: Stanford Univer. Press, 1925. Terman. L. M., & Oden, M. The gifted child grows up. Palo Alto, Calif.: Stanford Univer. Press, 1947. Tredgold, R. F., & Soddy, K. A text-book on mental deficiency. (9th ed.) London: Baillibre, 1956. Wolf, M. M., Risley, T. R., & Mees, H.L. Application of operant conditioning procedures to the behavior problems of an autistic child. Behav. res. Ther., 1964, 1, 305-312. Zimmerman, D. W. A conceptual approach to some problems in mental retardation. Psychol. Rec., 1965, 15, 175-183.

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Classical Conditioning and Discrimination Learning Research with the Mentally Retarded' LEONARD E. ROSS DEPARTMENT OF PSYCHOLOGY, UNIVERSITY OF WISCONSIN, MADISON, WISCONSIN

I. Introduction

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11. Classical Conditioning and Discrimination Learning

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Trends in Learning Theory and Implications for Retardation ..................................... B. T h e Role of Classical Conditioning and Discrimination Learning in Investigations of Retardate Learning ............................................. C. Problems in Classical Conditioning and Discrimination Learning Research with Retardates .......... 111. Current Research Involving Classical Conditioning and .-........ Discrimination Learning .................... A. Classical Conditioning ............................ B. Discrimination Learning ......................... IV. Concluding Comments ................................ References ...........................................

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A.

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1. INTRODUCTIQN

This chapter is concerned with the use of two types of learning situations in research with the retarded. I t is not a survey of past work in these areas (see Denny, 1964; Lipman, 1963; Stevenson, 1963) but discusses certain aspects of the use of these learning procedures with the retarded and presents some current work in these areas. T h e topics to be considered in the first section are (1) the rationale for the use of these paradigms in learning research, (2) the particular aspects of these procedures that make them of interest to those concerned with the learn1 Preparation of this chapter was made possible by National Institute of Health Grant MH 10235. T h e research reported in the second section of the paper was supported by this grant and by NSF Grant GB-765.

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ing processes of the retarded, and (3) some problems of strategy and methodology that arise in this type of research. T h e second section of the chapter presents a description of classical eyelid conditioning work with retardates currently underway at Wisconsin, as well as a description of several studies using discrimination learning procedures that were designed to compare certain learning processes in retarded and normal children. II. CLASSICAL CONDITIONING AND DISCRIMINATION LEARNING

The behavioral learning situations that provide the focus of this chapter, classical conditioning and discrimination learning, have had a long and useful history in research concerned with learning. In discussing the use of these paradigms in research with retardates, it is instructive to consider why these particular procedures have been, and continue to be, so popular with psychologists who have been interested in investigating the learning process. The historical importance of classical conditioning, providing as it did the chief vehicle for Pavlov’s discoveries, is well known, and even a cursory survey of learning terminology reveals our debt to this early experimentation. While those in learning no longer believe that complex behavior can be considered a simple compound of classically conditioned responses, if indeed this position was ever held in its naive form, classical conditioning remains an active area of concern. The reasons for this continuing and increasing interest are several in number. As the “model” or “mediating mechanism” type of theorizing has grown in popularity, classical conditioning has been selected in a number of cases to provide the inference rules for the model, as is the case in incentive and frustration theorizing. Also, of course, there has been a long history of conceptualizing the acquisition of fear and anxiety as a classical conditioning process. In general then, classical conditioning has been presumed to underlie instrumental behavior of various kinds and complexities, and logically it follows that an understanding of classical conditioning will be useful, if not a prerequisite, in the development of laws and theories of more complex behaviors. Lachman (1960), in one of the few discussions of the use of the model in psychological theory construction, has suggested that the conditioning model may play the same role in psychology that the mechanical model served in physics. Those working in what Miller (1959) calls the “liberalized” S-R tradition have found classical conditioning to be of considerable usefulness, since, as Miller points out, the hall-

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mark of their approach is the application of the same laws to central or mediating processes as to peripheral stimuli and responses. Finally, the degree of control possible in classical conditioning has attracted many, the exact control of temporal relations suggesting that this paradigm might prove most amenable to investigations of the neurophysiological processes underlying learning. There are other characteristics of classical conditioning, discussed in later sections of this paper, that make it particularly useful in developmental studies. In the early 1900's discrimination learning was initially used to study the sensory capabilities of animals. After several false starts, largely concerned with the requirement that differential stimulation be received at the receptors, various selective learning situations replaced the more complex problem boxes and multiple mazes used in the early laboratory learning research in the United States. In the 1940s and well into the middle 1950's, discrimination learning was the principal experimental situation used in work concerned with the many controversies that arose regarding the nature of the concepts used to represent the hypotheticaL changes taking place in learning and the conditions believed to b e necessary for these changes. For a considerable period these controversies, which largely developed around the few dominant theorists of the time (e.g., Guthrie, Hull, Tolman), were the focus of interest in learning. Discrimination learning situations provided the data used in arguing absolute and relational views of discrimination learning, continuity and noncontinuity interpretations of learning, latent learning, place versus response learning, etc. In many cases this activity did little to further understanding of learning phenomena, and much of the recent research involving discrimination learning has been concerned with such matters as (1) the processes, e.g., attentional and verbal, that are involved in selective learning, and (2) problems involving phylogenetic and ontogenetic comparisons. One source of interest in both classical conditioning and discrimination learning has been the relative simplicity of the experimental situation and the behavior being examined. Just as laboratory research itself developed in order to provide for simplification and control, the approach of most psychologists has been to move still further in these directions, within the laboratory situation, until the relationships obtained become more meaningful in terms of basic processes or are amenable to quantification. The success of the physical sciences in working with relatively closed systems has led the psychologist to try to approach the complex from the simple, or at least to deal with situations where su5cient control can enable reasonable experimental studies of the learning process. It would seem that most of the advances in the learning

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area hare come from this approach, and while some have voiced dissatisfaction with the pace of the progress and others have objected to its “abstract” nature, there is little to indicate that other more “real-tolife” approaches have led to anything more than verbal systems that are viable only because they are untestable. In this regard it should be noted that not even the most positivistic of learning theorists argue that the methods of the physical sciences serve as a substitute for the creativity of the researcher in formulating hypotheses or for the insight of the individual who, for example, forms hypotheses, from observation, about developmental processes in children. Similarly, the approach that stresses analytic, controlled, laboratory research into the learning processes of the retarded child would be seriously handicapped if it were to ignore observation in the learning situation as a source of hypotheses or fail to examine the ideas and opinions of those who .deal with the retardate on a daily basis. However, unless these ideas and hypotheses are brought into the laboratory, translated in some meaningful way into experiment,al manipulations, and tested under controlled conditions, their value is quite limited. In this respect it would appear that a large part of what passes for theory in retardate learning has, so far at least, escaped meaningful systematic laboratory investigation. This is not unique to retardation, of course, and many in the area recognize the problem and are trying to rectify the situation. There remains, however, a suspicion that all of the undesirable aspects of learning theory in retardation are not just a matter of lack of time, money, and trained personnel. Rather, it would seem plausible to hypothesize that any area passes through stages of development in the type of theorizing employed, and that at present the area of retardate learning is in a relatively early stage. Since a great deal of learning research with retardates presumably has been theory oriented, and since it will be argued that there should not be an “area” of retardate learning divorced from ongoing experimental and developmentally oriented learning research, it is useful to briefly consider general trends and the current status of learning theory. A. Trends in learning Theory and Implications for Retardation

The single most important trend in general learning theory has probably been the shift away from a concentration on the major systems, and the learning controversies that developed from them, to a new emphasis on phenomena centered theories that are smaller in scope and closer to the empirical data. This change, which began to be evident in the early 1950’s, represented a reaction to certain characteristics of the major systematic positions. Thus, while these approaches contributed a

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great deal to the development of the area and are still recognizable to varying degrees in current formulations, many of the positions and controversies were not formulated so that the positions could be unambiguously tested and the issues resolved at the empirical level. While these approaches often served as a general framework and were valuable for heuristic reasons, many did not fulfill a required function of theories, that of integrating and predicting laws. As this fact became more and more apparent, both because of the obvious persistence of the issues and the growing sophistication of those in the area, the activity centered on smaller theories that were more limited in scope but more specific and testable. This was, in part, due to the recognition that learning was a very complex phenomenon and that the development of theories possessing both scope and precision was unlikely with the existing state of empirical knowledge. Other objections were raised, of course. Some learning psychologists believed that some classes of variables were being neglected, while others argued that theoretical activity of this sort was premature. In any case, the nature of learning theory has dramatically changed. In addition to its phenomenon centered aspects, learning theory is becoming more and more characterized by the use of the model and mediation process notions. Of course these latter approaches must also meet the basic requirements of producing testable predictions, etc. I n this respect Lachman (1960) has discussed criteria for evaluating the use of models in theory construction and, of particular interest, the limitations of models that provide only pictorial visualizatioh without also providing t h e inference rules that lead to prediction. While one cannot argue that specific minimum criteria of testability, etc., must be met before models or theories are useful, evidence of the realization of the limits of some types of “theorizing” in all areas of learning, including retardation oriented work, would be most welcome. It should be noted that developmental theorizing has recently been showing signs of a similar shift from the “grand” theory to smaller more testable formulations (see Zigler, 1963), and theorizing with respect to retardate learning may be expected to follow a similar course of development. In this context that tendency of retardate learning theorizing to stress the action of a single variable or class of variables to explain normalretardate differences should be briefly discussed. First, it would seem most unlikely that unitary notions will “explain” retardate learning performance any more than similar ideas have been found useful in other areas of learning. Positions such as those that suggest that the retardate suffers from an inhibition or attention deficit, is under different motivation conditions, or uses verbal processes differently, may focus attention on quite important processes or variables, but one cannot be very hope-

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ful that a single general factor will provide the ultimate key to understanding the learning processes of the retardate. This is especially true if work with the factor is limited to demonstration type studies, where the effects of the variable are arbitrarily assumed to affect learning or performance in some way, and support for the “theory” is claimed when the “predicted” results are obtained. The point is that theoretical ideas are useful when they allow for unambiguous prediction. In some cases the analogy or prediction may seem plausible, but upon examination it may prove to be quite ad hoc, with diametrically opposed predictions just as reasonable. While the emphasis on a particular variable may prove to be a correct strategy, with future elaboration resulting in useful empirical and theoretical advances, the search for a variable of special importance in considering retardate-normal learning differences should not be viewed as a theory. What it may actually represent is a useful emphasis that will elaborate the role of the variable in various aspects of the learning process. The above should not, of course, be interpreted as criticism of systematic research involving a variable or class of variables. In fact, the most useful knowledge we have about retardate learning has come from such research. The great danger is that one-shot type “demonstrations” of the effects of a factor may be taken as support for the “theory,” so that further research that will point out the limits of the effects, its complex interactions, etc., is not undertaken. Unless all that has been learned from other learning research is misleading, and the retardate is involved in much simpler learning processes than any other organism so far studied, the complexity of learning phenomena is so great that the work completed so far must be viewed as a barely perceptible beginning. Consider the complex interactions of variables that have been demonstrated in learning research, e g., the finding that the relationship between motivation and performance is not necessarily a monotonic one. The recognition that this may lead us to expect equal, higher, or lower performance with differences in drive level, depending upon a number of factors such as task complexity, suggests caution in assuming that differences in drive level can be simply defined in terms of performance level. Another example is discrimination reversal. At one time this was believed to be a rather simple process, and various concepts were defined in terms of speed of reversal learning. Now the processes involved appear quite complicated, as evidenced by the belated recognition that reversal performance reflects a complex of acquisition and inhibition processes that themselves are functions of a number of other variables, some investigaors have moved back to even simpler situations in order to gain a better understanding of reversal learning (e.g., Birch, Json, & Sperling, 1960;

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Ison, 1962), and the overlearning-reversal effect has provided a focal point for theoretical activity of the previously mentioned phenomenon centered type. As this work progresses and more becomes known about the basic processes involved, the results of retardate reversal learning studies and the comparison of these data with the data obtained from normals and other organisms may prove to be quite valuable with respect to identifying the different learning characteristics of the group.

B.

The Role of Classical Conditioning and Discrimination Learning in Investigations of Retardate Learning

Assuming the desirability of working intensively and systematically with retardate learning problems, a question that remains to be considered is why classical conditioning and discrimination learning should warrant special attention in these efforts. Any discussion of this question must be qualified, for it is not proposed that these learning situations should be the only, or even the primary, areas of investigation in retardate learning. Indeed, it would seem essential that research involving the retarded be integrated into all areas of learning research to the greatest extent possible. Retardation as an area cannot hope to develop inclependently of other learning and developmental work, although it is an unhappy fact that many of these involved in research in these areas have not considered problems of retardate learning. This is especially true of academic psychologists, who until recently have rarely been involved in research with retardates even when i t could have been valuable in helping to understand the learning processes in normals that were their primary interest. Perhaps this is not too surprising in view of the academic psychologist’srelative neglect of children compared to the attention given the rat, pigeon, and college sophomore. However, it is regretable that research with retardates has not been more closely tied tq ongoing learning research. The amount of research that has been necessary to develop our understanding of learning processes in normals to its present primitive stage makes the attempt to replicate this work with retardates prohibitive. The best strategy is to take advantage of the “screening” work previously done in learning research, interest those previously not involved in work with retardates in these problems, and at the same time keep ongoing retardate learning research abreast of the approaches, empirical knowledge, and theoretical developments as they occur in all other learning areas. This then leads to one reason for interest in conditioning and discrimination learning: these situations represent two of the most intensively worked and currently active learning paradigms. It is suggested that these areas are in such stages of methodological, empirical, and theoretical

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development (relative to other areas in learning) that it is now possible to integrate retardate research in a reasonable manner. Certain advantages immediately accrue. For one thing, retardate-normal differences and similarities will be more meaningful in that they can be interpreted in terms of more basic learning processes. It is also true that until a certain level of empirical development is reached it will continue to be difficult to determine which behavioral tasks will provide data that are iiieaningful within the conceptual and theoretical framework of other basic research. The more complicated paradigms that often provide the useful data are not selected by chance, but come into use because of prior research that indicates that they will serve the desired purpose. Typically, considerable time and research is necessary before the paradigm is methodologically refined to the point where the results obtained from it are relatively unambiguous in the sense that at least the major parameters and processes involved are identified. Whimsically seizing upon a particular experimental situation to answer some “theoretical question” in a one-shot study is likely to be a dangerous procedure. At least with many classical conditioning and discrimination learning situations, the pitfalls and complexities are known, even if they cannot be entirely avoided. Classical conditioning and discrimination learning each have specific features that make them of value in investigating retardate learning. One very attractive aspect of classical conditioning is the fact that the data can be relatively independent of the S’s “volitional” control, and while it is true that “cognitive variables” often affect conditioning, there are ways of identifying this kind of subject involvement in some classical conditioning situations. If distracting tasks are employed in working with children, the data may be relatively independent of such factors as instructions, the S’s interpretation of the instructions, motor strength aiid skill, etc. The advantages of avoiding the interactions of these variables when comparing normal and retardate learning are obvious. What is wanted is information about the basic learning processes of these populations, and it is undesirable to have experimental data that is confounded in terms of these other factors. The same argument could be used to point out the advantages of classical conditioning procedures for developmental studies across broad age ranges where changes in intellectual functioning and motor skills make it difficult to compare instrumental performance from age level to age level. With what other procedures is it possible (theoretically at least) to obtain comparable data on newborns, infants, grade school children, and possibly young adults as well? In view of these desirable features it is quite surprising that so few classical conditioning

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studies have been reported with retardates, or for that matter, with any children. Work that has been done (see Lipman, 1963) has tended to be fragmentary with little in the way of systematic investigation, except for a series of GSR conditioning studies by Grings, Lockhart, and Dameron (1962) and a research program (Lipsitt, 1963) involving newborns. By far the greatest amount of classical conditioning work in the United States has been classical eyelid conditioning. Yet a survey of the recent eyelid conditioning literature (Ross & Hartman, 1965) revealed only three studies which used retardates or normal children, as compared to over 150 investigations which involved college students. Also, the possibility that classical conditioning will prove to be that learning paradigm which is iiiost useful in relating learning to neurophysiological processes suggests that comparisons of normal and retardate conditioning data might well turn out to be extremely valuable. Franks and Franks’ (1962) study relating conditioning performance to degree of organic brain damage is an intriguing glimpse at possible lines of research. While eyelid conditioning has been found to be a much more complicated procedure than originally believed (Ross, 1965), it offers an excellent and largely overlooked technique for use in studies of learning in populations which differ widely in age and/or intelligence. Discrimination learning has been extensively used to investigate learning i n both normal children and retardates. In fact, the major problem is not the existence of systematic research with these populations, but the fact that so little work has been done that involved both populations within the same experimental paradigm. Perhaps one should not expect more of the work in this area since this type of systematic research is SO scarce in psychology, but our knowledge of retardate learning, and the learning of normals as well, would undoubtedly have been considerably ad\.ancetl if retardate and normal research had been integrated. Recent important discrimination learning research includes that of Zeaman and House (1963) and H. H. Kendler and T. S. Kendler (e.g., 1962). M’hile these research programs differ in the type of constructs employed (attentional and verbal respectively), the theoretical framework is similar in the use of “two-stage” or “chaining” med.iating processes. Furthermore, the most commonly utilized experimental situation in both cases is that involving discrimination transfer situations where, typically, performance is compared on various reversal and nonreversal (extradimensional and intradimensional) paradigms. Obviously this work has progressed far beyond a point where retardate-normal differences in the original learning phase of simple discrimination learning are of major interest. T he possibility of gaining a great deal of understanding of the

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attentional and verbal processes that mediate learning in discrimination and discrimination shift learning situations is ample incenthe for a considerable investment in research in this area. C. Problems in Classical Conditioning and Discrimination learning Research with Retardates

Methodological problems and questions of research strategy arise in connection with research involving any learning problem and subject population, but there are several issues concerned with retardate research that are fairly specific in working with this population. Some of these have been discussed at length elsewhere, and some may represent the naive reaction of the author, who only recently started working with retardates in learning research. In any case, they represent rather general questions that should be given some consideration. 1. COMPARISON GROUPS

One of the most widely discussed questions in retardate-nornial research is that of the appropriate matching procedures, which in the course of discussion usually resolves to the issue of MA or CA matching. Denny (1964) has argued for the use of both MA and CA matching groups, but this is done very infrequently. Apparently few experimenters have the resources or available populations to carry out this double matching procedure, or perhaps it is felt that research in the area is still at such a primitive level that the advantages are as yet not great enough to justify the added effort. It is sometimes said that the choice of an MA or CA matching group depends on the particular interests of the experimenter, but these interests are rarely spelled out in detail sufficient to make the rationale for the choice of one rather than the other obvious. The usual reason for the use of matching (comparison) groups in learning research is to rule out some factors as “explanations” of differences. That is, if normal-retardate learning differences are found, it inay be desirable to attribute these to some kinds of basic learning processes aside from differences that would arise due to MA or CA per se. In some cases CA might be more likely to interact with the experimental parameters; in other cases MA factors might be more suspect. It is the author’s bias that the latter is more likely than the former in most learning situations, at least in those not involving complex motor skills. Denny (1964) points out that differences found with MA-matched reflect IQ deficits; with CA-matched, low-MA-low-IQdeficits. Presumably it is the IQ deficit that is of primary interest to those concerned with retardation, although the MA comparison is also of considerable interest from a developmental

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point of view. Indeed, if enough normal developmental data were available the matching problem would be of less importance. It has been argued that matching for MA equates many of the variables that are of interest to the experimenter and reduces the probability of obtaining normal-retardate differences. This position may reflect the particular interests of some investigators, but generally those interested in basic learning processes are not likely to be as concerned with the sort of performance that enters into test definitions of MA as are others in the retardation area. From this point of view, differences found in CAmatched studies may be differences of importance to learning, or they may only reflect differences in complex behavior at a gross descriptive level. It certainly is important to know how normals and retardates of equal CA differ, but probably this will be of little help to most psychologists whose concern is with specific, often abstractly defined, learning processes. Much of the dissatisfaction with matched MA studies has been due to rather widespread failure to find normal-retardate differences. It could be argued, however, that in many of these cases learning situations have been used that would not be expected to reflect learning process differences even if such differences were actually involved. More complex paradigms that will be sensitive to the differences that are of interest may be required. As mentioned previously, these paradigms usually develop from previous research and in a sense are designed to ‘‘ask‘’ certain questions. It must be admitted that the usefulness of MA comparison groups is severely limited by the characteristics of the tests employed. The problem of test reliability and the lack of satisfactory standardization procedures have led to a great deal of skepticism regarding the usefulness of matching on some test instruments. Also, it is clear that although groups are matched on total score, subtest profiles may differ markedly for normal and retardate populations. Using subtests, especially when the subtests deal with processes thought to be important in the learning situation being used, would appear to offersome hope. Unfortunately, however, the unreliability of these subtests make this procedure of value only in rare cases. Apparently any test score niatching must be viewed with caution and accepted only as the grossest kind of comparison procedure. In view of these limitations in constituting comparison groups, the most useful procedure might be to match on the basis of some highly related learning task. This is especially appropriate when discrimination transfer situations are used. Sometimes the normal and retardate groups may not differ on the initial discrimination learning task. When this is the case (e.g., Sanders, Ross, & Heal; 1965), subsequent difftrerces may

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be interpretable in ways not otherwise possible. I n these circumstances one is relatively certain that normal-retardate differences in shift problem performance are not due to factors such as sensory capacities, interpretation of instructions, motivational differences, etc., unless there are some quite complicated and unlikely interactions of these factors with the original and shift conditions. Indeed, for these reasons, experimental situations where the performance of normals and retardates does not differ may be quite valuable to use if further transfer conditions then show differences. Too often experimental paradigms have not been systematically probed beyond initial no-difference findings. When groups do not happen to have similar performance on a prior related task, i t is possible to select subjects in order to match normal and retarded groups. An example of this procedure is found in a doctoral dissertation by Heal (1964). In this study the subjects were given four training sessions, each involving a different type of discrimination, or discrimination shift, problem, before the experimental treatments. Training on these buffer problems was continued for forty trials or until a criterion of six consecutive correct responses was met, with the experimental groups balanced on the basis of errors on the third and fourth training problems. T h e rationale for the use of this matching method was given by Heal as follows: “(1) they provided an easy, one-step-at-a-time training for the ED and ID shifts that were the experimental treatments, helping to assure that subjects, one selected, would complete all treatments; (2) they trained Ss to respond with facility to either the form or the color dimension; (3) they reduced cue preference and simultaneously familiarized Ss with the non-novel treatment cues, making the novel cues more striking when they were introduced; (4) they provided the data needed to equate normal and retardate populations with regard to general discrimination ability; (5) they tended to eliminate the differential inter- and intra-population discrimination learning experience. This last point is particularly critical for the present study, for many of the retardates but none of the normals had been used as subjects in previous discrimination learning experimen ts.” There are obviously a number of advantages to be gained from this training problem approach that should be carefully considered by those working in the area. This type of procedure does involve the selection of subjects, and it may be aigued that the resulting population bias limits the generality of the results, but this is true in any case where a population of retardates is selected that can either learii a specific problem or be handled in the experimental situation without too much trouble. Learning research of the type under consideration typically is

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not concerned with normative learning information but rather is interested in the identification of the variables and processes related to learning and in the development of theory regarding these processes. T h e selection of subjects to form matching groups as well as to meet practical and theoretical considerations is often necessary in this kind of research.

2. RETARDATES AS EXPERIMENTAL SUBJECTS There are a number of problems that frequently occur in learning work with the retarded. Mention will be made here of two that appear to have received little explicit attention. Research with animals and normal children typically involves naive subjects for each study, unless the experimental design calls for repeated testing of the same subjects. With institutionalized retardates, however, the same subject population may be used extensively in different research programs or by the same experimenter across a series of problems. T h e difficulty is obvious, Research often compares naive normal subjects with a highly tested population of sophisticated retardates. In many situations this is of critical importance, since research has conclusively demonstrated the influence such experience can have on performance in learning situations. Aside from specific learning set factors, there are the related complications of habituation to the experimental situation, possible boredom or increased emotionality depending on the child's past experience in similar situations, and the chance that stimulus preference or other factors may result in transfer from previous learning situations. This last possibility argues for complete research participation record keeping, including the positive and negative stimuli used, and similar details. There are several strategies that may partly mitigate this problem, such as attempting to follow the normal groups so that they receive a series of problems comparable to those given the retardates. An alternative, and more practical, solution is to give a series of buffer or training problems which at least tend to give the subjects similar experience on some related tasks just prior to the experimental treatment. T h e training problems given by Heal served this function and provided as well a basis for matching the normal and retardate groups. Brief comment should be made concerning a n attitude, held by many working in the retardation area, to the effect that any comparison of retardate and animal learning performance -is in some way derogatory to the retarded child. Th e sensitivity and emotional involvement of these people is to be commended, but phylogenetic comparisons should be viewed as a necessary part of the attempt to better understand the retardate rather than as something not quite in good taste. Comparisons of the learning of animals and normal children have been better accepted,

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and recent comparisons of the discrimination learning and shift performance of animals and children (e.g., Kendler, Kendler, & Silfen, 1964) have been quite interesting. Within limits, work with animals can be useful in screening to identify variables that are of importance in learning situations. Work of this type would be even more useful if animals and children could be tested under more comparable motivational conditions. I t may well be that the consequences of nonreward in discrimination learning situations, e.g., comparing the performance of food deprived animals with children who have just finished a meal and are rewarded with candy, may be so great as to account for some of the differences obtained. Since it is much simpler to vary the motivational state of animals, research comparing animal and human learning performance should perhaps involve animals with several levels. of drive, including some after very short deprivation periods. This is especially important in cases where this sort of variable has been demonstrated to be related to the obtained learning performance. Most classical conditioning procedures seem to avoid this problem.

3. ETIOLOGICAL CLASSIFICATIONS AND LEARNING There has been little, if any, success in comparing the learning performance of etiologically classified groups of retardates with a view of characterizing these groups behaviorally. Those involved in such classification point with sophisticated dismay at the instruments available for the business of classification and express a lack of surprise that such attempts have failed. On the other hand, those primarily working with the behavioral situations point to the often superficial nature of the learning tasks used in “behavioral-battery” approaches and plea for the use of more specialized learning paradigms. Compounding the problem of the reliability of classification is the small size of the subgroups available for research. Learning research has typically involved rather large numbers of subjects, and until the tasks are refined to reduce the variability commonly found, the prospects for this approach are not good. Obviously improvement in both areas is necessary. It may be that cytogenetics will open new fields for learning research, but a great deal of learning task refinement may be necessary before advantage may be taken of these developments. It may be, of course, that gross learning process differences will not be found among the various retardate etiology subgroups, but the investigations must be made with the most sophisticated behavioral paradigms before this conclusion can be accepted. Such a specialized task “depth” approach may prove more useful than the more commonly found behavioral-battery procedures.

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111. CURRENT RESEARCH INVOLVING CLASSICAL CONDfTlONING AND DISCRIMINATION LEARNING

This section presents some ongoing research which uses classical conditioning and discrimination learning paradigms to investigate retardate learning. It is not suggested that this work successfully avoids the problems and difficulties discussed previously, nor is it proposed that it will lead to any dramatic discoveries that will drasticaIly change our ideas about the way in which learning processes operate. On the other hand, this use of classical eyelid conditioning is an extension of a relatively well understood experimental procedure to developmental problems of learning and inhibition in normal and retarded children, and the chances appear to be good that the technique will prove to be a useful one. I n the case of the discrimination learning studies, the emphasis is on the comparison of retardates and normals and the utility of using discrimination transfer and single stimulus presentation situations to compare these populations with respect to the various learning processes in which they are presumed to differ. A. Classical Conditioning

Eyelid conditioning is now being attempted with children of several age levels. As is often the case, relatively simple methodological problems had to be solved before the technique could be used in any more than a demonstration manner. The essential feature of eyelid conditioning, of course, is to reliably record the movement of the eyelid. This is typically done by making a mechanical connection of some sort from the eyelid to a headset microtorque potentiometer, which in combination with a DC amplifier and polygraph gives a linear recording of the movement of the eyelid in relation to the various CS and UCS onsets and offsets. In considering the use of this instrumentation with children, there are two choices. One is to switch to some alternative not involving a headband and direct attachment, e.g., the use of electrodes to pick up muscle action potentials or strain gauges to record movement of the muscles around the eye; the other is to try to work out some procedure so that the child will tolerate the headset. After considering the disadvantages of the former approach, which include such factors as the problem of scoring records, the difficulty of getting standard placements from subject to subject, and the lack of comparability of the records with the extensive data collected from college students, it was decided to try to ret,ain the usual mechanical-headset-pickup procedure. This turned out to be quite simple, All that was required was the use of a motion picture during

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the experimental session, a procedure that in a sense bribed the child to tolerate the headset. The success of this approach is obvious from the results of the first study. In this experiment (Ross, Koski, & Yaeger, 1964), 40 of 43 retarded children taken to the experimental room successfully completed the three experimental sessions. These were all severely retarded children (from wards at Central Wisconsin Colony and Training School), and while only about one-third of the retardates in the wards were selected, many of the others had physical disabilities or behavior problems that precluded their use. At least as many were conditioned as could be tested on the simplest discrimination problem. A tone CS was used to eliminate any problems of receptor orientation, and it was also necessary

FIG.1. Eyelid-conditioning headset on mongoloid child.

to station an experimenter next to the subject as a safety precaution. Otherwise the usual procedures were used, except that multiple sessions of 50 trials each were used to avoid the restlessness that might have been expected had a large number of trials been given. The success in getting conditioning data from this population was interpretated as indicating that systematic research using classical eyelid conditioning with normal and retarded children was quite feasible. At present similar procedures are being employed with younger children. Good records have been obtained from 6- and 7-year-old mongoloids, with the motion picture still serving as an effective distracter. Pilot work indicates that retarded children as young as 3 years old may be successfully eyelid conditioned. This work is being done in collaboration with Mary Headrick. Figure 1 shows the eyelid conditioning headset arrangement on a

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LEARNING RESEARCH WITH THE RETARDED

mongoloid child. Notice the thread attachment from the eyelid to the potentiometer arm. The attachment to the eyelid is by a small piece of plastic and double-backed adhesive tape. Both application and removal of the plastic eyepiece is quite quick and easy, and if properly placed it is hardly noticeable to the subject. Heart rate is concurrently being recorded in the present study in order to look for conditioning-heart-ratechange correlations. Brief mention should also be made of procedures being attempted with newborns in collaboration with Rachel Keen Clifton and Frances Graham. There are a number of problems in working with newborns, such as the I4 I-

:

e S I RECElVlNQ CONDITIONING AND TEST TRIALS PLUS THOSE DISCARDED FOR NOT ADAPTINQ TO THE PUFF (N437)

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PUFF ADAPTATION TRIALS FIG. 2. Eyelid response adaptation curves for college students receiving a weak air puff to the side of the temple. The two curves represent all subjects (solid line) and only those who met an adaptation criterion (broken line) (Ross, 1961).

short sleepwakefulness cycle, and work has not progressed far enough to indicate if any conditioning can be obtained. The paucity of conditioning data with the very young makes the attempt a reasonable one, however. Although at first the notion seems rather odd, it may be desirable to attempt, conditioning while the newborn’s eyes are closed. An air puff on the closed eyelid elicits a surprisingly large reflex UCR that is easily recorded, and this procedure would avoid the problem of trying to stimulate the baby before each trial so that the eyes would be open. If it is not possible to obtain conditioning with the newborns, it will still be feasible to study the adaptation of the reflex blink to the air puff. In conditioning it is desirable to use a UCS of sufficient strength to produce a UCR throughout the conditioning session. It is possible, however, to use a weak UCS so that rapid adaptation will occur. Figure 2

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shows an eyeblink adaptation curve obtained with college students when thirty 1.25-psi air puffs were delivered to the temple with an average 20-sec intertrial interval. Of 137 subjects only 17 failed to meet an adaptation criterion of having a mean amplitude on trials 26-30 that was less 1961). than 60% of their mean amplitude on trials one and two (ROSS, Similar rapid adaptation curves should be simple to obtain from newborns, and individual differences in rate of adaptation, spontaneous recovery, etc., should be of interest, particularly if conditioning of these subjects could be attempted at a later age. Assuming that eyelid conditioning procedures can be used with populations differing widely in CA and IQ, the question becomes one of strategy. Obviously there are a very large number of studies that could be attempted, and the particular line of research pursued in such a situation will reflect the experimenter’s biases and hunches, among other factors. Three areas are of particular interest for the present discussion, namely those concerned with (1) methodology, (2) the examination of certain conditioning phenomena developmentally, and (3) the investigation of those learning factors that long have been proposed to differentiate retardates and normals. The extent to which methodological studies will be necessary will depend upon the data obtained from retardates. That is, if response form and rate of conditioning are comparable to that of college students, there will be less necessity for extended methodological examination of retardate conditioning. Even so, it would seem desirable to do parametric studies of those variables which have proven to be of considerable importance in conditioning. It may be, for example, that the relationship between conditioning and CS-UCS interval is different for college students, retarded children, and normal children. Aside from being an interesting finding in its own right, such a result would have considerable implications for interpreting the “conditionability” of normals and retardates. Also of interest is the type of response given by these different populations under different conditions. Considerable attention (e.g., see Ross, 1965) has been given to questions of classifying eyelid responses as “voluntary” or “nonvoluntary,” the interest stemming from the fact that the subject in an eyelid conditioning experiment may adopt a “voluntary” or “operant” mode of response. This type of response, which is identifiable in form as a fast, smooth closure that is maintained until after the UCS, as well as by objective latency or slope criteria (Hartman & Ross, 1961; Spence 8c Ross, 1959) appears to follow different laws as compared to the irregular, slower, nonvoluntary response. This is as expected if the voluntary response is an operant “emitted” response, since it then should reflect different relationships and processes as compared to the

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“elicited” classically conditioned response. I t is not suggested that voluntary responses not be labeled as conditioned responses, since the term is used in diverse ways, but it does seem that differentiating types of responses may be more necessary with normal and retarded children than with college sophomores. From a commonsense point of view, closing the eye to avoid an air puff UCS is a quite rational decision. College students to a large extent “play the game” and follow instructions not to try to control the movement of the eyelid, but with children the problem becomes more acute. Experimenters will have to be careful not to use procedures and stimuli likely to elicit large numbers of voluntary responses (e.g., an intense UCS) unless this is the type of response desired. There are two relevant observations with respect to this point. First, Ross et al. (1964) reported that the retardates in their study gave a large number of responses that had the slope characteristic of a voluntary response but that did not remain closed until the UCS was received. If these were voluntary responses, they were very ineffectual voluntary responses. Secondly, in beginning pilot work with young mongoloid children the first subject presented the perfect picture of a voluntary responder. This may have been due to the rather strong air puff used, since it was thought the actual effectiveness of the UCS would be less due to the difficulty involved in placing the air nozzle so the air puff would strike the corner of the eye, and accordingly a more intense puff was employed. With distraction procedures there may be less of a problem since fewer voluntary responders are found under these conditions. On the other hand, the problem then is to equate the degree of distraction in the situation, since this has been demonstrated to be related to conditioning and extinction phenomena. Perhaps the wide appeal of low-level television fare makes it plausible that almost any movie material will be satisfactorily distracting for a wide age range. With respect to the second and third research areas that are of particular interest, there are a number of well established conditioning phenomena that should be investigated developmentally as well as compared in terms of normal and retardate differences. Any comprehensive listing of these would be prohibitive in length and the reader is referred to a recent survey of the eyelid conditioning literature (Ross & Hartman, 1965). One example that deserves specific attention is the effect of partial reinforcement on acquisition and extinction performance. Work with college students uniformly has found a partial reinforcement decrement in acquisition as well as greater resistance to extinction following partial reinforcement. The acquisition decrement has been attributed to “set” or other inhibitory factors (ROSS,1959). while the partial reinforcement extinction effect has been the center of a number of theoretical and

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quasi-theoretical formulations. However, in the Ross et al. (1964) study previously mentioned, the retardates showed little if any partial reinforcement decrement in acquisition, and on the first extinction trials demonstrated superior resistance to extinction on the part of the contiiluously reinforced group. Figure 3 shows this effect. Notice that college student

70 - RETARDATES 50 -

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BLOCKS OF TEN TRIALS

FIG.3. Percentage of conditioned responses made by normal and retarded subjects as a function of reinforcement schedule, and whether or not a movie was shown during the conditioning and extinction period.

control groups were run to control for the possibility that the different partial reinforcement effects could be attributed to the movie procedure per se. These college students provided a fairly good CA match, but no MA comparison groups have yet been run, and the possibility exists that this failure to find partial reinforcement effects will also be true with normal children. It should be noted at this point that the data from

L E A R N I S G RESEARCH WITH THE RETARDED

41

studies involving retarded children will undoubtedly provide important information about the learning processes of normal populations. Obviously the failure to find a commonly reported effect can lead to a much better understanding of the phenomenon if the different results can be identified as due to certain parameters, characteristics of the population, or an interaction of these factors. Thus, if the lack of a partial reinforcement decrement in acquisition is specific to retardates, and on the basis of other experimental evidence these retardates can be characterized as having an inhibition deficit, information will be gained both with respect to retardate learning and the nature of the partial reinforcement performance decrement in normals. T h e general topic of inhibition appears to be one that offers exciting possibilities for work in classical eyelid conditioning. “Discrimination learning” in eyelid conditioning typically takes the form of differential or single stimulus presentation conditioning. Thus, the positive and negative stimuli are presented in a predetermined order with the percentage conditioned responses to the CS+ increasing and that to the CS- showing an initial increase and then a decrease as inhibition accrues to the CS--. It should be noted that with this paradigm the growth of inhibition to the negative cue is represented by the CS- curve during the entire experimental session or sessions. This, of course, is in contrast to instrumental, choice, selective learning situations where the negative cue ceases to be chosen as learning progresses and as a result there is no indication of the level of response strength to the CS-. Positive and negative cues may be presented from the beginning of training, or the nonreinforced cue may be introduced after conditioning to the positive cue has reached a high level. In the first case, the initial segment of the response curve to the positive stimulus reflects both the growth of associative strength to that cue and, as inhibition grows, generalized inhibition. With the second paradigm, negative trials can be postponed until an asymptote of performance is reached SO that the effects of generalized inhibition can be assessed. In other words, inhibition can be studied as a function of level of training. There are many other possibilities, and such phenomena as spontaneous recovery and Pavlovian type induction effects can be thoroughly explored. Research has just been started along these particular lines, i.e., comparing inhibitory processes developmentally. If it proves feasible to eyelid condition newborns and icfants, ver.1 interesting information may be obtained about the development of these processes with age. The use of words as conditioning stimuli offers another rich developmental area that has hardly been touched by researchers in this country. Studies of semantic conditioning and generalization with children are nonexistent in the United States, and eyelid conditioning offers

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Leonard E. Ross

an excellent opportunity to study developmental aspects of language in a quite unique way. In summary then, eyelid conditioning represents a research tool that has the potential to investigate many important learning processes in normal and retarded children of all ages. This point has been made before but it bears repeating. It is difficult to understand why experimenters have not eagerly exploited these possibilities. 6. Discrimination Learning

T he first study to be discussed is one previously mentioned, that of Sanders, Ross, and Heal (1965). Aside from the data obtained, this experiment and a follow-up study just completed are valuable in demonstrating the danger involved in assuming that normal and retardate performance are identical, without looking at parameters that might interact with the experimental conditions. T h e study that provided the impetus for those described here was one by House and Zeaman (1962), in which it was reported that retarded children were poorer on extradimensional (nonreversal) shifts than reversal shifts, following discrimination learning. This was quite surprising, since these results replicated transfer effects found with normal children (e.g., T. S. Kendler & H. H. Kendler, 1959). I t simply did not seem that this should be the case if either verbal or attentional factors were operating to bring about the greater difficulty of extradimensional shifts as has been proposed by various experimenters, since retardates would be expected to show deficits in these processes as compared to normals. Thus, Sanders and associates used reversal and extradimensional transfer paradigms with both normal and retarded groups, approximately matched on MA. T h e various transfer conditions are shown in Fig. 4. I n original learning, and in each of the shift conditions, position was irrelevant, i.e., each stimulus combination appeared on each side an equal number of times with position never correct. Thus, each example in Fig. 4 represents only one of four configurations presented to the subject, since the combination shown would have its right-left positions exchanged on half of the trials, and the irrelevant form or color would have the opposite pairing with the relevant (correct and incorrect) color or form to make two more combinations. Two extradimensional conditions were used in order to see if familiarity with or “learning to ignore” irrelevant cues would retard subsequent learning when they became relevant, as compared to learning when the relevant cues were from the irrelevant dimension but new. Mean original learning errors were practically identical for the iiomals and retardates (23.40 and 23.86, respectively), but shift performaiice was

43

LEARNING RESEARCH WITH THE RETARDED

ORIGINAL LEARNING

FORM RELEVANT COLOR IRRELEVANT

-

4-

SAME FORMS NEW COLORS CORRECT

EXTRADIMENSIONAL OLD

-

NEW FORMS SAME COLORS ONE COLOR

CORRECT

I

-

EXTRADIMENSIONAL

+

+

-

NEW FORMS NEW COLORS ONE COLOR CORRECT

FIG. 4. Transfer conditions used in the Sanders et al. (1965) study. For explanation see text.

FIG. 5. Mean number of errors made by normals and retardates during reversal and two nonreversal (extradimensional) shift conditions (NRO and NRN) (Sanders et al., 1965).

44

Leonard E . Ross

quite different as is shown in Fig. 5. Here it can be seen that the normals showed the previously reported superiority of reversal over extradimensional shifts but that the retardates performed equally well under both conditions. T h e results, then, failed to replicate the House and Zeaman data and supported, the notion that the retardates were deficient in the mediation processes, verbal or attentional, that presumedly lead to faster reversal than extradimension shift learning for normal children of their MA. Attention was next directed to finding the parameter or parameters responsible for this difference. Despite the fact that the House and Zeaman and the Sanders et al. studies differed in a number of ways, an obvious suspect was the number of trials given on the original discrimination problem, since House and Zeaman gave 125 overtraining trials before introducing the shift problems. To test this, Elizabeth Schowalter Ohlrich has just completed a study involving four groups of retardates, including one reversal and one extradimensional shift group which received the same original learning as in the Sanders et al. (1965) study, while the other reversal and extradimensional group was given an extra 125 trials on the original problem before their shift training. All four groups were run with the same apparatus and the same general procedures as those used in the Sanders et al. study. T h e results are portrayed in Fig. 6. Note that the criterion-only reversal and extradimensional groups show very similar performance, replicating the Sanders et al. results, but that the overlearning groups are quite diI1) transformed scores] as referent [t = 2.07, p < .05 for log (errors ported by House and Zeaman. Not only do these results reconcile the conflicting results of the two previous studies and point out the interaction of overlearning on the shift performance of normals and retardates with concomitant implications for differencesin the learning processes of these populations, but they also emphasize the dangers involved in assuming that normal-retardate learning processes are identical without going through a thorough “parameter probing” of the paradigm. Discrimination learning has often been utilized as a tool to investigate basic questions about the learning processes of normal and retardate children. One example of this has been the various attempts to determine the relative utilimion of positive and negative cues in discrimination learning. A doctoral dissertation by Laird Heal (1964) provides what is one of the best available answers to this question, as well as an illustration of the relative complexity sometimes necessary to control for extraneous factors in these situations. A number of previous studies investigating positive vs. negative cue utilization have used “partial intradimensional” shift discrimination trans-

+

45

LEARNING RESEARCH WITH THE RETARDED

fer problems in which either the original-learning positive or negative cue is replaced by a new cue and the value of the retained cue is reversed. T h e comparison of the positive-retained and negative-retained groups presumably assesses the relative importance of these cues in original learning. The problem with this design lies in the fact that the new cue is positive in the positive-retained condition (the retained cue is reversed in value) and negative for the negative-retained group. If there is a tendency to choose the new (novel) cue, the positive-retained condition will be easier whether or not there is a positive-negative difference per se. To avoid this problem Heal introduced his positive- and negativeretained conditions as an extradimensional shift. Since the relevant diED

-0

-

ED

W

a W

10

ROT

ORIGINAL LEARNING

SHIFT LEARNING

FIG.6. Mean number of errors made by retardates in original learning and shift learning conditions including reversal and extradimensional shifts without overtraining (R and ED): and reversal and extradimensional shifts with overtraining (RO T and ED-OT).

mension in the transfer problem was different from that in original learning, the novel cue was neither positive or negative (it was not on the relevant dimension) so that any effects due to novelty would effect equal transfer in both the positive- and negative-retained cases. Intradimensional groups were also run replicating the previously employed paradigms, so that the effects of novelty could be assessed by comparing the intradimensional and extradimensional results. Some details of this study will be presented since it is as yet unpublished. Twenty-four normal kindergartners and 24 retardates matched on discrimination ability were used in the experiment, each being given half the treatments of a 23 design in which the three factors were (1) positivecue-retained vs. negative-cue-retained, (2) extradimensional shift vs. intradimensional shift, and (3) criterion of 6 consecutive trials vs. criterion plus 40 overtraining trials. For instance, the positive-cue-retained intra-

46

Leonard E . Ross

dimensional with overtraining condition involved an original simultaneous two-choice discrimination learned to a criterion of 6 consecutive correct trials, 40 trials of overtraining with stimulus-reward contingencies unchanged from original learning, and 20 shift trials in which the original positive cue was retained but made negative and the original negative cue was replaced by a new cue. For the similar extradimensional condition, the relevant dimension during the shift learning phase was the irrelevant dimension of original learning rather than the same dimension, as was the case with the intradimensional conditions. A noncorrection procedure was used throughout. For half the problems the form dimension was relevant and for half the color was relevant. The positivecue-retained extradimensional and nega tive-cue-retainedextradimensional conditions compared transfer effects of positive and negative cues when the novel cue was correlated with reward on 50% of the trials, instead of 100% and 0% as was the case with the positive-cue-retained intradimensional and negative-cue-retained intradimensional problems respectively. That is, the posi tive-cue-retained extradimensional and negativecue-retained extradimensional conditions permitted a test of cue value effects that was unconfounded from cue novelty effects. The results (errors in transfer trials) showed very little differential transfer associated with either the cue value conditions or the interaction of cue value with shift type (i.e. cue novelty). However, there was large shift effect, the intradimensional shifts being easier.than the extradimensional shifts (1, < .OOl), and also a significant shift type X overtraining interaction, extradimensional being impaired but intradimensional facilitated by overtraining (1, < .025). Although populations did not differ in total errors, retardates showed significantly poorer performance than normals on those trials for which their original learning and shift trials cue values were opposed (1, < .025). This finding was interpreted as indicating a general inhibitory deficit for retardates, which was likened to a deficit in “transfer suppression” ability. A fixed sequence of cue-position relationships was used for all conditions, with the first three trials requiring a discrimination reversal and the fourth (an “optional shift” trial) requiring the subject to choose between his original-learning negative and the original-learning irrelevant cue that had been redundant with the original-learning negative for the first three shift trials. While the normals consistently chose the originallearning negative, indicating a discrimination reversal preference, the retardates performed at chance, indicating neither a discrimination reversal nor an extradimensional shift preference. These optional shift results are consistent with what would be predicted from the reversal-

LEARNING RESEARCH WITH THE RETARDED

47

extradimensional shift data of the Sanders, Ross, and Heal study although the error data are not. T o finish this section two other discrimination learning studies will be briefly described, one in progress that employs what might be called an attentional or incidental learning paradigm, the other a single stimulus (or differential) learning situation that so far has been relatively unexploited in retardate research despite its unique advantages for some purposes. The study in progress, which was started at Peabody College in collaboration with Bryan Shepp, was initiated to provide information regarding the inhibition that might be expected to accrue to irrelevant dimensions in the learning of a discrimination problem. Thus, during the course of learning, the irrelevant dimensions are presumedly rejected, or ignored, or the subject fails to develop differential response tendencies to the cues, the terminology depending upon the particular “theoretical” frame of reference of the experimenter. This should carry over with negative transfer for some period of time, i.e., the subject should be less likely to respond to these irrelevant cues or dimensions as compared to the tendency to do so at the start of original learning. If normals and retardates differ in inhibition or attentional processes, they might be expected to differ in the amount of negative transfer found in such paradigms. It will be recalled that the Sanders, ROSS, and Heal study had two kinds of extradimensional shifts, one involving the old irrelevant cues and the other new cues from that dimension, a comparison which might have been expected to pick up such differences. No large effects were found however, and it was decided to use a different paradigm in the present study, since the introduction of the shift might have overriden any effects (i.e., if the subjects started systematic “hypothesis testing” upon receiving a nonreinforcement and seeing new cues introduced) or since the dimension rather than the specific cues might have been the vehicle for the negative transfer, in which case no differences would be expected. The paradigm selected was a variant of one previously used in animal studies concerned with the continuity-noncontinuity issue (e.g., Bitterman & Coate, 1950). The design used is schematized in Fig. 7. It involved (1) training the subjects to a learning criterion with a relevant dimension (color) and an irrelevant dimension (form) and then (2) confounding, or making redundant, the irrelevant dimension so that a single form was always paired with the correct color, and the other with the incorrect color, during this period. Thus, the previously irrelevant dimension was made relevant after learning, although the subjects could continue to “respond to” the originally relevant dimension throughout. The question, then, was whether or not this pairing would result in any different per-

Leonard E . Ross

48

formance in (3) a subsequent shift period when the originally irrelevant, now redundantly relevant cues, became the only relevant cues for learning. In this final period the performance of subjects whose positive and negative cues of this period had been paired respectively with the positive and negative cues of original learning (positive transfer expected) was compared with a group who had the reverse pairing in the “redundancy” period (negative transfer expected if the pairing had an effect). A third group had no redundancy phase, but the original learning was continued for a number of trials equal to those of the other groups. In other words,

PHASE

I

PHASE

II

PHASE

III

i-

,

-

’

+

-

GROUP

S

-

t

I

ORIGINAL LEARNING, COLOR RELEVANT, , FORM IRRELEVANT

,

NDANT PHASE, FORM AND COLOR CONSISTENTLY PAIRED

TEST PHASE, NEW COLORS, FORM RELEVANT, P R {RRELEVANT

GROUP D

FIG.7. Experimental design of study described in text. For each phase double the number of configurations shown were presented to subject, since position was always irrelevant. A third group was run that had Phase I continued without change through the Phase I1 period. In Phase 111, Group Same (S) had the form correct that was paired with the correct color in Phase 11, Group Different (D) had the form correct that was paired with the incorrect color in Phase 11.

L E A R N I S G RESEARCH WITH THE RETARDED

49

the test was whether or not the pairing resulted in differential response strength, i.e., whether the subjects attended to the pairing or “focused” on the originally relevant cues to the exclusion of the other cues even after they were made relevant. One might also interpret the situation as one involving the inhibition of responses to the originally relevant cues, although it is clear that there is no operational (or rational) grounds to choose between the operations of attentional or inhibitory processes at this level of analysis. In any case, the redundancy stage had a considerable effect, the group receiving the positive-positive-negative-negative pairing requiring a mean of only 79.75 trials to reach a criterion of 9 out of 10 consecutive correct responses in the shift phase as compared to means of 131.69 and 134.12 for the positive-negative-negative-positive and no pairing control groups respectively. This difference is significant (F = 3.43 p < .05). T he above data were gathered with retarded subjects, and nonnal comparison data are now being collected. Very preliminary data indicates that the redundancy period has less effect on normals and that what effect is found is reduced with older children. This would be congruent with notions of retardates being more distractable, focusing less, having less inhibition, having an attention deficit, etc. Again it should be noted that these terms are not operationally distinguishable in terms of actual performance predictions in such an experimental situation. Perhaps they are different ways of viewing o r labeling but a single process. T h e final discrimination learning situation to be described is one used by Judy Ann Yaeger to compare inhibition and “work minimization” processes in retardates and normals. While a stimulus preference factor complicated the interpretation of the results of this particular experiment, the study is valuable in that it demonstrates the potential usefulness of single simulus paradigms in this type of research. T h e notion that retardates have a general inhibition deficit is widespread (e.g., see Denny, 1964), but, as discussed previously, most of the research designed to test this notion has involved the simultaneous presentation of two or more stiinuli with a response to one of the stimuli required on each discrete trial. I t is obvious that in such a situation tendencies to approach the positive cue and avoid the negative cue are confounded, in acquisition as well as reversal learning. Since an inhibition deficit hypothesis deals specifically with the inhibition that accrues to the negative cue, data from simultaneous discrimination learning situations cannot be considered to be directly relevant to the hypothesis. These considerations led to the adoption of a single stimulus, or “gono go” paradigm which has the advantage of response measures being obtained to the negative cues throughout learning. T h e particular response selected was the lifting of a 284, one-inch diameter dowel (handle) that

50

Leonard E . Ross

protruded 4-& inches through a 10 inch )( 1 inch slot cut in the front screen of the apparatus. A “response” consisted of lifting the handle 1 inch or more from its resting position at the bottom of the slot (at 1 inch the handle broke a photocell beam). Thus, a “response” could vary in amplitude from 1 inch to 10 inches. The arm was connected to a potentiometer, DC amplifier, and polygraph, so that a continuous record of the subject’s response was obtained. A small light located below the handle slot served as the reward-nonreward cue. Responses were rewarded when it was on and nonrewarded when it was off for half the subjects, with the reverse contingencies for the other half. The positive and negative discriminanda were presented alternately for varying intervals of time. Amplitude of response measures were examined in the present study because of the interesting results obtained by taking intensive response measures in recent learning studies. Of particular relevance is the recording of intensive measures of the response in operant situations, e.g., force (Notterman, 1959), duration (Margulies, 1!%l), and amplitude (Herrick, 1963). Burke (1963), in a doctoral dissertation at Wisconsin, which involved a rat operant discrimination situation, found that response amplitude and duration diminished in the course of presenting the positive cue, while responses to the negative cue, although decreasing in frequency through time, did not change very much from their initial large amplitudes and durations. T h e decrease in amplitude and duration to the positive cue, which was also found in straight conditioning groups, was attributed by Burke to a “work minimization principle.” This diminution in response presumedly would be brought about by inhibition processes, and a retardate-normal difference should be expected from an inhibition deficit hypothesis. Unfortunately there were two problems with the present experiment that precluded obtaining meaningful comparisons of response strength to the positive and negative cues for the two populations. The major difficulty was a light preference on the part of the retardate. In fact, the retarded subjects who had light-on as the positive discriminative stimulus initially responded at such a high rate in its presence that no improvement was shown across training. The normal subjects did not show this preference. A second problem was the fact that the 20 normals averaged slightly less than 20 months older in MA than the 20 retarded subjects, so that covariance techniques were required to compare the populations. Despite these difficultiessome useful data were obtained. A discrimination index (percentage of responses to the positive cue) showed no significant difference between retardates and normals in acquisition (performance correlated .54 with MA), but in reversal the normals’ per-

LEARNING RESEARCH WITH THE RETARDED

51

formance was significantly (p < .Ol) superior to that of retardates (reversal performance correlated -. 11 with MA). T h e amplitude of response data showed normals making significantly smaller amplitude responses with the amplitudes decreasing across trials, while the retardates continued responding at their higher original level (the interaction was significant, p < .05).This result lends some support to an inhibition deficit notion of retardate performance. Further work using this type of single stimulus presentation situation is planned with positive and negative stimuli that are equated for “operant” response level. IV. CONCLUDING COMMENTS

Perhaps the most disturbing aspect of learning research with retardates, at least for one new to the area, is the impatience of many for the researcher to quickly solve the problems, settle the issues, o r provide the learning techniques. It is easy to understand the motivation for these desires; humanitarian instincts argue for the immediate amelioration of the retardate’s situation, and the social importance of the problem is obvious and pressing. Also, behavioral research with the retarded has been seriously neglected by psychologists and those in related. behavioral areas. One could not argue this point more cogently than to refer to the Report of the Task Force on Behavioral and Social Research of the President’s Panel on Mental Retardation (1964), which commented on the “limited research participation of the behavioral and social sciences in mental retardation” and pointed out explicitly with respect to learning . there is, in general, a very great disparity between what is that, known about learning in the normal individual and what is known about learning in the retarded . . . there are many areas and techniques which would be strategically wise to pursue.” At the same time an acceleration of research in retardation can be disadvantageous if it results in attempts to shortcut the usual development of basic scientific knowledge by (1) the promulgation of expansive theories which do not have supporting empirical evidence or (2) ignoring principles of experimental procedure. At the other extreme is the situation where the desire to do research with retardates is translated into the activity which is characterized by the simple replication with retardates of research done with normal children or rats, without any rationale as to why the particular research might have any important implications for our understanding of retardate or normal learning. These pitfalls occur in every area of research, but they are especially likely to be troublesome when an area is expanding rapidly under pressure to solve particular problems. One other aspect of this pressure is the tendency to push “in-

“. .

52

Leonard E . Ross

terdisciplinary research” regardless of the state of readiness of the individual discipline. It cannot be denied that one criterion of the stage of development of a n area is the degree to which interdisciplinary research becomes rewarding, and this stage is rapid,ly being reached in some areas of learning. At the same time it is unlikely that the shotgun wedding of disciplines will hasten the development of the areas involved. Initiation of interdisciplinary research is best left to the disciplines, with ready support available for this type of research when it is needed. T h e best antidote for some of these detours is the realization that the accumulation of knowledge is a slow, painstaking task, and that the “breakthroughs” that often excite the imagination are almost always based on a tremendous backlog of basic research. One of the best expositions of this general point of view is by Morison (1960), who quotes a passage from Pavlov that might well be repeated as a credo for all faced with the problems and frustrations of learning research with the retarded. Said Pavlov: “First, gradualness. About this I never can speak without emotion. Gradualness, gradualness, and gradualness. From the very beginning of your work, school yourselves to severe gradualness in the accumulation of knowledge. Learn the ABC of science before you try to ascend to its summit. Never begin the subsequent without mastering the preceding. Never attempt to screen an insufficiency of knowledge even by the most audacious surmise and hypothesis. However this soap bubble will rejoice your eyes by its play, i t inevitably will burst and you will have nothing but shame. “School yourselves to demureness and patience. Learn to inure yourselves to drudgery in science. Learn, compare, collect the facts! “But learning, experimenting, observing, try not to stay on the surface of the facts. Do not become the archivists of facts. Try to penetrate to the secret of their occurrence, persistently search for the laws which govern them.” REFERENCES Birch, D., Ison, J. R., & Sperling, S. E. Reversal learning under single stimulus presentation. J . exp. Psycho!., 1960, 60, 36-40. Bitterman, M. E., & Coate, W. B. Some new experiments on the nature of discrimination learning in the rat. J . comp. physiol. Psychol., 1950, 43, 198-210. Burke, R. E. Operant response amplitude, duration, and form during acquisition, extinction, and discrimination learning. Unpublished doctoral dissertation, Univer. of Wisconsin, 1963. Denny, M. R. Research in learning and performance. In H. A. Stevens & R. Heber, (Eds.), Mental retardation. Chicago: Univer. of Chicago, 1964. Pp. 100-142. Franks, V., & Franks, C. M. Conditionability in defectives and in normals as related to intelligence and organic deficit: the application of a learning theory model to

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a study of the learning process in the mental defeotive. In B. W . Richards, (Ed.), Proceedings of London conference on the scientific study of mental deficiency, 1960. Dagenham, England: May & Baker, 1962. Pp. 577-583. Grings, W. W.. Lockhart, R. A., & Dameron, L. E. Conditioning autonomic responses of mentally subnormal individuals. Psychol. Monogr., 1962, 76, No. 39. 1-35. HarLman, T. F., & Ross, L. E. An alternative criterion for the elimination of “voluntary’’ responses in eyelid conditioning. J. exp. Psychol., 1961, 61, 334-338. Heal, L. W. Discrimination transfer in normal and mentally retarded children of comparable dscrimination ability: partial intradimensional and extradimensional shifts as a function of overtraining. Unpublished doctoral dissertation, Univer. of Wisconsin, 1964. Herrick, R. M. Lever displacement during con3tinuous reinforcement and during a discrimination. J. cornp. physiol. Psychol., 1963, 56, 700-707. House, Betty J., & Zeaman, D. Reversal and nonreversal shifts in discrimination learning in retardates. J . exp. Psychol., 1962, 63, 444-451. Ison, J. R. Experimental extinction as a function of number of reinforcements. J . exp. Psychol., 1962, 64, 314-317. Kendler, H. H., & Kendler, T. S. Vertical and horizontal processes in problem solving. Psychol. Rev., 1962, 69, 1-16. Kendler, T. S., & Kendler, H. H. Reversal and nonreversal shifts i n kindergarten children. J . exp. Psychol., 1959, 58, 56-60. Kendler, T. S., Kendler, H. H., & Silfin, C. K. Optional shift behavior of albino rats. Psychon. Sci. 1964, 1, 5-6. Lachman, R. The model in theory construction. Psychol. Rev., 1960, 67, 113-129. Lipman, R. S. Learning: verbal, perceptual-motor, and classical conditioning. In N. R. Ellis (Ed.), Handbook of mmtal deficiency. New York: McCraw-Hill. 1 k 3 . Pp. 391423. Lipsitt, L. P.,Learning in the first year of life. Advanc. child Developm. Behav. 1963, 1, 147-195. Margulies, S . Response duration in operant level, regular reinforcement, and extinction. J . exp. anal. Behav., 1961, 4, 317-321. Miller, N. E. Liberalization of basic S-R concepts: Extensions to conflict behavior, motivation, and social learning. In S. Koch (Ed.), Psychology: a study of a science. Vol. 11. General systematic formulations, learning and special processes. New York: McGraw-Hill 1959. Pp. 196-292. Morison, R. S. “Gradualness, gradualness, gradualneas” (I. P. Pavlov). Amer. Psychologist, 1960, 15, 187-197. Notterman, J. M. Force emission during bar pressing. J. exp. Psychol., 1959, 58, 341-347. Report of the Task Force on Behavioral and Social Research. President’s Panel on Mental Retardation. Washington: Supt. of Documents, 1964. Ross, L. E. The decrernental effects of partial reinforcement during acquisition of the conditioned eyelid response. I . exp. Psychol., 1959, 57, 74-82. Ross, L. E. Conditioned fear as a function of CS-UCS and prohe stimulus intervals. J. exp. Psychol., 1961, 61, 265-273. Ross, L. E. Eyelid conditioning as a tool in Psychological research: Some problems and prospects. In W. F. Prokasy (Ed.), Classical conditioning: A symposium. New York: Appleton, 1965. Ross, L. E., & Hartman, T.F. Hu,man eyelid conditioning: the recent experimental literature. Genet. Psychol. Monogr., 1965, 71, 177-220.

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Ross. L. E., Koski, C. H., & Yaeger, J. Classical eyelid conditioning of the severely retarded: Partial reinforcement effects. Psychon. Sci. 1964, 1, 253-254. Sanders, B., Ross, L. E., & Heal, L. W.Reversal and nonreversal shift learning in normal children and retardates of comparable mental age. J . exp. Psychol., 1965, 69, 84-88. Spence, K. W., & Ross, L.E. A methodological study of ,the form and latency of eyelid responses in conditioning. J . exp. Psychol., 1959, 58, 376-381. Stevenson, H. W. Discrimination learning. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Pp. 424-438. Zeaman, D., & House, Betty J. The role of attention in retardate discrimination learning. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGrawHill, 1963. Pp. 159-223. Zigler, E. Metatheoretical issues in developmental psychology. I n M. H. Marx (Ed.), Theories in contemporary psychology. New York: Macmillan, 1963. Pp. 341-369.

The Structure of Intellect in the Mental Retardate’ HARVEY F. DINGMAN CALIFORNIA STATE DEPARTMENT OF MENTAL HYGIENE, PACIFIC STATE HOSPITAL, POMONA, CALIFORNIA

AND

C. EDWARD MEYERS CALIFORNIA STATE DEPARTMENT OF MENTAL HYGIENE, UNIVERSITY OF SOUTHERN CALIFORNIA, LO9 ANGELES, CALIFORNIA

I. Introduction ......................................... 11. Identifying and Naming Factors ...................... 111. Research Models for Use in Factorial Study of Abilities in the Retarded ...................................... A. Analyses of Conventional Tests . . . . . . . . . . . . . . . . . . . B. Structure of Intellect Model ..................... IV. Problems of Applying Factor Study to Young and Retarded Children ...................................... V. Factor Analytic Processes and the Availability of Computers ............................................... VI. Uses of Factor Analysis . .................... A. Analysis of Existing ................... B. Hypothesizing and Seeking Factor Structure ........ C. Utilization of Factor Findings .................... D. Use of Factor Scores .... ................... E. Use of Factored Measures as Controls in Experiments ........................................... F. Use of Factor Batteries in Program Planning ...... VII. Problems of Factorial Investigation of Subgroups of Retarded ............................................ VIII. Factorial Studies Using Preliterate Normal and Retarded Children ............................................. A. Early Reports ................................... B. Reports on Age Scales ............................ C. Studies of Retarded on Wechsler Tests ............ D. Factor Hypothesizing Studies ..................... 1

56 57 59 59 60 61

64 64 65 65 66 67 67 68 68 70 70 70 70 71

Supported in part by the National Institute of Mental Health Grant No. MH-

08667: Socio-Behavioral Study Center for Mental Retardation. Pacific State Hospital,

Pomona, California.

55

56

H . I;. Dingman and C. E . Meyers IX. Factors Established at Preliterate Levels . . . . . . . . . . . . . . . . X. Summary and Conclusions ............................ Referenm ...........................................

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1. INTRODUCTION

This chapter reviews the role that factor analysis can play in research on mental retardation. Attention will be given to findings as they apply to the retarded, as well as to the limits of the method and to potentialities not yet applied to this field of investigation. Factor analysis is a data reduction technique, and its employment and consequences depend on the particular research problem, whether in the area of personality, motivation, or ability. The mathematical theory and other statements of factor analysis have been spelled out by Harmon (1960) and Thurstone (1947). The present discussion will not duplicate them but rather will attend principally to the employment of the processes in their area of most relevance to the study of retardation-the study of the abilities of children of preliterate levels of development. An explanation is required to make later commentary meaningful. The total variance of a set of test results may be considered to consist of “true” and “error” variance. The former is called variance due to reliability, the latter due to error or unreliability. But if a group of tests has been administered and all measures reduced to a common form such as r-scores, then the total variance may be thought of as having three components: (a) Variance due to common factors; or variance due to more than one test variable (this sums to a term called the “communality”). (b) Variance due to factors specific to individual test variables. (c) Variance due to error. “True” variance now has two components. A factor analysis utilizing communalities reveals the presence of common factors (common in a particular study). If the reliability of a test greatly exceeds the communality (or hz), the investigator may be curious to know what human trait is being measured, over and above the common factor variance identified thus far, if any. He may therefore program his next factor analysis to couple the test with other tests likely to bring forth the trait presumably being sampled, but not yet identified, as a common factor. Thus, what might at first have been inferred to be a specific variance for the test may be shown ‘to consist of one or more further common factors. If no estimate of reliability is available, and if the h* value is high, the researcher is much less certain that there is further investigative work worth doing from the standpoint of the common factor composition of a test.

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II. IDENTIFYING AND NAMING FACTORS

When the above concepts are applied to research i n retardation, one can use multiple measures with a group of subjects. The measures are intercorrelated. Factor analysis of the intercorrelations will permit conclusions to be drawn as to the kind and number of underlying variables in order to explain the data. The commonest of the measures applied to retardation are those of ability which are applied in order to determine the common factors which underlie the separate tests of memory, vocabulary, spatial relationships, analogies, comprehension, etc. Aspects of personality, as given by ratings and other assessments, have been analyzed (McKinney, 1962). One can similarly discriminate the underlying rubrics of physical growth, motivation, motor skill, and other domains of interest, and some of these have in fact been investigated factorially. Given a set of intercorrelated test (or other) scores, the factor analysis may produce one of two or ‘three varieties of results. If a predominant common factor saturates all or most of the test variables, one calls it a “general” factor. A general factor is most likely to be found when the intercorrelation matrix is “flat,” that is, lacks highs and lows and shows no clustering of tests. On the other hand, if clearly different common factors emerge, saturating different tests in some meaningful way, the term “common factor” or “primary” or “group factor” is employed. Sometimes both a general factor and lesser group factors are obtained; this has happened on Wechsler-type scales, with a general factor saturating most subtests, attended by verbal and performance common factors. It is necessary to distinguish between the appearance of a factor and the name given to it, for the latter assumes acceptance of the factor as a true facet of ability (or of personality, etc., depending on ,the context). Factors can be artifacts of the situation. For example, if a first and significant general factor obtains, it may or may not warrant interpretation as a general mental ability. It may rather reflect a nonability source of common variance due to age variability, difficulties in understanding directions for all tests, or other irrelevant sources. Group factors are likewise subject to spurious determination. For example, two tests which are so like each other as to represent alternate forms of the same test may have a high intercorrelation which is really a reliability c o d cient, thus determining a so-called doublet factor. It is possible to use odd-even intercorrelations on each test administered, thereby securing a “factor” for each test. Doing so defeats the whole purpose of the analysis, which is to serve parsimony. When, then, is a factor as obtained accepted as a true indicator of ability, or of whatever component of personality it appears to indicate? There is a technical criterion and a contextual one. As a rule the technical criterion is composed of two

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steps. First, the factor should be represented by three or more test variables. When only two load on the factor, interpretation is insecure and replication in further work, using some of the same variables with some new ones, is generally required. T h e initial or the replicative work will include factor determination around the new factor. T o give an example, the ability called ideational fluency or divergent semantic ability consists of being productive in language (e.g., giving lots of good reasons, giving many uses for an object, etc.). If such an ability is identified, it must be distinguished from verbal comprehension (cognitive semantic ability), and the same test matrix should have included sufficient verbal comprehension tests (vocabulary, similarities, etc.) to permit factorial separation of them from the fluency tests. The contextual criterion for accepting a factor is probably obvious. T h e factor must make psychological sense in its own right, as distinguished from neighboring factors. In the instance used above, the separation of verbal comprehension from expression must be in accord with other observations of children and differences among them. One must acknowledge the existence of children whose ability to comprehend differs from their level of ability to be expressive. In this instance, such children are found, even extreme clinical types such as aphasics and autistics. The name selected for the factor usually stems from tests most heavily saturated with it. Occasionally a clear replication of a factor identification is not noticed because different names have been used. Illustratively, the commonly found perceptual speed factor has been called figural identification, evaluation of figural units, and other terms. I n the factor analyses of the ITPA it was labeled “figural decoding” (McCarthy and Kirk, 1963). Occasionally the names given bear only an oblique relation to the qualities sampled in the most representative variables. Confusion would be reduced by employment of a coded system such as Guilford’s (Guilford & Hoepfner, 1963) or Cattell’s (1957). A further definitional element requires discussion. After factor extraction, the factors are “rotated” to achieve a meaningful structure. Choices lie in the hands of the investigator (although he may have programmed the choices to be exercised objectively by a computer, most common nowadays). T h e choices are determined by the criteria to be served. One is so-called “positive manifold,” or a belief that abilities can exist only in the positive form. There is rarely a serious question raised about this. A second, about which there is debate, is degree of correlation permitted between factors. Sometimes a good “orthogonal” structure cannot be achieved. Orthogonal, of course, means that the factors are to be essentially uncorrelated. A frequent problem with such rotations involves bothersome loadings of small and moderate size. Although these

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loadings do not make psychological sense, they accompany the larger loadings that do make psychological sense. Perhaps the tests have not been made pure enough, or perhaps it is a truth of nature that the perceived ability cannot exist independently. Whatever the reason. the investigator may choose to accept correlated factors. The argument is best seen in the famous analogy that states that while weight and stature are correlated, they are nevertheless separately meaningful attributes. T o permit correlated factors may yield a better factor structure, at least in appearance, but it may also tend to cause one to forget that the obtained factors do interrelate. In any case, the investigator must report the kind of rotation he performed and must show a table of factor intercorrelations if he permitted such. He may pursue his study by making a secondary analysis of these, to yield, possibly, second-order factors. Some theorists prefer rotation to correlated factor structure, because their basic postulate about the nature of ability is one of a hierarchy (Cattell, 1963; Humphreys, 1962; Thurstone, 1947). This is in contrast with Guilford (1964) who prefers to hold to orthogonal standards of rotation. In the area of retardation, particularly with children, the construction of pure tests that will give orthogonal factors is very difficult and time consuming. In specific studies of selected groups, the emergence of some factors of intellect might well be truncated. For example, patients with cerebral palsy may not show a strong factor of motor ability when given a large battery of intellectual and motor tasks. Studies of infants must produce fewer factors, since reasoning and arithmetic skills probably develop later. It would, however, be useful to try to devise reasoning tests for infants. This supposition of factors in the handicapped and very young may produce correlated factors on the dimensions that do emerge. It would be interesting to note the emergence of factors, since it is an open question whether the new factors will split away from established factors or will develop independently. 111. RESEARCH MODELS FOR USE IN FACTORIAL STUDY OF ABILITIES IN THE RETARDED

There are, from the standpoint of their source data, two types of factorial study of the abilities of normal and handicapped children. One of them utilizes the files of existing test data, if suitable, for factor analysis. The other starts with hypotheses and then develops new data for empirical demonstration or defeat of the hypotheses. A. Analyses of Conventional Tests

The first type of factorial study is exemplified in the work of Ball (1961) and Stott and Ball (1963). They sought to determine the extent

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to which separate factors of ability could be demonstrated in infants and young children. T o do so, they used the responses given by young subjects when examined on the existing instruments for the measurement of mental development (e.g., the Gesell scales, the Merrill-Palmer, the Stanford-Binet, etc.). T h e behaviors sampled by these instruments were the ones which the scale makers found easiest to elicit and which seemed to have face validity for appraisal of general behavioral development. Comparison of the items utilized at different developmental levels indicates little continuity in the specific functions elicited by the items. Full continuity is, of course, precluded because of the limited responsiveness of the younger child, particularly the infant. T h e makers of these scales did not have co?tinuity of specific psychological functions in view as an end in itself, but rather sought an overall assessment of development. Thus, any search for continuity of specific functions (or factors) of ability, such as Stott and Ball (1963) have attempted from infancy through nursery years, is limited by the nature of the data. Similarly limited by their source data are the factor analyses of such scales as the Binet and WISC at older ages. These also can reveal no more factors than happen to be present, and what is present is variable from age level to age level. Since children are capable of so many more functions than are represented in the general scales, it is patent that such scales cannot provide an exhaustive foundation for the study of abilities. B. Structure of Intellect Model

The investigations of abilities in the young adult provide a more sophisticated model for the study of childhood intellect and personality. Factor analysis has had its finest hour in its many applications in college, military, and industrial settings. The work has gone far beyond the mere identification of characteristics present in the existing repertory of aptitude devices. It employs a hypothetico-deductive process in which each analysis leads to another one, following the postulation that there are always more human functions to be sampled. Only the study of personality has enjoyed a similar level of factorial exploration, and some day there will be similar development in the analysis of human motives, interests, psychomotor skills, and other domains. Because of its sophistication as a model for imitation, the status of factor analysis of abilities in young adults will be considered, together with a look at its present-day outcome, the structure of intellect. T h e psychometric monograph by French (1951) and the papers by Fleishman (1953; 1957) demonstrate a consistency of findings from one research to another in which factor analysis has been employed with rotation to simple structure and positive manifold. McNemar (1964), although he

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disagrees with some applications of factor analysis, points ,to the similarity of findings routinely arrived at in the field of ability measurement whether the research was done with college students or aviation cadets, or on the East or West coast, or compared with investigations made in different universities. The consistency of findings has led to Guilford's attempt in 1959 to define a structural framework of human abilities and to the availability at Educational Testing Service of a large battery of tests, with known factor loading, developed with the assistance of Division 5 of the APA. It is certainly true, as McNemar (1964) points out, that the tests of the factored variety have no greater validity for certain purposes than ordinary tests, but at least the factor findings of research have been clear. It is regrettable that, in spite of the existence of such aids as the ETS battery or the Guilford model or Cattell's (1957) UI series, there continue to be published a number of factor analyses of standard intelligence tests with interpretations unguided by one of these frames of reference. Without such guidance the results are difficult to interpret, highly redundant, and of little use in guiding future investigation. The diverse results published in the monograph by French (1951) have been gathered by Guilford (1956) into a single theoretical framework which he refers to as the structure of intellect. In all, Guilford hypothesizes that there may be as many as 120 factors reported in common tests of intellectual capacities. This issue, however, is viewed incorrectly if one sees only the 120 separate abilities. Guilfords structure is best perceived if viewed as three-dimensional. As such, it is a simplification of the findings collected by French in his monograph and progressively systematized by Guilford (1956; 1958; 1959). Not all of the actual and hypothetical factors in the structure are expected to serve as ability hypotheses for young and retarded children (as is seen below), for such subjects are not expected to have so much differentiation of structure. The particular value of the structure as a model for research with retarded and preschool children is its provision of a systematic guide for hypothesizing abilities. It thereby directs the attention of the investigator beyond the limitations of the behavior samples customarily employed in infant and child tests. IV. PROBLEMS OF APPLYING FACTOR STUDY TO YOUNG AND RETARDED CHILDREN

Two principal factors have thus far precluded extensive exploration of abilities in young and retarded children in spite of obvious clinical and research interest. The first is theoretical. It was generally assumed,

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with good reason, that abilities in the young are not well differentiated. Garrett (1946) was of this opinion and was seconded by Thurstone (1948). Under such a belief there is less promise of a rewarding search. In addition, the practical success of compound tasks, as employed in general instruments such as the Binet or Gesell, in giving a useful overall appraisal of a subject, meant that no strong demand had to be made for revised instrumentation. What need did arise was satisfied by auxiliary devices such as the Bender, Drawa-Man, etc. The second difficulty is expense. T h e adult factor studies, which led to the Guilford model, enjoyed the advantage of educated, cooperative subjects capable of being tested in large groups by means of IBM answer sheets. This advantage is also enjoyed in explorations of high school and upper elementary grades. Below fourth grade, however, the assumptions about group testing of normal children, much less the retarded, are not so trustworthy; and for the kindergarten-primary level, testing in small groups by paper-pencil means can be regarded as little more than a screening process. As lower CA’s and MA’s are approached, the call for psychometric skill is ever greater, and clinically competent individual testing is required for satisfactory data. Furthermore, the paper-pencil capabilities of a normal child at, for instance, the first grade level, are so undeveloped that even individual testing with such instruments would be limited and would miss the excellent spectrum of competencies otherwise available. Those familiar with clinical psychometry of young and handicapped children need not be informed of the difficulty of such testing and of the problem of getting subjects in the precious moments when they are not concerned with naps, anxieties, illness, and the like. With handicapped children one must also consider the possible effect of drugs on behavior. There is, therefore, expense not only in individual test-giving, but also in the need to use two or more sessions to secure data on a single subject. In contrast with the room full of cadets as captive subjects, the young child as one subject must be sought out and parental permission must be secured before testing is ever started. Because tasks must be accepted by subjects, ingenious ways must generally be tried to place the difficulty where it is intended. A so-called picture vocabulary might not be a test of verbal comprehension, as intended, if the principal difficulty resides in interpreting the cartoonlike picture (this may be demonstrated with some materials presently used). Frequently a “set” has to be taught; for example, if the oddity principle is employed to study perceptual discrimination, the manner of attending and responding must first be taught with abundant examples. The demand for care is greater than in clinical testing for a general score. In the latter, for

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instance, a subject‘s refusal or other spoilage of an item requires only that the examiner “omit and pro-rate” in his scoring. Missing a subtest in a factor study, however, spoils all the data for that subject. Similarly, the clinician is interested in the overall score, whereas a good measurement in a factor study must be secured for each individual scale. A further element of cost is implicit in the requirements for factor identification. Mention was made above of the ETS battery of tests. These and other instruments have established factor saturation, and they, together with new instruments which represent new hypotheses, are used as “reference” or “marker” tests in a battery thus enabling the new to be interpreted in terms of the old. Such established factor tests are not available, except in a nascent way, for the preliterate levels. To take a factor which has been established at higher levels down to the preliterate level is a step largely into the unknown; the particular behavioral characteristics representative of the factor in question will require considerable extrapolation and adaptation. As stated earlier, three tests or more must be employed to represent a hypothesized ability factor. Without a pre-existing established structure of reference tests, doubt would remain until there is suflicient replication. Three tests or more per hypothesis means, perhaps, a dozen or more altogether, for a factor-hypothesizing study can never be done piecemeal. Without simultaneous data on a breadth of competencies, findings would lack interpretation. Furthermore, it is difficult to develop three or more tests per factor. It is not sufficient to simply make alternate forms of a test, for this would only yield reliability coefficients, and would not contribute to factor structure. Good ideas for tests sometimes do not work out; the subject may be too absorbed in the material to accept a test task, or the source of individual differences may lie in some element beyond control (at young age levels the chief culprit is difficulty with attention). Hence, before any testing is done, a considerable developmental period with much experimenting, casting aside, revising, and inventing is necessary. The procedures also have the unhappy consequence of using up available subjects before there is an accumulation of usable data. In addition, factor analysis in test modification and development is an iterative process. One does not simply perform an analysis and let it go at that. Tests developed for an analysis rarely function at first as well as planned by the experimenter. Frequently they prove impure in that they sample traits other than the one intended and may poorly measure the one for which intended. Under such circumstances the factor analysis has merely served as an aid in understanding the actual process used by the subjects in arriving at their test scores. The informa-

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tion is then utilized in the next revision of the tests. The revised instrument may hopefully perform as desired. There are related problems. A test factored and shown to be a good measure of a specified ability may perform differently with different subjects. This may be true because the subjects varied in maturity level or practice in skills, or because the new battery may not have included sufficient instrumentation to identify and separate the factor from related factors. V. FACTOR ANALYTIC PROCESSES AND THE AVAILABILITY OF COMPUTERS

There were formerly two principal barriers hindering all factor analytic investigations. One was the cost of procuring data which led to the redundant studies that were used to analyze the existing files on such data as WISC subtests. The other was the cost of the elaborate calculation required for factor analysis and rotation. The first cost remains and was discussed above. The second is being brought under control. Programs for large-scale digital computers now perform not only the factor extraction but also the objective rotation, and costs have therefore decreased markedly. Government and other funds are now available for research in retardation making it feasible to administer large batteries to persons of limited mental ability to further the body of knowledge. Eventually it should be possible to have a structure of factors for young and retarded children. This would have been unrealizable 5 or 10 years ago. With the computers have come developments in their programming. Experimenting is presently being carried on with (1) new techniques that will utilize curvilinear correlations and continuous variables, and with (2) objective rotations to both orthogonal and oblique criteria. Still further, new computer programs for estimating factor scores earned by individual subjects will be available soon. Thus, in a few years, when one can make tests of statistical significance between groups on the basis of their factor scores and when one can conduct factor analysis on other than bivariate normal distributions, most of the criticisms of factor analysis will have been met from the statistical standpoint. VI. USES OF FACTOR ANALYSIS

Although the general literature of factor analysis reveals all of the levels of utilization possible, the level of utilization with handicapped and normal children has thus far been primitive. Several uses may be

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outlined, with the principal examples being those that apply to the retarded. A. Analysis of Existing Test Data

Because of expense (mentioned above), most of the factor studies have been analyses of “canned” data, performed on files of test results secured over a period of time in schools, clinks, or research centers on standard instruments such as the Gesell, Merrill-Palmer, Binet, WISC, and WAIS, the last two being most popular recently. Such data were not first compiled for the purpose of studying “structure,” but for purposes in which, as a rule, the IQ or DQ as a whole was of interest. This type of factor analysis can reveal nothing new. The scales, except for the verbal and performance contrasts possible in Wechsler’s scales, were not developed for purposes of revealing differentiated ability. Use of subtest comparisons is, in fact, discouraged by the makers. In the instance of the Stanford revisions of the Binet, much effort indeed was expended to purify the “general” nature of the instrument by utilization of the internal consistency criterion €or selective retention of items (McNemar, 1942; Terman, 1916; Terman & Merrill, 1937; 1960). Such source data are therefore thin soil for the discovery of factors of intelligence. As seen below, the Wechsler tests as a rule yield only two or three factors. There is no objection to finding what structure, if any, exists in such an instrument, but two reflections on the published efforts must be made. First, such analyses often carry brave hopes and titles not warranted by the little that could have been accomplished, as for example, “The factor structure of . . . .” Second, little structure of an interpretable nature could emerge without “marker” variables in the factored matrix. While it is true that marker or reference variables do not exist for younger ages, some instruments do exist which, if added to the matrix to be analyzed, will help interpretation (as in Satter’s work, 1955). There is therefore a bit of bravado in an analysis that is limited to a single scale such as a Wechsler or Binet. The use of them has beclouded the issues to a degree and has slowed the search for wider spectrums of human abilities in childhood. B. Hypothesizing and Seeking Factor Structure

By going beyond the mere scrutiny of existing data, the hypothesizing and searching for structure makes a greater use of the potential of factor analysis. When the collation of many factor reports (French, 1951) indicated consistency in factor findings, it became logical for Guilford to develop his structure, as described above. The Guilford structure is not so much an end in itself as it is a means

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toward other ends. Serving as a model or theory, the structure clarified what was becoming a bewildering collection of information. I t also provided a code or labeling process by which abilities could be described. It presently plays a hypothetico-deductive role in determining the direction of further research in abilities not yet identified by inferring from the known to the nature of the unfilled portions of the 120-celled structure. The prospective investigator is again warned that hypothesizing and seeking factors is expensive business, especially when individual testing is required. An additional expense that must be made explicit lies in the hours of creative effort required to formulate reasonable hypotheses. These must be arduously derived from the observation of human abilities not yet put into testing forms, from the literature of learning and human difference, from the previously performed analyses, and from the consideration of variables that do not behave as they were hypothesized. Hypotheses come from many places, but one must work to obtain them. C. Utilization of Factor Findings

The determination of factors from a set of data does not imply an end of a process. There are two aspects to this. The first utilizes factors identified in the repetitious process of the improvement of measures, approaching factor purity where possible, and/or ascertains the structure, even if factorially complex, of clinically significant instruments such as a Bender. This first use, then, is essentially one of measurement improvement. From a clinical point of view, improvement of measurement has another side. I t involves the reduction of redundancy currently suffered when an extended battery must be administered to secure a good description of the patient. A clinical record often shows that not only has a WISC been administered but also the Binet, a Bender, Raven, Frostig, and perhaps now an ITPA or Peabody, all in a very short period of time. It is possible that as much as half of the effort is thereby wasted. For example, if a “general-verbal” as found in the WISC is of interest, it is redundantly secured from many WISC subtests as well as from some ITPA variables and the Peabody. If clinical tinie and subject effort are wasted in redundancy, there is less hope for expanding the battery to include newly found aspects of performance, such as semantic or figural divergence, social reaction, or psychomotor competencies, Some of which may prove of considerable significance in eventual clinical prediction.

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D. Use of Factor Scores

Factor analysis is also used to determine factor scores (possible if loadings are obtained, whether the measures approach purity or not) which summate the factor qualities of subjects. The scores can then be utilized in intergroup comparison, differential diagnosis, clinical prediction, educational planning, etc. It is remarkable how little utilization of obtained factors has thus far been made. There is, perhaps, much too much comfort in finding and reporting the factor loadings as a final determination of “the results” or “the factor structure.” Even the primitive findings on Wechsler’s tests should have then been used to study and contrast clinical types, age levels, etc., not so much in factor structure, but in profiles of factor scores. One good use was the relating of retardednormal difference in WISC factor structure to Ellis’s (1963) trace theory of retardation (Baumeister & Bartlett, 1962a; Baumeister & Bartlett, 1962b); in this, factor-developed information was carried to the learning laboratory. The use of factor scores will move more rapidly with new computerized programs to manage the considerable calculations required. No factor scores are possible, however, without factor determinations, and this work has just begun for children and the retarded population. While even ,the two or three WISC factors might have some merit, they will be insignificant when compared with the dozen or more factors that are expected to be yielded by present research. In such instances it may be necessary to use a system of profile analysis. The mamage of factor analysis and profile study, has, in fact, already been suggested (Nunnally, 1962). E. Use of Factored Measures as Controls in Experiments

Although many elaborate experiments are set up with expensive equipment and advanced designs, their controls are sometimes insufficient. Among the variables used to exercise subject control in typical experiments are the intelligence test, tests for brain damage, especially developed tests for personality, etc. It has been found that the intelligence test, as a measure of general ability, is often related to performance in an experimental setting if the range of abilities of the subjects is large enough. However, use of factored ability tests should make it possible to control more precisely ,the abilities most closely related to the criterion. Different abilities would be expected to be significant from one criterion to another. For example, serial verbal learning ought to be more easily predicted by semantic memory ability .tests than by perceptual speed tests. This in turn, would provide better controls for

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learning tasks involving perceptual discrimination. Factor-pure tests of psychomotor ability, hand-eye coordination, etc., are presently available for older levels of retardates, and they are better suited as control data than is a general IQ. F. Use of Factor Batteries in Program Planning

If a battery of tests capable of sampling a wide spectrum of separate abilities in retarded children were available, schools, institutions, and habilitation centers could direct their efforts to the specific deficiencies indicated in the results of the battery, where these were deemed significant enough to develop, and could capitalize on the strengths also revealed by the battery, In addition it would be possible to provide grouping of children according to the specific deficits requiring attention rather than on the basis of composite level of ability. The deficit in the verbal area among Down’s syndrome patients is well known. It is not well known what other deficits can be found among etiologic types, partly because instrumentation has not yet been sharp enough to develop the patterns. VII. PROBLEMS OF FACTORIAL INVESTIGATION OF SUBGROUPS OF RETARDED

The preceding discussion of ,the uses of factor analysis leads both to suggestions for study and to the mention of some of the complications known to the authors through firsthand and vicarious experience. I n addition to test development and refinement and the development of measures of motivational and personality traits, it is inviting to speculate about the factorial manifestations of the perceived qualitative differences among, for example, diagnostic groups. Again, the behavior of such classic groups as those with Down’s syndrome is a well known example. What might be the objective specifications of this behavior in precise terms of independent factors of ability and temperament? How might such specification help in programming and in further research? What varieties of idiot savant can be determined? How does late prenatal injury specifically differ from early postnatal? The investigation of these intriguing issues has not gone far beyond the blueprint stage. T h e history of the USC-Pacific State factor studies gives some of the reasons why progress must be slow. In order to secure clarity of factor structure, there must be control over sources of spurious correlation, especially CA and MA range. Until lately, the achievement of such control has been more important than the securing of representative diagnostic groups. Recently a further ex-

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ploration of abilities at mental age four in retardates was planned. Only 30 subjects within a few months of that mental age could be secured from a total institutional roll of 3,000, incredible as that may seem. The remaining subjects had to be secured elsewhere. Why were so few available? For one thing, some reasonably narrow range of CA’s was desired; cutoffs were established which eliminated adults. More importantly, the sample was narrowed by requirements of testability. This problem has been mentioned elsewhere (Meyers, Dingman, Orpet, Sitkei, & Watts, 1964; Clausen, 1964) and appears to be a source not only of subject loss but also of interpretation of handicap. For example, the use of a battery of 15 tests for semantic, memory, and visual-perceptual hypotheses requires that all subjects, as explained earlier, be given all tests. The visually limited are therefore categorically excluded, because they cannot react properly to the visual-perceptual materials. The autistic and aphasic are eliminated if they do not respond with language where that is called for. The highly disturbed will yield troublesome scores, if any at all. Thus, the sample does shrink. It has only been barely possible to collect sufficient subjects of any etiology to fit the specifications for a good factor study. When the time comes to seek factorial distinctions between such groups, means will have to be found (as in pooling subjects among institutions and schools) to secure sufficient numbers who will be comparable on other grounds as well, such as CA and general MA. Another point also requires development. Many of the subjects were not included at all, and these are the ones who, for reason of their untestability, should show the grossest dips in factor profiles. For the present they are left out of consideration while the most basic work in establishing some idea of factor structure goes on. How to handle, as an epistemological matter, the untestability of the subject who is disturbed or blind is a matter probably best left for the future. At any rate, the full story of ability factor structure in the handicapped will not be told until the matter is settled. The reader may wonder why there was some concern to delimit subjects in a factor investigation by CA and general MA. Methodologically, one is advised to have as few potential sources of extraneous variability as possible. Retarded differ so greatly, from the multiple-handicapped, nonambulatory cases to the mildly retarded cases in day school classes for the educables, that if some lines were not drawn it would be impossible to draw conclusions. The reduction of CA and MA variability is just as important as the avoidance of excessive variability in other matters such as gross untestability. This is especially true in early stages. When the time comes to compare groups which vary in one of these

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atributes, the variation is the focus rather than the risk of the investigation. VIII. FACTORIAL STUDIES USING PRELITERATE NORMAL AND RETARDED CHILDREN

A. Early Reports

The first known American study reporting common factors was the work of Kelley (1928), who in his day stood alone in not placing full trust in a general ability as the sufficient description of mental ability in young children. His common factors were like those later found by the Thurstones and others. In 1953 Thurstone and Thurstone published an edition of their “Primary Mental Abilities” based on early factorial investigation which they apparently had not previously published.

B. Reports on Age Scales Richards and Nelson (1938; 1939) and Nelson and Richards (1938; 1939) analyzed Gesell data on infants and found evidence for two or more factors in each group. McNemar (1942) reported unrotated analyses of the 1937 Stanford-Binet. His purpose was not to locate factors as ends, but to determine whether item selection had been carried out well enough to guarantee an essentially “general” instrument. Hofstaetter (1954) made a T-analysis of age-to-age correlations of infant and preschool test results from the California growth study, that showed a progression of the scales through three different factors. Ball (1961) and Stott and Ball (1963) reviewed the literature on infants and young children and included some original analyses of data gathered on general scales such as the Gesell, Binet, and Merrill-Palmer. They report, consistently with earlier work, that no such study fails to reveal factor structure, in spite of the fact that the scales attempted to measure general ability. C. Studies of Retarded on Wechsler Tests

The first of a recent series was that of Alderdice and Butler (1952), whose matrix included the Bellevue subtests and Binet total IQ. Next was Satter (1955), whose matrix included those tests in addition to the Raven, HTP, Porteus, Bender, Vineland, and others. Alderdice and Butler had reported a general-verbal and a performance common factor, the latter limited to the performance subtests. Satter found in retarded the same general-verbal and performance factors as well as a third factor saturating digit span and digit symbol substitution. Since this third factor had not previously been reported, Satter could not explain it, but

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in two subsequent reports, Baumeister and Bartlett (1962a; 1962b) Obtained a similar result. On the WISC they found a general factor and separate verbal and performance common factors, saturating respective variables. But retarded Ss, unlike their normal contrast groups, revealed a fourth factor which, like Satter's on retarded, appeared to be identifield as a variability in short-term memory (Ellis, 1963). T h e validity of this apparent difference is questioned below.

D. Factor Hypothesizing Studies In addition to the historic work of Kelley and Thurstone and Thurstone, there have been several reports in recent years. A study of 6-yearold normals by Avakian (1961) revealed only fair separation of abilities. A running series reported in two monographs (Meyers, Orpet, Attwell, & Dingman, 1962; Meyers et al., 1964) and in other miscellaneous sources is still in progress. These studies hypothesized four abilities in normal children at ages 2, 4, and 6 and in retarded of comparable mental ages. Work in progress has explored the semantic abilities in normals at age 6 (McCartin & Meyers, 1964), divergent, memory, and evaluative abilities at age 6 (Orpet & Meyers, 1965), and several abilities a t mental age 4 (Carlson, Meyers, & Dingman, 1965). T h e series, as planned, will extend the concepts of the structure of intellect to the study of retarded and will eventually make interdiagnostic comparisons and longitudinal studies. Loeffler (1963) replicated and expanded the first USC-Pacific State study with retarded subjects. Both Strong (1964) and Michener (1964) have studied the retarded with extensive batteries; Strong included the ITPA subtests. McCarthy and Kirk (1963) reported factor analyses of the ITPA intercorrelations. Clausen (1964), not seeking factor structure as such, performed a study comparing normals and retarded on several variables, with factorial overtones. From Sweden, Kebbon (1964) reported a study, patterned somewhat after the USC-Pacific studies, hypothesizing and finding several factors on normal and retarded groups. IX. FACTORS ESTABLISHED AT PRELITERATE LEVELS

The recent blossoming of factor reports suggests a need for going beyond the general IQ as well as a need for available techniques and computer services. It is now possible to make a few confident statements about the status of factor identification and structure of intellect for the preliterate levels of normal and retarded children (a more complete review is provided by the authors elsewhere; Meyers & Dingman, 1965). (1) A general IQ may continue to be of clinical utility in the future,

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but it can no longer be regarded as a sufficient description of human intellect. No study performed has failed to yield some evidence of structured ability, while employment of the Bender, Raven, and others testifies to the need for added measurement. (2) Some abilities appear in sufficient replication to warrant present acceptance, at least in 5- and 6-year-old normals, if not younger. These are in nearly orthogonal relation to each other and meet fairly severe criteria for factor validity: (a) Perceptual speed, or evaluation of figural material. The quick and accurate identification or noting of differences. This is evident even in infancy. (b) Verbal comprehension, or cognition of semantic material. Understanding the language. Also evident from the first year of life. (c) Verbal fluency, ideational fluency, or divergent semantic ability. The ability to be productive with verbal ideas and examples, given a cue. Certain at 6 years of age, not yet demonstrated at 4 years with confidence, appears to be missing in retarded even if the verbal comprehension is of the 4-year level. (d) Psychomotor ability (hand-eye coordination, etc.). (e) Figural reasoning or convergent production of figural units. Evident even at mental age 4 in normals and retarded on such instruments as the Raven, modified for use with younger subjects. Not certain at 2 years. ( f ) Immediate memory for figural content. Recall of figures, toys, etc., just observed. (g) Immediate memory for verbal and symbolic content. An ability, apparently separate from ( f ) above, to reproduce digits, letters, words, etc. (h) Several other factors await replication.

(3) Studies have not yet reported consistent factorial differences between groups of normals and retarded when MA is constant. This has been true of Kebbon’s studies and of USC-Pacific studies. The demonstration by Baumeister and Bartlett of a factor possibly identified as a short-term memory or “trace” in the retarded but not in the normals is questionable. (a) T o find a factor in the retarded, which is not found in normals, is not to be interpreted as a quality in retarded not present in normals, but rather a variability great enough to produce a factor in the one group compared with the other. It is reasonable to expect the retarded to differ among each other in short-term memory more than normals do. If as a class they had poorer memory than normals, that fact would not necessarily be revealed by factor analysis.

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@) Identifying and naming the factor on the basis of the limited evidence of the WJSC subtests is risky. There are many reasons why spurious factors can emerge or real ones be hidden in an analysis of a matrix; the evidence for a factor or difference in factors must be more convincing than the WISC alone can provide. (c) Finally, Orpet and Meyers (1965) have demonstrated a short-term memory factor in normal children of 6.

The above is not to say that substantial differences between groups will not be found. The lack of difference is due to some extent to programming the comparative studies so as to give the same instruments to all subjects, normal and retarded. This causes one to omit test items not responded to by a group, and to omit from the retarded group subjects who cannot respond. Once these methodological hurdles are surmounted, it is expected that normals will demonstrate superiority in such domains as the symbolic and semantic and in such operations as the convergent and divergent. X. SUMMARY AND CONCLUSIONS

It is becoming more apparent that the use of factor analysis is evolving into a more useful tool in research on the preliterate child, whether he is retarded or simply very young. As the number of research centers increase, more tests for abilities will be developed. There will also be more replication of the early factor analysis studies. These will provide research workers with more confidence in the results of factor analyses on retarded subjects. As the confidence in the results increase, more use will be made of factor scores in planning experimental research. The use of factor scores and patterns of factor scores should provide a needed stimulus to the investigators of particular diagnostic entities in the field of mental retardation. The lack of verbal ability in patients with Down’s syndrome has been noted, but the specific nature of the types of deficits in verbal ability has not been studied. No knowledge at all is available concerning the patterning of the abilities of patients with such disorders as phenylketonuria and galactosemia. These hereditary deficits are understood from a biochemical level, but the locus and nature of the insult to the brain are not well understood. More generalized insults to the brain, such as hydrocephalus and microcephaly, may not produce patterning in intellectual functioning, but the evidence is far from clear. Since the damage to the central nervous system that produces retardation can produce differences in physical development (Mosier, Grossman, & Dingman, 1965), some systematic differences in intellectual functioning might also be produced.

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Very little is known about the extent to which the abilities reflected in a factor analysis can be changed by training. The patterns of factor scores should challenge educators tc develop programs for those patients who show deficits in their factor score patterns. At the same time, the knowledge of the factor score pattern should be useful for planning education and habilitation programs. The development of programs around the skills of the patient and the avoidance of specific areas of his handicap could lead to better training and fewer frustrations and emotional difficulties in the learning situation. As more factor studies are carried out with young children, factorial tests will be available to begin longitudinal studies to aid in the investigation of the development of the intellect. Studies at selected age levels seem to show a continuity of factorial development, but it seems clear that there must either be more splitting of factors or development of new factors before a child reaches adulthood. T h e specific nature of these changes must be understood if a complete picture of the evolving intellect is to be understood. Of course, the understanding of the developing intellect should provide the basis for experimental work in accelerating the progress of certain skills that may have special social utility. Thus, the value of factor analysis as a research tool increases as large scale digital computers make the technique more available to research workers in the area of mental retardation. I t can be seen that factor analysis can be used in many different types of research endeavors. The technique has many possible advantages in the development of training or research programs, but the knowledge and the skill of the individual scientist are the major limitations. In a truly multivariate universe, the scientist who limits his investigations to one or two variables must also find his conclusions limited. T h e reduction of the multiplicity of effects and variables to those that are really most important (in the sense of parsimony of description) simplifies research and makes the findings more general. REFERENCES Alderdice, E. T., & Butler, A. J. An analysis of the performance of mental defectives on the revised Stanford-Binet and the Wechsler-Bellevue Intelligence Scale. Amer. J . ment. Defrc., 1952, 56, 609-614. Avakian, S. A. An invesfigation of trait relationships among six year old children. Genet. Psychol. Monogr., 1961, 63, 339-394. Ball, Rachel S. Factor analysis of mental tests at infant and pre-school level. Paper presented at Amer. Psychol. Ass.. N.Y.,1961. Baumeister, A. A., & Bartlett, C. J. A Comparison of the factor structure o l normals and retardates on the WISC. Amer. 1. ment. Defic., 1962, 66, 641-646. (a)

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Baumeister, A. & Bartlett, C. J. Further factorial investigation of WISC performance of mental defectives. Amer. J. ment. Defic., 1962, 67, 257-261. @) Carlson, D. C., Meyen, C. E., & Dingman, H. F. An investigation of language, memory and perceptual abilities in retardates of mental age four. Unpublished manuscript, Staff Library, Pacific State Hospital, 1965. Cattell, R. B. A universal index for psychological facton. Psychologia, 1957, 1, 74-85. Cattell, R. B. Theory of fluid and crystallized intelligence. J. Educ. Psychol., 1963, 54, 1-22. Clausen, J. Ability structure and subgroups of retardates. Paper presented to annual meeting, Amer. Ass. of Ment. Defic., Kansas City, May, 1964. Ellis, N. R. Ed. The stimulus trace and behavioral inadequacy. In Handbook of mental deficiency. New York: McGraw-Hill, 1963. Fleishman, E. A. Testing for psychomotor abilities by means of apparatus t e s t a Psychol. Bull., 1953, 50, 241-262. Fleishman, E. A. A comparative study of aptitude patterns in unskilled and skilled psychomotor performances. /. appl. Psychol., 1957, 41, 263-272. French, J. W.The description of aptitude and achievement tests in terms of rotated factors. Psychometr. Monogr., 1951, No. 5. Garrett, H. E. A developmental theory of intelligence. Amer. Psychologist, 1946, 1, 372-378. Guilford, J. P. The structure of intellect. Psychol. Bull., 1956, 53, 267-293. Guilford, J. P. A system of the psychomotor abilities. Amer. 1. Psychol., 1958, 71, 164-174. Guilford, J. P. Three faces of intellect. Amer. Psychologist, 1959, 14; 46-79. Guilford, J. P. Zero correlations among tests of intellectual abilities. Psychol. Bull., 1964, 61, 401-404. Guilford, J. P., & Hoepfner, R. Current summary of structure-of-intellect factors and suggested tests. Rep. Psychol. Lab., No. 30. Los Angeles: Univer. Southern California, 1963. Harmon, H. H. Modern factor analysis. Chicago: Univer. of Chicago Press, 1960. Hofstaetter, P. R. The changing composition of “intelligence”: a study of T-technique. J . genet. Psychol., 1954, 85, 159-164. Humphreys, L. D. The organization of human abilities. Amer. Psychologist, 1962, 17, 475-483. Kebbon, L. Ability structure and special defects in the mentally retarded, Int. Copenhagen Congr. sci. Stud. ment. Retard., Aug. 7-14, 1964. (Abstract) Kelley, T. L. Crossroads in the mind of men. Stanford: Stanford Univer. Press, 1928. Loeffler, F. J. An extension and partial replication of Meyers et al., primary abilities at mental age six. Paper read a t SOC. for Res. in Child Develpm., Berkeley, April, 1963. McCarthy, J. J., & Kirk, S. A. The construction, standardination and statistical characteristics of the Illinois Test of Psycholinguistic Abilities. Urbana: Inst. for Except. Child., 1963. McCartin, Sr. Rose Amata, & Meyen, C. E. An exploration of six semantic factors a t first grade. Unpublished manuscript, Staff Library, Pacific State Hospital, 1961. McKinney, J. P. A multidimensional study of the behavior of severely retarded boys. Child Develpm., 1962, 33, 923-938. McNemar. Q. The revision of the Stanford-Binet scale. Boston: Houghton, 1942. McNemar, Q. Lost: Our intelligence? Why? Amer. Psychologist., 1964, 19, 871-882.

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Meyers, C. E., & Dingman, H.F. Factor analysis and structure of intellect applied to mental retardation. In Mental retardation abstracts. Columbus, Ohio: Amer. Ass. on Ment. Defic., Docum. Serv., 1965, 2, 116-127. Meyers, C. E.,Dingman, H. F., Orpet, R. E.,Sitkei, E. G., and Watts, C. A. Four abilityfactor hypotheses at three preliterate levels in normal and retarded children. Monog. SOC.Res. Child Develpm., 1964, 29, No. 5. Meyers, C. E., Orpet, R. E., Atwell, A. A., & Dingman, H. F. Primary abilities a t mental age six. Monog. SOC. Res. Child Develpm., 1962, 21. No. 1. Michener, R. The intellectual factor composition of some standardized Piaget tests. Paper presented at convention of Amer. Ass. on Ment. Defic., Kansas City, 1964. Mosier, H. D., Grossman, H. J., & Dingman, H. F. Physical growth and mental defectives: A study in an institutionalized population. Monogr., Pediatrics, 1965, 36, No. 3, Part 11. Nelson, V. L., & Richards, T. W. Studies in mental development: I. Performance on Gesell items a t six months and its predictive value for performance on mental tests a t two and three years. J . genet. Psychol., 1938, 52, 303-325. Nelson, V. L., & Richards, T. W. Studies in mental development: 111. Performance of twelve months old children on the Gesell schedule and its predictive value for mental status a t two and three years. J . genet. Psychol., 1939, 54, 181-191. Nunnally, J. The analysis of profile data. Psychol. Bull., 1962, 59, 311-319. Orpet, R. E., & Meyers, C. E. Studies of evaluative, memory, and divergent factom at six years. 1965. In press. Richards, T. W., & Nelson, V. L. Studies in mental development: 11. Analysis of abilities tested at the age of six months by the Gesell schedule. J . genet. Psychol., 1938, 52, 327-331. Richards, T. W., & Nelson, V. L. Abilities of infants during the first eighteen months. J . genet. Psychol., 1939, 55, 299-318. Satter, G. Retarded adults who have developed beyond expectation-Part 111: Further analysis and summary. Train. Sch. Bull., 1955, 51, 231-243. Stott, L., & Ball, Rachel S. Evaluation of infant and preschool mental tests. Detroit: Merrill-Palmer Inst., 1963. Strong, R. T., Jr. Factorial analyses of psycholinguistic abilities in mentally retarded youth: I. Common factor solution. Unpublished report, Refort of Progress, Columbus, Ohio, 1964. Terman, L. M. The measurement of intelligence: an explanation of and a complete guide for the use of the Stanford revision and extension of the Binet-Simon Intelligence Scale. Boston: Houghton, 1916. Terman, L. M., & Merrill, M. E. Measuring intelligence: a guide to the administra. tion of the new revised Stanford-Binel Tests o f Intelligence. Boston: Houghton, 1937. Terman, L. M., & Merrill, M. E. Sanford-Binet Intelligence Scale: manual for the third revision, Form L - M . Boston: Houghton, 1960. Thurstone, L. L. Multiple-factor analysis. Chicago: Univer. of Chicago Press, 1947. Thurstone, L. L. Psychological implications of factor analysis. Amer. Psychologist, 1948, 3, 402-408. Thurstone, L. L., & Thurstone, Thelma G. SRA Primary abilities for ages 5-7. Chicago: Sci. Res. Ass., 1953.

Research on Personality Structure in the Retardate EDWARD ZIGLER DEPARTMENT OF PSYCHOLOGY, YALE UNIVERSITY, NEW HAVEN, CONNECTICUT

77 I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 11. The Lewin-Kounin Formulation ....................... 82 111. The Motivational Hypothesis .......................... IV. Social Deprivation and Institutionalization . . . . . . . . . . . . 85 90 V. Positive- and Negative-Reaction Tendencies . . . . . . . . . . . . 94 VI. The Reinforcer Hierarchy ............................. . . . . . . . . . . . 97 VII. Expectancy of Failure . 99 VIII. Outer-Directedness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IX. Conclusions . . . . . . . . . . . . . . . . . . . . . . 103 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

1.

INTRODUCTION

It has long been the author’s view that many of the reported behavioral differences between familial retardates and normal children of the same MA are a product of a variety of differences in the motivational systems of these two types of children rather than a result of any immutable effects associated with mental retardation per se. It has become increasingly popular for theoreticians to conceptualize the familial retardate as pursuing not only a slower and more limited course of cognitive development, but as suffering from a variety of specific physiological or quasi-organismic defects as well. Indeed, a plethora of such defects has now been postulated. We have been informed that retardates suffer from (1) a relative impermeability of the boundaries between regions in the cognitive structure (Kounin, 1941a; Kounin, 1941b; Lewin, 1936), (2) primary and secondary rigidity caused by subcortical and cortical malformations, respectively (Goldstein, 1943), (3) inadequate neural satiation related to brain modifiability or cortical conductivity (H. H. Spitz, 1963). (4) impaired attention-directing mechanisms (Zeaman, 1959), (5) a relative brevity in the persistence of the stimulus trace (Ellis, 1963), (6) malfunctioning disinhibitory mechanisms (Siege1 & Foshee,

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1960), and (7) improper development of the verbal system resulting in a dissociation between the verbal and motor systems (Luria, 1956; O’Connor & Hermelin, 1959). Postulating such defects has given rise to what I have referred to as the “difference orientation,” that is, all retardates, regardless of etiology, are viewed as inherently different. Within this orientation retardates are seen as a homogeneous group of defective organisms, with the specific nature of the defect varying from theoretician to theoretician. The difference orientation receives its most vivid expression in those comparative studies where mental retardates are conceptualized as occupying a position on the phylogenetic scale somewhere between monkeys and children of average intellect. [See Zigler (1966), for a full discussion of the difference orientation in mental retardation.] It should be noted that in respect to the familial retardate, no convincing physiological evidence has been found indicating the presence of any of the defects noted above. Rather, these defects have been postulated on the basis of differences in performance between retardates and normals on some types of experimental tasks. An implicit assumption in much of this work has been that performance on such tasks is an inexorable product of the cognitive structure or intellectual level alone. The author does not believe this to be the case. Performance on many, if not all, experimental tasks is most appropriately conceptualized as a multiply determined phenomenon, influenced by both cognitive or intellective factors and motivational or emotional factors. A division between cognitive and motivational factors is, in many ways, an artificial one. However, in most of our work these two factors have been sufficiently orthogonal for us to demonstrate how each independently may affect the child’s performance. Motivational differences between normal and retarded children, which are themselves the result of differences in environmental histories, must be ruled out before any difference in performance can be considered prima facie evidence in support of a defect position. Over the years, then, our goal has been to discover the part played by differences in the experiential histories in producing the differences in performance so frequently noted in comparisons of normals and retardates of the same MA. II. THE LEWIN-KOUNIN FORMULATION

Our initial research efforts can be traced directly to one particularly influential and widely accepted defect position; namely, the cognitiverigidity formulation of Kurt Lewin (1936) and Jacob Kounin (1941a; 1941b). In Lewin’s general theory the individual is treated as a dynamic system with differences among individuals derivable from differences in:

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(1) structure of the total system; (2) material and state of the system; or, (3) its meaningful content. The first two factors play the most important role in Lewin’s theory of mental retardation. Lewin viewed the retarded child as being cognitively less differentiated, i.e., having fewer regions in the cognitive structure than a normal child of the same CA. Thus, in respect to the number of cognitive regions, the retarded child resembles a normal younger child. However, in terms of the material and state of the system, Lewin argued that even though a retarded child corresponded to a normal younger child in degree of differentiation, they were not to be regarded as entirely similar. He explicitly stated that he conceived “the major dynamic difference between a feebleminded and a normal child of the same degree of differentiation to consist in a greater stiffness, a smaller capacity for dynamic rearrangement in the psychical systems of the former” (Lewin, 1936). Lewin presented a considerable amount of observational and anecdotal material, as well as the findings of one experiment, to support his theoretical position. Unfortunately, Lewin’s experimental findings were ambiguous at best. Kounin (1941a) provided clear experimental support for the position that retarded individuals are more rigid than normal individuals having the same degree of differentiation, i.e. MA. Kounin (1941a; 1941b; 1948), building upon Lewin’s work, advanced the view that rigidity is a positive, monotonic function of CA. It is imperative to note that by “rigidity” Kounin, like Lewin, was referring to “that property of a functional boundary which prevents communication between neighboring regions” and not to phenotypic rigid behaviors, as such. Thus, with increasing CA, the individual becomes more differentiated, i.e., has more cognitive regions, which results in a lower incidence of rigid behaviors, while, at the same time, the boundaries between regions become less and less permeable. Furthermore, while this lack of permeability in the boundaries between regions often results in behaviors which would be characterized as rigid, in some instances it leads to behaviors which could be characterized as indicative of “flexibility.” (For an example of this latter possibility see the results of Kounin’s lever-pressing task presented below.) Kounin offered the findings of five experiments in which he employed older retarded individuals, younger retarded individuals, and normals. The degree-of-differentiation variable was controlled by equating the groups on MA. As predicted, the performance of the three groups differed on certain instruction-initiated tasks, e.g., first being instructed to draw cats until satiated and then to draw bugs until satiated: and first being instructed to lower a lever and then to raise the lever in order to release marbles. As predicted from the Lewin-Kounin hypothesis, the

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normals showed the greatest amount of transfer effects from task to task, the younger retardates a lesser amount of transfer, and the older retardates the least amount of transfer. That is, following satiation on the first drawing task, both retarded groups drew longer on the second task than did normals, with the least cosatiation effects (longest drawing time on second task) being observed in the older retardates. Kounin also found that the retarded subjects spent considerably more total time on the tedious drawing tasks than the normal subjects, a finding not derivable from the Lewin-Kounin formulation. This was attributed to the “rigid state” of the retarded which evidently spells itself out behaviorally in persistence on boring tasks. Another unpredicted and rather surprising finding was that the older retarded group had a negative cosatiation score, that is they spent less time drawing on the first task than on subsequent drawing tasks involving highly similar figures. More will be said about this rather intriguing finding later. On the lever-pressing task, the greatest number of errors, lowering rather than raising the lever on task two, was made by the normals, the least number by the older retarded, with the younger retarded falling between these two groups. One should note that on this task the lesser “rigidity,” as defined by Lewin and Kounin, of the normals resulted in a higher incidence of behavioral responses often characterized as rigid, i.e., perseverative responses. One should further note that this lack of influence of one region on another in the performance of the retarded would be predicted only in those cases where the retarded individual is “psychologically” placed into a new region by instructions, eg., “push down; now push up.” In those instances where the individual must, on his own, move from one region to another, the Lewin-Kounin formulation would predict that such movement would be more difficult for the retarded than for the normal individual. This prediction was confirmed by Kounin’s concept-switching experiment in which the child was given a deck of cards which could be sorted on the basis of either one (form) or another (color) principle. In this experiment the subject was asked to sort the cards and was then asked to sort the cards some other way. Here the normals evidenced the least difficulty and the older retardates the most difficulty in shifting from one sorting principle to another, while the younger retardates again fell between these two groups. Thus, in the instance where a child is not psychologically placed in a new region but must move through a cognitive boundary on his own, it is the retardate who evidences the greater incidence of perseverative responses. The Lewin-Kounin theory of rigidity in the retarded is a concep

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tually demanding one in that it sometimes predicts a higher, and sometimes a lower, incidence of “rigid” behaviors in retarded as compared to normal individuals. However, the fact that it generates specific predictions as to when one or the other state of affairs will obtain is a tribute to this theory. Kounin thus offered impressive experimental support for the view that with MA held constant the older and/or more retarded an individual is, the more will his behaviors be characterized by dynamic rigidity, i.e., less permeable boundaries between regions. However, the findings of Plenderleith (1956) presented a serious contradiction to Kounin’s position. Her results indicated that Kounin’s generalization relating retardation and rigidity does not hold when normal and retarded children are tested on discrimination learning and discrimination reversal tasks. Plenderleith’s study was specifically designed to test the validity of hypotheses derived from the Lewin-Kounin formulation of more rigid boundaries within the life space in the retarded than in the normal child of the same degree of differentiation, i.e. MA, In this study the subjects were required to learn to choose one of two stimuli. After this discrimination was learned, the stimuli were reversed, and the subjects were required to shift their response to the previously incorrect stimulus. Contrary to the predictions derived from the Lewin-Kounin formulation, the retarded children had no greater difficulty than did normal children in making the reversal when the reversal trials were given a day after the original learning. Plenderleith’s study, although embarrassing to the Lewin-Kounin position, has been criticized at some length by the present author (Zigler, 1958). It is sufficient to note here that these criticisms have been directed at the inappropriateness of certain of Plenderleith’s derivations from the Lewin-Kounin formulation, the overly easy nature of the learning task, and the failure to equate certain of the experimental groups carefully on pertinent variables. Stevenson and Zigler (1957) conducted a study that was similar to Plenderleith’s in that it was designed to test the validity of the LewinKounin theory of rigidity. This study also investigated the ability of normal and retarded subjects to acquire one response and then to switch to a new response in a discriminative learning situation. Moving from Kounin’s postulate that the boundaries within the life space are more rigid in the retarded than in normals, Stevenson and Zigler hypothesized, “. . . that the solution of a reversal problem would require movement to a new region of the life space and that such movement would be more difficult for the feebleminded subject because of the more rigid boundaries separating the regions of the life space.” As to the actual rigid behavior resulting from such rigidity in a reversal problem, Stevenson

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and Zigler chose as their measure the incidence of previously correct responses during the solution of the second problem. It would appear that such a perseverative response following the switch is the most direct evidence that the subject has remained in a prior region and has not moved to a new region. Three groups of subjects were used; an older retarded group, a younger retarded group, and a group of normal children, with the groups equated on MA. The results indicated a striking equivalence in performance among groups. They did not differ significantly on the number of trials required to learn the initial discrimination problem, the number of correct choices on the reversal problem, the number of subjects in each group who learned the reversal problem, or on the direct measure of rigidity employed, the frequency with which subjects of each group made the response on the reversal problem which had been correct for them on the initial discrimination problem. Although the switching problem employed by Stevenson and Zigler was more difficult than Plenderleith’s reversal problems, the possibility still remained that the switching problem they employed was too easy to allow differences between the groups to become manifest. In order to investigate this possibility, Stevenson and Zigler conducted a second experiment, designed to investigate the performance of normal and retarded individuals on a more difficult reversal problem. On the basis of the findings of the first experiment, Stevenson and Zigler rejected the Lewin-Kounin formulation, assuming instead the hypothesis that rigidity is a general behavior mechanism. From this hypothesis it may be deduced that the frequency with which rigid behaviors are shown is a function of the complexity of the problem. They predicted that the frequency of rigid responses (perseverations) would be greater for both the normal and retarded groups in the second experiment than in the first experiment, but that there would be no differences between the groups. All predictions made for the second experiment were confirmed. 111.

THE MOTIVATIONAL HYPOTHESIS

In an effort to evaluate the disagreement of their findings with those of Kounin, Stevenson and Zigler advanced a motivational hypothesis to explain Kounin’s findings. These investigators noted that in their experiments the subjects were required to learn two successive discriminations in which there was minimal interaction with the experimenter, while in Kounin’s tasks the response had been made primarily on the basis of instructions. Thus, differences in rigid behaviors between normal and retarded individuals of the same MA in the instruction-

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initiated tasks may be related to differences in the subjects’ motivation to comply with instructions rather than to differences in cognitive rigidity. This hypothesis was based on the assumption that institutionalized retarded children tend to have been relatively deprived of adult contact and approval and hence have a higher motivation to procure such contact and approval than do normal children. This assump tion appears congruent with the view advanced by other investigators that both institutionalized retarded and institutionalized normal individuals exhibit an increased desire to interact with adult figures (Clark, 1933; Sarason, 1953; Skeels, Updegraff, Wellman, & Williams, 1938). The first test of this motivational hypothesis was contained in a study by Zigler, Hodgden, and Stevenson (1958). These investigators, in an effort to employ tasks comparable to Kounin’s instruction-initiated satiation tasks, constructed three simple motor tasks, each having two parts and each allowing the experimenter to secure a satiation, cosatiation, and error score, The study deviated from Kounin’s procedure in that two conditions of reinforcement were used. In one, the experimenter maintained a nonsupportive role and did not reinforce the subject’s performance; in the second, the experimenter made positive comments and in general reinforced the subject’s performance. Two specific hypotheses were advanced: (1) support has a reinforcing effect which results in an increment in performance over that found in nonsupport conditions; and (2) interaction with an adult and adult approval provide a greater reinforcement for the responses of institutionalized retarded subjects than they do for those of normal subjects. Two retarded groups (a support and a nonsupport) equated on CA and two normal groups (support and nonsupport) equated on CA were employed. All four groups were equated on MA. The utilization of these two hypotheses allowed for the derivation of six predictions. Five of the six predictions made were fully or partially confirmed. It was found that: (1) Retarded subjects spent a significantly greater amount of time playing the games under the support than under the nonsupport condition, while normal subjects did not. (2) Retarded subjects spent more time on the games than the normal subjects in both reinforcement conditions. (3) There was a significantly greater difference in length of performance between support and nonsupport conditions for the retarded than for the normal subjects. (4) There was little difference in the cosatiation scores for normal subjects between support and nonsupport conditions. However, for retarded subjects, support not only resulted in lower cosatiation scores but in scores that were negative in value (the subject plays longer on part two of the game than on part one). (5) Cosatiation effects were generally less for retarded than

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for normal subjects under both conditions of support and nonsupport. (6) The proportion of errors was not significantly greater (or less) for normal than for retarded subjects. I n addition, a significantly greater number of retarded subjects stopped the games at points where the experimenter asked them if they wanted to play other games. This was interpreted as further indication of their greater compliance with instructions. Zigler et al., in comparing their study with that of Kounin, noted certain procedural differences which, they felt, had considerable influence on his findings. They pointed out that while Kounin spent a week with his retarded subjects and attempted to develop a friendly relationship with them before beginning the experiment, he had no such pre-experimental contact with the normal subjects. Also, Kounin’s retarded subjects were selected only after a considerable effort was made to ascertain that each subject really wanted to take part, while normal subjects were not so screened. It would appear that Zigler et al. could have stressed more strongly this last difference between their study and Kounin’s, for it seems that Kounin’s procedure led to differential sampling across the two types of subjects. Kounin, in reference to the freedom existing in his experimental situation, stated that over one half of the retarded individuals initially selected “felt sufficiently free to refuse after the experimenter demonstrated the activities to them . . . .” A careful scrutiny of Kounin’s original presentation indicates that normal subjects were not given the same opportunity to refuse. Kounin’s differential handling of subjects is understandable in view of Lewin’s criticism of his own (Lewin’s) satiation experiment. Lewin noted that the more rigid behaviors of the retarded could be due in part to their not feeling as secure in the experimental situation as did normal subjects. Kounin, therefore, made an effort to see that his retarded subjects did indeed feel secure in his experimental situation. In the process, Kounin appears to have introduced an equally important difference between the two groups. It would seem fair to assume that those retardates who chose to continue as experimental subjects were highly motivated to interact with an adult. Since the Zigler et al. study indicates that such motivation influences performance on the type of task used by Kounin, it would appear that his procedure introduces a possible experimental error. It is questionable whether Kounin’s theory of rigidity could be extended even to those retarded subjects who did not care to “play the games.” However, with the exception of the organically retarded, Kounin in no way limits his generalizations.

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IV. SOCIAL DEPRIVATION AND INSTITUTIONALIZATION

The study of Zigler et al. lends support to the view that reported differences in the incidence of "rigid" behaviors between normal and familial retarded individuals of the same MA are a function of the greater social deprivation experienced by the retarded rather than of their inherent cognitive rigidity. In a second test of the position that rigid behaviors observed in retardates are a result of the social deprivation they have experienced, Zigler (1961) hypothesized that within an institutionalized retarded population a relationship should exist between the degree of deprivation experienced and the amount of rigidity manifested. The specific hypothesis tested was the following: The greater the amount of pre-institutional social deprivation experienced by the feebleminded child, the greater will be his motivation to interact with an adult, making such interaction and any adult approval or support that accompanies it more reinforcing for his responses than for the responses of a feebleminded child who has experienced a lesser amount of soda1 deprivation.

In order to examine the social deprivation that retarded children have experienced, a measure that would reflect long-term deficits was required. Since the population of events which constitutes social deprivation has never been adequately delimited, the procedure employed in this study was to have raters evaluate the pre-institutional history of the child for degree of social deprivation and note the specific factors in the social history which determined the rating. It was hoped that this procedure would result in not only an assessment of social deprivation for each subject, but also in the extraction of a universe of specific events, the occurrence or nonoccurrence of which could be employed as a definition of social deprivation in future investigations. On the basis of these ratings, 60 retarded children were divided into two groups, high and low socially deprived. The groups did not differ significantly on either MA, CA, or length of institutionalization. The study employed an instruction-initiated two-part satiation game similar to those used in earlier studies. Three of the four predictions derived from the hypothesis were confirmed. The more sodally deprived subjects: (1) spent a greater amount of time on the game; (2) more frequently made the maximum number of responses allowed by the game; and (3) evidenced a greater increase in time spent on part two over that spent on part one of the game. The fourth prediction, that the more socially deprived subjects would make fewer errors, only reached a borderline level of significance. These findings represent a strong refutation of the Lewin-Kounin rigidity hypothesis, which cannot explain differences in performance

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between groups of retarded children equated on both CA and MA. T h e findings offer further support for the view that the rigid behavior observed in retarded individuals is a product of higher motivation to maintain interaction with an adult and to secure approval from him through compliance and persistence. These results also offer evidence that the institutionalized retarded subjects’ higher motivation to interact with an adult is related to the greater pre-institutional social deprivation such subjects have experienced. Furthermore, individual differences among the retarded in persistent and/or compliant behavior can be related to differences in the amount of social deprivation experienced. Since the persistence and compliance exhibited by retarded subjects have been found to be related to social deprivation, the prediction can be made that these characteristics would also be shown by subjects of normal intelligence who have experienced similar social deprivation. A further test of the view that the incidence of rigid behaviors is a function of the greater social deprivation experienced by the institutionalized retarded child rather than a function of his inherent rigidity was carried out by Green and Zigler (1962). These investigators used three groups of subjects, institutionalized retarded, noninstitutionalized retarded, and normals. It was assumed that the noninstitutionalized retarded child has suffered a lesser amount of social deprivation than the institutionalized retarded child. All three groups were equated on MA, and the two retarded groups were also equated on CA. As in the earlier studies, only familial retardates were employed. Again a two-part satiation type task was used. T he Lewin-Kounin rigidity formulation would lead to the predication that the performance of the two retarded groups would be similar and that their performance would differ from that of the normal group. T h e social deprivation hypothesis would lead to the prediction that the performance of the normals and the noninstitutionalized retarded would be similar and that their performance would differ from that of the institutionalized retarded. T h e latter hypothesis was supported with no significant differences in performance found between the noninstitutionalized retarded and normals. Both of these groups differed significantly from the institutionalized retarded. Again, it was the institutionalized retarded who showed the relatively long satiation times, a perseverative behavior that has been employed as evidence for the inherent rigidity of the retarded. Zigler (1%3) conducted a further test of the view that perseveration on open-ended satiation type tasks is a result of an enhanced effectiveness of social reinforcers stemming from the greater social deprivation experienced, rather than a product of an inherent cognitive rigidity. This

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study differed from that conducted by Green and Zigler primarily i n that it included a group of institutionalized normal children. I n this study institutionalized children of both normal and retarded intellect were found to play a socially reinforced satiation type task longer than did groups of noninstitutionalized normals and retardates of the same MA. This greater effectiveness of social reinforcement for both institutionalized normal and retarded children as compared with noninstitutionalized normal and retarded children has also been found by Stevenson and Fahel (1961). T h e studies noted above clearly indicate that certain behaviors of the institutionalized retarded that previously have been attributed to their inherent rigidity can more parsimoniously be viewed as a product of the greater social deprivation experienced by the institutionalized retarded child. It is not clear at this point whether this greater social deprivation is to be attributed to institutionalization as such, to the fact that the pre-institutional environment of the institutionalized child is characterized by excessive social deprivation, or to some interaction between these two factors. Pertinent to this issue are Zigler’s (1961) findings that the effectiveness of social reinforcers, as measured by length of playing time, was related to the amount of pre-institutional social deprivation exprienced but not to length of institutionalization. It should be noted that in this study i t was possible that a relationship between social reinforcer effectiveness and length of institutionalization was obscured by the effects of a third variable, MA. Since MA was found to be negatively related to the effectiveness of social reinforcers dispensed, while being positively related to length of institutionalization, a general enhancement in the effectiveness of social reinforcers with longer institutionalization may have been concealed. While there is a clear consensus among social scientists that institutionalization represents a condition of social deprivation, the author has come to the conclusion that institutionalization qua institutionalization is not a clear measure of social deprivation. Although there can be little doubt that the contemporary conditions of institutionalization must be a determinant of the child’s current behavior, the results of such institutionalization are far from clear. A fact that has been rarely recognized is that institutionalization is not, in itself, a psychological variable. At best it refers to a vague social status of the individual. In order to relate institutionalization to social deprivation, one must designate specific social interactions in the institution that give rise to particular behavioral propensities. Anyone who treats institutionali7ation as a homogeneous entity must

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be prepared to defend the proposition that critical social interactions are constant from institution to institution. But how can such a defense be made when there has been no systematic effort to discuss the psychological features, if any, that are common to all institutions. I concur with Sarason and Gladwin (1958) in their amazement that so little systematic work has been done on retardates concerning the effects of institutionalization. While the author has certain misgivings concerning Rent5 Spitz’s work (1945), his report of striking differences between children in two institutions is pertinent here. Especially relevant to the question of the effects of institutionalization on the performance of the retarded are the findings of a recent study by Butterfield and Zigler (1965a). Groups of mentally retarded children, matched on a variety of variables, from two institutions which differed markedly in their social climate were compared on a measure of their need for social reinforcement of two types, attention and attention plus verbal approval. Children from the more unenlightened, depriving institution were found to have a significantly higher motivation to obtain both types of reinforcement. Why, then, one might ask, have fairly constant findings been reported when institutionalized children are compared with noninstitutionalized children? What is the common feature of institutions that gives rise to the findings? The answer may be that there is some highly significant factor that as yet is unspecified. If such is the case, then the foregoing discussion may be considered an appeal for cross-institutional investigation conducted for the purpose of isolating this factor. However, another possibility may be considered. Perhaps the commonality in the findings of studies in which institutionalization is employed as a variable is due not to a common feature of institutions, but instead to the fact that children who are institutionalized come from homes that present a common and relatively homogeneous psychological environment. The latter possibility suggests that it is the pre-institutional social deprivation experienced by the child that needs evaluation. Institutionalization should be analyzed for its particular psychological features and for its effects viewed as interacting with the effects of the pre-institutional psychological environment. Thus, one and the same institution would be viewed as having different effects on children whose pre-institutional histories differed. Support for such a view is contained in a study by Zigler and Williams (1968). After an interval of three years, these investigators retested the children employed by Zigler (1961) and discovered that with this increased length of institutionalization, the motivation for social reinforcement of all of the children had increased. However, the increase between the two testings in motivation for social reinforcers was related to the amount

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of pre-institutional deprivation experienced. Children coming from relatively good homes evidenced a much greater increase in their motivation for social reinforcers than did children coming from more socially deprived homes. It thus appears that the general motivational effects of institutionalization depend on the pre-institutional history of the child, with such institutionalization being more socially depriving for children from relatively good homes than for children from homes characterized by a considerable amount of social deprivation. An unexpected finding of the Zigler and Williams study was that a general decrease in IQs of the retardates had occurred between the two testings. This change in IQ, discovered in the context of a study employing the amount of pre-institutional social deprivation as an independent variable, is reminiscent of a finding by Clarke and Clarke (1954). These investigators found that changes in the IQs of retardates following institutionalization were related to their pre-institutional histories. They discovered that children coming from extremely poor homes showed an increase in IQ with no such increase observed in children coming from relatively good homes. Zigler and Williams, however, found that the magnitude of the IQ change in their subjects was not significantly related to pre-institutional deprivation. Although this finding was contrary to that of Clarke and Clarke, it should be noted that the only subjects in the Zigler and Williams study who evidenced an increase in IQ were in the highdeprived group. The failure of Zigler and Williams to replicate the findings of Clarke and Clarke may be due to two factors: the subjects used by Clarke and Clarke were older and had been institutionalized at a later age than the retardates employed by Zigler and Williams; and, the IQ changes reported by Clarke and Clarke took place during two years of institutionalization, while the I Q changes reported in the Zigler and Williams study were based on five years of institutionalization. This latter factor becomes increasingly important in view of Jones and Carr-Saunders’ (1927) finding that normal institutionalized children show an increase in IQ early in institutionalization and then a decrease in IQ with longer institutionalization. The work of Clarke and Clarke, Jones and Carr-Saunders, and others (e.g., Guertin, 1949), dealing with changes in IQ following institutionalization, has given central importance to the intellectual stimulation provided by the institution contrasted with that provided by the original home. This orientation suggests that the change is one in the actual intellectual potential of the person. The Zigler and Williams study suggests that the change in IQ reflects a change in the child’s motivation for social interaction rather than an actual change in his intellectual potential. That is, as social deprivation, resulting from increased length

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of institutionalization, increases, the desire to interact with the adult experimenter increases. Thus, for the deprived child the desire to be correct must compete in the testing situation with the desire to increase the amount of social interaction. That this conflict would be resolved in favor of the latter motivation is suggested by the recent finding (Zigler & delabry, 1962) that “being right” is relatively low in the reinforcer hierarchy of institutionalized retarded children. This argument would appear to provide the conceptual framework for Clarke and Clarke’s finding that highly deprived subjects evidence an increase in IQ with relatively short institutionalization, while the less deprived subjects demonstrate no greater increase than a test-retest control group. One would further expect that with increasing institutionalization all children would exhibit a decrease in IQ, the phenomenon found by Jones and Carr-Saunders (1927), and one that appears in the Zigler and Williams study. Direct support for this view comes from the finding in the Zigler and Williams study of a positive relationship between the magnitude of the decrease in IQ and the child’s motivation for social reinforcement as measured by the amount of time the children performed on the satiation task. V.

POSITIVE- AND NEGATIVE-REACTION TENDENCIES

Although an atypically high motivation for social reinforcement appears to be an important factor in the performance of institutionalized retardates, it cannot account for all of the reported behavioral differences in comparisons of retardates and normals of the same MA. A recurring theme in the author’s work has been the necessity for appreciating the complexity of the retarded individual. It has certainly not been his goal to replace the view that the retardate is to be understood in terms of some single physiological or quasi-organismic defect with the view that the retardate is to be best understood in terms of some single motivational factor. The gross observation of the behaviors of the retarded indicates that a wide spectrum of motivational factors are influencing them. A factor completely antithetical to the retardate’s increased desire for social reinforcement (a phenomenon the author has labeled the positivereaction tendency) has been noted, namely the retarded child’s reluctance and wariness to interact with adults (Hirsh, 1959; Sarason & Gladwin, 1958; Wellman, 1938; Woodward, 1960). This orientation toward adults (which the author has labeled the negative-reaction tendency) appears capable of explaining certain differences between retardates and normals reported by Kounin, differences that have heretofore been attributed to the greater cognitive rigidity of retarded individuals. As noted earlier,

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Kounin employed a cosatiation-type task as one measure of rigidity. In this type of task, the subject is instructed to perform a response and is allowed to continue until he wishes to stop. He is then instructed to perform a highly similar response until again satiated. T h e cosatiation score is the measure of the degree to which performance on the first task influences performance on the second task. T h e theoretical positions of Lewin and Kounin, as well as Stevenson and Zigler, predicted that the absolute playing time of subjects on task two, after satiation on task one, would be greater than that of normal subjects. However, neither of these positions can explain the recurring finding (Kounin, 1941a; Zigler, 1958; Zigler et al., 1958) that, as a group, retarded subjects, under certain conditions, perform longer on task two than they do on task one. Groups of normal children, on the other hand, have invariably been found to perform longer on task one than on task two. In an effort to explain the longer playing times of retardates on task two relative to task one, Zigler (1958) advanced the following hypothesis: Institutionalized feebleminded subjects begin task one with a positive-reaction tendency higher than that of normal subjects. This higher positive-reaction tendency is due to the higher motivation of feebleminded subjects to interact with an approving adult. At the same time feebleminded subjects begin task one with a negative-reaction tendency higher than that of normal subjects. This higher negative-reaction tendency is due to a wariness of adults which stems from the more frequent negative encounters that feebleminded subjects experience at the hands of adults. If task one is given under a support condition, the subject’s negative-reaction tendency is reduced more during task one than is his positive-reaction tendency.

T h e institutionalized child learns during task one that the experimenter is not like other strange adults he has encountered who have initiated painful experiences (physical examinations, shots, etc.) with supportive comments. This reappraisal of the experimental situation results in a reduction of the negative-reaction tendency. When the deprived child is then switched to task two he meets it with a positivereaction tendency which has been reduced less than has been his negative tendency. T h e result, then, is that his performance on task two is lengthier than it was on task one. T h e finding that normal children exhibit a decrease in length of performance during task two as compared to task one follows if one assumes that they have a relatively low negativereaction tendency when they begin task one. When normal Ss are switched to task two, it is the positive-reaction tendency which has been reduced more, through fatigue and satiation effects, than any negativereaction tendency they might have had. T h e result, then, would be a briefer performance on task two than on task one. Thus, Zigler has suggested that the cosatiation score mirrors motiva-

Edward Z igler

tional determinants rather than inherent rigidity. This view was tested in a study by Shallenberger and Zigler (1961). T h e cosatiation score was obtained on a two-part experimental task similar to those used in the earlier studies. The study differed from the earlier cosatiation studies in that three experimental games preceded the two-part criterion task. These experimental games were given under two conditions of reinforcement. In a positive reinforcement condition all of the subject’s responses met with success, and he was further rewarded with verbal and nonverbal support from the experimenter. It was assumed that this reinforcement condition reduced the negative-reaction tendency the subject brought to the experimental setting. I n a negative reinforcement condition all of the subject’s responses met with failure, and the experimenter further punished ‘the subject by noting his lack of success. It was assumed that this reinforcement condition increased the negative-reaction tendency. (Ignoring the positive-reaction tendency was dictated by the assumption that this tendency was less open to experimental manipulation than was the negative tendency.) Two groups of retarded and two groups of normal subjects, all matched on MA, were employed. One normal and one retarded group were given the positive experimental condition, while the other two groups received the negative condition. All subjects were run on the criterion task under identical conditions, i.e., during both Part I and Part I1 all subjects received liberal amounts of verbal and nonverbal social reinforcement. The most striking finding of this study was the confirmation of the prediction that both negatively reinforced groups would evidence a greater increase in time spent on Part I1 over that spent on Part I of the criterion task, than would the normal and retarded groups who played the experimental games under the positive reinforcement condition. This difference was such that the two groups receiving the negative condition played Part I1 longer than Part I, while the two groups receiving the positive condition played Part I longer than Part 11. These findings indicate that cosatiation effects are not the product of inherent rigidity, but rather of the relative strength of certain motivational variables, i.e., positive- and negative-reaction tendencies. These tendencies, and their relative strengths, seem to be the product of particular environmental experiences and apparently are open to manipulation and modification. Thus, the Shallenberger and Zigler study presents further evidence that differences in the performance of retarded and normal individuals of the same MA can be attributed most parsimoniously to different environmental histories and motivations. The findings of this study offer further vaIidation for the general motivational hypothesis, while also indicating a need for its extension.

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Whereas the earlier studies emphasized the increased motivation to interact with and receive the support of an adult, the Shallenberger and Zigler study demonstrated the role of another motivational variable, the negative-reaction tendency. It would seem that the experiencing of that population of events which has been described as soually depriving gives rise to an increased desire to interact as well as a wariness to do SO. This suggests that future research be concerned with the isolation of those specific events which give rise to each of these opposing mouvational factors. One other suggestion is in order. Further investigation of such positive- and negative-reaction tendencies, their interactions, and the specific events which give rise to them may clarify issues much more global in nature than the troublesome finding that under certain conditions retarded individuals will play a second part of a two-part cosatiation task longer than the first part. The author specifically has in mind the current controversy over whether social deprivation leads to an increase in the desire for interaction or to apathy and withdrawal (Cox, 1953; Freud & Burlingham, 1948; Goldfarb, 1953; Irvine, 1952; Spitz & Wolf, 1946; Wittenborn & Myers, 1957). This issue has been followed up in a series of studies with children of normal intellect (Berkowitz, Butterfield, & Zigler, 1965; Berkowitz & Zigler, 1965; McCoy 8c Zigler, 1965). These studies have all been directed at further validation of what has come to be known as the valence posi,tion. Stated most simply, this position asserts that the effectiveness of an adult as a social reinforcing agent for a particular .child depends upon the valence that that adult has for the child. This valence is determined by the relative amount of positive and negative experiences the child has had at the hands of the adult or other adults from whom he has generalized. The three studies noted above employed length of playing time on a boring satiation-type task as the measure of the adult’s social reinforcer effectiveness. These studies have produced considerable evidence indicating that prior positive contacts between the child and the adult increase the adult’s effectiveness as a reinforcer, while negative contacts decrease it. If the experimentally manipulated negative encounters in these experiments are conceptualized as the experimental analogue of what institutionalized retardates actually have experienced, then the often reported reluctance and wariness with which such children interact with adults becomes understandable. A logical conclusion here is that this wariness of adults, and the tasks that adults present, .leads to a general attenuation in the retarded child’s social effectiveness. Failure of institutionalized retardates on tasks presented by adults is therefore not to be attributed entirely to intellectual factors but must

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be interpreted in light of the retardates’ atypically high negative-reaction tendency. This tendency motivates him towards behaviors, e.g. withdrawal, that reduce the quality of his performance to a level lower than that which one would expect on the basis of his intellectual capacity alone. VI.

THE REINFORCER HIERARCHY

Another concept advan.ced by the author and his colleagues to explain differences in performance between normals and retardates of the same MA is that of the reinforcer hierarchy, i.e., for any individual, reinforcers can be ordered from most to least effective. While the motivational factors noted previously can explain many of the normal-retarded differences found by Kounin, they cannot handle parsimoniously Kounin’s finding that retardates evidence greater difficulty than do normals on a concept-switching task. An early explanation of this finding advanced by Zigler (1958) relied heavily on the retarded child’s heightened motivation to interact with an adult and the relationship of this motivation to the child’s compliance. Zigler suggested that while this heightened motivation results in greater compliance when it increases the degree of social interaction, it may not lead to greater compliance when such compliance terminates the interaction as seems to be the case in Kounin’s card-sorting task. Thus, the argument can be made that institutionalized retardates are thrown into a conflict between making the switch, which leads to the termination of the social interaction, and failing to make the switch, which results in the continuation of the interaction. Since normal children would experience this conflict to a much lesser degree, their performance would be superior on Kounin’s task. T h e author felt that this argument, though plausible, could not satisfactorily explain the sizable differences in concept-switching between normals and retardates found by Kounin. Furthermore, the argument contained an inherent weakness in the assumption that all of Kounin’s subjects were aware that re-sorting the cards would result in a termination of the social interaction. A closer examination of Kounin’s card-sorting task led the author to de-emphasize the importance of social interaction and focus instead on the relative “weakness” of the reinforcer employed by Kounin to motivate retarded children on this task. T h e only reinforcer obtained by Kounin’s subjects for correctly switching concepts was whatever reinforcement inheres in being correct. Being correct is probably more reinforcing for the performance of normal than for retarded children, who may value the interaction with, and attention of, the experimenter much more than the satisfaction derived from performing the task correctly.

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T h e hypothesis suggested here is that if equally effective reinforcers were dispensed to normals and retardates of the same MA for switching concepts, no differences in the ability to switch would be found. Such a hypothesis demands the assumption that the positions of various reinforcers in the reinforcer hierarchies of normal and retarded children differ. Basic to this assumption is the view that for every child there exists a reinforcer hierarchy, and the particular position of various reinforcers is determined by: (1) the child’s developmental level; (2) the frequency with which these reinforcers have been paired with other reinforcers; and (3) the degree to which the child has been deprived of these reinforcers. Several recent studies attest to the feasibility of attributing the differences in performance between normals and retardates on a conceptswitching task to such differing reinforcer hierarchies rather than to the greater cognitive rigidity of retardates. Terrell, Durkin, and Wiesley (1959) found that middle-class children did better on a discrimination learning task when an intangible rather than a tangible reinforcer was employed, while lower-class children evidenced superior performance when the reinforcer was a tangible one. This social class finding is pertinent to the relatively poor performance of institutionalized familial retardates on concept-switching tasks since such retardates are drawn predominantly from the lowest segment of the lower socioeconomic class (Zigler, 1961). T h e importance of the specific reinforcer being dispensed in work with the retarded is further suggested by the finding of Stevenson and Zigler (1957) that when tangible reinforcers were given, the institutionalized familial retarded were no more rigid than normal subjects of the same MA on a discrimination reversal learning task. Furthermore, on a concept-switching task identical to Kounin’s (1941a), both retarded and upper-class children switched more readily in a tangible than in an intangible reinforcement condition. Contrary to Kounin’s findings, no significant main effect associated with the normal-retarded dimension was found (Zigler & Unell, 1962). This suggests that the differences obtained by Kounin (1941a) on his concept-switching task resulted from a comparison of retardates with middle-class children who valued the intangible reward of being correct much more than did the retardates. These studies further suggest that not only retardates but lower-class children in general would be inferior to middle-class children when such a reinforcer is employed. However, middle-class children should not be superior to either retarded or lowerclass children of the same MA when these latter children are rewarded with more optimal reinforcers, i.e., reinforcers high in their hierarchies. This view was tested by Zigler and deLabry (1962) in an experiment

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utilizing Kounin’s concept-switching task, groups of institutionalized familial retardates (lower-class and middle-class normal children), and two reinforcement conditions. In one condition, Kounin’s original reinforcer, the reinforcement that inheres in a correct response, was employed. In a second condition, the reinforcer was a tangible reward, a small toy. Half the subjects in each group received the tangible reinforcer and half received the intangible reinforcer for switching from one concept (either form or color) to the other. T h e reinforcement hypothesis, and the predictions derived from it, were supported by the findings. The retarded and normal lower-class children did better (fewer trials to switch) in the tangible than in the intangible condition, while the normal middle-class children did slightly better in the intangible than in the tangible condition. Reminiscent of Kounin’s results was the finding of significant differences among the three groups who received intangible reinforcers. However, no differences were found among the three groups who received tangible reinforcers. Furthermore, no differences were found among the three groups that exhibited maximal performance (retarded-tangible, lower-class-tangible, and middle-classin tangible). This differential effectiveness of particular reinforcers can be attributed to differences in experiential histories. Several investigators (Davis, 1941; Davis, 1943; Davis, 1944; Douvan, 1956; Erickson, 1947) have noted that the emphasis on being right is primarily a middle-class phenomenon and that this particular intapgible reinforcer is more frequently paired with other primary and secondary reinforcers in middle-class than in lower-class populations. Being right is probably valued even less by institutionalized retarded children, for whom the incidence of failure is so high that more emphasis is given to doing one’s best than to being right. T h e enhanced effectiveness of tangible reinforcers for institutionalized retarded and lower-class children would appear to be due to the relative deprivation of tangible rewards, such as toys, experienced by these children. The finding that with proper motivation retarded children perform as effectively as normal children of the same MA on a concept-switching task is congruent with the findings of Osborn (1960), who also reported that retarded and normal children of the same MA did equally well on a concept-formation task. Again the implication is that differences in the performance of normal and retarded children, matched on MA, are a result of motivational differences which arise from diverse environmental histories and conditions.

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EXPECTANCY OF FAILURE

Another factor frequently noted as a determinant in the performance of the retarded is their high expectancy of failure. This failure expectancy has been viewed as an outgrowth of a lifetime characterized by frequent confrontations with tasks with which the retarded are intellectually ill-equipped to deal. That failure experiences and the failure expectancies to which they give rise affect a wide variety of behaviors in the intellectually normal has now been amply documented (Atkinson, 1958a; Atkinson, 1958b; Katz, 1964; Rotter, 1954; Sarason, Davidson, Lighthall, Waite, & Ruebush, 1960). However, experimental work employing success-failure manipulations with retardates is still somewhat inconsistent. The work of Cromwell and his students (reviewed in Cromwell, 1963) has certainly lent support to the general proposition that retardates have a higher expectancy of failure than do normals. This results in a style of problem-solving for the retardate which causes him to be much more motivated to avoid failure than to achieve success. However, the inconsistent research findings suggest that this fairly simple proposition is in need of some further refinement. One investigator (Gardner, 1957) found that retardates performed better following success and poorer following failure as compared to a normal control group. Heber (1957) found that the performance of normals and retardates is equally enhanced following a failure condition, and that while success enhances the performance of both normals and retardates, the performance of retardates is enhanced more than normals. Kass and Stevenson (1961) found that success enhanced the performance of normals more than that of retardates. Another study also found that failure had a general enhancing effect for both normals and retardates but that failure enhanced the performance of normals more than that of retardates (Gardner, 1958). In a recent study by Buttefield and Zigler (1965b), one factor capable of producing this type of inconsistency was isolated. These investigators found that both normal and retarded children reacted differentially to success and failure experiences as a function of their responsivity to adults, i.e., their desire to gain an adult's support and approval. The nature of the difference between normals and retardates in their reaction to success or failure experiences appeared to be determined by this latter variable. Among high responsive subjects, failure, as compared to success, attenuated the performance of retarded while improving the performance of normal subjects. Among low responsive subjects, failure, as compared to success, attenuated the performance of normals while improving the performance of retardates. One problem involved in the success-failure experiments is that the

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experimental manipulations typically involved very simple, circumscribed experiences of success or failure. They do not constitute an adequate experimental analogue of the lengthy and repeated history of failure assumed for the retardate. In a study involving prolonged failure, a condition more representative of what the retardate actually experiences, Zeaman and House (1960) found that retardates were unable to solve an extremely simple problem although they had previously been able to do so. As reported below, fairly clear results are also obtained when the experimenter simply assumes that the retardate has a “failure set,” rather than attempting to see how such a set is influenced by one more failure or success experience. Assuming such a failure set, Stevenson and Zigler (1958) tested the hypothesis that retardates would be willing to “settle for” a lower degree of success than would normal children of the same MA. These investigators employed a simple position discrimination task involving three knobs which the child could push to obtain marbles. Only one knob was reinforced, and the degree of reinforcement for the three conditions employed were loo%, random 66%, or random 33%. Maximizing behavior on such a task would involve pushing only the reinforced knob on every trial. As might be expected, such maximizing behavior was exhibited by both normal and retarded children who received 100% reinforcement. As had previously been found with adults, normal children did not evidence maximizing behavior in the 33% and 66% reinforcement conditions but rather tended to match reward probabilities, i.e., they selected the correct knob on a little more than 33y0 and 66% of the trials, respectively. Goodnow (1955), in an analysis of the determinants of choice behavior of this type, has suggested that one of the conditions influencing whether or not the subject will maximize his guesses of the more frequently reinforced stimulus is the level of success the subject will accept in the task. Goodnow suggests that maximizing behavior will be found when the subject will accept less than 100% success as a good final outcome, while other distributions of choices will be found when the subject has an interest in 1 0 0 ~ success o or in a level of success which is greater than that allowed in the situation. It may therefore be hypothesized that different types of behavior will be obtained with subjects who differ in the degree of success that they have learned to expect. Normal children, such as those used by Stevenson and Zigler, may be assumed to have learned, on the basis of their everyday experience, to expect a high degree of success. Probability matching rather than maximizing behavior would be predicted for those subjects.

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Institutionalized retarded children, however, may be assumed to have learned to expect and therefore to settle for lower degrees of success. T h e prediction would be that such retardates would maximize to a greater degree than would normal subjects of the same MA. This, in fact, was what Stevenson and Zigler found. Retardates in both the 33% and 66% reinforcement conditions evidenced more maximizing behavior than did the normal MA controls. An alternative explanation of the Zigler and Stevenson findings should be noted. It could be argued that the greater tendency of retarded, as compared to normal subjects, to "stick" with the partially reinforced knob did not reflect the lower expectancy of success of the retarded but rather their greater rigidity. In an effort to further validate the expectancy-of-reinforcement hypothesis, Stevenson and Zigler (1958) conducted another experiment involving two groups of normal children performing on the knob-pressing task. Prior to performing on this task, one group received 33% reinforcement on their responses across three nonlearning games. T he other group received 100% reinforcement. Both groups then played the position discrimination knob-pressing task under a 66% random reinforcement schedule. As predicted from the expectancy-ofreinforcement hypothesis, the subjects in the 100% pretraining condition chose the reinforced knob significantly less frequently than did subjects in the 33% pretraining condition. We thus see again that if normal children receive the experimental analogue of the real-life experiences of retardates (in this instance low degrees of reinforcement across tasks) they behave in much the same manner as do retardates. VIII.

OUTER-DIRECTEDNESS

Another series of experiments (Green & Zigler, 1962; Turnure & Zigler, 1964; Zigler et al., 1958) has suggested that the high incidence of failure experienced by retardates generates a style of problem-solving characterized by outer-directedness. Th at is, the retarded child comes to distrust his own solutions to problems and therefore seeks guides to action in the immediate environment. Zigler et al. (1958) found that institutionalized retardates tended to terminate their performance on experimental games following a suggestion from an adult experimenter that they might do so. Normal children tended to ignore such suggestions, stopping instead of their own volition. Originally this finding was discussed in terms of social deprivation and heightened motivation for social reinforcement and was interpreted as reflecting a greater compliance on the part of institutionalized retardates. T h e position here was that social deprivation resulted in an enhanced motivation for social rein-

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forcers and, hence, greater compliance in an effort to obtain such reinforcement. However, Green and Zigler (1962) found that, while normal children again exhibited little tendency to do so, a higher percentage of noninstitutionalized than institutionalized retardates terminated their performance upon a cue from the experimenter. This finding is incongruent with the social deprivation interpretation, which would generate the prediction that noninstitutionalized retardates would be similar to normal children in their sensitivity to adult cues. This dissimilarity in the performance of noninstitutionalized retardates and normals led Green and Zigler to suggest that such sensitivity to external cues is most appropriately viewed as a general component of problem-solving, having its antecedents in the child’s history of success or failure. Of the three types of children employed by Green and Zigler (1962), the normal child would be expected to have had the highest incidence of success emanating from self-initiated solutions to problems. As a result such a child would be the most willing to employ his own thought processes and the solutions they provide in problem-solving situations. Antithetically, the self-initiated solutions of retardates would be expected to result in a high incidence of failure, thus making retardates wary or distrustful of these guides to action. This type of child should then evidence a greater sensitivity to external or environmental cues, particularly those provided by social agents, in the belief that these cues would be more reliable indicators than those provided by his own cognitive efforts. Retardates in general, then, would be more sensitive to external cues than would normal children. T h e institutionalized retardate lives in an environment adjusted to his intellectual shortcomings and should therefore experience less failure than the noninstitutionalized retardate. This latter type of child must continue to face the complexities and demands of an environment with which he is ill-equipped to deal and should, as Green and Zigler found, manifest the greatest sensitivity to external cues. This general position was first tested by Turnure and Zigler (1964) who examined the imitation behavior of normal and retarded children of the same MA on two tasks. One task involved the imitation of a n adult and the other the imitation of a peer. Prior to the imitation tasks the children played three games under either a success or a failure condition. T h e specific hypotheses tested were that retardates would be generally more imitative than normals and that all children would be more imitative following failure experiences than following success experiences. These hypotheses were confirmed on both imitation tasks. To the extent that the behavior of normal children is considered the

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preferred mode, this study indicates that the outer-directedness of the retarded child results in behavior characterized by an oversensitivity to external models with a resulting lack of spontaneity and creativity. However, i t must be emphasized that heightened outer-directedness is not invariably detrimental to performance on problem-solving tasks. Turnure and Zigler conducted a second experiment in order to test further the hypothesis that retarded children are more outer-directed than normal children of the same MA. I n this study an effort was also made to demonstrate that outer-directedness may be either detrimental or beneficial, depending upon the nature of the situation. Normal children and noninstitutionalized retardates of the same MA were instructed to assemble an item, reminiscent of the object-assembly items on the WISC, as fast as they could. While the subject assembled the item, the adult E put together a second object-assembly item. T h e hypothesis was that the outer-directedness of the retarded child would lead him to attend to what the E was doing rather than concentrating on his own task, thus interfering with his performance. When the child had completed putting together his puzzle, the E took apart the puzzle that he himself had been working on. He then gave this second puzzle to the child and told him to put it together as quickly as he could. Here the cues that the retarded child picked up as a result of his outer-directedness should facilitate performance on the second puzzle. Again, the predictions were confirmed. Th e normal children were superior to the retardates on the first task, whereas the retardates were superior to the normal children on the second task. No statistically significant differences were found in the control condition in which the experimenter did not put together the second object-assembly task while the subject was working on the first. Further confirmation of the outer-directed hypothesis was obtained by a direct measure of the frequency with which the children actually glanced at the experimenter. As expected, the retardates were found to glance at the experimenter significantly more often than the normal children. T h e findings of this study not only confirmed the hypothesis that retarded children are more outer-directed in their problem-solving, but also suggest the process by which the outer-directed style of the retardate is reinforced and perpetuated. There are undoubtedly many real-life situations in which the child is rewarded for careful attentiveness to adults. However, it is also clear that there will be many situations in which such attending will be detrimental to the child's problemsolving. Across tasks, optimal problem-solving requires a child to utilize both external cues and his own cognitive resources. T h e retarded child's overreliance on external cues is understandable in view of his life history

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T h e intermittent success accruing to the retarded child as a result of such a style in combination with his generally lowered expectation of success across problem-solving situations (cf. Stevenson & Zigler, 1958) suggests the great utility which such outer-directedness would have for the retarded. It must be emphasized, however, that the retarded child is not more outer-directed than the normal child simply because he has a lower IQ. How outer-directed any child will be would appear to depend on two factors: (1) the level of cognition attained, e.g. mental age; and (2) the degree of success experienced through employing whatever cognitive resources he has available. Ignoring the second factor, it may be asserted that the lower the mental age the more outer-directed the child, since such outer-directedness would be more conducive to successful problemsolving than dependence upon poorly developed cognitive abilities. With the growth and development of greater cognitive resources, the child should become more inner-directed, since such cognitive development releases the child from his dependence on external cues. Furthermore, independence training with increasing age is characterized by a continuous reduction in the cues provided the child by adults which further reduces the effectiveness of an outer-directed style. Thus, the shift from outer- to inner-directedness in normal development would be viewed as a product of both the increasing cognitive ability of the child and the withdrawal of external cues which had previously made the outerdirected style an effective one. This general developmental argument does not explain the findings of the Turnure and Zigler (1964) and earlier investigations (Green & Zigler, 1962; Zigler et al., 1958) which indicated that retardates are more outer-directed than normal children even when matched on MA. Apparently in these studies the crucial variable is not the level of cognition attained, but rather the success or failure experienced by the child when employing his cognitive resources. It would appear that certain age expectancies are firmly built into our child-training practices and that society reacts to a child more on the basis of chronological age than mental age. T h e normal child’s mental age is commensurate with his chronological age, and he is continuously presented problems that are in keeping with his cognitive resources. With increasing maturity he experiences more and more success in utilizing these resources in dealing with problems. T h e retarded child, on the other hand, is continuously confronted with problems appropriate to his chronological age but inappropriate to his mental age. These problems are too difficult for him and he does not experience that degree of success which would lead him to discard his outer-directedness in favor of reliance on his own

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cognitive abilities. That success, as compared to failure, leads the child to become less outer-directed was demonstrated in Turnure and Zigler’s first experiment. It may be hypothesized that outer-directedness, which is learned relatively early due to the rather effective cues provided by adults and peers, would generalize to a multiplicity of other external stimuli. This generalization would impel the child to attend to a wide variety of stimuli impinging upon him since such behavior has been conducive to more successful problem-solving. Such a style should be given u p relatively early in the development of the typical child but should continue to be characteristic of the retarded child, due to the inordinate amount of failure he experiences when relying on his own resources. One would probably describe a child utilizing such a style as being distractible, and, in fact, distractibility has often been attributed to the retarded child (Cruse, 1961; Goldstein & Seigle, 1961). T h e outer-directedness hypothesis suggests that distractibility, rather than being an inherent characteristic of the retarded, actually reflects a style of problem-solving emanating from the particular experiential histories of these children. Employing this view, one would expect this style of problem-solving and the trait of distractibility in normal children whose self-initiated solutions to problems have often been inadequate, e.g.; the very young child, or the inappropriately reinforced child, e.g., the child whose parents make intellectual demands not in keeping with the child’s cognitive ability. IX.

CONCLUSIONS

T h e work of the author and his collaborators outlined in this paper appears to have provided support, in varying degrees, for the following six hypotheses. 1. Institutionalized retarded children tend to have been relatively deprived of adult contact and approval, and hence have a higher motivation to secure such contact and approval than do normal children. 2. While retarded children have a higher positive-reaction tendency than normal children, due to a higher motivation to interact with a n approving adult, they also have a higher negative-reaction tendency. This higher negative-reaction tendency is the result of a wariness which stems from retarded children’s more frequent negative encounters with adults. 3. T he motive structure of the institutionalized retardate is influenced by a n interaction between pre-institutional social history and the effects of institutionalization. This effect is complicated by the fact that institutionalization does not constitute a homogeneous psychological variable.

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Instead, institutions differ, and underlying psychological features of the particular institutions must be considered before predictions can be made concerning the effects of institutionalization on any particular child. 4. T h e positions of various reinforcers in a reinforcer hierarchy differ as a function of environmental events. Due to the environmental differences experienced by institutionalized retarded children, the positions of reinforcers in their reinforcer hierarchy will differ from the positions of the same reinforcers in the reinforcer hierarchy of normal children. 5. Institutionalized retarded children have learned to expect and settle for lower degrees of success than have normal children. 6 . An inner- versus outer-directed cognitive dimension may be employed to describe differences in the characteristic mode of attacking environmentally presented problems. T h e inner-directed person is one who employs his own thought processes and the solutions they provide in dealing with problems. T h e outer-directed person is one who focuses on external cues provided either by the stimuli of the problem or other persons in the belief that such attention will provide him with a guide to action. T h e style which characterizes the individual’s approach may be viewed as a result of his past history. Individuals whose internal solutions meet with a high proportion of failures will become distrustful of their own efforts and adopt an outer-directed style in their problemsolving. Since retardates unquestionably experience a disproportionate amount of failure, they are characterized by this outer-directedness. Many behaviors that are thought to inhere in mental retardation, e.g., distractibility, may be a product of this cognitive style. I t is the author’s view that the psychological processes underlying these hypotheses operate in combination more often than in isolation. This is merely to assert that the behavior of the retarded child on any task is a complex and multiply determined phenomenon. This view is congruent with the overall position of the investigator and stands in opposition to those efforts which postulate some single inherent deficiency. It cannot be emphasized too strongly that much of the work reported in this paper is very recent. Many of the findings related to the hypotheses listed above are more suggestive than definitive. However, the author’s view is that the factors enumerated in these hypotheses are extremely important ones in determining the retardate’s general level of functioning. An increase in our knowledge concerning these motivational and emotional factors, and their ontogenesis and possible manipulation, is mandatory before we can fully comprehend the behavior of retarded individuals.

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ACKNOW LEDCMENTS T h e author would like to thank Susan Harter and Frances Capobianco for their critical reading of the manuscript. Much of the research reported in this paper was supported by grants from the National Institute of Mental Health, the Social Science Research Council, and by the Gunnar Dybwad Award of the National Association for Retarded Children. REFERENCES Atkinson, J. W. Motivational determinants of risk taking behavior. In J. W. Atkinson (Ed.), Motives in fantasy, action, and society. Princeton: Van Nostrand, 1958. Pp. 322-340. (a) Atkinson, J. W. Towards experimental analysis of human motives in terms of motives, expectancies, and incentives. In J. W. Atkinson (Ed.), Motives in fantasy, action, and society. Princeton: Van Nostrand. 1958. Pp. 288-305. @) Berkowitz, H., Butterfield, E. C., & Zigler, E. The effectiveness of social reinforcers on persistence and learning tasks following positive and negative social interactions. J. Pers. soc. Psychol., 1965, 2 , 706-714. Berkowitz, H., & Zigler, E. Effects of preliminary positive and negative interactions and delay conditions on children’s responsiveness to social reinforcement. J. Pers. ZOC. P~ychol.,1965, 2, 500-505. Butterfield, E. C., & Zigler, E. The influence of differing institutional social climates on the effectiveness of social reinforcement in the mentally retarded. Amcr. J. mcnl. Defic., 1965, 70, 48-56. (a) Butterfield, E. C., & Zigler, E. The effects of success and failure on the discrimination learning of normal and retarded children. J. abnorm. Psychol., 1965, 70, 25-31. (b) Clark, L. P. The nature and treatment of amentia. Baltimore: Wood, 1933. Clarke, H., & Clarke, A. Cognitive changes in the feebleminded. Brit. I. Psychol., 1954. 45, 173-179. Cox, F. T h e origins of the dependency drive. Aust. J. Psychol., 1953, 5, 64-73. Cromwell, R. L. A social learning approach to mental retardation. I n N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Pp. 41-91. Cruse, D. Effects of distractions upon the performance of brain-injured and familial retarded children. Amer. J. ment. Defic., 1961, 66, 86-92. Davis. A. American status systems and the socialization of the child. Amer. SOC. R e v , 1941, 6, 345-354. Davis, A. Child training and social class. In R. G. Barker, J. S. Kounin, & H. F. Wright (Eds.), Child behavior and development. New York: McGraw-Hill, 1943. Pp. 607-620. Davis, A. Socialization and adolescent personality. Yearb. nut. Soc. Stud. Edric., 1944, 43, 198-216. Douvan, E. Social status and success striving. J. abnorm. soc. Psychol., 1956, 52, 219-223. Ellis. N. R. (Ed.) T h e stimulus trace and behavioral inadequacy. In Handbook of mental deficiency. New York: McGraw-Hill, 1963. Pp. 134-158. Erickson, M. Social status and child rearing practices. In T. M. Newcomb & E. L. Hartley (Eds.), Readings in social psychology. New York: Holt, 1947. Pp. 494-501. Freud, A,, & Burlingham, D. Infants without families. New York: International Univer. Press, 1948. Gardner, W. I. Effects of interpolated success and failure on motor task performance i n mental defectives. Paper read at Soiitheast. Psychol. Ass. Meetings, Nashville, Tennessee. 1957.

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Gardner, W. I. Reactions of intellectually normal and retarded boys after experimentally induced failure: a social learning theory interpretation. Ann Arbor, Michigan: Univer. Microfilms, 1958. Goldfarb, W. The effects of early institutional care on adolescent personality. J. exp. Educ., 1953, 12, 106-129. Goldstein, H., & Seigle, D. Characteristics of educable mentally handicapped children. In W. Rothstein (Ed.), Mental retardation: Readings and resources. New York: Holt, 1961. Goldstein, K. Concerning rigidity. Charact. 6. Pers., 1943, 11, 209-226. Goodnow, J. J. Determinants of choice distribution in two-choice situations. Amer. J. Psychol., 1955, 68, 106-116. Green, C., & Zigler, E. Social deprivation and the performance of retarded and normal children on a satiation type task. Child Develp., 1962, 33, 499-508. Guertin, W. H. Mental growth in pseudo-feeblemindedness. J. clin. Psychol., 1949. 5, 414-418. Heber, R. F. Expectancy and expectancy changes in normal and mentally retarded boys. Ann Arbor, Michigan: Univer. Microfilms, 1957. Hirsh, E. A. The adaptive significance of commonly described behavior of the mentally retarded. Amer. J. ment. Defrc., 1959, 63, 639-646. Irvine, E. Observations on the aims and methods of child rearing in communal set.tlements in Israel. H u m . Relat., 1952, 5, 247-275. Jones, D., & Carr-Sanders, A. The relation between intelligence and social status among orphan children. Brit. J . Psychol., 1927, 17, 343-364. Kass, N., & Stevenson, H. W. The effect of pretraining reinforcement conditions on learning by normal and retarded children. Amer. I . ment. Defic., 1961, 66, 76-80. Katz, I. Review of evidence relating to effects of desegregation on the intellectual performance of Negroes. Amer. Psychologist, 1964, 19, 381-399. Kounin, J. Experimental studies of rigidity. I. The measurement of rigidity in normal and feebleminded persons. Charact. dr Pers., 1941, 9, 251.273. (a) Kounin, J. Experimental studies of rigidity. 11. The explanatory power of the concept of rigidity as applied to feeblemindedness. Charact. G Pers., 1941, 9, 273282. (b) Kounin, J. The meaning of rigidity: a reply to Heinz Werner. Psychol. Rev., 1948. 55, 157-166. Lewin, K. A dynamic theory of personality. New York: McGraw-Hill, 1936. Luria, A. R. Problems of higher nemous activity in the normal and nonnormal child. Moscow: Akad. Pedag. Nauk RSFSR, 1956. McCoy, N., & Zigler, E. Social reinforcer effectiveness as a function of the relationship between child and adult. J. Pers. SOC. Psychol., 1965, 1, 604-612. O'Connor, N., & Hermelin, Beate. Discrimination and reversal learning in imbeciles. J . abnorm. SOC. Psychol., 1959, 59, 409-413. Osborn, W. Associative clustering in organic and familial retardates. Amer. J. ment. Defic., 1960, 65, 351-357. Plenderleith, M. discrimination learning and discrimination reversal learning in normal and feebleminded children. J . genet. Psychol., 1956, 88, 107-112. Rotter, J. B. Social learning and clinical psychology. Englewood Cliffs, N.J.: PrenticeHall, 1954. Sarason, S. B. Psychological problems in mental deficiency. (2nd ed.) New York: Harper. 1953.

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Sarason, S. B., Davidson, K., Lighthall, F., Waite, R., Lk Ruebush, B. Anxiety in elementary school children. A report of research. New York: Wiley, 1960. Sarason, S. B., & Gladwin, T. Psychological and cultural problems in mental subnormality: a review of research. Genet. Psychol. Monogr., 1958, 57, 7-269. Shallenberger, P., & Zigler. E. Rigidity, negative reaction tendencies, and cosatiation effects in normal and feebleminded children. J. abtiorm. SOC. Psychol., 1961, 63, 20-26. Siege], P., & Foshee, 1. Molar variability in the mentally defective. J. abnorm. SOC. Psychol., 1960, 60, 141-143. Skeels, H. M., Updegraff, R., Wellman, B. L., & Williams, H. M. A study of environmental stimulation, an orphanage prcschool project. Univer. Iowa Stud. Child W e l f . . 1938, 15, No. 4. Spitz, H. H. Field theory in mental deficiency. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Pp. 11-40. Spitz, R. A. Hospitalism: an inquiry into the genesis of psychiatric conditions in early childhood. Part I. Psychoanal. Stud. Child, 1945, 1.53-74. Spitz, R. A., & Wolf, K. Anaclitic depression: an inquiry into the genesis of psychiatric conditions in early childhood. Psychoanal. Stud. Child, 1946, 2, 313-342. Stevenson, H. W., & Fahel, L. S. T h e effect of social reinforcement on the performance of institutionalized and noninstitutionalized normal and retarded children. J. Pers., 1961, 29. 136-147. Stevenson, H. W.,& Zigler, E. Discrimination learning and rigidity in normal and feebleminded individuals. J. Pers., 1957, 25, 699-711. Stevenson, H. W., & Zigler, E. Probability learning in children. J. e x p . Psychol., 1958, 56, 185-192. Terrell, G , , Jr.. Durkin, K., & Wiesley, M. Social class and the nature of the incentive in discrimination learning. J. abnorrn. SOC. Psychol., 1959, 59, 270.272. Turnure, 1.. & Zigler, E. Outer-directedness in the problem solving of normal and retarded childrcn. J . a h o r m . soc. Psychol., 1964, 69, 427-436. Wellman, n. L. Guiding mental development. Childh. Educ., 1938, 15, 108-112. Wittenborn, I., & Myers, B. T h e placernetit o f adoptive children. Springfield, Ill.: Thomas, 1957. Woodward, M. Early experiences and later social responses of severely subnormal children. Brit. J. tnrd. Psyrltol., 1960, 33, 123-132. Zeaman, D. Discrimination learning in retardates. Train. Sch. Bull., 1959, 56. 62-67. Zeaman, D., & House, Betty 1. Approach and avoidance in the discrimination learning of retardatcs. In D. Zeaman el al., Learning ond transfer in mental defectives. Progr. Rep. No. 2, NlMH USPHS, 1960. Res. Grant M-1099 to Univer. of Connecticut. Pp. 32-70. Zigler, E. The effect of pre-institutional social deprivation on the performance of feebleminded children. Unpublished doctoral dissertation, Univer. of Texas, 1958. Zigler, E. Social deprivation and rigidity in the performance of feebleminded children. J . abnorm. SOC. Psyclrol., 1961. 62, 413-421. Zigler, E. Rigidity and social reinforcement effects in the performance of institutionalized and noninstitiitionalized normal and retarded children. J . Pen., 1963, 31, 258-269. Zigler, E. Mental retardation: Current issues and approaches. In M. L. Hoffman & L. W. Hoffman (Eds.). Review of child development research. Vol. 11. New York: Russell Sage Foundation, 1966.

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Zigler, E., & delabry, J. Concept-switching in middle-class. lower-class, and retarded children. I . abnorm. sot. Psychol., 1962, 65, 267-273. Zigler, E., Hodgden, L., & Stevenson, H. W. T h e effect of support on the performance of normal and feebleminded children. I . Pers., 1958, 26, 106-122. Zigler, E., & Unell, E. Concept-switching in normal and feebleminded children as a function of reinforcement. Amer. J . ment. Defic., 1962, 66, 651-657. Zigler, E., & Williams, J. Institutionalization and the effectiveness of social reinforce. ment: a three-year follow-up study. 1.abnorm. SOC. Psychol., 1963, 66, 197-205.

Experience and the Development of Adaptive Behavior H. CARL HAYWOOD' DEPARTMENT OF

PSYCHOLOGY,

GEORGE PEABODY COLLEGE FOR m c H E ) u ,

NASHVILLE, TENNESSEE

AND

JACK T. TAPP DEPARTMENT OF

PSYCHOLOGY,

VANDERBILT

UNIVERSITY, NASHVILLE,

TENNWSJlE

I. Introduction . . . . . . . . . . . . . . . . . A. The Independent Variable B. The Dependent Variables ................ C. The Problem of Age . . . . . 11. The Behavioral Variables . . . . . . . . . . . . . A. Effects of Environmental Deprivation . . . . . . . . . . . . . B. Effects of Environmental Enrichment . . . . . . . . . . . . . C. The Quality of Early Stimulation . . . . . . . . . . . . . . . . D. Preweaning Vs. Postweaning Stimulation . . . . . . . . . . E. Critical Periods .................................. 111. A Brief Synopsis of the Human Research . . . . . . . . . . . . . . IV. Theories of the Effects of Early Experience . . . . . . . . . . . . V. Implications for Mental Retardation . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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111 113

115 121 122 129 135

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I. INTRODUCTION

In the 60 years since Sigmund Freud (1905) first gave modem emphasis to the importance of early experience for the adequate development of adaptive adult patterns of behavior, psychological science has been intrigued with the problem and has accumulated a considerable fund of data. Observations have ranged from anecdotal reports to rigorously controlled experimentation, with the latter forming a significant proportion of the reports only in the last 20 years. 1 Present address: Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.

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The purpose of this paper is to review the major findings regarding the effects of early experience on later adaptive behavior and to draw the implications of this work for the understanding of mental retardation. The major portion of the paper will be concerned with animal research, since most of the work in early experience has been performed on infrahuman organisms whose life histories could be regimented to attain the necessary experimental control. As we proceed we shall seek to formulate a theoretical statement that will summarize the findings and serve as a guide to future research. Because this is our goal, we have intentionally addressed this review to particular questions which have occupied the interest of experimenters, not because they are allinclusive, but because they seem to us to be the most important problem areas and can thus serve as focal points around which a review and a theory can be organized. A. The Independent Variables

Research on the effects of early experience has centered around two extremes in the manipulation of experience: either animals were raised in restricted environments where stimulation was minimal or they were given experience in excess of that received in typical laboratory rearing. It is difficult to distinguish the former from the latter except by the experimenter’s intent, for often the control group in a study on environmental stimulation was reared under conditions identical to those used for the experimental group in a study on environmental impoverishment. We shall take the author’s intent as sufficient justification for the classification of each study. Manipulations of early experience have been accomplished in a number of ways within these extremes. In this regard the evaluation of the effects of experience during growth must address itself to the question of whether the quality of the early stimulation employed has produced differential effects on behavior. B. The Dependent Variables

Experiments have investigated the effects of early experience on learning, emotionality, resistance to stress, social adjustment, and other dependent measures. These measures are not necessarily independent of each other; for example, an animal that is “emotional” will be reluctant to run in a maze and thus may show much slower acquisition of a habit than will his less emotional littermate. T h e relative primacy of broad classifications of behavior and the nature of their interactions are problems that beset all behavioral sciences, and the interpretation of the results of any experiment must be considered in the light of all

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other available evidence. Our views on this issue will become apparent although our justification for these views may not. The early part of this review will be concerned with those studies in which some aspect of behavior is measured, but because we think that behavior is produced by physiological activity we will review some of the experiments which measure physiological variables as they are affected by early experience. These studies will be offered as evidence for our physiological point of view. C. The Problem of Age

Since this review is primarily concerned with the effects of experience at one age on the behavior of the organism at another age, care must be taken to determine whether or not early experience is early and late behavior is late. Many experiments that will be included have not examined “later” behavior, but rather behavior that occurred immediately after stimulation. Such studies are important to the overall picture only if the early experience occurred during development. Another problem associated with the age parameter is embodied in the “critical periods” hypothesis. This notion asserts that certain classes of stimuli will have particularly strong and specific effects if they occur, or fail to occur, during a circumscribed period of early development. This is the “weak statement” of the hypothesis. In its stronger form, the hypothesis asserts that these stimuli will have little or no effect if they occur before or after some “critical” time period, An associated question is whether stimulation at different developmental periods produces different behavioral effects; for example, stimulation during .one period may affect learning while stimulation during another may affect responsiveness to stress. This question has dictated a considerable amount of experimentation and discussion and is a very important part of the early experience literature. Having specified some of the basic issues in this area of reseanch, we shall proceed to examine the nature of the experimental evidence which has accumulated in attempts to elucidate the issues and offer resolutions to the problems that have been raised. II. THE BEHAVIORAL VARIABLES

A. Effects of Environmental Deprivation

Experimental situations of subnormal sensory stimulation may be divided into three levels: (a) extreme sensory deprivation, in which the animal is restricted from moving about; is given little or no opportunity for sensory stimulation through the visual, auditory, and

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tactile modes; and is reared for some period in an unchanging surround: (b) social isolation, in which the animal is given no opportunity to interact with members of his own species and little opportunity to interact with any animals; and (c) unimodal deprivation, in which the animal is reared under conditions of structural or artificial restriction of one sensory mode (e.g., rendered deaf by surgery or having a hood placed over his eyes). There is evidence that all of these treatments during the developmental period result in a reduction in the efficiency of adaptive behavior when the animals are tested at a later period in their lives, either at weaning or maturity. That environmental restriction in the early experience of dogs results in a much lower capacity for adaptive behavior was clearly demonstrated in the now classic work of Thompson and Heron (1954). These authors worked with 26 Scottish terriers, all descendants of the same litter. Thirteen nonrestricted pups were reared as pets from weaning to the age of 18 months. The other 13 were reared under one of three conditions of restriction (severe, moderate, and slight) for periods from 7 to 10 months after weaning. Following these experiences, all animals were reared alike for a year and then tested for “intelligence.” The animals reared in restricted environments were less efficient in spatial orientation, problem solving in a barrier (umweg) situation, and maze learning. Isolated animals showed . . a lack of ability to discriminate relevant from irrelevant aspects of the environment, or to adapt to changes made in the experimental situation” (Thompson & Heron, 1954, p. 29). Furthermore, the attention processes of the restricted animals seemed to undergo detrimental change as a result of their early deprivation. Melzack and Scott (1957) reared Scottish terriers in “restricted environments” from puppyhood to maturity. The controls were again reared as pets. When tested at maturity in a shock-avoidance learning problem, the restricted animals learned much more slowly than did the controls, i.e., they required many more shocked trials in order to learn to avoid the shock apparatus. I n addition, the early restricted dogs were less efficient in learning to avoid a lighted match and a pin following experience with burning and pricking. Both in this study and in the study by Thompson and Heron (1954) the social behavior of the dogs was clearly disrupted. Studying a less general effect, Melzack (1962) reared two beagles from 3 weeks of age to 9 months of age in cages that permitted perception of diffuse light but no pattern vision. Their three littermates were reared under normal conditions. At maturity all five dogs were tested for a simple black-white discrimination and subsequently a reversal of this I‘.

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discrimination. Even though the restricted dogs and the control dogs were not different in brightness perception, the restricted dogs required many more trials to learn the original simple discrimination, as well as more trials to learn the reversal. Melzack concluded that restricting the early visual experience of these animals resulted in impaired ability to discriminate brightness, as well as impaired ability to learn problems requiring this discrimination. The general nature of these results has been confirmed in other species. Ganz and Riesen (1962) reared infant monkeys from birth to 10 weeks of age in the dark and compared them with light-reared controls on the learning of a problem requiring a key-pressing response to a particular hue. Generalization of the response to different hues was much more efficient in the light-reared monkeys than in those receiving subnormal early visual stimulation. Bingham and Griffiths (1952) reared rats in squeeze cages with low illumination, in a normal laboratory environment, or in free-environment cages. The restricted animals proved to be inferior to the freeenvironment ones on both Warden-Warner and inclined-plane mazes, but the restricted rats were not significantly different from the normally reared ones. Cohen and Serrano (1963) reared Sprague-Dawley rats under three conditions: spatial confinement, free exercise, and forced exercise. Confined rats were inferior in learning maze problems between 67 and 83 days of age. In a more restricted experiment, NovAkovA, Koldovskf, Faltin, and Flandera (1963) weaned one group of male rats prematurely (at day 15), thus depriving them of the normal stimulation of continued nursing, while controls were weaned normally (usually from day 20 to day 28 in laboratory strains of albino rats but occurring at day 30 in this study). The prematurely weaned rats required more pairings of the conditioned and unconditioned stimuli to elaborate a conditioned reflex at 8 months of age than did the rats weaned at 30 days of age. The generalization made by Ratner and Denny (1964) that “subnormal stimulation leads animals to show more fear but to learn more slowly than normal groups” is clearly supported by the weight of the evidence. 8. Effects of Environmental Enrichment

If environmental deprivation during the developmental period produces decrements in adult learning and adaptive emotionality, it is reasonable to ask whether environmental enrichment would result in ,

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superior performance on similar tasks. Experiments which have examined this question have used a variety of procedures to manipulate the organisms’ experience at different periods in development. Weininger (1956) and Eells (1961) gentled rats after weaning and found them less emotional and more active in an open field than nonstimulated controls. Ader (1957) and Erlich (1959) observed similar effects in handled animals. Spence and Maher (1962a) measured emotionality by measuring the latency for animals to return to drinking after a foot shock and found that stimulated animals returned to drinking much faster after trauma than did nonstimulated controls. Tedeschi and Harburg (1963), Denenberg and Morton (1962), and Levine (1958; 1959a) reported similar effects for animals stimulated in the preweaning period. These treatments also affect learning rates. Bingham and Griffiths (1952), Forgays and Forgays (1952), Woods (1959), and Bernstein (1957) raised rats after weaning in environments differing in complexity and showed that they were superior to their impoverished controls in a variety of problem-solving tasks. Preweaning stimulation also seems to improve learning. Levine, Staats, and Frommer (1958b) reported faster running times and less time a t the choice point in a T-maze for rats handled in the first 20 days of life. Levine (1956), Levine and Otis (1958), and Denenberg (1964) found that rats stimulated in infancy were more efficient in learning a shockavoidance task than nonhandled controls. Although species variables have not been manipulated to the same extent for early stimulation studies as for early deprivation experiments, several experiments indicate that the nature of these results will depend on the genetic characteristics of the animals studied. Cooper and Zubek (1950) used rats that had been bred selectively over many generations for “bright” behavior and “dull” behavior, defined as learning in a Hebb-Williams maze. Groups from each genetic strain were reared under environmental conditions of great restriction, no restriction, or enrichment. Bright animals reared in the highly restricted environment made as many errors in the Hebb-Williams maze as did dull animals raised in that condition. Dull animals raised in a normal laboratory environment made as many errors as did bright or dull animals raised in the restricted condition, while dull rats raised in the enriched environment made as few errors as did bright animals raised either in the normal or in the restricted conditions. Environmental restriction, then, obliterated the native advantage in learning ability of the bright rats, while with environmental enrichment the dull rats were able to learn as well as bright animals reared under normal circumstances (or even in an enriched environment). Environ-

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mental restriction impairs the abilities of initially bright rats but results in no further impairment of the abilities of initially dull rats, while environmental enrichment serves to overcome some of the initial deficit of the dull rats but does not help the bright ones to learn. Levine and Broadhurst (1963) found that open-field defecation was reduced in an emotional strain of rats (Maudsley Reactive) as a result of infant handling. Levine and Wetzel (1963) reported that shockavoidance learning in two strains of rats was differentially affected by early experience. Sprague-Dawley rats were not affected but two substrains of Long Evans rats made significantly more avoidance responses when handled in infancy. King and Eleftherion (1959) found similar differential early treatment effects in two species of the deermouse (Peromyscus maniculatus). These experiments when taken together indicate that early environmental stimulation or the lack of adequate stimulation can affect later behavior. Furthermore, the genetic endowment of the organism is important in determining the nature of these effects. T h e specific problem then becomes: how does early stimulation, or the lack of it, produce these effects on the behavior of the adult organism?

C. The Quality

of Early Stimulation

One critical problem in determining how early experience effects are produced is whether or not early stimulation results in effects that are specific to the kind of stimulation the young organism receives. It is possible that early experience does not represent a psychological phenomenon any different from that studied in experiments on transfer of training. Early stimulation has taken a variety of forms. Young animals have been handled, i.e., picked up and moved from their home cage to a neutral area, gentled, shocked, shaken, and cooled. They have been subjected to environments which vary in size, in the complexity and variety of available stimuli, and in the presence or absence of manipulanda. Numerous experiments have questioned whether these differential experiences produce different effects on later behavior. For a long time after the popularization of Freudian psychology, it was assumed that what Freud had “discovered”-i.e., that early experience has pronounced effects on adult behavior-was a simple and direct relationship. According to this assumption, one would expect noxious or “traumatic” stimulation in infancy to eventuate in increased emotionality and behavior disruption in adulthood, working through some such mechanism as conditioned fear. There is scant support for such a position. A more usual finding is that the effects of noxious stimulation (usually electric shock) and affectively pleasant stimulation

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(usually handling and/or gentling) are quite similar and that both result in a reduction in adult emotionality (e.g., Salama & Hunt, 1964). Many experiments have looked at this notion by shocking rats in infancy and testing them for emotionality in “stressful” situations at adulthood. Levine, Chevalier, and Korchin (1956) manipulated the presence or absence of shock in infancy and found in adult avoidance learning that groups that received daily handling, whether shock or not, did not differ from one another but that all groups were superior learners to the nonhandled controls. Stanley and Monkman (1956) confirmed this finding and showed that if the young animals were allowed to escape during the early shock experience they showed more rapid learning when tested in adulthood. T h e general nature of these experiments has been confirmed by Brookshire, Littman, and Stewart (1962), Baron, Brookshire, and Littman (1957), Denenberg and Smith (1963), and in mice by Bell and Denenberg (1963). Contrary to the Freudian hypothesis these results suggest that any early stimulation will result in decreased emotionality at adulthood. Confirmation of this hypothesis has been offered by Denenberg, Carlson, and Stephens (1962a) and Stanley and Monkman (1956), who measured emotionality in the open field. I n spite of the general interest in this problem, only rarely have experimenters manipulated several kinds of early stimulation and measured their effects on several kinds of response measures within the same experiment. For this reason, a recent study by Salama and H u n t (1964), although not unique, stands as a tour de force in this area and will be described in some detail here. Partially as a test of the “conditioning” theory of anxiety, Salama and Hunt reared littermate rat groups under five conditions. Controls (CC) were left unmolested in the nest until weaning at 28 days. They were then moved to individual rearing cages but were given shock training from day 59 to day 63. T h e shocked (S) group was shocked daily from day 11 to day 20 for 3 min, then returned to the cage. T h e handled (H) group was removed from the cage daily between days 11 and 20, placed on an unelertrified grid for 3 min, and then returned to the cage. T h e gentled (G) group received the same treatment as the handled group, except that they were stroked by hand continuously for the 3 min daily that they were out of the cage. From day 29 until day 50 all subjects were caged individually and undisturbed. Subjects were then given experience exploring a T-maze, deprived of food for 23 hours, given further experience in the T-maze, given 40 trials of one-shock learning in the T-maze, given 50 trials in the T-maze (al! groups but CC) with electric shock after the choice point, run on the same problem to a reversal criterion (two successive

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reversals-i.e., runs to the previously nonrewarded goalbox), and timed for survival in cold water. Neither reward learning nor shock learning revealed any significant difference among the rearing groups; however, the three stimulated groups exhibited less emotionality, as measured by defecation and urination, while exploring the T-maze than did the nonstimulated control groups. The effects of the three different stimulation treatments on these measures of emotionality were strikingly similar. With “timidity” measured as time to leave the startbox and enter the goalbox of the T-maze, the unmolested animals were least timid on first encounter with the unfamiliar T-maze, but on the second encounter with it a day later, the infant-shocked animals were least timid. Early stimulated animals decreased in timidity significantly more from the first to the second encounters with the unfamiliar maze than did unmolested animals. The authors concluded that “Infantile stimulation increases the capacity of an organism to ‘profit from experience’” (Salama & Hunt, 1964, p. 147). Similarly, there was no difference among the groups in number of goalbox entries on first encounter with the T-maze, but on second encounter the early stimulated animals made significantly more goalbox entries; this difference was sustained when covariance adjustments were made for the number of entries made on first encounter. The authors concluded (Salama & Hunt, 1964, p. 149): “Here is solid evidence that the stimulated rats did ‘profit’ more from the first encounter than did the unmolested controls.” Following shock training, S rats (with H and G following in that order) required the smallest number of unrewarded trials to bring about a change of goalbox choice (excluding group CC, in which no shock training was given). Apparently, noxious stimulation in infancy decreases “fixated” behavior.2 When all the animals were placed on restricted feeding for 2 weeks and weighed on day 64, it was the S group that showed by far the least weight loss. This effect, however, did not generalize to capacity for survival in cold water; in this final test, the unmolested controls survived longest, but the difference was not significant. Salama and Hunt (1964, p. 158) concluded that ‘‘ . . . encounters with varied stimulation . . . do help to innoculate an organism against the fears of the unfamiliar and the strange. Moreover, even though electric shock is presumably painful, it appears in the main to share, with such other variations of infantile experience as being shaken, being cooled, being handled, and being petted, this effect upon reaction to the un2 This finding might alternatively be explained as a leaser resistance to extinction, and hence a reflection of less adequate learning, in the case of the shodred animala.

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familiar, which is quite contrary to any contention that anxiousness and fear are inevitable consequences of painful stimulation.” T h e observation by Levine and others that handled but nonshocked controls also differed from nonhandled groups was further tested and confirmed in a number of experiments. This has led to experiments which have attempted to examine the nature of the stimuli that, imposed during this early period of life, bring about decreased emotionality later. Levine (1959a) placed rats on a vibrator in their home cages and oscillated them for 2 min with or without their mothers. All groups were significantly less emotional in the open field than were the undisturbed controls. Similar decreased emotionality has been reported for rats that have received inconsistent handling during growth (Eells, 1961) or have been traumatized by loud sounds (Spence 8c Maher, 1962a). Meyer (1962) found that carrying the brood cage a distance of 80 feet, once a day for 4 days, produced changes in later exploratory behavior. Even different means of delivering the food to the cage before weaning can alter later behavior (Denenberg & Whimbey, 1963). Taken together, these studies indicate that the effect of early stimulation is not specific to any situation. Stimulation at a n early age seems to produce an animal more capable of adapting to a wide variety of situational variables as an adult. A number of experiments have attempted to ascertain the commonality in procedures used in the manipulation of early experience. For example, the failure to show specificity in the preweaning treatment effect has led Schaefer, Weingarten, and Towne (1962), Schaefer (1963) and Hutchings (1965) to suggest that these treatments all reduce the animal’s body temperature and that the critical stimulus manipulation for producing these effects is lowered temperature. Schaefer (1963) handled rats or exposed other rats to low temperatures and found that adrenal ascorbic acid levels (an index of response to stress) did not differ in these groups but that both differed from nonhandled controls. I n a further study, animals handled in an incubator which maintained their body temperature did not differ on this measure from nonhandled controls. Both groups differed from animals handled at room temperature. On the behavioral side Hellmer (1943) found that rats reared at 55°F were more efficient in maze running than were rats reared at 75°F or 90°F. Hutchings (1963) placed rats in cans lowered into 8”12°C water. Animals so treated were inferior to the nonhandled group in the performance of a bar-pressing response after conditioned fear had been established. I n a followup study, a handled group was included. This group was superior in bar pressing to both the nonhandled

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and cooled groups, suggesting to the author the possibility of a curvilinear relationship between body-temperature loss and emotionality. Another factor which seems important in mediating early experience effect is the effect of the treatment on the mother. T h e majority of these experiments treat the young rats by removing them from the home cage. This may increase the emotionality of the mother, which in turn may alter the behavior of the pups. Denenberg, Ottinger, and Stephens (1962~)shocked mother rats and increased open field emotionality and avoidance learning in the offspring. Denenberg and Whimbey (1963) demonstrated that handled mothers, which were less emotional, had less emotional progeny than did nonhandled mothers. Confirmation of the importance of this variable was given by a further experiment of Ottinger, Denenberg, and Stephens (1963). Ader and Conklin (1963) handled pregnant rats for 10 min three times daily and found that their offspring were generally less emotional than were the offspring of nonhandled mothers. I n all of these experiments the animals were stimulated prior to weaning (about 21 days in the rat). Hebb’s (1949) speculation that early perceptual stimulation is an important determinant of adult behavior led to a great number of experiments which varied the environments in which the organism is reared. Typically, these studies begin where the previous experiments left off, after weaning. T h e experiments by Cooper and Zubek (1950), Hymovitch (1952), and Bingham and Griffiths (1952), indicated that animals can profit by experience in an unrestricted environment. T o determine whether this effect was mediated by perceptual learning which occurred during rearing, Forgus (1954; 1955) reared rats in three environments: (a) large black cages with white manipulanda; (b) large black cages with objects visible but out of reach; and (c) small, unfurnished boxes, Rats reared under conditions (a) and (b) moved around faster, were less emotional, exhibited more varied behavior, and were more efficient at solving insight problems when compared with animals reared under condition (c). I n problems requiring visual discrimination, animals reared under condition (b) were superior to those reared under condition (a). In the second experiment, rats were reared as before; then discrimination learning began in a maze with visual cues which were removed before learning was complete. Subsequently, the rats reared under “visuomotor” conditions (a) learned in 19.5 trials and made 60.5 errors, while the rats reared under “visual only” conditions (b) learned in 26.6 trials and made 83.1 errors. These differences were greater than could be explained on the basis of chance variation. In a third experiment (Forgus, 1956), the experimenter reared rats from 16 to 41 days, or from

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41 to 66 days, in cages with geometric forms on the walls. Their littermate controls were similarly reared, but without the forms. The early stimulated rats and their controls were tested in the same problem at 66 days. The early stimulated rats required the smallest number of trials to learn the discrimination problem and made the fewest errors on a generalization test. Those stimulated from 41 to 66 days required slightly more trials to learn and made more than twice as many errors on the generalization test. The poorest performances in both situations were given by the unstimulated control groups, which did not differ from each other. In a similar experiment which provided both greater intensity and greater variety of stimulation, Luchins and Forgus (1955) reared rats during the postweaning period in cages equipped with blocks, alleys, and elevated platforms, and played with them for 1 hr per day. Controls lived in cages without these visual stimuli and manipulanda, and “without much contact with people.” I n later tests the stimulated rats moved around more in a new situation, exhibited more insightful behavior in solving problems, and were able to drop an old solution and change to a new problem-solving approach more rapidly than could controls. Opportunity to move about freely during the developmental period appears to be important for later behavior. Hymovitch (1952) raised rats (after weaning) in free-environment cages, stovepipe cages, and cages with an activity wheel attached. While none of the groups differed as adults in learning a T-maze, the free-environment animals were superior to the others in learning in the Hebb-Williams maze. This effect was probably due to greater opportunities for perceptual learning through exposure to more variety in stimulation in the free-environment group, since the stovepipe groups and the activity-wheel group did not differ from each other. Woods (1959) confirmed the general nature of these findings, and further suggested that the earlier the experience in the unrestricted environment, the greater its effect. Cohen and Serrano (1963) investigated the effects of postweaning activity on learning. Rats were divided into three groups receiving conditions of confinement, voluntary activity, or forced activity. Voluntary activity animals showed superior learning. Krech, Rosenzweig, and Bennett (1962) found that animals raised in a complex environment showed superior performance on discrimination reversal learning when tested at adulthood. Thus, it appears that both perceptual experience and motor activity during postweaning development are important factors which influence adult behavior patterns. The experiments on postweaning stimulation

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also indicate that experience at this period of development affects later problem-solving behavior. These results when taken together with the preweaning stimulation studies indicate that the effects of preweaning and postweaning stimulation differ in some important ways. D. Preweaning Vs. Postweaning Stimulation

Several investigators have examined the preweaning and postweaning treatments within the same experiment in an attempt to ascertain the nature of these differences. Mogenson and Ehrlich (1958) compared the effects of postweaning shock and handling on exploratory behavior in a Y-maze and in a Dashiell maze. I n contrast to preweaning stimulation they found the postweaning-handled animals to be more active than nonshocked controls, which were more active than the shocked group. In a more direct experimental test of this question, Levine (1958) compared the effect of shock and handling in infancy upon water consumption under deprivation in adulthood. All animals receiving shock in adulthood took longer to drink, with nonhandled animals taking longer than the shocked and handled groups. Levine and Otis (1958) showed that early handled animals (1-20 days) were more resistant to terminal stress than were late-handled animals (21-42 days). Spence and Maher (1962a; 1962b) examined the differential effect of handling and shock on latency to drink after shock and found that the earlier the handling, the shorter the drinking latency. They also found that early handled or shocked animals were faster in a runway than were late handled or shocked animals but that both early and late treatment groups were faster than controls. Both Levine (1956) and Levine and Otis (1958) reported that rats receiving preweaning handling (from birth to 20 days) take fewer trials to learn a shock-avoidance habit and are less emotional than rats handled during the postweaning period (e.g., from 50 to 70 days). They also reported that infant-stimulated rats are heavier and survive severe stress longer. Denenberg and Morton (1962) examined the effects of preweaning handling and postweaning free-environmental experience in a factorial study. Handled animals were less emotional than were nonhandled groups regardless of the postweaning treatment. In a replication of this experiment the subjects were tested in the Hebb-Williams maze for problem-solving ability. Performance for the handled and nonhandled groups did not differ after initial adaptation to the maze. Free-environmental experience during postweaning did result in fewer maze errors than did confinement regardless of the preweaning treatment. I t is unfortunate that there are not more experiments which directly

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compare preweaning and postweaning treatments on the same tasks, but most of those that do suggest that preweaning and postweaning treatments produce differential effects. Preweaning stimulation decreases the animals’ emotionality or response to stress-producing situations. This conclusion is partially confirmed by the fact that the majority of learning differences reported to follow preweaning treatments have been demonstrated on shock-avoidance tasks. In a study of the effect of early stimulation on adult T-maze learning, rats handled in infancy took less time to run the maze and spent less time at the choice point, but groups did not differ in the number of errors, a result suggesting emotionality rather than direct learning differences. In contrast, postweaning stimulation seems to affect primarily the animals’ behavior in complex learning situations. There is some suggestion that there are at least two general periods within which stimulation results in differential effects on later behavior: (1) an early period (between 1 and 10 days in the rat) during which stimulation alters emotionality or the response to stress-producing stimuli, and (2) a later period (between 15 and 20 days in the rat) during which stimulation alters the animal’s capacity for problem-solving behavior. E. Critical Periods

Within the preweaning and postweaning stages of development] several experimenters have attempted to delineate smaller periods during which experience produces maximal effects on later behavior. Such experiments have derived theoretical impetus from the critical periods hypo thesis. T h e critical periods hypothesis had its origin in experiments on embryological development, but its application to behavior has come primarily from an examination of the occurrence of imprinting in precocial birds. Its strongest statement was given by Lorenz (1935, cited in Levine, 1962, p. 144), who wrote: “There are specific and restricted periods during which the stimuli which will evoke certain instinctive responses are permanently determined. After the critical period has passed, the environment cannot alter the nature of the affective stimulus.” It is clear that Lorenz was speaking specifically of unlearned behavior, but current advocates of the critical periods hypothesis apply it equally strenuously to morphology and to learned (and quite complex) behavior. Most of the experimentation undertaken to establish optimal periods for the effects of some type of experience on later behavior have concentrated on the first part of Lorenz’ statement, and many investigators have been content merely to assume the immutability of behavior so

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determined. Most of the earlier research directly concerned with behavioral critical periods was done within the framework of the imprinting paradigm. “Imprinting” refers to the formation of an “emotional” attachment (usually measured later by observing following behavior) to some visual or auditory stimulus which is perceived during some “critical period” early in the developmental history of the animal. It appears to be a phylogenetically sequenced maturational phenomenon. I n experiments to establish the occurrence and duration of the critical period for this phenomenon, Hess (1959a; 1959b) exposed different groups of birds (Peking ducks or Vantress chicks) to a moving stimulus at different ages during the first few hours after hatching and later tested them for the strength of the following response and for discrimination between the original imprinting stimulus and a previously unseen stimulus. Highly reliable critical periods have been reported, with initial exposure between 12 and 16 hr after hatching providing the strongest response on later testing. With the single exception of unpublished data from the Peabody College Laboratory, the authors know of no study in which imprinted behavior has been tested at any considerable temporal separation from the original imprinting experience in order to assess its permanence. In an unpublished study (Haywood, 1963) 24 Vantress chicks from an imprinting experiment were saved because they had followed the imprinting model more than 50% of the time on test at around 56 h r of age. These strongly imprinted animals were then put back in the imprinting apparatus every 3 days and given the opportunity to follow as the model made 20 revolutions around the circular track. T h e relationship of percent following responses to age in days was a perfectly linear decaying function, reaching zero at 21 days. While these tests were made only incidentally to another experiment and used a restricted sample of subjects, the striking linear decay of following as a function of time in these strongly imprinted chicks must call into question the frequent assertion of the permanence of responses which are dependent upon some occurrence during a critical period in development. Careful longitudinal study is certainly indicated. If such “maturationally scheduled” behavior (Hess, 1959b) could be delayed or advanced in time by the withholding or imposition of different amounts of sensory stimulation, it would provide some evidence from which one could construct hypotheses concerning the delaying or hastening of the development of adaptive abilities in general. Some such attempts have been made recently. In the first of these, Moltz and Stettner (1961) fitted an experimental group of Peking ducklings

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with latex hoods that prevented form perception. Their control animals were also fitted with latex hoods, but with holes cut for the eyes. They found that it was possible to obtain imprinting at much later ages in the visually deprived ducklings than in the controls. These relationships are depicted in Fig. 1. Taking an opposite strategy, Haywood and Zimmerman (1964, p. 653) reared experimental groups of Vantress chicks in a “ . . . complex environment, rich in sensory stimulation, from hatching until imprinting 3, 6, 9, 12, 15, or 18 hours later.” Control animals were reared in a far less stimulating environment and imprinted at the same times. The period of maximum effect of the imprinting experience (as

z

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FIG. 1. Median following-scores obtained by ducklings deprived of pattem-light stiinulation (experimentals) and by controls after different exposure ages. (Moltz & Stettner, 1961.)

determined by the strength of the following response on later test) occurred earlier for the chicks reared in the complex sensory environment than for those reared in the less stimulating environment, and the following response was distinctly stronger over the range of imprinting ages, as can be seen in Fig. 2. These two studies appear to indicate that certain aspects of development can be delayed by restricting the sensory environment or can be hastened by enriching it. In the Haywood and Zimmerman study (1964), the critical period for imprinting appeared to be extended in both directions, i.e., the following response was stronger in the enriched groups even at the later imprinting ages. This result suggests that whatever responsive capacity of the organism is heightened by the imposition of early stimulus enrichment is a relatively enduring one (within the very brief time periods usually studied in imprinting research). A second study by Haywood (1965) using substantially the same procedures but requiring the animals to

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discriminate between the initial imprinting stimulus and a previously unseen one, demonstrated a strong effect of the imprinting experience for the stimulus-enriched groups, but showed no differential occurrence of the critical period; however, in this study, even the less-stimulated controls showed a period of maximum effect of imprinting which was

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FIG. 2. Percentage of following responses during test as a function of age at imprinting for animals reared in complex environment and for animals reared in restricted environment. (Haywood & Zimmerman, 1964.)

much earlier than that reported by previous investigators. The discrimination data are depicted in Fig. 3. Research on mammals that has been addressed specifically to the question of critical periods for the effects of early stimulation and deprivation has generally shown that there are circumscribed periods in development during which stimulation (or deprivation) will have greater effects on later tests of learning and emotionality than will experience given (or withheld) at other times. I n general, the results indicate that the earlier the treatment, the more obvious will be the later effect. Still within the imprinting paradigm, Thompson and Dubanoski (1964) found that handling chicks at 5 hr of age significantly increased the strength of the following response at 30 and 54 hr of age, while handling at 9 hr had no effect. Levine (1962, p. 144), citing the work of Scott (1958) and Freedman, Elliott, and King (1958). stated that "The experimental evidence for

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the critical period hypothesis with reference to socialization is fairly clear, and generally indicates that if there is some disturbance in the social environment, i.e., removal from the litter, isolation, etc., during this period critical for socialization, there then appears a marked destruction of the social capacity of the organism. It is important to note that so far as critical periods and socialization are concerned, no ex-

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FIG.3. Percentage of correct discriminations on test as a function of age at imprinting for chicks reared in a complex environment and for chicks reared in a restricted environment. (Haywood, 1965.)

perience occurring during the neonatal period of dog development appeared to have any permanent effect on subsequent behavior. The critical period for socialization in dogs appears to extend from three weeks of age to ten weeks of age.” Experiments which have examined the critical periods hypothesis for other forms of behavior have not been as definitive in their results. Although, as indicated above, there seem to be differential effects on behavior associated with pre- and postweaning experience, examinations within these periods are only suggestive. Within the preweaning period, Schaefer (1957) reported that rats handled between the first and seventh days and the first and twentyfirst days were significantly less emotional at adulthood than were rats

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handled between the eighth and fourteenth days or between the fifteenth and twenty-first days. Since the effects on the 1- to 21-day group cannot be separated from the 1- to 7-day group, Schaefer seems to have found an optimal period sometime during the first 7 days of life for the rat. Denenberg and Karas (1960) found that animals handled from days 1-10 make more avoidance responses in 40 trials than do those handled from days 11-20, 1-20, 11-15, or 16-20, or nonhandled controls. Within this period of early infancy, Kline and Denenberg (1964) found better avoidance learning in rats shocked at 4 days of age than in those shocked at 2 days of age. Denenberg et a2. (1962a) reported that animals shocked on days 1 and 2 have higher open-field activity than do those shocked on day 2 only or do nonshocked controls. Meyer (1962) looked for critical periods in rats for emergence from the home cage into an exploratory alley. All treated subjects showed shorter entrance latencies than did controls, with animals stimulated (carried 40 feet across the room in their home cage) between days 6 1 0 and 11-15 showing the fastest emergence. Denenberg (1962) compared critical periods for a number of measures. Animals were stimulated by removing them from their home cage for 3 min per day for days 1-3, 6-8, 8-10, 1-5, 6-10, or 1-10. These were compared with nonhandled controls. Subjects stimulated for the periods 3-5 or 1-5 days survived longer under terminal stress. Animals stimulated from days 6-10 or 1-10 made a greater number of avoidance responses than did all other groups. Denenberg interpreted these data as evidence against the critical periods hypothesis and suggested that the duration of stimulation is the critical variable producing this effect. On the basis of these data it would seem that the critical periods for these behavioral effects occurred within the first 10 days of life for the rat, This generality is not entirely consonant with the findings of Henderson (1964a) who shocked or handled mice at 1, 8, 15, 23, 30, 40, or 55 days of age, then tested them in an open field at 60 days and in an avoidance learning task at 85 days. Henderson found that the mice shocked at 23 and 30 days both learned faster and exhibited greater emotionality than did the other groups. While Henderson's results with respect to emotionality are somewhat dissonant with those of other investigators, his work merits close attention, since he typically employs very large numbers of animals and meticulously controls the experiences of multiple control groups (e.g., Henderson, 1964b; 1965). Within the postweaning period, Hymovitch (1952) reported that rats raised in free-environment cages from days 30-70 gave superior performance in a Hebb-Williams maze when compared to a comparable group living in the cages from days 86-130.

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I n a more recent experiment Forgays and Read (1962) conducted an experiment to determine the critical period for free-environmental experience. Animals were raised in large cages with toys for varying I0-day periods after weaning and then tested for exploration in a maze and for errors in the acquisition of a Hebb-Williams maze. There were five groups which received enrichment from days 0-21, 22-43, 44-65, 66-87, and 88-109 and a nonstimulated control group. T h e nonstimulated animals were inferior in the Hebb-Williams to all but the 88- to 109-daygroup. I n addition the 22- to 43-day group differed from the 88- to 109-day group and the 1- to 21-day group and tended to be lower than the other groups. T h e authors suggested that the critical period for this effect seems to occur long before maturity and soon after the eyes are first opened. While there are studies in abundance to show that one particular developmental period is optimal for producing effects on later behavior, there is little agreement, even within a single organism (usually the white rat), concerning exactly what period of time is optimal for what forms of later behavior. In general, preweaning treatments produce greater effects than do postweaning treatments (Bernstein, 1952; Forgus, 1956: Levine, 1956; Levine & Otis, 1958). Some investigators have delineated smaller optimal time units within the preweaning period of development for other behavioral effects (e.g., Bell, 1964; Bell & Denenberg, 1963; Denenberg & Bell, 1960: Kline & Denenberg, 1964; Levine & Lewis, 1959; Lindholm, 1962; Schaefer, 1957), but there is little agreement on the setting of any one period as critical in the strictest sense for the effects of experience on adult behavior. Even when dealing with postweaning periods exclusively, the earlier of two such periods seems to be superior to the later period in producing measurable effects of experimental treatments. I n spite of the difficulty of specifying a precise age span during which the effects of experience are maximal, it seems safe to conclude that the greatest effects are obtained when the experience is imposed prior to weaning, and probably during the first 10 days of life if the dependent variable is a measure of emotionality. It also seems that for the rat, differential experience imposed between 15 and 30 days of age may alter later problem-solving ability. This is not the same as a critical period in the strictest sense, since substantial effects of experience have been obtained with postweaning manipulations, some of which have reached into adulthood. It seems reasonable to conclude that some maturation must have taken place before experimental treatments can have significant later effects, but the treatments will have greater effects if they are imposed during the period in which such treatments will still constitute

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some fairly large proportion of the organism’s total life experience. As the animal grows older, standard laboratory treatments (often 3 min per day of handling, gentling, or shocking) will constitute a decreasing proportion of his total experience and might well be expected to have proportionately less effect. 111. A BRIEF SYNOPSIS

O F THE H U M A N RESEARCH

Because of the far greater control that is possible in animal experimectation, this review has concentrated on the evidence concerning the effects of early experience upon adaptive abilities in laboratory animals. For purposes of the present volume we would be remiss if we did not attempt to show the relevance of some of this work for intellectual development in the human organism. Clearly, the relevance of animal research to knowledge of human behavior is not direct; indeed, one of the striking generalizations that can be made from the animal literature in early experience is that there are reliable species differences in the effects of early experience upon later behavior. It is equally true, however, that some relationships can be postulated by simple extrapolation from comparative studies, and from such extrapolation it is possible to form hypotheses concerning human behavior. Such hypotheses are then subject to test by the kinds of evidence that it is possible to accumulate on human beings, i.e., survey data, correlational studies, inferences gathered from studying the accidents which frequent the human estate, and, most recently, truly experimental studies in which it is possible to intervene in the lives of human children and provide different levels of environmental stimulation during important developmental periods in their lives. We would be equally remiss and somewhat presumptuous to present an extended review of the various sorts of evidence that have accumulated which bear on the question of the effects of experience on the growth of human intellect. Excellent reviews have been presented by Hunt (1961; 1964) and by McCandless (1964). T h e three principal preconceptions whose validity must be assessed before one can deal extensively with a theory of intellectual development-i.e., predeterminism, preformationism, and the constancy of the IQ-have been dealt the coup de grace by Hunt’s incisive review and reinterpretation of both old and new evidence (Hunt, 1961). With these hampering concepts now in a most doubtful position, it is possible to conceive of a dynamic intelligence evolving ontogenetically from the interaction of the individual’s genetic given and the experiences afforded by his environment. What we shall do is present a sample of representative studies concerning

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the growth of intelligence in human beings and relate these to the hypotheses derived from the animal literature and from developmental theory. If the growth of the intellect comes about simply as a maturational process, independent of experiential factors, one should find substantially the same correlation between the IQs of parents and the IQs of their children, whether they are reared together or apart. If, on the other hand, experience plays a significant role in the development of intellect, one would expect a relationship between the circumstances of rearing and the ultimate level of intellectual performance. While the usual correlation found between the IQs of parents and the IQs of their own children is of the order of +.SO, Snygg (1938) reported a correlation of only +.IS between the IQs of mothers and the IQs of their children living in foster homes. In the same paper, Snygg reported that when the children of 98 mothers with IQ scores less than 70 were removed from the home before the age of 4 years and placed in foster homes (which were described as somewhat less than ideal), the IQs of the children averaged 91, a score that falls within the low average range. Speer (1940) studied a group of 28 children whose mothers had a mean IQ of 49. Sixteen of these children remained with their own mothers until they were 12-15 years old, and their IQs averaged 53, quite close to the scores of their mothers. The other 12 children were separated from their mothers before they were 2 years old and reared in somewhat more stimulating circumstances. Their average IQ was 100.5, a score that is average for an unselected sample from the population. While both of these sets of data take advantage of what might be called “accidental” circumstances, and of the statistical phenomenon of regression to the mean, the differences between the IQs of those reared in limited surroundings and those reared in somewhat more stimulating surroundings are quite substantial and suggest that early enrichment of the child’s environment can result in far greater intellectual functioning than would be predicted from inferred genetic endowment alone. In the same Sort of study, but focusing on continued conditions of deprivation, Pringle and Bossio (1958) and Pringle and Tanner (1958) reported that children reared under deprived conditions in residential nursery schools “. were retarded in the formal aspects of language . . . [and] . . lacked the ability for verbalizing phantasy and for using speech in making social relationships with contemporaries” (Pringle and Bossio, 1958). Concentrating upon language behavior, Badt (1958) related levels of abstraction in vocabulary definitions on the S tanford-Binet Intelligence Test to length of institutionalization among 60 educable mental retardates

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between 7 and 15 years of age. With mental age and chronological age held constant, Badt found a correlation of -.71. T h e study of mental retardates has provided a natural laboratory in the search for knowledge on the development of intellect. Within this laboratory, it has been convenient to compare the Performances of mentally retarded persons with the performances of intellectually average or above-average subjects and also to compare institutionalized retardates with noninstitutionalized retardates. I n the latter strategy one can avoid the confounding of intelligence levels with the effects of institutionalization. T h e usual finding is that continued residence in a large public institution for the retarded results in further depression of ability. A study of this sort is that of Stedman and Eichorn (1964), who compared 10 healthy mongoloid children (between 15 and 31 months of age) in an institution with 10 pair-matched mongoloid children living at home. Both mental and social maturity scales revealed significant differences in favor of the home-reared children. Stedman and Eichorn (1965) reported that “. . . eight of the 10 home-group subjects were found to be walking, while only two of the 10 in the hospital group walked.” Of 14 anthropometric indexes, the home-reared children were significantly larger in calf circumference, full length, and weight. There were no statistically significant differences in favor of the hospitalized children. On 13 of the 14 measures the observed differences were in favor of the home-reared group. T h e unique significance of this study lies in the fact that the hospital-reared children were preselected, avoiding some of the unspecifiable selective biases in sampling deriving from factors which might have caused them to have to be placed in an . . located through cominstitution. In addition, both groups were munity agencies and selected for freedom from severe physical handicaps other than mongolism” (Stedman & Eichorn, 1964, p. 401). Even more striking data are reported by Dennis (1960), who observed Iranian children from 1 to 3 years of age in public and in private institutions. T h e institutions differed widely in stimulation value, with the private institution providing much more attention and fondling. Children in the public institutions were found to be quite severely retarded in motor development, but this was not true of the children in the private institution. These studies illustrate what is by now almost a general principle: that continued residence in the large, public-supported, impersonal institutions often results in a progressive decrease in the IQ, and, if institutionalization occurs early, some motor retardation and retardation of general growth as well. It is also clear from previous research that children who have been reared in relatively stimulating environments I‘.

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have higher IQs and more satisfactory development in general than do children reared in less stimulating environments. These latter studies have usually taken advantage of naturally occurring situations, in which it has not been possible to control, or even to know about, many of the circumstances of rearing, and in which the “experimental treatments” themselves have been largely unspecifiable and unreplicable. While such studies are interesting as population studies and are useful in the construction of hypotheses concerning the growth of the intellect, they are less than optimal for providing definitive data. A few studies have been conducted with human subjects using both specifiable and replicable stimulation treatments, with untreated control groups. McCandless (1964) cited unpublished data gathered from the Pine School, where a “total push” program was undertaken with the families of “socially disadvantaged” children. These children received the services of social workers, psychologists, pediatricians, nurses, and nutritionists, and attended nursery school and kindergarten. The children were divided into two age groups (5 years or more, and under 5 years). “The gain in IQ for the younger and total group was significant at less than 0.05 level. The younger group gained significantly more than the older group, while the gain for the older group was not significant . . . the younger a child is when he undergoes such experiences, the greater the effect they have on the child’s development” (McCandless, 1964, pp. 187-188). One of the earliest of the intervention studies was a study by Skeels and Dye (1939), which has become a developmental classic. In 1965 Skeels gave a preliminary report of followup data obtained on the 1938 sample of 25 children. The 13 children in the experimental group were removed from a minimally stimulating institution and placed in another institution which provided mother surrogates for them; 11 of them were subsequently placed in adoptive homes. The 12 children in the contrast group remained in the unstimulating institution “over a prolonged period of time.” By the time of the early report, the children in the experimental group had already shown an increase in “rate of mental growth,” while the other children showed “progressive mental retardation.” After an interval of 21 years, current data have been obtained on the whole sample, and the comparisons are at least as dramatic as they were in 1938. The median subject in the experimental group has completed the twelfth grade, while the median subject in the contrast group has completed only the third grade. One-third of the experimental subjects have been to college, and one has a baccalaureate degree. The whole range of occupations is represented in the experimental group, while in the contrast group “. . . 50 per cent of the subjects

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are unemployed, and those that are employed are, with the exception of one person, unskilled laborers” (Skeels, 1965, p. 33). Skeels (1965) reported the case of one girl in the experimental group who in the original study had an I Q of 35. This subject has graduated from high school, has one semester of college, is married, and has two children with IQs of 128 and 107. Except for the educational data, one might argue that these studies are great success stories about teaching social skills to the mentally retarded and that the subjects remain highly socially skilled mental retardates; however, it is difficult to believe that such retarded children eventually achieve a high school diploma, go to college, and occupy themselves in professional, semiprofessional, skilled, and semiskilled jobs, while still retaining IQ ratings in the mentally retarded range. A shorter study, but one in which the treatments were more clearly specifiable, was one by Kirk (1958). Preschool children between 3 and 6 years of age and ranging in IQ from 40 to 80 were selected from the community and from two institutions for the mentally retarded. Experimental groups both in the community and in one institution received 1 to 3 years of nursery school experience, including individual tutoring tailored to specific needs. During the period of preschool attendance, the community experimental group showed an average gain of 11.2 I Q points, while the community contrast group (children who did not receive the nursery school experience) dropped an average of .6 IQ points. Among the institutional children, the experimental group gained an average of 12.0 IQ points, while the contrast group dropped an average of 7.2 points. (These figures reflect scores on the 1937 revision of the Stanford-Binet Intelligence Test.) Following the nursery school experience, all of the children entered either first grade or an ungraded primary class. In school, the community experimental group did not gain significantly in IQ (.5 points), but the community contrast group did (7.5 points). Hence, the overall gain from the beginning of the study through the first year in school for the community experimental group was + 11.7, while for the community contrast group it was 6.9. Among the institutional children, neither group changed significantly in IQ during the first year of school. Over the whole study, the institutional experimental group gained 10.2 IQ points, while the institutional contrast group lost 6.5 IQ points. The children who received preschool experience gained significantly on the Stanford-Binet, the Kuhlmann Tests of Mental Development, and the Vineland Social Maturity Scale. Such formalized preschool experiences may be especially important for “culturally deprived” children, since Kirk reported that children from adequate homes who do not have preschool experience show accelerated

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mental and social development after entering school, but children from inadequate homes do not show such acceleration, i.e., even after entering school “deprived” children retain their lower level of mental and social performance. T he term “progressive retardation” has come to be associated with the frequently observed decline over time in the psychometric intelligence of culturally deprived children who remain in subnormal environmental circumstances (e.g., see Neff, 1938). T h e term itself implies rejection of the notion of a static intelligence. At least part of the intellectual and social subnormality of such children is thought to be attributable to the unstimulating environmental conditions in which they are reared. Dunn (1963, p. 64) asserted that “, . . there are no known causes for over 90 per cent of the mentally retarded individuals in the United States and Canada today.” In other words, all the present knowledge of genetic, metabolic, toxic, traumatic, and other etiologic factors is able to account for no more than 10% of cases of mental retardation. Dunn (1963, p. 65) further stated that . . there are no discernible neurological impairments for 99 per cent of the IQ 50-75 group . . . .” It is in the mildly retarded and dull normal groups that recent efforts have been made to arrest or offset the progressive retarding effects of adverse rearing circumstances, or “cultural deprivation.” T h e exemplary study in this area is one still in progress, being done by Susan Gray and Rupert Klaus of Peabody College. Culturally deprived Negro children in Tennessee have been given none, one, or two summers of preschool experience designed to stimulate the development of motivational, perceptual-cognitive, and language aptitudes. Throughout the study, specially trained preschool teachers have met weekly with the children’s parents in a n effort to increase the stimulation value of the homes. In addition to a control group in the same town, there is a distal control group in a comparable town. Gray and Klaus (1964) reported some interim data on the effects to date of this massive treatment, but they correctly emphasized that the most interesting assessment will come when all of the children have been in school for at least a year or two. As anticipated, the two control groups declined in psychometric intelligence, the local controls losing four points and the distal controls losing six points on the StanfordBinet. T h e 2-year treatment group gained nine IQ points, while the 1-year treatment group gained five points. Similar results were apparent using the Peabody Picture Vocabulary Test. T h e Illinois Test of Psycholinguistic Ability showed a general (and significant) superiority of the treatment groups over the controls in language development. T h e authors reported that “. . . on an elaborate battery of preschool screen‘I.

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ing tests given to all children entering the first grade in our main city, the experimental children did conspicuously better than the controls, and tend to approximate the non-deprived children in the school. On reading readiness tests they are again superior.” These preliminary data suggest that the progressive mental retardation which coexists with culturally deprived circumstances may be not only arrested, but actually reversed, by the application of stimulating programs of experience. IV. THEORIES OF THE EFFECTS OF EARLY EXPERIENCE

At tempts of behavior scientists to conceptualize the mechanism by which early experience exerts its effects on later behavior have taken two forms, These conceptual efforts may be characterized broadly as “arousal mediation” and as “hastened development.” T h e former is identified principally with V. H. Denenberg and his students, while the latter derives from the theories of D. 0. Hebb and S. Levine. They are not mutually exclusive, and some components of both, as well as additional theory derived from psychophysiology, may be required before full understanding of the mechanisms of these effects can be achieved. Denenberg (1964) proposed a monotonic relationship between intensity of stimulus input in infancy and emotional reactivity in adulthood, a notion that was empirically derived and received support from the work of Levine (1957a; 1958), Denenberg, Morton, Kline, and Grota (1962b), Lindholm (1962), Denenberg et al. (1962a), and Denenberg and Smith (1963). T h e hypothetical relationship is depicted in Fig. 4. In all of these studies “. . . the greater the amount of stimulus input in infancy the less was the level of S’s emotional reactivity in adulthood” (Denenberg, 1964, p. 341). T h e relationship between adult emotionality (or generalized arousal level) and various performance and learning measures is less straightforward. Most arousal theorists (e.g., Duffy, 1957; Hebb, 1955; Malmo, 1959) now assume an optimal level of arousal with respect to efficiency of performance. Denenberg (1964) proposed that the typical “inverted U” function is applicable only when the criterion task is of moderate difficulty, invoking the Yerkes-Dodson Law (Broadhurst, 1957) to relate optimal motivation to task difficulty. T h e hypothetical relationships between adult emotionality and adult performance are depicted in Fig. 5. Since most experimental tasks in the animal developmental laboratory can be described as moderately difficult, it is usually with the moderatetask function (inverted U shape) that psychologists are principally

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concerned. Empirical support for Denenberg’s argument is derived from the studies of Levine et al. (1956), Denenberg (1959), Denenberg and Kline (1964), Bell and Denenberg (1963). and Denenberg and Karas (1960; 1961), all of which can be interpreted to yield an inverted U function of performance by levels of infantile stimulation. From these studies one can generalize that whether the stimulation is described as “noxious” or as affectively “pleasant” the important dimension is the intensity of

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FIG.4. Theoretical curve relating stimulus input in infancy to emotionality in adulthood. (Delienberg, 1964.)

such stimulation, since the emotional effects of shocking, handling, and and gentling are substantially the same (McMichael, 1961; Salama & Hunt, 1964) and since in both shocking and handling procedures it is the amount of stimulation given (or the length of the period over which stimulation is given) that produces reliable variations in adult performance. An alternative (perhaps a complementary one) to the notion that the y effects of early stimulation upon adult performance are mediated b a generalized arousal level is the notion that early sensory experience may directly hasten the process of development. This notion derives from the conceptions of D. 0.Hebb and is closely related to the critical

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periods hypothesis. Hebb (1949) postulated a period of “primary learning,” early in the organism’s life, during which repeated sensory stimulation may form relatively enduring neural connections called “cell assemblies.” Through development and variety of experience, these cell assemblies are later combined into “phase sequences,” which mediate sequential or programmed behavior of the sort that is characteristic of most relatively complex activity. Obviously, the greater the variety of

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adequate sensory experience during the period of primary learning, the greater the possibility for complex formations of phase sequences, hence the greater the probability that the organism will have a n appropriate experiential program for dealing with any particular environmental situation later in his life. Thus, early sensory experience may exert a very direct influence upon the adequacy of the mechanism for later learning and adaptive behavior. Relevant parameters would be the number, variety, and intensity of early stimulating experiences. Seymour Levine (1962) extended the hastened development hypothesis derived from Hebb’s theoretical view to encompass the experimental work on the effects of preweaning stimulation on adult behavior. Unlike

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Hebb, Levine did not hold that the effect of preweaning stimulation is mediated by perceptual experience; rather, he postulated that early stimulation increases the rate of maturation in preweaning animals and thus alters the animal’s capacity to respond adaptively in stressful situations. While the maturational sequence is probably a phylogenetic phenomenon, i.e., it is relatively invariant within a given species, the absolute speed with which it occurs may well be an ontogenetic phenomenon, free to vary across the members of a species with the adequacy of early experience. Thus, while walking usually does not occur in the human species before the child has some experience sitting and standing, the age at which any particular individual achieves each of these developmental steps varies widely among human children and is probably influenced by the amount of freedom of muscle movement that has been available to the child, as well as by the relative integrity of his nervous system (see, e.g., Dennis, 1960). Such a possibility raises the questions of whether development may be retarded through the mechanism of early stimulus deprivation and whether development may be hastened through the mechanism of early stimulus enrichment. The early experience phenomena occur within the context of a growing organism; therefore, it is necessary to understand not only the nature of the growth process and the behavioral effects of behavioral manipulations, but also the interactions between experience and growth. Since the nervous system is presumed to mediate behavior, it is easy to see how alterations in neural structures may produce changes in behavior. The next step is to devise a conceptual system from which it is possible to predict alterations in the developing structure as a consequence of experience during growth. One of the most comprehensive theoretical statements of the relationship between neural growth and the development of adaptive behaviors is Anokhin’s (1964) theory of systemogenesis. According to this view behavior is regulated by integrated functional systems composed of interacting parts built into the organism by its genetic composition. Each functional system becomes operative as an integrated unit during growth when it is necessary for the survival of the young of the species. This view emphasizes not only the importance of the neural control of behavior but also the function of the evolutionary process in the selection of adaptive developmental behavior patterns. Anokhin addressed himself principally to the operation of such systems as they appear at birth, but the major tenets of his argument can be applied to the emergence of behavior patterns and their replation after birth. For this reason we shall summarize the general principles

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of systemogenesis with the aim of integrating much of what has been reviewed above. Systemogenesis is defined as the “. . . selective and temperatureaccelerated development in the process of embryogenesis of those structural organizations which on the whole provide for the survival of the newborn” (Anokhin, 1964, p. 58). A slight modification of this definition will extend the theory substantially. Neural growth is far from complete at birth. Most mammals require a more or less prolonged period after birth before the range of their behavioral capacity reaches .idult levels. This period is marked by the development of systems of behavior that promote the survival of the growing organism. By substituting “growing organism” for “newborn” the theory of systemogenesis is made much more inclusive, yet the general assumptions and tenets of the theory are in no way altered. According to Anokhin’s view, there are four principles which guide systemogenic development. T h e first of these is the principle of ~ y n chronic arrangement of the functional system. This principle emphasizes the fact that different components of the functional system develop at different rates; by the time particular systems are necessary for survival, their development as an integrated unit is complete. T h e central neural components of these systems are very important parts of their development. Growth in the nerve centers of the brain, particularly the appearance of synaptic connections, makes possible the integration of the sensory and muscular components of the system and permits the time control necessary for behavioral regulation. T h e second principle, the principle of fractionation of an organ in the process of development, stresses the fact that certain aspects of a n organ of the body develop before others. These developing organ parts are the ones which are necessary for the organization of the essential functional system for survival. As an example, Anokhin cited his work with the development of the sucking response in infants. In the innervation of facial muscles necessary for this behavior, those cells of the fifth cranial nerve which are necessary for the elaboration of sucking are completely developed at birth. T h e rest of the development of this nucleus proceeds at a different pace, ultimately resulting in the appearance of other behavioral capacities, e.g., smiling and vocalization. T h e third and fourth principles are closely interrelated. T h e third is the principle of consolidation of the components of the functional system and the fourth is the principle of minimal provision of the functional system. These can best be clarified by discussing them simultaneously. According to the third principle, there is a period of time in the organism’s development when the components of the system con-

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solidate. T he units of the system come together to make the system operational. This is not an all-or-none phenomenon. T h e fourth principle points out that the components do not consolidate synchronously, just as they do not mature simultaneously. A few of the structural units mature at a given time and combine to provide less than perfect organization. Thus, the functional system, early in its appearance as a consolidated unit, provides minimal support for the organism’s survival. T h e complete integration of the system occurs by the time it is needed. Taken together these last two principles suggest a physiological analogue to the idea of critical periods as it has been used by investigators of the effects of early experience. T h e period during which consolidation of the functional system is occurring constitutes the phase of development during which particular regulatory systems emerge. These periods are related to the integration that is occurring in the neural components of the functional system. T h e literature on brain growth indicates that there are three phases in the postnatal growth of the brain that are characterized by differential morphological and biochemical activity. We would like to point o u t that there are relationships between these phases of neural growth and the periods during which early experience produces its differential effects on later behavior. T o be more specific, the early experience literature suggests that stimulation in the period from l to 10 days of age in the rat alters the animal’s responsiveness to fear-producing situations. This period corresponds to the first phase of neural growth, when the rate of development is maximal in the subcortical brain areas. Postweaning stimulation from about 20 days to puberty in the rat seems to alter learning and problem-solving behaviors. This period corresponds to the third phase of neural growth when development is most extensive within the neocortex of the rat. These relationships, taken together with the fact that animals deprived of early stimulation do not show the same adaptive behaviors as do those who receive early stimulation, point to a fifth principle which we shall present as an extension and elaboration of the theory of systemogenesis. This can best be described as the principle of experiential mediation, which states that the rate of growth within a functional system is dependent upon the properties of the environment within which the organism is living during the period when consolidation of the system is occurring. There is a continuum of possible environments which varies on the dimension of more or less stimulation. Stimulation will modify the rate of consolidation in proportion to its relative amount. Denenberg (1964) supported the argument that the effects of prewean-

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ing stimulation on emotional reactivity increase with the amount of stimulation. This same argument could be applied to the postweaning phenomena. As the material reviewed above indicates, the greater the organism’s opportunity both for perceptual experience and motor experience during postweaning development, the better his ability to perform problem-solving tasks. The principle of experiential mediation suggests that the effects of early stimulation are mediated through their influence on physiological growth, particularly the rate of consolidation of the neural systems that regulate the specific forms of behavior involved. Experiments on the effects of environmental stimulation or deprivation on physiological growth can be offered in support of this hypothesis. T h e now-classic experiments of Riesen (1961) and his associates represent the paradigm for research in which animals are reared in restricted environments to study the effects on physiological and morphological growth. When animals are reared in darkness, catastrophic effects occur within the retina which markedly alter the capacity of the eyes. T h e ganglion cells and optic nerve fibers atrophy, cytoplasmic and nucleolar RNA levels are reduced in the eye, and light reflexes disappear. These effects do not seem to be limited to the eye alone. Krech (1964) reported decreases in cortical weight and increases in acetylcholine activity in the visual cortex of animals raised in darkness. In the Krech study, the weights of the somesthetic cortex increased in these same animals, but changes in acetylcholinesterase activity depended on the nature of the experience the animals had. Hubel and Wiesel (1963) studied the effects of visual deprivation in cats on the morphology and electrical activity of the cat brain. They reported some atrophy in the cells of the visually deprived lateral geniculate bodies that is most marked in kittens deprived of patterned vision from birth. No histological changes were observed in the retinas, optic nerves, superior colliculi, or striate cortex. Vision in the deprived eye was markedly deficient. Following responses, visual placing and form perception were absent, although pupillary light reflexes were normal. Only 1 of 84 cells observed was responsive to stimulation in the occluded eye. Sherrer and Fourment (1964) reported a normal electrocorticogram for rabbits reared in darkness. Evoked responses to visual stimulation were slower, with lower amplitude and shorter duration. Responses to auditory or tactile stimuli were much greater than normal and were observed throughout the brain. Such an observation is reminiscent of the repeated finding of greater emotional reactivity in unstimulated animals. These studies all emphasized the fact that environmental stimulation

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is necessary for the adequate growth of the developing system just as it is for the development of adaptive behavior. More research along these lines is quite necessary before we can understand exactly how the environment supports systemogenesis, but it is obviously an important factor. T h e obverse relationship appears also to hold: stimulation can serve to enhance the growth process. According to Levine (1962, p. 163) ". . . the rate of development is itself dependent upon the infantile environment." However, as has been indicated previously, it is difficult to distinguish across different experiments what constitutes an experimental condition and what constitutes a control condition. Typically, controls are isolated and reared under rather impoverished conditions. The experimental groups are given stimulation on the magnitude of that observed if the organisms were being reared in their natural habitat. The relative term higher or lower used in the description of the results of these studies will depend on the point of view. Numerous experiments have directly investigated the effects of stimulation on physiological variables. The majority of these have not been concerned with the manner in which stimulation affects the growth process per se, but rather with some variable at a particular age that might be taken as indicative of increased growth. For example, early stimulation has been shown to increase adult weights (McClelland, 1956; Mogenson & Erlich, 1958; Weininger, 1956; Weininger, McClelland, & Arima, 1954) and skeletal length (Ruegamer, Bernstein, & Benjamin, 1954). Other studies more directly related to the growth process reported that stimulation leads to earlier eye opening (Levine, 1959a), earlier appearance of adult coat characteristics (Meier & Stuart, 1959) and earlier sexual development (Morton, Denenberg, & Zarrow, 1963). An early experiment by Langworthy (1933) demonstrated that stimulation is important for the normal development of visual nerve fibers. He blindfolded one eye of cats at birth and left the other eye open for visual stimulation. The optic tracts of the blindfolded eye showed considerably less myelination than was present in the neural fibers arising from the stimulated eye. Clark (1942) reported failure in the development of certain retinal elements in animals restricted to an environment of blue light from birth. Levine also studied differential maturational patterns that are produced as a function of early stimulation using two indicants of the growth of physiological function. The adrenal response to cold stress, as measured by the depletion of adrenal ascorbic acid, is elaborated earlier in stimulated animals than in unmolested controls (Levine, Alpert, & Lewis, 1958a), and cholesterol levels seem to increase more

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rapidly in stimulated animals (Levine & Alpert, 1959). Meier (1961) demonstrated that early stimulation in cats leads to earlier development of the adult EEG pattern. It is unfortunate that more studies of this kind have not been carried out, since testing animals at one age cannot reflect changes in growth characteristics. Other experiments which have investigated physiological changes in stimulated organisms have typically taken measures of physiologic activity at a relatively fixed age. An important series of such experiments was conducted at the University of California at Berkeley in the Brain Chemistry and Behavioral Research Project. This work was reviewed by Rosenzweig (1964) and Bennett, Diamond, Krech, and Rosenzweig (1964). Subjecting different strains of rats to environmental enrichment procedures similar to those described for the behavioral experiments reviewed above, they reported small but significant increases in brain weight and cholinesterase activity for stimulated animals. T h e magnitude of this effect is greater for the cortex than it is for the rest of the brain. Furthermore, these biochemical effects seem to be confined to the acetylcholine biochemical system. Similar effects are not observed for other proteins (Bennett et al., 1964) or for another possible neural transmitter, serotonin (Pryor, 1964). T a p p and Markowitz (1963) examined acetylcholinesterase changes in animals stimulated for the first 10 days of life. T h e pattern of changesin the brain produced by these procedures is different from that produced by postweaning enrichment procedures. Subcortical cholinesterase levels are lower in the stimulated animals while cortical cholinesterase levels do not differ for the two groups. Subcortical brain weights are higher for the handled animals but, again, they do not differ in cortical weight. Thus, it seems that preweaning and postweaning stimulation produce different effects on brain weight and brain cholinesterase just as these experiences seem differentially to affect behaviors. Much more work clearly needs to be done to examine further these relationships and to elucidate the mechanisms which mediate the behavioral effects, but these experiments suggest that stimulation has different effects in the brain and that the nature of the effects is a function of the age at which stimulation occurs. V. IMPLICATIONS FOR MENTAL RETARDATION

T h e data presented in this review indicate that in laboratory animals early reduction of sensory stimulation leads to later performance deficits in learning tasks and to hyperemotionaIity, while early supernormal stimulation often leads to enhanced performance in learning tasks and

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to reduced emotionality. T h e data on the human organism, which has a much longer developmental period, indicate that “unstimulating” rearing conditions are accompanied by limited psychometric intelligence and social functioning, while experimental programs of enrichment have been able to offset some of this deficit. Data on the growth of the nervous system suggest that those developmental periods when stimulus deprivation or enrichment may have their largest effects are correlated with periods of maximum consolidation of functional neural systems, and these growth data suggest the mechanism through which early experience is translated into enduring effects. Clearly, some of mental retardation is related to predetermined structural limitations in the nervous system. Just as clearly, the structural basis of moderate and mild retardation is far more subtle. Viewed as a statistical deviation rather than as a qualitatively defined disease entity, retardation can be profitably studied within the context of the growth of intelligence in a more general sense. Work u p to this time has suggested that, within the broad limits set by the genetically determined structure of the nervous system, both “intelligence” and neural structure may develop partially as a function of the variety, intensity, and time of occurrence of environmental stimulation. I n practical terms, this view would see a large percentage of mild and moderate mental retardates as victims of relatively unstimulating early environments, constituting what has come recently to be called “cultural depiivation.” While lower-class status does not necessarily involve a condition of cultural deprivation, the sad fact is that the two most often go hand in hand. By the same token, middle-class status does not ensure rearing in a highly stimulating environment, but it does carry a higher probability of heightened stimulation. A disproportionately high percentage of mild and moderate retardates come from lower-class homes, where stimulation of a diffuse sort is likely to be greater during the first year of life than for the middle-class child. This relationship would predict that the later fearfulness and emotionality of the lower-class child would be less than that of the middle-class child. As the child becomes mobile and begins to express his curiosity, this relationship reverses. I n the mobile period, the harried lower-class parent is less apt to encourage, or even to tolerate, the child’s exploratory behavior, and negative reinforcement for such behavior may often ensue.3 8 Parts of this analysis of class differences in child-rearing practices have been gleaned from many conversations with our colleagues. The principal ideas here probably belong to Susan Gray, who is presently experimentally involved with these problems. Some of the ideas expressed here have probably also come from J. McV. Hunt, who has certainly exerted a powerful influence on the thinking of the authors.

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On the other hand, the middle-class child is more likely to be reinforced positively for exploration and is almost certain to have a physical situation more nearly approximating a “free environment” (within the limits of physical safety). At this point also, the quality of stimulation available to the child is likely to become quite different as a function of social class. In the premobile period the lower-class baby is probably exposed to more general and difluse stimulation (more people in a smaller space, constantly going television, perhaps even more handling); after 1 to 2 years, the middle-class child is getting far more of the specific kinds of stimulation that may later result in his superiority in language, space, and number concepts. Particularly in the case of verbal interaction with adults, the middle-class child has an advantage and is more likely to be reinforced specifically for verbal exploration. This superiority in specific stimulation for the middle-class baby comes at the most advantageous time, i.e., when neocortical structures may be expected to undergo maximal postnatal consolidation. It is assumed that such structures will eventually mediate those behaviors which are tapped by tests of “intelligence.” The foregoing analysis has been somewhat speculative, showing how differential levels and qualities of early experience might influence the intellectual development of children differently as a function of social class. If it contains an element of accuracy, it could help to explain the preponderance of mild and moderate mental retardates coming from lower-class homes. I t also sets a pattern for “progressive retardation.” but at the same time suggests antidotes for such an environmentally produced phenomenon. REFERENCES Ader, R. Effects of early experience on emotionality. Amer. Psychologist, 1957, 12, 410. Ader, R.,& Conklin, P. M. Handling of pregnant rats: Effects on emotionality of their offspring. Science, 1963, 142, 411-412. Anokhin, P. K. Systemogenesis as a general regulator of brain development. In W. A. Himwich & H. E. Himwich (Eds.), The developing brain. Amsterdam: Elsevier, 1964. Pp. 54-86. Badt, M. I. Levels of abstraction in vocabulary definitions of mentally retarded school children. Amer. J . ment. Defic., 1958, 68, 241-246. Baron, A., Brookshire, K. H., & Littman, R. A. Effects of infantile and adult shocktrauma upon learning in the adult white rat. ]. comp. physiol. Psychol., 1957, 50, 530-534. Bell, R. W. Note: Emotionality after mild chronic stress as a function of infantile handling. Psychol. Rep., 1964, 14, 657-658. Bell, R. W., & Denenberg, V. H. The interrelationships of s h o d and critical p e r i d s in infancy as they affect adult learning and activity. Anim. Behav., 1963, 11, 21-27. Bennett, E. L., Diamond, M. C., Krech, D., & Rosenmeig, M. R. Chemical and anatomical plasticity of brain. Science, 1964, 146, 610-619.

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nunn, L. M. (Ed.) Educable mentally retarded children. Exceptional children in the schools. New York: Holt, 1963. Ch. 2. Eells, Janet F. Inconsistency of early handling and its effect upon emotionality in the rat. .I. comp. physiol. Psychol., 1961, 54, 690-693. Erlich, Annette. Effects of past experience on exploratory behavior in rats. Canad. J. Psychol., 1959, 13, 248-254. Forgays, D. G., & Forgays, J. W. T h e nature of the effect of free environmental experience in the rat. ]. comp. physiol. Psychol., 1952, 45, 322-328. Forgays, D. G., & Read, Janet M. Crucial periods for free environmental experience in the rat. J. comp. physiol. Psychol., 1962, 55. 816-818. Forgus. R. H. T h e effect of early perceptual learning on the behavioral organization of adult rats. J. comp. physiol. Psychol., 1954, 47, 331-336. Forgus, R. H. Influence of early experience on maze-learning with and without visual cues. Canad. J. Psychol., 1955, 9, 207-214. Forgus, R. H. Advantage of early over late perceptual experience in improving form discrimination. Canad. J. Psychol., 1956, 10, 147-155. Freedman, D. G., Elliott, O., & King, J. A. Developmental capacities for socialization in puppies. Paper presented at Amer. Psychol. Assoc., Washington, 1958. Cited in Levine (1962). P. 157. Freud, S. Three essays on sexuality. In J. Strachey (Ed.), The standard edition of the complete psychological works of . . . . London: Hogarth Press, 1953. (German edition, 1905.) Ganz, L., & Riesen, A. H. Stimulus generalization to hue in the dark-reared Macaque. J. comp. physiol. Psychol., 1962, 55. 92-99. Gray, Susan W., & Klaus, R. A. An experimental preschool program for culturally deprived children. Unpublished paper given at Amer. Ass. for the Advanc. of Sci., Montreal, 1964. (Mimeo.) Haywood. H. C. Duration of following in strongly imprinted chicks. Unpublished research, George Peabody College, 1963. Haywood, H. C. Discrimination and following behavior in chicks as a function of early environmental complexity. Percept. mot. Shills, 1965, 21, 299-304. Haywood, H. C., & Zirnmrrman, D. W. Effects of early environmental complexity on the following response in chicks. Percept. mot. Skills, 1964, 18, 653-658. Hebb, D. 0. The organization of behavior. New York: Wiley, 1949. Hebb, D. 0. Drives and the C.N.S. (conceptual nervous system). Psychol. Rev., 1955, 62, 243-254. Hellmer, L. A. T h e effect of temperature on the behavior of the white rat. Amer. J. Physiol., 1943, 56, 408-421. Henderson, N. D. Behavioral effects of manipulation during different stages in the development of mice. J. comp. physiol. Psychol., 1964, 57, 284-289. (a) Henderson, N. 1). Parameters which influence the effects of early treatment on later emotionality. Paper read at Amer. Psychol. Ass., Los Angeles, 1964. (b) Henderson, N. D. Acquisition and later effects of conditioned fear during different stages in the development of mice. Paper read at Midwest. Psychol. Ass., Chicago, 1965. Hess, E. H. Imprinting. Science, 1959, 130. 133-141. (a) Hess, E. H. T h e relation between imprinting and motivation. In M. R. Jones (Ed.), Nebraska symposium on motivation, 1959. Lincoln: Univer. of Nebraska Press, 1959. Pp. 44-77. (b)

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Pryor, G. T. Brain serotonin and behavior in selected strains of rats. Unpublished doctoral dissertation, Univ. of California, 1964. Ratner, S. C., & Denny, M. R. Behavior consequences of early behavior: Early experience. Comparative psychology: Research in animal behavior. Homewood, Ill. Dorsey Press, 1964. Pp. 351-368. Riesen, A. H. Stimulation as a requirement for growth and function in behavioral development. In D. W. Fiske & S. R. Maddi. (Eds.), Functions of varied experience. Homewood, Illinois: Dorsey Press, 1961. Rmenzweig, M. R. Effects of heredity and environment on brain chemistry, brain anatomy, and learning ability in the rat. Kansas Stud. Educ., 1964, 14, 3-34. Ruegamer, W. R., Bernstein, L., & Benjamin, J. D. Growth, food utilization and thyroid activitv in the albino rat as a function of extra handling. Science, 1954. 120, 184-185. Salama, A. A., & Hunt, J. McV. “Fixation” in the rat as a function of infantile shocking, handling, and gentling. J. genet. Psychol., 1964, 105, 131-162. Schaefer, T. T h e effects of early handling: Infant handling and later behavior in the white rat. Unpublished doctoral dissertation, Univ. of Chicago, 1957. Schaefer, T. Early “experience” and its effects on later behavioral processes in rats: 11. A critical factor in the early handling phenomenon. Trans. N.Y. Acad. Sci., 1963, 25, 871-889. Schaefer, T., Weingarten, F. S., & Towne, J. C. Temperature change: T h e basic variable in the early handling phenomenon? Scienre, 1962, 135, 41-42. Scott, J. P. Critical periods in the development of social behavior in puppies. Psychosom. Med., 1958, 20, 42-54. Sherrer, J.. Lk Fourment, A. Electrocortical effects of sensory deprivation during development. In w. A. Himwich & H. E. Himwich (Eds.), T h e developing brain. Amsterdam: Elsevier. 1964. Skeels, H. M. Effects of adoption on children from institutions. Children, 1965, 12, 33-34. Skeels, H. M., & Dye, H. B. A study of the effects of differential stimulation on mentally retarded children. Proc. Amer. Ass. ment. Defic., 1939. 44, 114-136. Snygg, D. T h e relation between the intelligence of mothers and of their children living in foster homes. J. genet. Psycho!., 1938, 52, 401-406. Speer, G. S. T h e mental development of children of feeble-minded and normal mothers. 39th Yearb., nat SOC. for the Stud. Educ., 1940, 309-314, Part 11. Spence, Janet T., & Maher, B. A. Handling and noxious stimulation of the albino rat: I. Effects on subsequent emotionality. 1. comp. physiol. Psycho]., 1962, 55, 247. 251. (a) Spence, Janet T., & Maher, B. A. Handling and noxious stimulation of the albino rat: 11. Effects on subsequent performance in a learning situation. J. comp. physiol. Pvchol., 1962, 55,252-255. (b) Stanley, W. C., & Monkman, J. A. A test for specific and general behavioral effects of infantile stimulation with shock in the mouse. J. abnorm. SOC. Psychol., 1956, 53, 19-22. Stedman, D. J., & Eichorn, Dorothy H. A comparative study of the growth and developmental trends of institutionalized and noninstitutionalized mongoloid children. Amer. J . ment. Defic., 1964, 69, 391-401. Stedman, D. J., & Eichorn, Dorothy H. A comparative study of the growth and developmental trends of institutionalized and noninstitutionalized mongoloid children. 111

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H.C. Haywood & R. W. Woodcock (Eds.), Abstracts of Peabody studies in mental retardation, Vol. 3. Nashville: George Peabody College, 1965. (No. 6) Tnpp, J. T., SC Markowitz, H. Infant handling: Effects on avoidance learning, brain weight, and cholinesterase activity. Science, 1963, 140, 486-487. Tedeschi, J. T., & Harburg, E. The effects of infantile stimulation on emotionality and hoarding in rats. J . genet. Psychol., 1963, 103, 175-183. Thompson, W. R.,Ik Dubanoski, R. A. Early arousal and imprinting in chicks. Science, 1964. 143, 1187-1188. Thompson, W. R., & Heron, W. T h e effects of restricting early experience on the problem-solving capacity of dogs. Canad. J. Psychol., 1954, 8, 17-31. Weininger, 0. T h e effects of early experience on behavior and growth characteristics. J . comp. physiol. Psychol., 1956, 49, 1-9. Weininger, O., McClelland, W. J., & Arima, R. K. Gentling and weight gain in the albino rat. Canad. J. Psychol., 1954, 8 , 147-151. Woods, P. J. T h e effects of free and restricted environmental experience on problem solving behavior in the rat. J. comp. physiol. Psychol., 1959, 52, 399-402.

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A Research Program on the Psychological Effects of Brain Lesions in Human Beings RALPH M. REITAN NEUROPSYCHOLOCY

LABORATORY, INDIANA UNIVERSITY INDIANAPOLIS, INDIANA

MEDICAL

CENTER,

I. Introduction . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . 153 11. Selection of Tests for Neuropsychological Assessment

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111. Methodological Approach , . . . . . . . . . . . . .. . .. . . . . .. . . . IV. Description of Psychological Test Battery . . . . . . . . . . . . . . A. Halstead's Neuropsychological Test Battery .. . . . . . . . . B. Additional Tests as Part of the Battery . . . . . . . . . . . . C. Sensory-Perceptual Disturbances . . . . . . . . . . . . . . . . . . . V. Research Results .. A. Qualitative Vs. Quantitative Psychological Effects of Cerebral Lesions , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Differential Effects of Left and Right Cerebral Lesions C. Aphasic and Related Sensory-Perceptual Deficits . . . . D. Acute Vs. Chronic Brain Lesions . . . . . . . . . . . . . . . . . . . E. Linear Discriminant Function Analyses F. The Complexities of Relating Neurolog chological Variables in Individual Patients . . . . . . VI. Interpretation of Results for Individual Patients . . . . . . . . A. Patient W. C. . . . . . . . . . . . . ................ B. Patient W. B. . . . . . . . . . . . . ................ C. Relationships to Mental Re ................ VII. Concluding Comments . . . . . . References . . . . . . . . . . . . . . . . . . . , . . . . , , . . . . . , , . , , , . . , . . . .

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INTRODUCTION

The problems of developing a research program concerned with investigation of brain-behavior relationships in human beings include many which arise well in advance of special taxation upon the investigator's 1

The research reported in this chapter has been supported mainly by grantr NB-

1468 and NB-5211 from the National Institute of Neurological Diseases and Blindness

and grant CD-15 from the Division of Chronic Diseases. Public Health Service.

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creative insights. Before the researcher in this area has any opportunity to be creative, he must face practical problems related to availability of patient material, the need for adequate criterion information from colleagues in the neurological sciences, the selection of a test battery which may be adequate, and many others. This chapter will be oriented toward describing relevant operational considerations in the history of the Neuropsychology Laboratory of the Indiana University Medical Center and will focus upon research results as well as upon critical future problems which will require practical ingenuity as well as creative insights for their solution.2 The Neuropsychology Laboratory was founded in 1951 as part of the Section of Neurological Surgery at the Indiana University Medical Center. An administrative setting of this type was and continues to be relatively unique, although close cooperation between neurological surgeons and psychologists is becoming increasingly common. The outstanding advantage of such cooperation relates directly to improved definition of independent variables for research purposes. Neurological surgeons and neuropathologists represent the two professional disciplines from which the most accurate information can be obtained regarding the characteristics of brain lesions in human beings. The decision to initiate the laboratory in this professional setting was deliberately taken because of the obvious advantages that would result. It seems remarkable that a great number of psychologists continue to focus on research regarding psychological effects of brain lesions within a psychiatric setting, particularly in view of the fact that psychiatrists rarely identify a cerebral lesion in a human being with any degree of precision. It should be pointed out that psychiatric patients, in the main, do not have brain lesions which are susceptible to clear or compelling descriptions, and specialists in the neurological disciplines would, in a large number of instances, provide no more significant neurological information than is forthcoming from psychiatrists. This fact, however, does little if anything to attenuate the neurological criterion problems that are certain to be present in most psychiatric settings. In practice, if a patient has signs or symptoms which suggest a brain lesion, he is likely to be worked up for this possibility by neurological specialists in any case. The psychologist, therefore, is well advised to effect an arrangement whereby he can obtain his neurological criterion information from a firsthand source. The above comments are not intended to imply that psychiatric patients do not sometimes have brain lesions, nor that brain lesions, if present, are of no z The specific orientation of this chapter, requested by the editor, did not permit a formal review of many of the excellent studies which have appeared in the literature on the same or related problems.

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significancewith respect to the emotional and adaptive difficulties in these patients. In fact, the frequency and significance of cerebral dysfunction in psychiatric patients with adaptive breakdowns are in need of a great deal of further study. If one wishes to study the relatively uncomplicated psychological effects of cerebral lesions, however, neurological patients represent a much better general source of material. Another practical consideration of great significance relates to the contribution that is made by neurological colleagues. Psychologists vary greatly with respect to their backgrounds and degree of sophistication in the neurological sciences, although it is probably safe to say that the median amount of knowledge in this area exceeds by relatively little that of professional persons generally considered. Most psychologists have received a scanty introduction to the nervous system in which neuroanatomy has been represented by a diagrammatic presentation of the neuraxis and neurophysiology by efferent and afferent pathways together with a statement of the all-or-nothing principle of neural firing. Thus, many psychologists obviously have no appropriate background for developing a meaningful role as serious students of the effects of brain lesions. Psychology has shown a growing tendency to develop subspecialties, however, and not the least of these is physiological psychology. In fact, a growing number of physiological psychologists have achieved recognition as leading figures in various aspects of the physiology of the nervous system. This knowledge and experience, however, usually has little direct relevance to the problems encountered by the psychologist who studies lesions of the human nervous system. Most physiological psychologists never come in contact with a patient except, perhaps, when one of their relatives is ill. Exceptions, of course, have occurred, but the present point is that research on the effects of brain lesions has usually fallen in the domain of the clinical psychologist, and the training of clinical psychologists in clinical neurological disciplines is often grossly inadequate. Thus, it is apparent that a psychological research endeavor in the area of the neurological sciences will be heavily dependent upon the contribution made by neurologists, neurological surgeons, and neuropathologists. The psychologist must advance his own sophistication to the greatest extent possible in order to fulfill a position of responsibility with respect to standards maintained in his personal research, but he is inescapably dependent upon the special skills of his neurological colleagues. Our laboratory was initiated because of the interest of Doctor Robert F. Heimburger, Director, Section of Neurological Surgery. T h e opportunity to explore the relationship between neurological and psychological

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variables has been a direct function of the continuing interest and contribution of Doctor Heimburger and other colleagues in the neurological sciences. Without the degree of support which is manifested by pointed and continuing special assessments of neurological criterion information on individual patients, the potential of a laboratory in clinical neuropsychology would be seriously handicapped. Because of the limited number of psychological laboratories in clinical neurological settings and in the face of an apparently growing interest in this prospect by psychologists, it may be worthwhile to illustrate the types of criterion problems which are encountered. Several years ago we examined a patient who had been operated on for a lesion identified at another hospital as a glioma of the left cerebral hemisphere. Our psychological results were not typical for a tumor of this type, but we are well aware of the variability in this class of lesions. We had the opportunity to examine the patient again 2 years later, and he showed clear improvement as compared with his first test results. This result is highly atypical in patients having intrinsic tumors because these lesions are basically progressive in nature. I became curious as to the validity of the basis for the diagnosis and fortunately was able to obtain a complete copy of the patient’s chart from his initial hospitalization. The surgeon had certainly operated on the left cerebral hemisphere and had recorded a definite conclusion that the lesion was a glioma. The tissue specimen had been examined microscopically but no evidence of a tumor had been found. I n all probability the patient did not have a cerebral tumor, particularly since he showed no progression but rather demonstrated clear evidence of recovery both in terms of psychological testing and in his everyday life. Over the course of years we have encountered several instances of definite clinical diagnoses of cerebral neoplasms, but, when the histological findings were reviewed, insufficient evidence was found to be sure of such a diagnosis. We are not able to use these patients in our research as ones who have nonneoplastic cerebral lesions, but we certainly would not be willing to place them in a group with proved neoplasms. Another instance occurred in which a young man was diagnosed, on the basis of an angiogram, as having an arteriovenous malformation involving the right anterior cerebral artery. The clinical picture as well as the radiographic findings did not suggest the advisability of surgical correction, but the patient was followed on a regular basis. Repeated angiograms over time eventually provided evidence for concluding that the patient did not have an arteriovenous malformation and that the initial X-ray was misleading. If we had not been closely involved in

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pursuing the eventual findings on this patient, with the necessary interest and cooperation of our neurological colleagues, this patient could easily have been misused in our research studies. Many experts in the neurological sciences would contend that much more serious problems than the above difficulties in diagnosis arise from the limitations of neurological diagnostic methods as they presently exist. The physical neurological examination is frequently normal or nonspecific in its significance in patients who are later proved to have cerebral lesions. Electroencephalograms are known to show both falsenegative and false-positive results in their usual clinical application, and in certain neurological conditions normal tracings are the rule rather than the exception. Contrast studies provide compelling evidence for cerebral lesions in many instances, but closed head injuries and many slowly progressive neurological conditions frequently show normal results. The history may be unequivocal in its significance if, for example, documented evidence is available to describe a cerebral contusion underlying a depressed skull fracture, but in many instances one does not know from the history whether the patient had a neurosis or a neurological disease. I n the face of these difficulties, many neurologists and neurosurgeons despair of providing adequate criterion information from clinical examinations as a basis for relating the condition of the brain to psychological test results. In fact, the comment is sometimes made that it is sheer foolishness to attempt to use the crude information usually available from neurological examination as a criterion against which to evaluate the carefully controlled, quantified scores that are obtained in psychological testing. Psychologists, however, show less inclination to become enthusiastic about the “careful” controls in psychological testing and are aware that some of their quantified scales are not much of an improvement over binary classification. Recognition of the problems of psychological test data does nothing, however, to resolve the dilemma created by inadequate neurological findings. When the Neuropsychology Laboratory was founded we were aware of the problems of this type that we would face and realized that the percentage of patients in whom adequate neurological information would become available, for certain kinds of studies, would be low. We looked forward eagerly, however, to those instances in which the brain would be available for postmortem study since, then, more direct evidence would be available. One of the first such instances occurred in the case of a child with a glioma of the right cerebral hemisphere. Contrast studies identified the tumor clearly and microscopic examination of the tissue removed at operation identified the lesion as a glioblastoma multiforme. We were able to test this child before surgery, but she was too ill follow-

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ing the operation to permit testing. Six months later the patient died. Necropsy examination showed that both cerebral hemispheres were widely infiltrated by the tumor, and there was no way to confirm the area of maximal involvement at the time of psychological examination 6 months before death. This instance illustrates another disappointing fact that frequently frustrates the attempt to effect brain-behavior relationships in the study of human beings. The problem may be summarized as follows. Since a degree of alertness and cooperation is necessary for any detailed psychological testing, it is rarely possible to test a patient when death is imminent. Thus, a period of time usually elapses between the last moment that valid psychological testing can be performed and the time of expiration, during which changes of unspecifiable degree occur in the brain lesion. As a result, it is frequently difficult to determine the validity of necropsy findings with relation to results of psychological testing. Halstead (1951) summarized this problem quite clearly. He wrote: “It is probably safe to say that no brain lesion has ever been completely specified. T o do so would require knowledge that simply is not yet available. Mapping of the lesion by histological techniques, usually possible only with lower animals, maps only a visible, structural feature of the lesion. Details of ultrastructure, metabolic aspects of synthesis of nucleoproteins, altered circulatory dynamics due to such considerations as changes in vascularity or sludging of the blood, specific chemical depletions or alterations associated with injury or removal of brain tissue, the temporal course of the lesion, and the extent of the personality trauma are all relevant but usually unknown factors. Until these matters can be taken into account, we cannot be sure that we are juxtaposing appropriate units of behavior and structure” (pp. 251-252). Obviously, the problems involved in developing an understanding of the relationships between biological and behavioral concomitants of brain lesions are not simple ones. Adoption of the position that the problem is too complex to be susceptible to progress, however, surely guarantees the absence of progress, whereas blithe indifference to the complexities of the problem which has characterized many psychological investigations conceivably may be worse than nothing at all. A careful, informed, and discerning approach is needed, with clear recognition that methodological deficiencies across the whole front of our research endeavors are inescapably present. Problems relating to criterion information. of course, are not new to psychologists engaged in research. They exist in one sense or another whether the research aim relates to psychiatric diagnosis, vocational

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success, performance efficiency in practical settings, or any other meaningful area. Essentially, the problem is one of definition. A meaningful definition, perhaps quantitatively substantiated, may be rather easily determined if the definition refers to a highly discrete and circumscribed phenomenon. Most such phenomena, however, are of limited general interest, and our ambition to make significant contributions carries US into areas in which the independent variables are not easily defined. Recognition of these circumstances implies a corollary to the effect that scientific progress in any area is represented by a series of approximations correcting and counterbalancing themselves as they proceed in time. Recognition of the inevitability of criterion problems also implies the necessity for exercising a special degree of responsibility and toughmindedness. T h e more difficult the criterion problem or the more fuzzy the research area, the greater is the need for constant alertness with respect to achieving definitions which are improved over those used in the past. These considerations turn us again to the psychologist who intends to work with neurological patients. Particularly because of his lack of expertise in the neurological sciences, he must recognize and attempt to compensate for his deficiencies in contributing toward meaningful definitions of relevant independent variables. One of the principal aims of the Neuropsychology Laboratory has been to effect a meaningful subdivision of the concept of “brain damage,” as such subdivisions relate differentially to psychological measurements. This effort required that we pursue with increasing specificity the various dimensions of cerebral lesions in human beings. Our efforts have involved comparisons of groups with diffuse cerebral lesions, lateralized cerebral lesions, and regionally localized cerebral lesions. Further, we have studied the differential effects of chronic, long-standing cerebral lesions as compared with acute or recent cerebral lesions. A number of more specific neurological findings (e.g., degree and lateralization of electroencephalographic disturbances, and homonymous visual field defects) have been used as criteria in individual studies in order to determine the consistency of their effects on various psychological measurements. A recent investigation has indicated the need for specific study and comparison of the psychological effects of various types of cerebral lesions. Our preliminary investigations suggest that the answers obtained with respect to other criteria (localization, for example) may differ somewhat depending upon the type of cerebral lesion that is present. Cerebral lesions of different types are known to produce quite different pathological effects as well as definite differences in associated conditions such as edema, intracranial hypertension, and degree of cerebral ischemia.

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Nevertheless, the possible differential psychological effects of lesions varying in type has not yet been studied very intensively. T h e localization variable has been given prime importance from an historical point of view. If one considers a point made by Hughlings Jackson about a century ago, the significance of type of lesion may seem more reasonable as a hypothesis. Jackson pointed out that the area of specific damage cannot represent the only consideration in localization studies since this area is presumably no longer functional. The manifestation of deficits by the subject must then represent the altered function of the rest of the brain in the presence of the damaged or destroyed area, rather than the lack of function in the damaged area per se. In this sense, a vascular lesion as compared with a neoplastic lesion, for example, may have rather different effects even though both lesions are located in the same area. It is well known that the developmental histories of various types of brain lesions differ at least to some extent and that their associated pathological changes also differ. Postmortem studies also suggest that in patients with focal cerebrovascular lesions the entire cerebrovasculature often reflects at least some stage of arteriosclerosis. One might well presume a greater degree of impairment of function in the rest of the brain in patients with focal cerebrovascular lesions than in, for example, patients with traumatic injuries of the brain or, probably, patients with neoplastic lesions. From the point of view of psychological test results, patients with varying types of lesions do in fact demonstrate different relationships among measurements. In the interest of clinical application, therefore, it appears to be necessary to focus on the interactional effects of the many covarying neurological dimensions that are appropriate in describing brain lesions in human beings. II. SELECTION OF TESTS FOR NEUROPSYCHOLOGICAL ASSESSMENT

Information indicating the systematic and sometimes profound effects of cerebral lesions on motor, sensory, and perceptual functions has been available for more than a century. Although psychology in its history has found that these content areas provide rich resources in psychological research, relatively little effort has been made to study deficits of these types resulting from cerebral lesions. Only recently have systematic efforts been made in this direction (Benton, 1959; Ghent, 1961; Semmes, Weinstein, Ghent, & Teuber, 1960; Weinstein, 1962; Weinstein & Sersen, 1961). The approach of the Neuropsychology Laboratory in composing a battery of tests has been to include sensory-perceptual and motor tasks,

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psychomotor problem-solving procedures, and higher level psychological tests relating to the symbolic and communicational aspects of language, the ability to deal effectively with visuo-spatial relationships in manipulatory settings, and abstraction and concept formation abilities. Our a p proach in terms of coverage was to sample the major areas of abilities that are manifested by human beings. A second principle that was followed related to a selection of tests indicated by controlled studies to be valid with respect to the effects of cerebral lesions. Rather than select tests in a particular theoretical orientation or framework, presuming that we knew what the effects of brain lesions should be, our approach was a good deal more modest in that it was structured as an exploratory effort. However, we were interested in developing a battery of tests that would have potential usefulness with respect to the various methods for inferring psychological deficit and, further, which would permit application of these methods in an integrated way with respect to drawing inferences about the individual subject. These various approaches to psychological deficit relate to the level of performance on psychological tests, pathognomonic signs of cerebral damage (qualitative deficiencies in performance), the differential score approach in which presumably normal performances can be compared with defective performances, possible analyses of patterns that might relate differentially to the neurological characteristics of cerebral lesions, and comparisons of sensory-perceptual, motor, and psychomotor performances on the two sides of the body. The manner in which these various approaches to inferring psychological deficit may be used in a complementary form with our standard battery will be illustrated below in the interpretation of results for individual patients. Finally, a necessary consideration for the selection of tests to compose a battery relates to the time available for examination of individual subjects. The temporal constraint is so severe in many settings that there is little hope in using a sufficiently diversified battery to meet the various criteria outlined above. In fact, the time factor has been so restrictive that in practice many psychologists knowingly make no serious effort to assess adequately the complexities of behavioral deficits associated with brain lesions. Acceptance of this constraint, however, can only lead to offering simple answers to complex questions-a practice which is hardly appropriate in furthering our knowledge of a specific area or in demonstrating the professional contribution that can be made. Our initial decision was to press for a battery that could be administered to the most impaired patient in 2 days. We find that the battery can be completed in 1 day for most patients.

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162 111. METHODOLOGICAL APPROACH

Much of the research that has been done on the psychological effects of brain lesions has been problem-oriented, and the results provide little possibility for direct application to individual patients. The methodological approach devised and used at the University of Chicago by Doctor Ward C. Halstead, who initiated the first full-time laboratory for the study of brain-behavior relationships in human beings with cerebral lesions, was adopted for the Neuropsychology Laboratory. There is no question that adoption of Halstead’s methodological orientation has had a profound influence on the progress made by our laboratory] and we gratefully acknowledge this assistance. Halstead’s approach has a number of aspects which enhance the opportunity for studying specific problems as well as for learning more about the effects of brain lesions in individual patients. The approach requires identification of a battery of psychological tests which is routinely administered to every patient. Furthermore, in the interest of objectivity of data collection, it requires independence in the neurological selection of appropriate patients and in the psychological examination of them. Again, the essential contribution of neurological colleagues is emphasized, since these persons must identify subjects who promise to meet satisfactory criteria of neurological diagnosis and refer these patients for psychological testing. The laboratory has attempted to examine every available patient at our medical center in whom a brain lesion has been well identified. In this way, we have a continuing opportunity to observe the psychological deficits manifested by patients who represent the broad range of neurological conditions which involve the brain. At the time of referral, neurological findings are usually not sufficientlycomplete to support a firm diagnosis, although the referring physician has reason to believe that compelling evidence may be forthcoming. The patients are examined in the Neuropsychology Laboratory by carefully trained technicians who have no knowledge of the neurological findings. After test results are obtained and scored by the technicians] an interpretation is written by one of the psychologists of the laboratory without knowledge of the history of the patient or findings from neurological evaluation. A written record of this “blind” interpretation is then available for comparison with independently obtained neurological findings which can be used as the criterion information. A complete summary of neurological findings and the resulting diagnosis is prepared for our research efforts by cooperating physicians in the neurological sciences. This procedure not only assures a complete absence of cross reference or contamination between the psychological and neurological results, but provides an excellent method by

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which to develop hypotheses for formal, controlled research studies as well as an opportunity to relate the intraindividual relationships in test results to the neurological description of the brain. This procedure may also be described as a continuing long-term experiment. The same battery of psychological tests is administered to patients across the years, gradually providing the opportunity to obtain groups of patients who may be categorized according to meaningful neurological variables. Although a good deal of time is required to compose adequately sized groups for study of specific problems, the approach has the advantage of providing day-to-day insights concerning the effects of brain lesions in individual subjects and a broad and balanced view that comes from seeing patients who cover the broad range of neurological diagnoses. It should also be noted that this approach has disadvantages as compared to the more conventional procedure of performing one problem-oriented study after another. The major difficulty derives from the necessary inflexibility of the psychological test battery. We are still administering the same tests in the same way we did more than a decade ago. Of course, standardization of testing procedure has been necessary in order to be in a position gradually to accumulate enough subjects for study of specific neurological variables. As a result, we have not been able to modify or manipulate the test battery in order to learn experimentally what the tests measure or the particular requirements of the tests which might be most sensitive to cerebral dysfunction. The approach has been oriented toward subdivision and analysis of the independent neurological variables while the dependent variables (psychological measurements) have been held constant. One is greatly tempted to engage in an analysis of the psychological functioning of a constant neurological reference group, as has been done recently by Talland (1965) in a group of chronic Korsakoffpatients. Teuber, Battersby, and Bender (1951; Teuber, 1952; Weinstein & Teuber, 1957) have also followed this procedure in studying braininjured soldiers from World War I1 and the Korean conflict. The approach used by these investigators requires long-term availability of experimental subjects with relatively static neurological conditions, and this is difficult to achieve in most medical centers. Furthermore, such groups do not provide a basis for generalization in the tremendous range of neurological conditions which exist in human beings. Both of these approaches can provide valuable information which should be of complementary value, although apparent differences in results, even though they probably should have been expected, may tend to cloud the complementary significance of the findings until resolved by the clearer insights that come with time. Control subjects are usually obtained from the hospital population in

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order to achieve some comparability with respect to the stress that may accompany hospitalization and physical illness. However, these patients are carefully evaluated from a neurological point of view in order to rule out cerebral damage or dysfunction. As control subjects, we have used subjects with primary neurotic disturbances, patients admitted to the neurology and neurological surgery services but in whom complete examination fails to indicate any past or present organic involvement of the nervous system, paraplegic patients without past or present evidence of cerebral damage, patients with peripheral nerve lesions in whom there is no evidence of serious motor impairment of the upper extremities, patients recovering from spinal cord lesions, and patients who have undergone appendectomies, herniectomies, etc. We have routinely avoided, as control subjects, patients with disorders that might involve the overall physiological economy of bodily functions, such as patients with cardiovascular lesions, metabolic disorders, and endocrinological disturbances. I t seems entirely possible that patients in these categories might well demonstrate psychological impairment because of the secondary influence of the diagnosed systemic disturbances on brain functions, and they therefore should be studied experimentally in their own right. IV. DESCRIPTION OF PSYCHOLOGICAL TEST BATTERY

T h e psychological test battery in use in the Neuropsychology Laboratory consists of Halstead’s battery of neuropsychological tests (Halstead. 1947), the Wechsler-Bellevue Scale (Form I) (Wechsler, 1944), the Trail Making Test (Armitage, 1946; Reitan, 1955c; Reitan, 1958a), an aphasia screening examination, tests of sensory-perceptual functions, and the Minnesota Multiphasic Personality Inventory (Hathaway & McKinley, 1943). Some additional tests which are in experimental use will not be described here. T h e Wechsler-Bellevue Scale and the Minnesota Multiphasic Personality Inventory are well known instruments in general use and are familiar to most readers. While the above tests are administered to persons who are 15 years of age or older, a battery which is essentially similar, though certain tests are simplified in some respects, has been developed for use with children age 9 through 14 years. In this age group, the Wechsler Intelligence Scale for Children is used instead of the Wechsler-Bellevue Scale. In addition, an experimental battery of tests has been devised for use with children age 5 through 8 years. This battery again represents simplifications and modifications of some of the tests to be described below and also includes a number of other procedures devised with the aim in mind of sampling performances from the behavioral areas represented by the battery for adults.

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A. Halstead’s Neuropsychological Test Battery

1. CATEGORY TEST This test utilizes a projection apparatus for presentation of 208 stimulus figures on a milk glass screen. Below this screen, attached to the apparatus, is an answer panel containing four levers which are numbered from one to four. The subject is told that he should depress one of these four levers for each of the pictures that appears on the screen. Depression of any of these levers will cause either a bell or buzzer to sound depending upon whether the lever selected is the “right” or “wrong” answer. Only one response is allowed for each item. Before the test begins, the subject is told that the test is divided into seven groups of pictures and that each group has a single principle running through the entire group from beginning to end. On the first item in any group, he can only guess, but as he progresses through the items of the group, the occurrence of the bell or buzzer with each response indicates whether his guesses are correct or incorrect. In this way, the test procedure permits the subject to test one possible principle after another until a hypothesis is hit upon which is positively reinforced consistently by the bell. The subject is never told the principle for any group regardless of the difficulty he might encounter, but the first and second groups are nearly always easily performed even by persons with serious brain lesions. The first group requires only the matching of arabic numerals above each of the answer levers with individual roman numerals that are shown on the screen. In the second group, the subject must learn to press the lever which has a number corresponding to the number of items appearing on the screen, regardless of their content. The examiner announces the end of each group and tells the subject that they are ready to proceed to the next group. The examiner points out that the principle might be the same as it has been or that it might be different and that the subject’s task is to try to discern the principle. The third group of items is based on a uniqueness principle. Four figures appear in each item and the subject must learn to depress the lever corresponding with the figure which is most different from the others. Although this group begins rather simply, it progresses to items in which one figure may differ from the others in three or more respects (such as size, shape, color, and solidness of figure) while the rest of the figures differ from each other in only two respects. Additional principles are used for remaining groups of items, but the last group is represented by various items which have occurred at different points throughout the test. The subject is so informed and before beginning this last group he is instructed to try to remember the right answer for each picture and give that answer as his response.

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The Category Test is a relatively complex concept formation test which requires fairly sophisticated ability in noting similarities and differences in stimulus material, postulating hypotheses that appear reasonable with respect to recurring similarities and differences in the stimulus material, testing these hypotheses with respect to positive or negative reinforcement (the bell and the buzzer), and the ability to adapt hypotheses in accordance with the reinforcement accompanying each response. While the test is not especially difficult for most normal subjects, it seems to require competence in abstraction ability, especially since the subject is required to postulate in a structured rather than permissive context.

2. CRITICAL FLICKER FREQUENCY AND CRITICAL FLICKER FREQUENCY DEVIATION In this test an electronic instrument (Strobotac) with a short flash duration is used to provide intermittent light of variable frequency. The Strobotac is housed in a specially constructed soundproof apparatus. The test involves the determination of the point at which a variably intermittent light fuses into the appearance of a steady light. The subject is required to adjust a knob until the flashing rate of the light is increased to the point where fusion is reached and the light appears steady to him. The frequency of intermittency, in terms of cycles per second, is recorded. An additional score is obtained as an expression of deviation from this point for the subject on successive trials. 3. TACTUAL PERFORMANCE TEST (TIME,MEMORY, AND LOCALIZATION COMPONENTS)

The Tactual Performance Test utilizes a modification of the SeguinGoddard form board. The subject is blindfolded before the test begins and is not permitted to see the form board or blocks at any time. His task is to fit the blocks into their proper spaces on the board using only his preferred hand. Next, he is asked to perform the same task again using only his other hand. Finally, he is asked to do the task a third time using both hands. The time recorded for each trial provides a comparison of the efficiency of performance of the two hands, but the time score for the test is based on the total time needed to complete the three trials. After the board and blocks have been put out of sight, the blindfold is removed and the subject is asked to draw a diagram of the board representing the blocks in their proper spaces. The memory component is based upon the number of blocks correctly reproduced in the drawing, and the localization component is based on the number of blocks approximately correctly localized. The Tactual Performance Test undoubtedly is a complex test in terms

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of its requirements. The ability to place the various shaped blocks in their proper spaces on the board depends upon tactile form discrimination, kinesthesis, coordination in movement of the upper extremities, manual dexterity, and visualization of the spatial configuration of the shapes in terms of their spatial interrelationships on the board. 4. RHYTHM TEST

The Rhythm Test is a subtest of the Seashore Test of Musical Talent. The subject is required to differentiate between 30 pairs of rhythmic beats which are sometimes the same and sometimes different. This test appears to require alertness, sustained attention to the task, and the ability to perceive differing rhythmic sequences. 5. SPEECHSOUNDSPERCEPTION TEST

The Speech Sounds Perception Test consists of 60 spoken nonsense words which are variants of the “ee” sound presented in multiple choice form. The test is played from a tape recorder with the intensity of sound adjusted to meet the subject’s preference. The subject’s task is to underline the spoken syllable, selecting from the four alternatives printed for each item on the test form. In addition to maintaining attention through 60 items, this test requires the subject to perceive the spoken stimulussounds through hearing and to relate these perceptions through vision to the correct configuration of letters on the test form. 6. FINGER OSCILLATION TEST

This test is a measure of finger-tapping speed, using first the index finger of the preferred hand and then that of the other hand. The subject is given five consecutive ten-second trials with the hand held in a constant position in order to be sure to require movements of only the finger rather than the whole hand and arm. Every effort is made to encourage the subject to tap as fast as he possibly can. This test would appear to be rather purely dependent upon motor speed.

7. TIME SENSE TEST (VISUAL AND MEMORYCOMPONENTS) The Time Sense Test requires the subject to depress a key which permits a sweep hand to rotate on the face of a clock. The subject’s task is to allow the hand to rotate 10 times and then stop it as close to the starting position as possible. After 20 trials during which the subject observes the rotation of the sweep hand on the face of the clock, the face of the clock is turned away and the subject is asked to duplicate the visually controlled performance as closely as possible. After 10 “memory” trials, series of 10 visual and memory trials are interspersed to represent a total

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of 40 visual trials and 20 memory trials in the entire test. The score, recorded separately for each procedure, represents the amount of error made. The visual component of this test requires the subject to maintain alertness and coordinate counting from one to ten with the rotation of the clock's sweep hand. Rather discrete visuo-motor coordination (a type of reaction time measure) is required to stop the hand's rotation in the correct position. The memory component requires estimation of the duration of time necessary for the hand to make 10 revolutions, using the subject's initial perception of this interval as the reference point.

8. HAUTEAD IMPAIRMENT INDEX The Impairment Index is a summary value based upon the 10 tests in the Halstead battery (omitting the visual component of the Time Sense Test in the 11 tests described above). It is determined for an individual subject merely by counting the number of tests on which the results fall into the range characteristic of the performance of braindamaged rather than normal subjects. B. Additional Tests as Part of the Battery

1. MODIFICATION OF HALSTFAD-WEPMAN APHASIA SCREENING

TEST9

This test provides a survey of possible aphasia and related deficits. The test samples the ability of the subject to name common objects, spell, identify individual numbers and letters, read, write, calculate, enunciate, understand spoken language, identify body parts, and differentiate between right and left. The requirements of the test are so organized that these various abilities are tested, to some extent, in terms of the particular sensory modalities through which the stimuli are perceived. The organization provides an opportunity for determining whether the limiting deficit is receptive or expressive in character. 2. TRAILMAKING TEST

The Trail Making Test consists of two parts, A and B. Part A consists of 25 circles distributed over a white sheet of paper and numbered from one to twenty-five. The subject is required to connect the circles with a pencil line as quickly as possible, beginning with the number one and proceeding in numerical sequence. Part B consists of 25 circles numbered from one to thirteen and lettered from A to L.The subject is required to connect the circles, alternating between numbers and letters as he proceeds in ascending sequence. The scores obtained are the number of seconds required to finish each part. 9

Halstead & Wepman (1949).

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C. Sensory-Perceptual Disturbances

1. SENSORY IMPERCEPTION This procedure attempts to determine the accuracy with which the subject can perceive bilateral simultaneous sensory stimulation after it has already been determined that his perception of unilateral stimulation on each side is essentially intact. The procedure is used for tactile, auditory, and visual-sensory modalities in separate tests. With respect to tactile function, for example, each hand is first touched separately in order to determine that the subject is able to respond with accuracy to the hand touched. Following this, unilateral stimulation is interspersed with bilateral simultaneous stimulation. The normal response is for the subject to respond accurately with the following alternatives: right hand, left hand, or both hands. Subjects with lateralized cerebral lesions are usually able to identify unilateral stimulation correctly but sometimes fail to respond under circumstances of bilateral simultaneous stimulation to the hand contralateral to the damaged hemisphere. Contralateral facehand combinations are also used with single or double simultaneous stimulation as part of our standard procedure. Testing for auditory imperception makes use of an auditory stimulus achieved by rubbing the fingers together quickly and sharply in a light manner. The test for visual imperception is applied through use of a small, discrete movement of the examiner's fingers while the subject focuses on the examiner's nose. Our standard procedure calls for as minimal a stimulus as is necessary to achieve consistently correct responses to unilateral stimulation. The test for perception of bilateral simultaneous stimulation is, of course, obviated if the patient has such a serious lateralized tactile, auditory, or visual loss that he is not able to respond correctly to unilateral stimulation on the affected side. Such unilateral impairment is rarely encountered in the tactile and auditory modalities but is not infrequently seen in instances of homonymous hemianopsia. 2. TACTILE FINGERRECOGNITION This procedure tests the ability of the subject to identify individual fingers on both hands after tactile Stimulation. Before the examination begins, the examiner must work out a system with the patient for reporting which finger was touched. Customarily, the patient will report by number but sometimes patients prefer to identify their fingers in other verbal terms. Although the test is given without the use of vision, it is sometimes necessary to give the patient practice with his eyes open in order to be sure that he is able to report reliably. Four trials are used for each finger on each hand, yielding a total of 20 trials on each hand. The score is recorded as the number of errors.

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170 3. FINGERTIP NUMBER WRITING PERCEPTION

This procedure requires the subject to report numbers written on the fingertips of each hand without the use of vision. Standard numbers are used and written on the fingertips in a standard sequence, with a total of four trials being given for each finger.

4. TACTILE FORMRECOGNITION This test requires the subject to identify, through touch alone, pennies, nickels, and dimes tested separately in each hand. The test is also given with coins being placed in each hand simultaneously. As an additional procedure for determining tactile form recognition, flat, plastic shapes (cross, square, triangle, and circle) are used as stimulus figures and are tested separately for each hand. V. RESEARCH RESULTS

Although the complexity of the criterion (neurological) variables has regularly been neglected in many psychological studies of human beings, it is probably advantageous to ask, initially, fairly general rather than specific research questions in order to provide a more orderly unfolding of the general and specific effects of brain lesions. In an attempt to order our investigations in such a way that serially forthcoming information will arrive in a context of necessary prior information, our general plan has been to inquire first about the effects of brain lesions considered heterogeneously; second, about the differential effects of lateralized cerebral lesions without regard to type; third, about regional localization effects; fourth, about differences in the effects of cerebral lesions which differ in their pathological type and duration; and finally, about the interactions of these various characteristics of cerebral lesions. This last consideration is essential in order to understand eventually the psychological effects of cerebral lesions in individual patients, since the particular combination of neurological characteristics of the lesion in the individual instance never fits exactly the criteria used in the composition of groups for formal research studies. Our first question was concerned with whether or not Halstead’s tests provided a sufficiently extensive breadth of relevant coverage of the abilities that may be impaired by cerebral damage (Reitan, 1955a). T h e possibility existed that certain types of deficits might not be tapped by these tests and that some subjects with cerebral lesions causing these particular deficits might therefore obtain normal scores. If any substan tial number of subjects with proved cerebral lesions obtained essentially normal scores, the prospects for valid use of the battery in individual

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assessment would be diminished. This postulate assumes, admittedly, that some impairment should result from proved cerebral lesions-an argument based on the belief that the brain is the principal organ of adaptive behavior and that damage to this organ will be expressed by some corresponding changes of adaptive behavior. It should be noted that the purpose of this study was not principally oriented toward determining the ability of Halstead’s battery to effect binary diagnostic classifications of subjects into groups with and without cerebral damage, as seems to be the aim in most studies in the literature, but rather to determine whether the battery was adequate to do justice to the complex range of disturbances resulting from cerebral lesions. While the same type of evidence is pertinent to both of these aims, the important point of difference is that one of the objectives prematurely represents an end in itself whereas the other objective seeks to lay the foundation for a research program. Our first study (Reitan, 1955a) compared results obtained with Halstead’s battery in a group of 50 subjects with proved cerebral damage or dysfunction and a group of 50 subjects who showed no past or present symptoms or signs of cerebral damage or dysfunction. Diagnoses among the patients with cerebral lesions were deliberately diverse, since our intent in this study was to provide for inclusion of the full range of adaptive deficits associated with cerebral lesions. Twenty-four % of the control group was made up of normally functioning individuals but the remaining 76% was composed of patients hospitalized for a variety of difficulties not involving brain functions. A substantial proportion of paraplegic and neurotic patients were included in this group in an attempt to minimize the probability that any intergroup differences could be attributed to variables such as hospitalization, chronic illness, and affective disturbances. The patients in the two groups were matched in pairs on the basis of color and sex, and as closely as possible for chronological age and years of formal education. The difference in mean age for the two groups was .06 year and the difference in mean education was .02 year. Standard deviations for these variables in the two groups were nearly identical. The results of comparing the two groups on Halstead’s tests are provided in Table I. The most striking intergroup differences occurred on the Halstead Impairmen Index and the Category Test. On the Impairment Index, not one of the brain-damaged subjects performed better than his matched control pair, although in six instances the Impairment Indexes for matched pairs were equal. In three instances, subjects with brain lesions performed better on the Category Test than the control subjects with

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whom they were paired, but results in the opposite direction occurred for the remaining 47 pairs of subjects. No difference between the groups was found on two measures derived from the Halstead test for critical flicker frequency measurement, but the remaining tests in the battery yielded statistically significant differences. Only on the memory component of the Time Sense Test (p < $02)was the probability level greater than .001. The final sentence in this first report was as follows: “Although further validity studies are necessary, the present results suggest that the TABLE I COMPARISONS ON HALSTEAD’S TESTS OF 50 PAIRSOF SUBJECTS WITH AND WITHOUT FOR RACE,SEX, AGE,AND EDUCATION CEREBRAL DAMAGE, MATCHED

Test

Control subjects better than brain-damaged pairs

Equal

Brain-damaged subjects better than control pain

%

%

%

88 94 44

12 0 0

0 6 56

42

8 0 18

50 14 16

12 24 2

4 12 14 24 34

Impairment Index Category Test Critical Flicker Frequency Critical Flicker Frequency Deviation Tactual Performance Test (time) Tactual Performance Test (memory) Tactual Performance Test (localization) Seashore Rhythm Test Speech Sounds Perception Test Finger Oscillation Test Time Sense Test (memory)

86 66

84 64 84 76 66

0 0

Halstead battery is sufficiently sensitive to the effects of organic brain damage to provide an objective and quantitative basis for detailed study of relationships between brain function and behavior.” In consideration of the results of this study, it appeared possible to use Halstead’s battery as the core-battery for more detailed studies. An additional study (Reitan, 1959a) was performed, however, to determine the comparative sensitivity of the Halstead Impairment Index and the summary scores from the Wechsler-Bellevue Scale (Form I). Halstead (1947) had postulated the existence of “biological intelligence” as measured by his battery in contrast to “psychometric intelligence” as measured by conventional tests of general intelligence. It seemed important, particularly in determining a valid answer to the first question as to whether or not a brain lesion was present, to compare the sensitivity of these indexes to cerebral damage. The same 50 subjects with and the same 50 subjects

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without evidence of brain damage were used as had been used in the study described above. The Impairment Index had previously been shown to differentiate the two groups, and study of the results on the WechslerBellevue Scale also showed differences. The braindamaged group obtained significantly lower scores than did the group without brain damage on all summary variables as well as on the individual subtests with the exception of the digit span subtest. A method of direct comparison of the Impairment Index and the Wechsler-Bellevue measures was devised. This procedure involved the rank-ordering of difference scores on each test between each pair of subjects in the two groups, and then comparing the rank-order of the pairs for different tests. The results indicated that the Impairment Index was more sensitive to brain damage (in terms of the degree of separation between brain-damaged and control pairs) than any of the Wechsler-Bellevue variables, including Verbal IQ, Performance IQ, Full-Scale IQ, Wechsler Deterioration Ratio, “hold” tests, and “don’t hold” tests. Each of the comparisons was significant beyond the .001 level of confidence. These results indicated that the Halstead Impairment Index provided a better basis for measuring the broad range of deficits associated with cerebral lesions heterogeneously considered than did the Wechsler-Bellevue Scale. Similar preliminary studies were performed with the Trail Making Test. In one study (Reitan, 1955c) comparable groups of 27 patients with and 27 patients without cerebral lesions were composed. These groups were essentially similar to those used in the studies above. Comparison of the two groups yielded highly significant statistical differences, with the nonbrain-damaged group obtaining the better scores. Using the optimal cutoff point for the two distributions, approximately 170/, of each group was misclassified. These results suggested that the Trail Making Test might well provide a valuable addition with respect to answering the first question of whether or not cerebral damage was present. A crossvalidation study, using larger groups, was also performed (Reitan, 1958a). The brain-damaged group was composed of 200 patients and the group without brain damage of 84 persons. The groups were comparable in terms of sex distribution, and mean values for age and education in the two groups were not significantly different. Again, highly significant differences were obtained in favor of the group without cerebral lesions. The optimal cutoff points in differentiation of the groups were identical with those obtained in the initial study (Reitan, 1955~).Part A of the Trail Making Test, even though intergroup differences were highly significant (critical ratio, 12.78:p < .001), did not provide distributions which appeared to be particularly promising with respect to identification of group membership for individual patients. On part B of the test, how-

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ever, overlap of the distributions on either side of the optimal cutoff point amounted to 11.5% for the group with cerebral lesions and 19.0% for the control group. Approximately comparable overlap in the distributions was obtained when combining the scores for parts A and B. Examination for aphasia and related sensory-perceptual deficits (a modification of the Halstead-Wepman Aphasia Screening Test) represents an additional major source of evidence in our test battery regarding the integrity of the cerebral hemispheres. While we have used this test principally to supplement the results obtained on other measures and have been particularly dependent on many of the findings with regard to lateralization of cerebral dysfunction, the test results are also susceptible to study with respect to their general sensitivity to cerebral damage. Using groups of 104 subjects without evidence of cerebral damage and 158 subjects with cerebral lesions, 68% of the control group performed the test with no evidence whatsoever of any deficit whereas only 15% of the subjects with cerebral lesions fell into this classification (Wheeler & Reitan, 1962). Analysis of the results indicated a probability of correct classification of each patient to his appropriate group of 78% when the differentiating criterion was no evidence of deficit vs. one or more signs of defective performance. This type of test appeared to be highly useful for many subjects because of the infrequency with which the control group gave evidence of defective performance. As mentioned above, 68% of the control group performed the test perfectly. An additional 28% had only one sign of deficit. Those with two or three signs of deficit completed the entire control group, with only 2yo in each classification. While 61% of the subjects with cerebral lesions had three or fewer signs of deficit, the remaining 39% were entirely beyond the limits of the distribution for the group without evidence of cerebral damage. For these subjects, the examination for aphasia and related sensory-perceptual deficits appeared to be especially useful in answering questions regarding the presence or absence of cerebral damage. These initial studies have in effect been replicated many times in later studies which used groups of subjects organized according to more specific neurological criterion information, since these later studies permitted observation of the results with a heterogeneous group (resulting from the combination of the more specific groups) as compared with the results obtained on a control group without cerebral damage. A. Qualitative Vs. Quantitative Psychological Effects of Cerebral lesions

Our next problem in attempting to establish a groundwork for a research program related to the possible nature of psychological deficit in patients with cerebral lesions. Some investigators have implied that defi-

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cits resulting from brain lesions represent differences in kind rather than in degree as compared with normal behavior. With respect to abstraction ability, for example, Goldstein (1940) has said: “Even in its simplest form, however, abstraction is separate in principle from concrete behavior. There is no gradual transition from one to the other.” If such a contention were correct, quantitative scaling or measurement of behavior and comparison of groups with and without cerebral lesions on the basis of such measurements obviously would be meaningless. Over and beyond this problem, the matter of equivalent scaling units in the parts of any scale principally represented by persons with and without cerebral lesions represented another problem that needed investigation. A series of experiments (Reitan, 1956a; Reitan, 1957a; Reitan, 1958b; Reitan, 195913; Reitan, 1959c) was performed to determine whether or not the same abilities, measured in a comparable way, were being tested in patients with and without cerebral lesions. T h e same groups of 50 paired subjects with and without brain lesions (Reitan, 1955a; Reitan, 1959a) were used for this study. As described above, previous comparisons had shown consistent and highly significant quantitative differences between the groups. These quantitative differences by themselves were clearly not adequate to answer the question of differences in the Kind of mental functions in persons with and without cerebral lesions (even though the same test format was used) if the hypothesis was correct that different kinds of psychological function existed in patients with cerebral lesions as compared with those having normal brain functions. I t seemed reasonable, however, to assume that if different kinds of abilities were used by the brain-damaged subjects, the interrelationships or correlations between various tests would differ from the interrelationships shown by the group without brain damage. Twenty-five psychological test measures were available for each group. This number of variables provided for a total of 300 coefficients of correlation when individual tests were arranged in all possible pairs. These coefficients were converted to Fisher’s z values, the standard error of the difference for z was found, and each pair of coefficients (brain damage vs. no brain damage) was compared for statistically significant differences. I n addition, the extent of agreement of the correlation matrices for the two groups was determined by computing the correlation between them. Variables from the Wechsler-Bellevue Scale provided 91 of the 300 coefficients for each group. In comparing the groups, only 2 of the 91 coefficients were “significantly” different at the .05 level of confidence. Correlation of these two arrays of coefficients was .79, further indicating the close agreement between the magnitude of the coefficients for groups with and without brain damage. Of the 300 coefficients, 156 represented

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correlations between Wechsler-Bellevue results and scores obtained on Halstead’s tests. Only 4 of these 156 pairs of coefficients showed differences that reached the .05 confidence level. Correlation of the 156 coefficients obtained in each group yielded a coefficient of .78. In comparing the 55 coefficients derived from interrelationships on Halstead’s battery, only 1 pair showed a significant difference and this barely reached the .05 level of confidence. A correlation of .64 between the matrices for the groups with and without brain damage was obtained. Correlation of the matrices of the total of 300 coefficients obtained for each group yielded an r of 35. These results provided us with some feeling of confidence that our scales were relatively appropriate and consistent over the area represented by groups with as well as without cerebral lesions. Furthermore, the results provided a strong argument that the effects of cerebral lesions are not, as claimed by Goldstein (1940) “a totally different activity of the organism” but instead seem to represent quantitative deviations from normal levels of the same kinds of abilities as measured in subjects with normal brain functions. An additional test of this general question was studied using results on the Halstead Category Test for groups of 52 patients with and without brain lesions (Reitan, 1959~).Our purpose was to compare subtests 5 and 6 of the Category Test, since, even though the subject is not so informed, the. subtests are based on the same organizing principle. We wished to compare the absolute number of errors on each subtest for the group, the absolute improvement shown from subtest 5 to subtest 6, and the proportional improvement. Our hypothesis was that the group with brain lesions would perform more poorly on each subtest and that possible differences in type of abstraction abilities might be reflected by differences in the absolute or proportional degree of improvement from subtest 5 to 6. We were particularly interested in testing Goldstein’s (1940) contention that brain lesions caused an essential change by transforming abstraction abilities into concrete performances. Our results showed clearly significant differences between the groups with respect to the number of errors made on each subtest considered individually. However, there was no significant difference between the groups in terms of either absolute or proportional improvement from one subtest to the other. Thus, while the brain-damaged subjects consistently performed more poorly than the group without brain damage, they showed the Same pattern of error scores between the two subtests. This same type of study was performed using data from the Halstead Tactual Performance Test (Reitan, 1959b). The group with brain damage was significantly poorer in comparison with the nonbrain-damaged group on the scores obtained with the right hand, the left hand, or both

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hands, as well as on the total time required for the three performances. However, there were no significant differences between the groups in any instance with respect to absolute or proportional amounts of improvement. The results suggested that the essential differences were quantitative ones in terms of level of performance rather than representative of different types of performances in the two groups. Both groups showed clear improvement with practice, and the intergroup differences in this respect were not statistically significant. It should be noted that these results are not relevant to interpretation of the intraindividual differences that may be obtained in patients with lateralized cerebral lesions but instead are referable to the general results obtained with heterogeneous groups of brain-damaged subjects. We were also interested, in this series of methodological studies, in obtaining information regarding the relationships between WechslerBellevue results and findings on Halstead’s tests. Halstead (1947) had postulated a concept of biological intelligence as measured by his tests in contrast to the concept of psychometric intelligence represented by Wechsler’s scales. As described above, our results had indicated that the Halstead Impairment Index was much more sensitive to cerebral damage than variables from the Wechsler-Bellevue Scale. Intercorrelations between the Wechsler-Bellevue Scale and Halstead‘s tests, however, were generally significant, indicating that these two concepts of intelligence are not entirely separate and certainly not antagonistic. B. Differential Effects of left and Right Cerebral lesions

Against the background of the above studies, the Neuropsychology Laboratory has investigated the differential effects of lateralized cerebral lesions on the Wechsler-Bellevue Scale (Form I), several tests from Halstead’s battery, the Trail Making Test, and our examination for aphasia and related sensory-perceptual deficits. 1. WECHSLER-BELLEVUE LATERALIZATION STUDIES Our first comparison (Reitan, 1955d) of subjects with right, left, or diffuse cerebral lesions was based on relatively small groups of patients composed according to all available neurological information on each patient. It was possible to identify 17 patients with lesions principally involving the right cerebral hemisphere, 14 patients with lesions of the left cerebral hemisphere, and 31 patients with evidence of diffuse cerebral damage. While these groups obviously were not matched in triads, there were no significant intergroup differences in mean age or education. As previously reported by Andersen (1950), our findings indicated fairly clear differences between the groups with lateralized lesions. The group

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with lesions of the left cerebral hemisphere had the lowest means on each of the verbal subtests of any of the three groups. Conversely, the group with right cerebral lesions had the lowest mean in each instance on the performance subtests. T h e consistency with which these differences were shown was indicated by the finding that 13 of the 14 patients with left cerebral lesions had lower verbal than performance total weighted scores; 15 of the 17 patients with lesions of the right hemisphere had higher verbal than performance weighted-score totals: and the 31 patients with diffuse cerebral damage included 17 with higher verbal than performance totals, 12 with higher performance than verbal totals, and 2 in which verbal and performance totals were equal. As a further indication of the differences in the groups with lateralized cerebral lesions, the block design subtest had the second highest mean of the 11 subtests for the group with left cerebral lesions but the third lowest for the group with right cerebral lesions. T h e similarities subtest had the fourth highest mean for the group with right cerebral damage but the third lowest of the 11 subtests for the group with lesions of the left cerebral hemisphere. A replication of this study (Fitzhugh, Fitzhugh, & Reitan, 1962a) showed very similar results to those reported above although it was based on entirely new subjects. T he consistency of these findings, when based on the full complement of neurological evidence relating to the description of brain lesions, prompted us to investigate more discrete criterion variables. Klave (1959a) replicated these studies using electroencephalographic information for the composition of groups. He composed four groups as follows: a group with EEG abnormalities over the left cerebral hemisphere: a group with EEG abnormalities over the right cerebral hemisphere; a group with generalized or diffuse EEG abnormalities; and a group with definite evidence of cerebral damage but with normal EEG tracings. T h e last of these groups showed no difference in level on the verbal and performance parts of the Wechsler-Bellevue Scale but performed somewhat better than the other groups on the total test. T h e groups with lateralized EEG abnormalities demonstrated the same type of differential performance on the verbal and performance parts of the Wechsler Scale that was found in the studies described above. I n another study, Klave and Reitan (1958) classified patients according to the presence of aphasic disturbances, difficulties in copying simple geometric figures manifested by distortion of the spatial configurations, and both of these difficulties. Similar results to the above were obtained, with the dysphasic subjects performing more poorly on the verbal subtests, and the group with distortion of the spatial configurations in their drawings performing more poorly on the performance subtests. Klave (1959b) repeated this study

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with patients classified in groups according to whether imperception of bilateral simultaneous sensory stimulation occurred on the left side, right side, both sides, or not at all. Sensory-perceptual difficulties of this type appear to have rather definite implications with respect to the differential functional status of the cerebral hemisphere, and again the Wechsler-Bellevue results were very similar to those obtained previously. Doehring, Reitan, and Klgve (1961) composed groups according to left homonymous visual field deficits, right homonymous visual field deficits, and proved cerebral lesions without evidence of homonymous visual field losses. Again, the results essentially replicated the findings on previous studies. Reed and Reitan (1963a) studied Wechsler-Bellevue results in patients with lateralized motor deficits resulting from cerebral lesions as compared with patients having proved cerebral lesions but no identifiable motor deficits of the upper extremities. While this criterion did not prove to be quite as powerful as several of the others, the results were clearly in the expected direction. Finally, Matthews and Reitan (1964) performed a study of the consistenciesin results of these various WechslerBellevue studies described above. Rank difference coefficients of correlation were computed between rank-orders of individual subtest means in a total of 20 groups of adult subjects with verified brain lesions. Comparisons were made with groups organized according to evidence (direct or inferential) of damage to the right, left, or both cerebral hemispheres. Consistencies in the rank-orders of subtest means, far beyond chance expectancies, were demonstrated within the lateralized brain-damaged categories, while highly significant differences in subtest rank-orders were shown between the right and left hemisphere groups. The results indicated that lateralization of brain lesions has a striking effect on rank-order of Wechsler-Bellevue subtest means and that consistent relationships are obtained across a wide range of structural, electrophysiological, and behavioral criteria of lateralized brain dysfunction.

2. TRAIL MAKING TF.ST Differential effects of lateralized cerebral lesions on the Trail Making Test have been investigated by Reitan and Tarshes (1959). Our predictions included one to the effect that patients with left cerebral lesions would perform poorly on part B of the Trail Making Test with relation to the performance on part A because of the more complex symbolic requirement on part B of differentiating numbers and letters and ordering them in an alternating progressive sequence. We postulated that differences in the level of performance on parts A and B would be less for patients with right cerebral lesions, since the limiting factor in this case might well relate to the spatial configuration represented by the stimulus

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material. Since the stimulus material is distributed approximately equally in space for both parts A and B, we expected the group with lesions in the right hemisphere to have comparatively less difficulty than the group with left cerebral lesions in progressing from part A to part B. A test of these hypotheses clearly confirmed them by comparing the distributions of difference scores between the two parts of the test. Using a median value of the combined groups, those with left cerebral lesions fell into a 25-75% distribution, those with right cerebral lesions fell into a 72-28% distribution, and the group with diffuse cerebral lesions fell exactly into a 50-5070 distribution on either side.

3. HALSTEAD'S TESTS Doehring and Reitan (1961a) compared 19 subjects with right homonymous visual field defects, 19 subjects with left homonymous visual field defects, 19 subjects with brain damage unaccompanied by visual field defects, and 19 subjects without evidence of cerebral lesions or visual field defects on six of Halstead's tests and the Trail Making Test. The four groups were comparable in age and education and the three groups with cerebral lesions had approximately comparable types of brain lesions. This comparison was concerned strictly with level of performance rather than with differences in performances on the two sides of the body. The control group was rather consistently superior to the three groups with cerebral lesions, but mean scores for the brain-damaged groups were generally not significantly different. A conclusion was reached that constriction of the visual fields did not result in any appreciable impairment of test performance on these measures over and above the impairment that resulted from other behavioral consequences of cerebral damage. The group with left homonymous visual field defects showed some tendency to be poorer than the other groups with cerebral lesions, possibly indicating that an intact right cerebral hemisphere is more important for certain of the nonverbal functions required by tests in Halstead's battery than an intact left cerebral hemisphere. Another study by Doehring and Reitan (1962) investigated possible differences in concept attainment of adult subjects with lateralized cerebral lesions. Goldstein (1940) concluded that impairment of the ability to abstract could result from any cerebral lesion. Rylander (1939) tested 32 patients with lesions of the frontal lobe and found no differences in the performance of various abstraction tests between patients with left and right frontal lesions. Halstead (1940) also found no association between laterality of lesion and proficiency in grouping heterogeneous test objects. However, McFie and Piercy (1952a; 1952b), using tests of abstraction applied by Goldstein, found that a significantly larger propor-

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tion of patients with left frontal lesions failed the test than did patients with right frontal lesions. Our study employed the Halstead Category Test which has been described above. Previous studies using this test (Shure & Halstead, 1958; Chapman & Wolff, 1959) had not found significant differences in patients with left or right frontal lesions. The study by Doehring and Reitan (1962) used 50 adults with left cerebral lesions, 50 adults with right cerebral lesions, and 50 adults without evidence of brain lesions. The groups were comparable with respect to age, education, and sex distribution, and only right-handed subjects were used. Although the group without cerebral damage was significantly better than either of the brain-damaged groups, the groups with lateralized cerebral lesions did not differ significantly in total errors. Furthermore, the patterns of errors made on individual subtests of the Category Test were quite comparable in all three groups. In spite of the similarities in the performances of patients with lateralized lesions found in this study, the postulate was offered that the relative proportion of verbal as compared with nonverbal content of concept-attainment tasks might very well be a significant factor in the demonstration of laterality effects. A study (Reitan, 1958c) oriented toward comparisons with the left and right upper extremities in patients with lateralized lesions, using the Halstead Tactual Performance Test and Finger Oscillation Test, revealed clearly significant differences. Eighteen patients with left cerebral lesions were compared with 30 patients having lesions of the right cerebral hemisphere. The groups were of approximately the same mean age and education. Only right-handed patients were used. Subjects with lesions of the left cerebral hemisphere required a mean of 8.86 min longer to complete the task with the right hand than with the left hand. Conversely, patients with lesions of the right cerebral hemisphere required a mean of 4.81 min longer with the left hand than with the right hand. This difference between the groups was highly significant. Eighteen patients with left cerebral lesions and 23 patients with right cerebral lesions were compared in terms of the differential finger-tapping speed of the right and left hands. These groups overlapped considerably in composition with those reported just above. Again, highly significant intergroup differences were obtained. The group with right cerebral lesions tended to tap more slowly with the left hand and the group with left cerebral lesions showed some impairment in finger-tapping speed with the right hand. A cross-validation study was presented as part of this report (Reitan, 1958~).New groups of patients with lateralized lesions were composed of 17 patients with left cerebral lesions and 15 patients with right cerebral lesions. Cutoff points for both the Tactual Performance Test and the

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Finger Oscillation Test, regarding the degree of proficiency shown by the right as compared with the left hand, were determined from data on the initial groups described above. Use of the cutoff point for the Tactual Performance Test, with relation to the differential level of performance of the two hands in the cross-validation groups, correctly classified 16 of the 17 patients with left cerebral lesions and all 15 of the patients with right cerebral lesions. Results on the finger-tapping test using the same procedure were not quite as dramatic. Thirteen of the 17 patients with left cerebral lesions were correctly classified as were 11 of the 15 patients with right cerebral lesions. While the previous study by Doehring and Reitan (196la) indicated at best a weak potential for differentiating patients with lateralized lesions on the basis of level of performance on these two tests, the latter results using comparisons of performances with the two hands showed very striking differences. C. Aphasic and Related Sensory-Perceptual Deficits

Following the approach which has been outlined above, our first inquiry with respect to aphasia was directed toward elucidation of its general characteristics as differentiated from psychological.effects of brain lesions without aphasia and presumably normal types of performances. Investigation of this problem has some general significance because of relationships between language functions and thinking that have been postulated for many years. Watson (1924), the father of behaviorism, proposed the most intrinsic of relationships between language and thinking-that thinking is subvocal speech. Kimble (1956), in his general psychology textbook, said: “Language is inseparably bound up with thinking and other symbolic behavior.” And Munn (1951), in his psychology textbook, said: “. . . we must admit that the symbols which represent most of the world are language symbols (verbal, gestural, or written) and that most of our thinking appears to be an internal manipulation of such symbols.” The question then of associated psychological deficits over and beyond language impairment in aphasic patients not only has significance for understanding the nature of aphasia but, as Meyers (1947) has pointed out, provides “. . . a singular opportunity to inquire into the language-thought relationships.” I n order to study this general problem, three groups of 82 subjects were composed (Reitan, 1960b). One group consisted of patients with brain lesions and dysphasia, another of patients with brain lesions but without dysphasia, and a third group of patients hospitalized for various reasons but with no anamnestic or clinical evidence of organic brain dysfunction. Subjects were matched in triads for sex, color, chronological age, and years of formal education. In addition, the two groups of brain-damaged sub-

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jects were matched quite closely with regard to type of cerebral lesion. Interestingly, identification of the subjects for this study required a review of medical records and results of aphasia examinations for more than 1500 patients. The psychological tests used in the study were the Halstead Neuropsychological Tests (excepting two measures based on critical flicker frequency), the Trail Making Test, and the Wechsler-Bellevue Scale (Form I), The results indicated that both braindamaged groups performed more poorly than the control group on all tests except the verbal subtests of the Wechsler Scale. On these tests the dysphasic group performed very poorly, but the nondysphasic group was not greatly inferior to the controls. In addition to the verbal subtests of the Wechsler Scale, the dysphasic group performed more poorly than did the nondysphasic group only on the Halstead Speech Sounds Perception Test and part B of the Trail Making Test. On all of the other tests the dysphasic and nondysphasic groups had almost equivalent performances, in spite of the fact that many of these tests are quite complex and appear very possibly to be aided in their solution by implicit verbalization. On the Halstead Category Test, for example, scores for both brain-damaged groups, while clearly inferior to the score obtained by the control group, were almost identical. T h e results of this study suggest that language function is less important in complex thinking than has generally been presumed. Except for tests specifically requiring the use of language symbols, adaptive abilities related to thinking and intelligence did not appear to suffer special impairment in the dysphasic as compared to the nondysphasic group. This finding suggests that language impairment in dysphasia is a relatively independent deficit rather than a direct manifestation of defective intelligence or thinking ability. With respect to aphasia per se, the results of the study should enhance the impetus for rehabilitational work with dysphasic patients in order to raise their language abilities to the level of their performances on complex tasks not explicitly requiring language functions. Heimburger and Reitan (1961) studied the lateralizing significance of some easily administered written tests selected from our examination for aphasia. Three of the four tests were intended to detect difficulty in copying simple geometric figures and required the subject to copy, from a model and as carefully as possible, first a square, then a Greek cross, and finally a triangle. The fourth simple test required the subject to repeat after the examiner the sentence, “He shouted the warning.” After repeating the sentence, the patient was asked to explain it so that we could be sure that he understood its content. Finally, he was asked to write this sentence. Results from a wide variety of neurological patients

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were obtained, and then this large group of patients was studied to identify those in whom right, left, or diffuse or bilateral cerebral lesions had been identified. Patients were selected for inclusion in the study only if sufficient information was available from complete neurological evaluation to permit assignment of each patient to one of these three groups. The groups finally composed consisted of 78 patients with lesions of the left cerebral hemisphere, 92 patients with lesions of the right cerebral hemisphere, and 69 patients with involvement of both cerebral hemispheres, a total of 239 patients. Results of our complete aphasia examination indicated a judged incidence of 81% in the left hemisphere group as having aphasia, 18% in the right hemisphere group, and 54% in the group with involvement of both cerebral hemispheres. When considering only the four tests selected for this study, clear differences were present in the groups with lateralized cerebral lesions. The group with involvement of both cerebral hemispheres consistently occupied an intermediate position with respect to the groups with lateralized lesions. In the group with left cerebral lesions, 17% had difficulties both in writing and in copying geometric figures, but when isolated deficits were present, they far more often involved writing than copying geometric figures (45yo to 10%). Several patients (10%) in the group with right cerebral lesions also demonstrated deficits in performing both types of tasks, but 48% had isolated difficulty copying the geometric figures while none had exclusive deficits of writing. The group with involvement of both cerebral hemispheres had isolated difficulties with the two types of tasks at a frequency intermediate to that of the groups with lateralized lesions. I n the total number of patients included in the study, 36y0 showed entirely negative findings on these simple tasks. It is somewhat surprising, however, that 64% of the total group showed deficits in the performance of one or more of these tasks. The results indicate that the procedures are not adequate to effect perfect classification of the subjects into their respective groups even when positive findings occur, but definite intergroup differences were present which indicate that these simple tests may provide valuable supplementary information in assessing the condition of the cerebral hemispheres. In a somewhat more detailed study of impairment of language functions in brain-damaged patients with and without homonymous visual field defects, Doehring and Reitan (1961b) found similar results. Additional confirmation of these findings was presented by Reitan (1958~)together with evidence of the lateralizing significance of sensoryperceptual functions such as tactile form recognition, tactile finger recognition, and tactile, auditory, and visual imperception with bilateral simultaneous stimulation. While it must be emphasized that a considerable proportion of patients with lateralized cerebral lesions fail to show

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deficits on these sensory-perceptual tests, lateralized deficits (ocaning on one side of the body or the other) are rarely misleading with respect to providing an indication of damage to the contralateral cerebral hemisphere. The lateralizing significance of results from the test for aphasia and related sensory-perceptual deficits was also studied by Wheeler and Reitan (1962). This study compared 104 control subjects, 47 subjects with lesions of the left cerebral hemisphere, 45 subjects with right cerebral lesions, and 54 subjects with bilateral or diffuse damage. Four rules were developed for applying the results to classification of individual subjects. Use of these rules gave the following conditional probabilities of correct classifications: controls, 780/,; left cerebral damage, 80y0; right cerebral damage, 85%; and nonlateralized cerebral damage, 84%. The rules, themselves, are defined in the original report. D. Acute Vs. Chronic Brain Lesions

I n accordance with our general plan of investigative procedure, our first effort (Fitzhugh, Fitzhugh, & Reitan, 1961) was to identify the general differences between groups of patients with acute brain lesions as compared with chronic brain lesions. In addition to a control group in whom there was no evidence of cerebral dysfunction, three braindamaged groups were composed. The acute group consisted of patients who had acute neurological illnesses and whose neurological signs and symptoms were present at the time of psychological testing. These patients had experienced a specific, temporally defined episode during which their current neurological findings had arisen or had developed a rapidly progressive brain disease with steady progression of neurological signs. The second group, identified as relatively static, was composed of patients who had either recovered from acute neurological signs if there had been an acute onset of symptoms or who had slowly progressive brain disease without evidence of acute or sudden onset. The third braindamaged group, identified as chronic-static, consisted of patients with chronic, longstanding brain dysfunction who were institutionalized in a state hospital for patients with neurological disorders. The four groups each consisted of 16 patients. The groups were closely matched with respect to chronological age, years of education, sex, and race. T o achieve comparability of these variables, individual subjects were matched across groups. This study reported intergroup comparisons based on results obtained with the Wechsler-Bellevue Scale (Form I) and 7 of the 10 tests in Halstead's battery. The results for the control group consistently exceeded those for any of the braindamaged groups on both the Wechsler-Bellevue variables and Halstead's tests, although the degree of difference tended to

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be somewhat larger for the tests in Halstead’s battery. This finding provides cross-validation of our initial studies reported above. Comparison of the groups identified as relatively static and chronic-static indicated that the relatively static group had the higher means on most of the tests, but on only one of the 22 test variables was the difference statistically significant. In contrast, the acute group performed less well than one or both of the static groups on all variables but one and significantly less well on a number of variables. These results suggest that the degree of psychological impairment associated with acute lesions of the brain is greater than customarily found with relatively static lesions and indicate that this variable should be considered in studies of psychological deficits among brain-damaged subjects. Our next study in this particular series (Fitzhugh, Fitzhugh, & Reitan, 1962a) involved comparisons of lateralization effects on the WechslerBellevue Scale in groups of patients with recently developed evidence of brain damage as compared with groups having chronic, long-standing brain lesions. Groups with left, right, and bilateral cerebral lesions were composed under the general headings of acuteness and chronicity of cerebral damage. The groups with acute cerebral lesions were composed of patients tested at the Neuropsychology Laboratory, and the groups with chronic brain lesions were made up of patients hospitalized at the New Castle State Hospital. A matched triads design was used for composing the three groups from each institution, yielding close control of chronological age, education, race, and sex. However, it was not possible to achieve comparability in this study of mean age and education between the groups from the two institutions, and thus the data for each set of three groups was handled separately. The results from the groups with acute cerebral lesions (medical center groups) were very similar to those initially reported by Reitan (1955d) and thus provide a cross-validation of lateralization effects. Impairment was shown on the verbal part of the Wechsler Scale in groups of patients with left hemisphere lesions, impairment on the performance part in the group with right hemisphere lesions, and an absence of differential impairment on the two parts in the group with diffuse or bilateral cerebral damage. However, the groups with chronic, long-standing brain damage did not differ significantly from each other on any of the Wechsler variables, although the group with predominantly left hemisphere damage tended to be inferior to the other two chronic groups on verbal subtests. Thus, only a slight trend of results in the predicted direction occurred in the groups with chronic brain dysfunction. It would appear from these findings that lateralization of cerebral damage is not an entirely pervasive criterion in its own right, but must be considered with relation to the

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acuteness or chronicity of the lesion. Since a large proportion of patients with brain lesions studied by psychologists in clinical situations fall in a chronic category, the results of this study provide an important limitation of the generalizations which might be drawn from the previous investigations described. Certainly, the results indicate a need for caution in applying findings obtained in one setting to clinical evaluation of patients in a different setting. Furthermore, they emphasize the complex covariance of pertinent variables within the context of the condition frequently referred to as “brain damage.” Similar studies have been performed using the Trail Making Test. In the first of these (Fitzhugh, et al., 196213) four groups similar to those described above were composed. The control group was significantly superior to any of the brain-damaged groups on both parts A and B of the test. The relatively static and chronic-static groups tended to OCCUPY an intermediate position between the control and acute groups, with the acute group having the poorest scores on both parts. The second study of Trail Making Test results (Fitzhugh, Fitzhugh, & Reitan, 1963) used groups with lateralized cerebral lesions as well as groups having generalized cerebral dysfunction, and investigated the acuteness-chronicity factor within this context. No patient previously used in the study by Reitan and Tarshes (1959) was included in the present study. The three groups with lateralized and nonlateralized cerebral lesions of relatively recent onset provided results relating to comparative differences in difficulty of parts A and B which supported the results previously obtained by Reitan and Tarshes and thus constituted a cross-validation of these findings. In the three groups with lateralized and nonlateralized cerebral lesions that were long-standing and chronic in nature, only slight trends toward differential impairment were found. Thus, in addition to the level of performance being somewhat better in patients with relatively static as compared with acute cerebral damage, the sharpness of patterned differences between patients with lesions of the right and left cerebral hemispheres is diminished. These findings relating to acutenessdronicity effects may be relevant to explaining many of the inconsistencies in findings reported by various investigators in the literature, since, while many studies have been performed which vary on this dimension, its significance has not been specifically evaluated or controlled. E. Linear Discriminant Function Analyses

I n an effort to explore the limits of correct differentiation of subjects in various neurological criterion groups, the discriminant function has been used in a number of studies of our test battery. The theory of the discriminant function and its mathematical characteristics are described

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in the first of these publications (Wheeler, Burke, & Reitan, 1963). In each comparison of two groups, the discriminant function produces a single weighted score for each subject and an optimum, least-squares type of separation between the two sets of scores. The resulting distributions of summed, weighted scores in each comparison may be inspected for the point of minimal overlap, and an individual's weighted score, falling above or below this point, categorizes him as belonging in a particular group. Our first application of discriminant functions was applied to 24 behavioral indexes from each of 140 subjects. The 24 scores were based on the 11 Wechsler-Bellevuesubtests, 11 scores from Halstead's battery, and parts A and B of the Trail Making Test. I n addition to 61 control subjects without evidence of cerebral dysfunction, the groups consisted of 25 subjects with damage of the left cerebral hemisphere, 31 subjects with damage of the right hemisphere, and 23 subjects with diffuse or bilateral cerebral involvement. Using the neurological groupings of these subjects as the criterion, the results may be expressed as follows in terms of percentages of correct prediction: controls vs. all categories of cerebral damage, 90.7%; controls vs. left damage, 93.0%; controls vs. right damage, 92.4%; controls vs. diffuse damage, 98.8%; and right vs. left damage, 92.9%. The overall percentage of correct predictions for the control group vs. all cerebral damage groups for 36 variables examined individually indicated that 20 variables exceeded the 75% correct-prediction point. Chronological age and years of formal education, treated in this study as dependent variables along with the psychological test scores, were among the poorest differentiators. The 24-variable discriminant function achieved the highest percentage of correct predictions, but it is interesting that it was scarcely better than the Halstead Impairment Index by itself. A cross-validation study (Wheeler & Reitan, 1963) indicated that correct predictions were between 10% and 207; lower than in the initial study. Although the obtained accuracies in cross-validatioii predictions were considered to be high enough to indicate that the discriminant function had practical value, it appeared that exploitation of nonlinear relationships that exist in the data is necessary for improvement of percentages of correct prediction. Discriminant function analyses have also been applied to the data generated from the examination for aphasia and related sensory-perceptual deficits (Wheeler, 1963). The results, based on this data alone and expressed in terms of percentages of correct predictions, were as follows: controls vs. all cerebral damage groups, 81.7%; controls vs. left cerebral damage, 93.4%; controls vs. right cerebral damage, 85.1%; controls vs. diffuse damage, 87.3%; left vs. diffuse cerebral damage, 82.2%; right vs. diffuse cerebral damage, 77.5%; and right vs. left cerebral

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damage, 91.3%. These results indicate the striking potential for differentiating subjects with and without cerebral lesions as well as subjects with lesions of one cerebral hemisphere or both on the basis of the data derived from the aphasia examination. It is also of special interest that the results of the aphasia test discriminant function analysis were almost completely congruent with those obtained from the same kind of analysis from the Wechsler-Bellevue Scale, Halstead battery, and the Trail Making Test. Finally, Wheeler (1964) applied the discriminant function analysis to fewer but more complex behavioral indexes. He examined a very limited set of variables including the Wechsler-Bellevue verbal and performance weighted score totals, the Halstead Impairment Index, parts A and B of the Trail Making Test, a single prediction based on the aphasia screening test, and the age of the subject (for control purposes). The groups were composed of 92 subjects without evidence of brain damage, 47 with diffuse or bilateral damaye, 39 with damage of the left cerebral hemisphere, and 46 with damage of the right cerebral hemisphere. T h e resul ts, expressed as percentages of correct prediction, were as follows.: control vs. all brain-damaged groups, 83.0%; left cerebral damage vs. all remaining subjects, 87.5%; right cerebral damage vs. all remaining subjects, 85.7%; and diffuse or bilateral cerebral damage vs. all remaining subjects, 84.4%. Each of these measures was examined individually for percentages of correct prediction, but the discriminant function was superior in all instances. Its efficiency was approached only by the Halstead Impairment Index in one comparison and by the predicted value derived from the aphasia examination in two comparisons. This 7variable discriminant function was approximately as efficient as either of two previous functions that included more than 20 variables each. However, consideration must be given to the fact that the variables used in this study were generally additive in nature, being based on a considerable number of subtest scores.

F.

The Complexities of Relating Neurological and Psychological Variables in Individual Patients

On the basis of the above research findings, we have been encouraged by some to construct a comprehensive theory of the psychological effects of brain lesions in human beings, if not a comprehensive theory of brainbehavior relationships, as has been proposed by others who apparently have had the advantage of less awareness of the complexity of relationships in individual patients, less research data, and imaginations less fettered by these constraints, We have nothing against theory-building if it leads to meaningful hypotheses which can be subjected to rigorous

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experimental tests. We also feel that a meaningful theory should not just deal with generalities derived from formal research procedures but should have relevance in contributing to the meaningful understanding of the effects of brain lesions in individual human beings. The overall characteristics of human subjects are sufficientlycomplex and unique that they rarely assume a total configuration which is subject to classification according to the criteria for group composition used in formal research efforts (Reitan, 1962a). The result of this is that we constantly face, at least in part, a dilemma in our attempts to apply results of formal research investigations to evaluation of the individual subject. The purpose of this section will be to indicate some of the difficulties that arise from the complexities of individual description either in neurological or psychological terms, and the insufficiencyof our usual statistical models (and perhaps the underlying mathematics) in attempting to deal with these complexities. As described earlier, the Neuropsychology Laboratory has consistently focused on the problem of relationships between neurological and psychological findings in each individual patient examined, in addition to attempting to make contributions through more formal research studies. This effort has had a special advantage in providing some ongoing insight into the strengths and limitations of the generalizations derived from formal research efforts in terms of their application to assessment of individual subjects. We have been impressed by the observation that formal research efforts customarily center around level of performance with each variable or test being considered as an individual unit. It seems unlikely, however, that the individual human subject is susceptible to very complete or adequate description, whether brain-damaged or not, through the use of this model. Psychological clinicians have long recognized that one does not obtain a very well organized, integrated, or adequate description of a human individual, even in fairly specific respects, by describing him as a serial presentation of one psychological test score after another without considering the order in which the scores are presented or their interrelationships. Exactly this procedure is used time and time again, however, in psychological research. While this criticism is just as true for psychological research dealing with animal behavior as with human behavior, there has been growing recognition in biology that isolation and linear measurement of the substances of which living organisms are composed is not the most promising avenue to further understanding. For example, E. B. Wilson (1925) said ". . we cannot hope to comprehend the activities of the living cell by analysis merely of its chemical composition. . . Modern investigation has, however, brought ever-increasing recognition of the fact that the cell is an

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orgunic system, and one in which we must recognize some structure or organization.” Sinnott (1950, p. 20) more recently has elaborated on this contention as follows: “Others, however, . . realize that it is not the character of the constituents of a living thing but the relation between them which are most significant. An organism is an organized system, each part or quality so related to the rest that in its growth an individual marches on through a series of specific steps to a specific end or culmination, maintaining throughout its course a delicately balanced state of form and function which tends to restore itself if i t is altered. This is the most important thing about it.” We undertook a study of differential psychological effects of variously regionalized cerebral lesions (Reitan, 1964a). Statements such as those of Wilson and Sinnott (with susceptibility inbuilt through a long-standing biological orientation) led us to believe that brain function, not to mention psychological function of the total human organism, was no less complex in its organizational status than the single cell. Furthermore, our own experiences in evaluating the psychological effects of brain lesions in individual subjects made us aware of the likely possibility of cancelling, confounding, and “washing-out” potentialities of a statistical analysis oriented toward central tendency and variability of distributions based on psychological test variables considered individually. As a result of these considerations, two conjoint but separate studies were performed. One was concerned with subjective interpretation of psychological test results for individual patients (in order to give us all the possible opportunities to exploit whatever relationships in the individual’s test results seemed meaningful), and the other was based on statistical analyses of the same psychological test data with the same subjects classified into groups according to the type or location of their brain lesions. The first step in the procedure was to identify subjects with criterionquality frontal, nonfrontal, or diffuse cerebral lesions based on all available neurological information. I n order to provide for a rigorous test of the generality of any frontal vs. nonfrontal differences in each cerebral hemisphere, our intent was to compose each regional localization group of equal numbers of subjects with intrinsic tumors, extrinsic tumors, cerebral vascular lesions, and focal traumatic lesions. Through a review of thousands of neurological protocols, we were able to identify four individual subjects with each of these types of lesions in each of the left anterior, left posterior, right anterior, and right posterior cerebral locations. Thus, we had a total of 64 patients who, when subdivided into groups of 16 with different locations of damage, contained equal representations of four different types of lesions, and who, when subdivided into groups of 16 according to type of lesion, had equal repre-

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sentations of the four different locations. Three additional groups, each composed of 16 subjects, were identified as having diffuse cerebral damage or dysfunction due to cerebral arteriosclerosis, closed head injuries, or multiple sclerosis. The addition of these groups provided a total of 112 patients. A form was drawn up for use in the first study which was used for recording independent judgments from the psychological test results and neurological findings for each patient. This form required three general decisions. First a judgment was made as to whether the lesion was focal or diffuse, next a lesion category was selected, and finally more detailed judgments were made within certain lesion categories. If, for example, the initial decision was that the lesion was focal rather than diffuse, the next judgment required selection of the right or left cerebral hemispheres, followed by selection of an anterior or posterior location within the hemisphere. Next, a judgment was required as to whether the lesion fell in the category of cerebral vascular disease, tumor, multiple sclerosis, or trauma. If the cerebral vascular disease category was selected, a judgment was required as to whether the lesion represented a hemorrhage or insufficiency. Further forced judgments as to the underlying basis for the evidence of cerebral vascular disease were made under each of these two categories. If the tumor category was selected, an additional judgment was required regarding whether the lesion was intrinsic or extrinsic. If the intrinsic tumor category was selected, a further judgment was required regarding whether the lesion was metastatic or a primary glioma. Under the trauma category, a judgment was required as to whether the lesion represented an open or closed head injury. This form was sufficiently complete to permit inclusion of all patients in terms of the neurological criterion information. Since the patients had initially been selected in terms of adequate neurological information for classification of the patients to their respective groups, judgments made on the basis of the neurological information represented the criterion information. When the rating form was filled out on the basis of the psychological test results alone, the procedure called for completion of the form for each patient even though sheer guesses had to be made. I n order to avoid any identifying clues when the ratings were made from psychological data, the material for the 112 patients was first arranged in alphabetical order, all identifying information concealed, and each patient given a number before the ratings were begun. Although the writer knew the number of patients who fell in each localization and lesion-type category (as described above), no reference was made during the course of the ratings to assignment of an appropriate number of patients to any particular group. Every effort was made to respond to the test results

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for each patient as an individual, and ratings were made from patient 1 to patient 112 without use of any type of running tally. Using the neurological ratings as the criterion, there were 64 subjects classified as having focal cerebral lesions. Fifty-seven of these subjects were so classified on the basis of psychological testing. In the group of 48 subjects with diffuse cerebral damage, 46 were judged to have d i h s e damage and 2 patients were judged to have focal lesions on the basis of the psychological test results. As mentioned above, 16 patients were in each regional localization group. The number of correct classifications on the basis of psychological test results for each of the locations was as follows: left anterior, 9; left posterior, 11; right anterior, 7; and right posterior, 15. Thus, 42 of the 64 patients were placed in their correct groups. Adding to this the correct classification of 46 of the 48 patients with diffuse cerebral involvement, 88 of the 112 patients were correctly classified. With respect to type of lesion, the 112 patients were broken down as follows: intrinsic tumor, 16; extrinsic tumor, 16; cerebral vascular disease, 32 (16 focal, 16 diffuse); head injury, 32 (16 focal, 16 diffuse); and multiple sclerosis, 16. The number of correct classifications on the basis of psychological inferences was as follows: intrinsic tumor, 13; extrinsic tumor, 8; cerebral vascular disease, 28; head injury, 30; and multiple sclerosis, 15. Thus, 94 of the 112 patients were correctly classified with respect to type of lesion. With regard to additional details, I3 of the 16 patients with focal cerebral vascular disease were correctly classified, and 12 of these I 3 were judged to have focal lesions. Of the 15 patients with diffuse cerebral vascular disease who were correctly put in this category, 14 were judged to have diffuse cerebral vascular disease. A total of 30 of the 32 head injury patients had been put in this category on the basis of their psychological test results, and 27 of these 30 had been correctly classified as to whether the lesions were focal or diffuse. The degree of concurrence between neurological and psychological ratings indicated above could scarcely have happened by chance. The results indicate that psychological test results are differentially influenced by focal and diffuse lesions; by the cerebral hemisphere damaged; by frontal and nonfrontal lesions within the hemisphere involved; by inuinsic tumors, extrinsic tumors, cerebral vascular lesions, head injuries, and mu1tiple sclerosis; by hemorrhage as compared with insufficiency in cerebral vascular disease; and by open as compared with closed head injuries. It is important to note that a study of this type serves a significant purpose in giving some insight into the degree to which PSY&+ logical test results may be ordered by brain lesions. Furthermore, this study indicates the complexity of the concept of “brain damage” in terms of indicating the many neurological variables, which occur in

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varying combinations for individual subjects, that are relevant in determining psychological measurements. However, a study of this type fails entirely to specify the characteristics of the psychological measurements which are differentially related to the complex of neurological factors. The second study with this data (Reitan, 1964a) was based only on the patients with relatively focal cerebral lesions: the three groups of subjects with diffuse cerebral lesions were omitted. A simple analysis of variance was performed, first with the groups composed according to locations of lesions and then with the patients categorized according to types of lesions. This analysis was followed by computation of t ratios for the measures on which significant intergroup variance was indicated. The results of this study, presented in detail in the original publication (Reitan, 1964a), may be summarized rather briefly for our present purposes. The paucity of significant differences in the various comparisons must be viewed as the outstanding finding. Some differences were present that seemed to characterize lateralization of cerebral lesions, but these related almost exclusively to impaired performances with the hand contralateral to the damaged hemisphere. Comparisons within types of cerebral lesions showed a few differencessuggesting that impairment may be more severe with intrinsic cerebral tumors and cerebral vascular lesions than with extrinsic cerebral tumors and cerebral damage from head injuries. The small number of significant differences, however, was almost sufficient to make one who is especially faithful to our conventional statistical models ask if it must not have been extrasensory perception which was responsible for the results of the first study. A more likely conclusion, however, would be that many of the significant effects of brain lesions are revealed in intraindividual rather than interindividual variations in psychological test scares. Certainly more sophisticated statistical techniques than were used in the second study could have been applied, but if the statistical anaIysis were still directed to differences in intergroup mean levels, we suspect that the analysis still would not do justice to the data. Cancelling and confounding effects apparently occur when patients are assembled into groups that conceal the intraindividual pattern and relationship of test results relevant to psychological deficit resulting from brain lesions in individual patients. The results of these two studies may well shake one’s confidence in our conventional methodo. logical procedures and statistical models, particularly when negative results are obtained. T o return to the paragraph introducing OUT description of these two studies, it appears that the limitations of our present investigational methods may well be so severe that presently available results hardly form a proper basis for building or rejecting theories of

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the psychological effects of brain lesions. We might do far better to recognize the complexity of the problems and to continue to struggle with them rather than anxiously to submit to the need for closure which seems to characterize much of our model building. Space limitations prevent reviewing in the present context a good deal of additional work of the Neuropsychology Laboratory. It has been necessary to obtain a good deal of experimental information concerning the effects of aging on tests in our battery and this requirement has led to a number of studies concerning the relationships of deficits produced by aging and by cerebral damage (Fitzhugh, Fitzhugh, & Reitan, 1964; Klflve, 1962; Reed & Reitan, 1962; Reed & Reitan, 1963b; Reed & Reitan, 1963~;Reitan, 1955b; Reitan, 1956b; Reitan, 1957b; Reitan, 1962b). We have also been concerned about emotional disturbances in patients with neurological disorders (Doehring & Reitan, 1960; Reitan, 1955e), and a good deal of work has gone into the evaluation of the effects of brain lesions in children (Reed, Reitan & KlBve, 1965; Reitan, 1964b). Our research on the relationships of psychological test results to cerebral lesions provides the groundwork for use of the battery in investigation of a host of conditions in which the adequacy or disturbance of brain function may be significant. While we have only begun to make inroads into this vast area, studies have been done on multiple sclerosis (Ross & Reitan, 1955), agenesis of the corpus callosum (Russell & Reitan, 1955), Gerstmann’ssyndrome (Heimburger, DeMyer, & Reitan, 1964), alcoholism (L. C. Fitzhugh, Fitzhugh, & Reitan, 1960), the effects of tranquilizing drugs (Reitan, 1957c; Reitan, 1960a), and the psychological effects of changes over time of serum cholesterol levels (Reitan & Shipley, 1963). VI. INTERPRETATION OF RESULTS FOR INDIVIDUAL PATIENTS

The above arguments will seem more plausible to some than others, depending upon the general orientation and past experiences of the individual reader. In any case, however, the argument cannot be as adequately presented by a general statement of what should be as it can by specific illustrations of what actually occurs. At this point we are unable to show what actually occurs except by illustration of the results obtained from individual patients. We are aware of the limitations in generalization that are inherent in case illustrations but can cite the fact that these interpretations were entirely bound by the psychological test data for each patient (since they were done without reference to other sources of information). Thus, we did not run the risk of making permissive and convenient selective references to criterion information or of postulating unmeasured types of associated impairment as a basis for

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explaining the findings. However, space limitations prevent inclusion of enough patients to demonstrate the degree of individual variability that exists (Reitan, 1959d). A. Patient W. C.

W.C.,a 58-year-old right-handed male high school graduate, had been employed as a tailor. His history at our medical center included two admissions prior to the admission during which neuropsychological examination was done. On the first admission, in October, 1955, a mass lesion was identified in the left lung. The left lung, containing a mass within the bronchus identified as epidermoid carcinoma, was removed. He was able to work until 3 weeks before the second admission (March 27. 1960) at which time he had developed some weakness of the left leg and some weakness and decreased tactile sensitivity of the left upper extremity. Neurological examination, electroencephalography, and cerebral angiography at the time of the third admission were all indicative of a lesion of the right cerebral hemisphere and offered evidence of a mass in the posterior part of the hemisphere. A right parieto-occipital craniotomy revealed a subcortical metastatic nodule, 6 cm in diameter, at the junction of the right temporal, parietal, and occipital lobes. The lesion was identified as epidermoid carcinoma. Neuropsychological test psults on this patient, obtained on September 28, 1960 (before surgery), are shown in Table 11. REPORTOF NEUROPSYCHOLOCICAL EXAMINATION a. Aphasic Symptoms and Sensory-Perceptual Deficits. The patient had no specific difficulties in the use of language for communicational purposes. He had, however, a mild central dysarthria and right-left confusion; he also confused arithmetical signs. The patient showed a pronounced tendency to imperceive bilateral simultaneous tactile stimulation on the left side and also failed on the left side with auditory stimulation. Visual stimulation was not tried because the patient apparently had a left homonymous hemianopia. The patient showed mild finger dysgnosia and fingertip number writing perception impairment as well as dysstereognosis. I n each instance these findings were more pronounced on the left hand than on the right hand. The patient also had a pronounced constructional dyspraxia. This 58-year-old man obtained a Verbal IQ of 100 and a Performance IQ of 80. He obtained this Performance IQ in spite of the fact that he was able to obtain very few points on any of the performance subtests. The tests of biological intelligence were much more poorly done than one would expect from the IQ values. The patient obtained an Inipair-

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ment Index of .9 which is consistent with severe damage of cerebral tissue. The very poor performance on the Trail Making Test confirmed this impression. Several findings in the test results suggested that the right cerebral hemisphere was far more seriously dysfunctional than the left cerebral hemisphere. The patient was able to tap considerably faster with his right hand than his left hand, and the various sensory findings

.

TABLE I1 RESULTS ON TESTS FOR PATIENT W.C. Halstead‘s Tests

Wechsler-Bellevue Scale 100 80 86 41 10 51 10 11 4 6 10 13

VIQ PIQ F S IQ

VWS PWS Total WS Information Comprehension Digit span Arithmetic Similarities Vocabulary Picture arrangement Picture completion Block design Object assembly Digit symbol

1

6 3 0 0

Trail Making Test Trails A Trails B Trail total

232 sec 545 sec 777 sec

Mile’s ABC Test of Ocular Dominance

R-0

L = 10

Category Test

121

Tactual Performance Test Right hand-15.0 min (4 placed) Time 45.0 Right hand-15.0 min (4 placed) Memory 3 Right hand-15.0 rnin (5 placed) Location 0 Seashore Rhythm Test (raw score, 12)

10

Speech Sounds Perception Test

26

Finger Oscillation Test Right hand Left hand

44 32

Time Sense Test Memory Visual

144.8 121.0 .9

Impairment Index Minnesota Multiphasic Personality Inventory 7

L

F K Hs D Hy

50 53 48 61 57 56 56

Pd Mf Pa Pt !k Ma

62 30 47 46 53 40

noted above also implied damage of the right cerebral hemisphere. His strength of grip in the left hand was only 22.0 kg as compared with 29.5 kg in the right hand. The same impression was supported by the patient’s extremely poor performance on the performance part of the Wechsler Scale. We strongly suspected that this patient had a tumor in the right cerebral hemisphere. In all probability such a lesion was posterior in location and involved the parietal and temporal areas and possibly the occipital area. The generally poor level of performance suggested dysfunction of other parts of the cerebral hemispheres as well. This con-

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sideration raised a question as to whether or not a cerebrovascular accident might be postulated, superimposed upon diffuse cerebrovascular disease. We thought this possibility very unlikely in terms of our findings, particularly because of the patient’s tapping ability with the left hand. We postulated that if the patient had such serious disorders of the right cerebral hemisphere and if the lesion were vascular in nature, he should have had more serious motor deficit of the left upper extremity. Considering then that the patient had a tumor, the remaining question was whether it was a glioma or metastatic carcinoma. This question was difficult to answer firmly from our test results. Certain of the poor perfoimances related to the function of the left cerebral hemisphere, and these findings suggested the possibility of more than one lesion. However, the patient was so severely impaired that we suspected some general effect of a lesion located in the posterior part of the right hemisphere. We could not safely differentiate the probabilities of a glioma as compared with multiple metastases, but our results leaned just a little in favor of the latter possibility. In any case, the posterior part of the right cerebral hemisphere was the area of maximal involvement. b. Comment on Interpretation. Our evaluation of test results usually follows the general sequence that has been used in our formal research efforts, with the additional provision that an attempt is made to understand the results as they relate to the description of an individual subject. Our first question is concerned with whether or not the evidence indicates the presence of a brain lesion. Next, we consider the question of localization. Could the findings be explained by postulating a focal lesion in one area or another? Will it be necessary to postulate a relatively large area, or more than one focal area, to explain the findings? Or, are the results compatible with generalized or diffuse cerebral dysfunction? Finally, in relation to these prior considerations, what kind of lesion or neurological condition would be compatible with the psychological test results? Serial ordering of questions in this manner has the advantage of providing some depth of interpretation regarding the condition of the brain. Incidentally, it also provides something of an answer to the base-rate problem in that a degree of uniqueness in interpretation is permitted which can then be judged for validity against concurrence with the combination of neurological factors which describe the individual. With regard to patient W. C., the evidence of brain damage was abundant and convincing. His performances were consistently ir, the range characteristic of cerebral dysfunction with the exception of the verbal subtests from the Wechsler-Bellevue. An even more convincing answer to this question, however, was provided by the evidence of

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damage to the right cerebral hemisphere. This evidence was supplied by several of the methods of inference of psychological deficit referred to earlier: comparisons of performances on the two sides of the body; patterns of intellectual deficits; and specific pathognomonic signs. His finger-tapping speed was slow and his strength of grip impaired in the left hand as compared with the right hand. I n addition to these indications of motor dysfunction, there occurred lateralized sensory-perceptual deficits, including imperception on the left side of tactile and auditory simultaneous bilateral stimulation. The patient also demonstrated more evidence of difficulty in tactile finger recognition and fingertip number writing perception on the left side than on the right. Consistent lateralized deficits of this sensory-perceptual type, added to the motor deficits, greatly increased the probability that the responsible lesion was in the brain rather than in the nervous system. The pattern of intellectual deficit was supplied principally by the Wechsler-Bellevue results. The patient performed relatively well on the verbal subtests, except for the digit span and arithmetic tests. Digit span is frequently depressed among hopitalized patients, even in our control subjects. The arithmetic subtest seems to be more sensitive to lesions of the right hemisphere than are the remaining verbal subtests. Thus, the pattern of verbal subtests was entirely compatible with a postulated lesion of the right cerebral hemisphere. The performance subtests were severely depressed, and provided a positive indication with regard to damage of the right hemisphere. The highest score was obtained on the picture completion subtest. Even this finding is typical of patients with right cerebral lesions, perhaps because of the substantial verbal response requirements of the test. Finally, specific signs of damage to the right cerebral hemisphere, including the apparent left homonymous hemianopia and the pronounced constructional dyspraxia, were found. The dyspraxia was indicated by serious distortions of the spatial configurations in the patient’s attempts to copy simple geometric figures. These findings provided definite evidence of cerebral damage which principally implicated the right cerebral hemisphere. The next question concerned more specific considerations regarding localization of the lesion. The pronounced constructional dyspraxia, the depression of the performance subtests of the Wechsler Scale, and especially the suggestive evidence of a left homonymous hemianopia suggested involvement of the posterior part of the right hemisphere. Evidence of auditory imperception on the left side probably implied that the right temporal lobe was dysfunctional. The abundant evidence of tactile deficits on the left side of the body (tactile imperception and impairment of finger localization and fingertip number writing perception) implicated the

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right parietal lobe. In addition, strength of grip and finger-tapping speed were somewhat depressed, which suggested involvement of the primary motor area in the posterior part of the frontal lobe. From a functional point of view, most of the right cerebral hemisphere appeared to be involved. Inferences regarding the structural localization of the lesion cannot be divorced from a consideration of the type of lesion, since some types of lesions have much greater impairing influences beyond their gross structural limits than do others. T h e extremely poor performances of W. C. on Halstead’s tests and the Trail Making Test, together with the strong lateralizing indications, strongly suggested a type of lesion that has grossly impairing effects. T h e likely possibilities, in these terms, were either a cerebral neoplasm or a vascular accident. T h e latter possibility is somewhat more likely in a 58-year-old male. A particular point of information from the test results, however, strongly indicated a neoplasm. This information came particularly from a comparison of the severity of impairment of higher-level functions associated with damage of the right hemisphere and the severity of impairment of motor functions. Higher-level functions, as described above, were severely impaired in this patient. He also demonstrated some impairment of motor functions of the left upper extremity, although this impairment was less pronounced. This combination of factors leaned our differential inference very much in the direction of a neoplastic lesion. While the observation stands in need of experimental study, our past experiences indicate that severe impairment of higher-level functions relating to lateralized cerebral damage is much more frequently accompanied by profound motor deficits in the case of cerebral vascular lesions than with cerebral tumors. Of course, motor dysfunction may be profound with either type of lesion in individual instances, and experimental validation of our hypothesis would require comparability in the two groups of impairment of higherlevel functions. Furthermore, if the hypothesis were validated, it might be useful only with those patients in whom lateralized motor dysfunction was clearly incomplete. Presuming then that the lesion was neoplastic, it was necessary to review the test results again with respect to the question of localization for this particular type of lesion. One would expect the preponderance of localization findings to relate to the gross structural location of the lesion, but “distance” effects may also be expected from a neoplasm. As described above, the preponderance of localization indicators pointed to the posterior part of the right cerebral hemisphere. T h e localization indicators also had to be evaluated with regard to those most likely to require gross structural damage of the appropriate area for their appear-

PSYCH0uX;ICAL EFFECTS OF BRAIN LESIONS

20 1

ance and those most probably a result of the “distance” effects. Parietal and temporal damage was strongly implied by the positive findings on tests of tactile and auditory perception of bilateral simultaneous stimulation and especially by the interruption of the geniculostriate pathway implied by the possible left homonymous hemianopia. T h e reduced finger-tapping speed and motor strength of the left upper extremity. however, was much more easily attributable to “distance” effects of the tumor. Thus, our inference regarding the gross structural aspects of the tumor was that it occupied a location in the posterior part of the hemisphere. After we reached this point in the interpretation of the results, a final consideration was necessary regarding whether the neoplasm was primary or metastatic. As far as we could judge from present insights based upon past experiences, our only prospect for achieving this differentiation related to the need for postulating more than one lesion to explain the test results. The likelihood of more than one lesion is far less for primary gliomas than for metastatic neoplasms. Our prospects for inferring two structurally separate lesions in one hemisphere are slim, but we not infrequently obtain evidence suggesting the presence of a structural lesion in each cerebral hemisphere. The results, however, were equivocal for patient W. C. Some findings more typical for left than right cerebral damage were present. The right hand was very poor on the Tactual Performance Test, but we had obtained no comparisons with the left hand. The examiner had judged that the left hand was too impaired to perform the test and therefore had given three trials with the right hand alone. The general level of performance was very poor, but this can be expected in patients with serious, structural brain lesions. However, patient W. C. did demonstrate clear right-left confusion, mild difficulties in finger localization on the right hand, and a pronounced tendency to misinterpret and confuse signs of specific arithmetical operations such as + and -. These deficits are much more frequently an indication of left rather than right cerebral damage (Wheeler & Reitan, 1962). On this basis we suspected that a lesion of the left cerebral hemisphere was present (which was much less significant than the lesion on the right side) and correspondingly leaned our interpretation slightly in favor of metastatic cerebral neoplasms. While clinical neurological findings did not confirm our inference of a possible left cerebral lesion, histological examination revealed that the lesion was an epidermoid carcinoma, metastatic from the lung. Although an autopsy was not performed, it may be noted that our inference concerning the left cerebral hemisphere could not have been proved correct in any case, since a metastasis, had one been found, could have occurred after our neuropsychological testing.

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Autopsy findings indicating the absence of any neoplasm in the left cerebral hemisphere, however, would have been very helpful since they would have proved our qualified inferences wrong. B. Patient W. 8.

Since it is not possible in the present context to provide more than an illustration of the interpretation of results for individual subjects, only one additional patient will be described. T h e first patient represented one in which the neurological diagnosis was unequivocal, and we have deliberately selected a second patient in whom the neurological examination was noncontributory although the question of brain dysfunction was raised by the history. Under these circumstances, neuropsychological examination may provide critical information with regard to the resulting diagnosis. Even when the neurological diagnosis is already established, however, it is important to assess corresponding psychological deficits in order to achieve a full understanding of the significance of the brain lesion. W. B. was a 19-year-old right-handed boy who had completed the first year of college. Six months prior to admission he had suffered a head injury and a fractured femur in an automobile accident. While he was not unconscious from the head blow, hospital records described him as being confused for about 1 week. His admission was precipitated by concern over the fact that while he had previously been a good student, his college work since the accident had been poor. Physical neurological examination was negative except for evidence of somewhat elevated blood pressure. EEG indicated a bitemporal dysrhythmia, grade I. N o other neurological studies were done and the question of brain damage as a basis for the change in his school work was not adequately answered. T h e neuropsychological test results obtained on this patient are shown in Table 111.

REPORT OF NEUROPSYCHOLOGICAL EXAMINATION a. Aphasic Symptoms and Sensory-Perceptual Deficits. N o evidence of dysphasia was found. There was mild impairment of tactile form recognition in both hands. This 19-year-old boy obtained a Full-Scale Wechsler-Bellevue (Form I) IQ of 105 (Verbal IQ, 112; Performance IQ, 95). T h e tests of biological intelligence yielded an Impairment Index of .8, consistent with mild impairment of adaptive abilities dependent upon organic brain functions. Although the Impairment Index was .8, the patient’s impairment was probably only mild since several tests were at a borderline level. Analysis of the pattern of test results indicated fairly consistently that the left

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cerebral hemisphere was more seriously damaged than the right. Nevertheless, the results implied diffuse dysfunction involving both cerebral hemispheres. Certain of the tests were done too well for us to think of an intrinsic tumor or destructive cerebral vascular lesion in either hemisphere. The results did fit quite well an impression of a moderately severe head injury (probably a closed head injury since we did not get any TABLE I11 RESULTSON TJSTS FOR PATIENT W. B. Wechsler-Bellevue Scale "IQ PIQ F S IQ

Halstead's Tests 112 95 105 56 48 104 14 12 7 9

VWS PWS Total WS Information Comprehension Digit span Arithmetic Similarities Vocabulary Picture arrangement Picture completion Blodc design Object assembly Digit symbol

14 12

13 9 9

I 10

Trail Making Test Trails A Trails B Trails total

53

Tactual Performance Test Right hand-7.1 min Time Left hand-3.5 min Memory Both hands-5.3 min Location

15.8 5 2

Seashore Rhythm Test (raw score, 25)

6

Speech Sounds Perception Test

8

Finger Oscillation Test Right hand Left hand

357.3 39.4 .8

Impairment Index Minnesota Multiphasic Personality Inventory ?

91 sec 151 sec

L

L=O

47 49

Time Sense Test Memory Visual

60sec

Mile's ABC Test of Ocular Dominance R =I0

Category Test

F K Hs D

Hy

50 50

Pd Mf

46

Pa Pt sc Ma

51 53 58 57

58 51 50 40 52 50

highly focal signs) with the left cerebral hemisphere more severely damaged. The results on the Wechsler Scale suggested that this patient was of perhaps high average intelligence; but his IQ had been lowered to the normal range, and in addition he had a fairly serious problem of general adaptive ability in association with impaired brain functions. Although the MMPI did not give evidence for any serious affective disturbance, it seemed likely from the test results that he would have quite a difficult problem working out a satisfactory adjustment. b. Comment on Interpretation. While the IQ values were fairly ade-

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quate, the Halstead Impairment Index was well into the range characteristic of brain damage. Th e disparity between these findings added to the significance of the Impairment Index, since the specificity of deficient performances on tests especially sensitive to brain damage was thereby highlighted. While the Impairment Index of .8 alone, in the context of the IQ values, would be a sufficient basis to infer cerebral damage, consideration of lateralizing indicators added to the evidence. T h e time required with the right hand on the Tactual Performance Test was long as compared with the speed achieved by the left hand. We expect about a 30% reduction of'the initial time, but not a 50% reduction, in normal subjects. Even more significant evidence was derived from the performance with both hands. Instead of showing further improvement, the time required to complete the task was distinctly increased over the trial in which the left hand alone was used. This finding suggested that on the trial using both hands, the right hand was a hindrance and the patient would have done better using the left hand alone. On the finger tapping test the subject was a little slower with the right than with the left hand; this is a very unusual occurrence in normal right-handed subjects. These findings, which implicated the right upper extremity in the presence of an Impairment Index of .8, strongly suggested dysfunction of the left cerebral hemisphere. T h e patient also demonstrated definite but mild and equal impairment of tactile form recognition in both hands. This finding, in addition to providing some specific evidence implicating the right cerebral hemisphere as well as the left, provided a distinct sensoryperceptual element to the motor and psychomotor deficits noted above. Thus, the patient definitely appeared to have cerebral damage involving the left cerebral hemisphere to a greater extent than the right. T h e next question concerned the type of lesion. Did these results suggest a neoplastic or vascular lesion? We answered negatively for several reasons. First, results on some tests (e.g., Speech Sounds Perception and Trail Making Tests), even though suggesting some impairment, were performed too well to make lesions of these types likely. A more convincing basis for the answer, however, related to the relatively good performances on language tests with relation to the indications from the Tactual Performance and Finger Oscillation Tests of involvement of the left cerebral hemisphere. A vascular or neoplastic lesion of the left hemisphere, causing the lateralizing indications yielded by the Tactual Performance and Finger Oscillation Tests, would almost certainly have caused at least mild dysphasia and poorer scores on the Speech Sounds Perception Test and verbal subtests of the Wechsler Scale. T h e inconsistency of the lateralizing findings (including the verbal and performance 19 values), instead of detracting from the positive lateralizing findings,

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led directly to a conclusion of brain trauma, since such findings are routinely seen in this class of lesions. We suspect that evidence of lateralized cerebral dysfunction may be fairly consistent shortly after a lesion is sustained, but that as brain functions reorganize, the recovery rate varies for different deficits perhaps depending on the degree of damage in various areas of the brain. The presence of bilateral deficit in tactile form recognition also was helpful in reaching the inference of brain trauma, since, as might be expected from the way in which the lesion is sustained (Holbourn, 1943), traumatic injury frequently causes widespread and bilateral cerebral damage. While the full complement of lateralizing indicators may be more consistently found in subjects with recent brain trauma, we suspect, on the basis of our observations, that specific evidence of damage to both cerebral hemispheres is also more frequently present. We would not have hesitated, on the basis of the test results obtained, to have postulated that W. B. had some time for recovery between the time of injury and psychological testing. Interpretation of results for individual subjects, with the battery of tests we use, obviously requires a good deal of experience. In addition, translation of the test results into neurological probabilities requires knowledge in the area of clinical neurology. Past experience has indicated that these skills can be communicated readily from one person to another and we estimate that a fairly high degree of reliability may be achieved between thoroughly trained psychologists. At least 1, and more likely 2, years of intensive training and experience is necessary to achieve competence. To return to the principal reason for presenting interpretations for individual patients in the present context, it should be apparent from the illustrations that intraindividual relationships among the test results, which can hardly be reflected by averages derived from groups, constitute a significant aspect of the psychological effects of cerebral lesions. C. Relationships to Mental Retardation

A research program on the psychological correlates of brain lesions has potential relevance to a number of areas insofar as these other areas of psychoIogica1 deficit may be related to impaired brain function. It is of pressing interest to learn more about the psychological effects of impaired cardiovascular functions (Apter, Halstead, & Heimburger, 1951; Birren & Spieth, 1962; Reitan, 1954a; Reitan, 1963; Spieth, 1962; Spieth, I964), endocrinological disorders (Reitan, 1953), chronic illnesses which may involve brain functions (Apter, Halstead, Eisele, 8c McCullough, 1948; Reitan, 1954b), and a number of other conditions. Direct evidence of cerebral involvement is often difficult to obtain in these various condi-

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tions and as a result it is necessary to determine the similarities between groups of subjects with these disorders and groups with known cerebral lesions. In addition, knowledge of expected results on particular psychological tests, as they relate to brain lesions, may provide an interesting background for the further understanding of psychological deficit which is measured in related conditions. I n aging, for example, results on the Halstead Impairment Index begin to go in the direction characteristic of brain damage at 45 to 50 years of age, with individual exceptions, of course (Halstead & Rennick, 1962; Reitan, 1955b). Furthermore, the rank-order of the degree to which our battery of tests differentiates younger subjects with and without cerebral lesions shows a correlation of .49 with these same tests in their differentiation of older and younger normal subjects (Reed & Reitan, 1963b). We have performed only a few formal investigations in the area of mental retardation, but the prospects for additional meaningful investigation appear to be substantial. Matthews, Guertin, and Reitan (1962) performed a factor analysis of rank-difference coefficients of correlation between Wechsler-Bellevue subtest rank-orders in 18 diagnostic groups, including retardates, several categories of cerebral damage, and various neurotic and psychotic disorders. Most of the systematic variance was accounted for in two major factors. The first factor, verbal impairment, on which all retarded groups loaded heavily, appeared to be associated with groups having histories of long-standing social-adaptive disabilities. The second factor, performance impairment, was contributed to by groups demonstrating significant psychological impairment following an extended period of relatively normal growth and development. The performance of retarded groups has also been compared with groups having identified cerebral lesions on the Halstead Tactual Performance and Category Tests. In both of these studies each retardate was matched within two points of his brain-damaged pair on Full Scale Wechsler-Bellevue IQ. The groups did not differ significantly with respect to absolute levels of ability demonstrated on the Tactual Performance Test on any of the three trials (Matthews & Reitan, 1962). Comparisons of absolute and proportional amounts of improvement from one trial to another, however, indicated greater improvement by the retardates from the second to the third trial. In a similarly designed study using scores from the Category Test (Matthews & Reitan, 1961), the retardates demonstrated significantly poorer abstraction ability but, at the same time, showed significantly greater absolute and proportional improvement than did the brain-damaged patients when the abstraction principle needed for solution of the problem remained constant. These studies suggest the need for using a broader battery of ability

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tests in studying mental retardation than has been customary. Sarason and Gladwin (1958) cited the deficiencies of conventional psychological tests as predictors of intelligent behavior in the retarded. As Matthews and Reitan (1963) pointed out, “. . the range of problem-solving behavior sampled in the majority of psychometric studies of the retarded is too narrow to justify the generalization and predictive burdens which have been placed upon these measures.” I n an effort to obtain information relevant to this problem, Matthews and Reitan (1963) investigated the relationship of differential abstraction levels in retardates to scores obtained on our neuropsychological test battery. In addition, abstraction ability was assessed with relation to levels of performance on tests requiring immediate problem-solving ability as compared with experiential background or “stored” information. Two groups of 30 mildly retarded subjects were matched in pairs on age, sex, and Wechsler-Bellevue Full Scale IQ. These groups, however, were selected from opposite ends of the normative distribution based on Category Test results for a large number of subjects from the Fort Wayne State School. Thus, one group had demonstrated relatively good abstraction ability whereas the other group was quite deficient in this respect. T h e results showed that the group with good abstraction ability performed significantly better than the group with poor abstraction ability on the tests which required immediate problem solving ability. However, the group with poor abstraction ability performed significantly better on the tests requiring experiential background. T h e full interpretation of these results will require additional research, but it is clear a t this point that the ability relationships in retarded subjects are far from simple. Clarification of these relationships may have definite significance with respect to both institutional placement and prediction of habilitative potential of retardates. Finally, neuropsychological examination of individual retarded subjects appears to make a substantial contribution to the understanding of their deficits. On the basis of approximately 400 such examinations, it is apparent that even though intellectual and cognitive abilities are often generally depressed in comparison with the average level, a good deal of meaningful intraindividual variability is still the rule rather than the exception. Comparisons of performances on the two sides of the body frequently show lateralized deficits on the same side across a number of sensory-perceptual and motor performances. A1 though it is difficult to obtain independent neurological criterion information concerning lateralized cerebral dysfunction in a retarded population, consistent differences in degree of deficit on the two sides of the body for a single individual almost certainly have an organic reference. One can hardly explain

.

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such lateralized impairment on grounds of general retardation, lack of cooperation or rapport in test administration, or emotional disturbances. The influence of these conditions would not be reflected only when the examination was performed on a particular side of the body. Integration of such deficits with the results of other behavioral and psychological examinations is still in a formative stage, but the potential for such integration can be illustrated by presenting results for individual patients. 1. PATIENTC. K.

Patient C. K. was a 15-year, 11-month-old boy who had suffered from a lifelong problem of extremely impaired visual acuity. Technically, he was classified as blind, although he was able to discriminate intensity changes of light and gross form discriminations. His mother had rejected him, and, as a result, he was living in a foster home. C. K. had received past training which was oriented toward emphasizing the development of skills not dependent upon vision so that his potential for productive performances was not precluded by visual requirements. I n fact, C. K. had been carefully protected from situations which require adaptation to the spatial aspects of his environment. The referring problem concerned the kind of additional training or therapy that this boy should receive with respect to the hope that he might eventually be able to lead at least a semi-independent adult life. He seemed at that time to be making little progress in that direction. He was unable to get about the city by himself, step down from a bus, or walk down a flight of stairs, even though persons with less vision than C. K. frequently can perform such acts with little difficulty. Since visual impairment seemed inadequate to account for C. K.’s practical difficulties of adjustment, the hypothesis had been proposed that emotional problems, stemming from the mother’s rejection, might be a significant basis for determining C. K.’s inability to engage in practical performances which were necessary in adapting to his environmen t. Our procedure with patients such as C. K. differs from that used with patients included in our formal research program with respect to performing “blind” interpretations. As will be noted from the report below, we tried to relate our interpretation to the presenting problems as well as to prior psychological test results in order to provide some insight into the question of relationships of deficits resulting from cerebral damage to the overall problems of adjustment experienced by the patient. Thus, the interpretation was performed with full knowledge of the history and prior evaluation. Report of Neuropsychological Examination. This 15-yearI11-month-old

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boy obtained a Wechsler-Bellevue (Form I) Verbal IQ of 84 and a Performance IQ of 40. T h e wide disparity between these IQ values indicated the invalidity of averaging them in order to obtain a Full Scale IQ but, nevertheless, the Full Scale IQ for the entire test was 59. Obviously, there was a great deal of disparity between the subtest values. T h e highest scores were obtained on the information, digit span, and similarities subtests, but even these scores did not quite come u p to the average level. One immediately raised the question as to whether the history of impaired vision in this child was responsible for his poor score on the performance subtest of the Wechsler Scale. It was entirely unlikely that visual impairment was a complete explanation, and it probably was not even a major factor. This will be indicated by the following description of the results on other tests. T h e neuropsychological tests gave convincing evidence of cerebral damage involving in particular the right cerebral hemisphere. T h e general level of performance suggested that cerebral damage had occurred and comparisons of performances with the right and left hands provided evidence which implicated the right cerebral hemisphere to a greater degree than the left. These latter findings included the fact that the patient was somewhat poorer on the Tactual Performance Test with his left hand than with his right hand. His finger-tapping speed was somewhat slower with his left hand; also his strength of grip was somewhat deficient in the left hand, and he clearly had more difficulty in tactile finger recognition with his left hand than he did with his right hand. In addition, the patient showed quite a pronounced constructional dyspraxia, consistent with damage to the right cerebral hemisphere. These various findings, which were not dependent upon visual acuity as such, strongly suggested damage to the right cerebral hemisphere and a consequent serious impairment of ability in dealing with visuo-spatial problems. Thus, the low Performance IQ was to a very considerable extent due to the brain damage that had been suffered by this subject rather than due to his primary visual problems. This child did very well in academic achievement considering the overall impairment shown by other tests. T h e Wide Range Achievement Test yielded a reading placement of 10.7 grades, spelling of 9 grades, and arithmetic of 6.2 grades. These abilities were relatively consistent with the Verbal IQ which, in turn, clearly represented the strongest point of this subject’s ability pattern. He was markedly deficient on any type of problem that involved visuo-spatial relationships or the understanding of sequential organization. In addition, the patient performed very poorly on the Category Test in spite of the fact that errorless performances on the “easy” first two subtests indicated that his vision was adequate for

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the test and that he understood the procedure. T h e fact that he made 107 errors on the test indicated a serious impairment of the ability to organize diverse stimulus material, propose meaningful hypotheses with respect to the solution, and make progress in solving relatively abstract problems. This finding certainly indicated that the subject’s ability to form reasonable concepts was markedly deficient. One would expect from this finding that the subject was unrealistic with respect to his assessment of himself and situations that concerned him in his everyday life. This lack of judgment and ability in concept formation was in all probability an expression of cerebral damage. T h e above findings were quite consistent with the psychological report by Dr. Charles Heineman based on testing done 14 months before our examination. We obtained IQ values very similar to his and were in a position as a result of having administered a more extensive battery relating to the condition of the brain to offer definite support for a number of his interpretations. His description of the impaired judgment of the patient with respect to vocational possibilities was probably also reflected by our Category Test and in turn represented one of the effects of brain damage. T h e hypothesis by Dr. Heineman of serious spatial disorientation due to damage of the right cerebral hemisphere was clearly borne out by our findings. It would certainly have been of value to this patient to have obtained some kind of special training to develop his ability to deal meaningfully with spatial configurations because he was seriously impaired in this respect. For example, the history on this patient indicated that he had a definite fear of steps, and the suggestion was made that this was related to his visual problem. Our results suggested thkit the patient’s fear of steps was probably only partly related to his visual problem and probably more importantly related to his great difficulty in dealing with visuo-spatial configurations. Unless he learned to adapt to this particular spatial configuration, there was an excellent chance of his falling down steps. T h e degree of impairment shown by this patient was of just such a nature that he could be expected to have great dificulty dealing with visuo-spatial problems that most of us take for granted. T h e question was raised in the social history as to whether this patient could be taught to get around by buses and on his own in order to relieve others of his transportation. We suggested that the patient be offered training in this type of activity, but cautioned that his impairment was of such a nature that he could very easily become entirely confused and lost even under the most ordinary circumstances. T h e above findings indicated that this patient would have a considerable amount of difficulty in working out an independent or semi-indeIlendent vocational adjustment in the future. Nearly any type of occupa-

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tional task requires at least to some extent a wide range of abilities. While this patient had adequate academic skills and verbal abilities to work productively, he was so seriously impaired in his concept formation, basic judgment] psychomotor performance, and ability to deal with spatial configurations that very special attention would have to be given to a vocational setting in which only the patient’s strengths would be called for. It was difficult to visualize an occupation that could be performed satisfactorily in a normally competitive way by this subject. The visual problems of this patient were probably a great disadvantage to him in that his difficulties in dealing with visuo-spatial problems were attributed to his visual impairment rather than to impairment of a basic ability dependent upon normal function of the right cerebral hemisphere. Thus, we hypothesized that this patient had been “excused” for these difficulties and that no rigorous attempt had been made to encourage the development of these deficient abilities. We strongly suggested that this patient, under close supervision, be given every opportunity to work with problems requiring an understanding of spatial relationships.

2. PATIENT W. B. It is unusual to encounter a subject with a Performance IQ less than half of his Verbal IQ as was true of the child in the preceding account. The results on patient W. B. were more characteristic of customary findings in retardates. W. B. was an Il-year, 6-month-old boy who was a patient at the Fort Wayne State School and Hospital. He was tested on March 22, 1963. Report of Neuropsychological Examination. This 11-year, 6-month-old boy obtained a Wechsler Intelligence Scale for Children Full Sale IQ of 48 (Verbal IQ 46; Performance IQ 60). The degree of scatter of scaled scores on the subtests was not remarkable, although the disparity between Verbal and Performance IQ values was clearly beyond the usual limits. The highest scaled score on the verbal subtests was a 3 on arithmetic, whereas only one of the six performance subtests was below this level. The patient had received various IQ tests in the past. On January 21, 1959, the Ammons Full Range Picture Vocabulary Test had yielded a Mental Age of 5 years, 3 months (IQ of 72); a Stanford-Binet (Form 1) on November 28, 1960, had yielded an IQ of 57, and a Peabody Picture Vocabulary Test on the same day had yielded an IQ of 66. The WISC Full Scale IQ was the lowest measure obtained up to that point. Without question this was largely a function of the subject’s poor performance on the verbal subtests of the WISC. Analysis of the results of our neuropsychological testing provided a fairly consistent picture of damage of the left cerebral hemisphere as

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a basis for the special impairment of verbal general intelligence. .Qlthough the subject was strongly right-handed, his strength of grip in the right hand was clearly less than that of his left hand. I n addition, his fingertapping speed with the right hand was barely faster than his speed with the left hand. He also performed rather poorly with his right hand on the Tactual Performance Test as compared with his left hand. Finally, the patient tended to fail to perceive tactile stimuli to his right hand, especially when the competing stimulus was to the left face. All of these findings suggested that the left cerebral hemisphere had sustained some organic damage. These findings were consistent with a previous EEG report on the patient. T h e findings were interpreted as being compatible with a chronic lesion of the left frontal-temporal area. Our results would have been perfectly compatible with this interpretation, but the rest of our findings suggested that there was some diffuse cerebral dysfunction as well as the damage in the left cerebral hemisphere. A major point of significance with respect to these findings related to the suggestion that this child may have had an especially difficult time in achieving academic skills. He had a Wide Range Achievement Test reading placement of .9 grades, spelling of .9 grades, and arithmetic of 1.2 grades. With the evidence of damage to the left cerebral hemisphere, however, it was entirely possible that this child’s academic achievements would be even less than for other children of comparable Verbal IQ levels. This child showed impairment in a number of other respects as well and these were also probably attributable, at least in part, to cerebral dysfunction. He performed quite poorly on the Category Test, and this suggested that he had a great deal of difficulty in forming reasonable and meaningful concepts with respect to diverse stimulus material. Undoubtedly this child had great difficulty in evaluating the elements of any total situation, whether they concerned his own behavior with relation to the larger picture or the behavior of others. This finding suggested that the patient needed a specifically and concretely structured environment in which to live, rather than one in which he would have to impose character upon his environment through his own judgment. T h e child was in very definite need of pointed training with respect to development of basic academic skills, but as noted above this may well have represented a special problem. Nevertheless, we recommended that efforts be directed toward this accomplishment. Furthermore, he needed to develop the ability to conceptualize and to understand how things fitted together with respect to their contributions to his everyday life. I t was important that every effort be made to point out to the subject the consequences of his behavior and to indicate to him how things fit together into meaningful relationships. It was apparent from our results that any communi-

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cation on a verbal level with the patient would have to be quite specific, direct, and concrete, whether the communication represented a directive or an explanation. T h e subject also needed frequent repetition of instructions and close supervision in carrying out behavior that represented a consequence of verbal communication. Although brain functions in this child seemed to be seriously impaired, our results gave no indication of a progressive type of brain disease. T h e history of this child seemed to be perfectly adequate to have predisposed him to seriously inadequate emotional development and difficulty in relating to others. Under these circumstances it was natural for his behavior to be characterized by emotional egocentrism and a pronounced lack of ego control. In addition, the record indicated that the child was rather markedly hyperactive and consequently a problem in the classroom situation. I t was difficult to sort out the possible contribution of adverse environmental factors as compared with the effects of brain damage. Undoubtedly both of these factors were of considerable influence with respect to this child’s development. T h e brain damage appeared to be of such a nature that little could be done to effect direct improvement in the organic condition of the brain. We should mention, however, that results of the type shown by this child are sometimes associated with epileptic disturbances. If this subject had been found to have epileptic seizures, these of course might have been improved by anticonvulsant medication, but one would not have expected this treatment to have improved his ability level or his basic personality structure. Previous recommendations for this child included the need for development of warm, close, and confident relationships with other people. Undoubtedly this child was very much in need of developing such relationships. There were further suggestions that an entirely permissive approach be followed with this child. T h e degree of impairment shown by the child prompted us to suggest that too much permissiveness in his life situation might lead to additional anxiety and insecurity, inasmuch as the child was not capable of imposing a reasonable plan on his procedures. T he responsibility implied by a permissive attitude on the part of others could well have been overwhelming for this child. He seemed sufficiently and broadly enough impaired to us to need rather concrete and firm direction as well as the development of basic habits of living that would stand him in good stead as routine responses when his own intelligence was not sufficient to reason through situations as they arose.

R a l p h M . Reitan

214 VII. CONCLUDING COMMENTS

As in most assessments of human beings, complex interrelationships must be expected among the factors which have contributed to the uniqueness of individual retarded subjects. The argument can be advanced that the necessary knowledge for dealing properly with a subject relates to his current psychological description alone rather than to causative or underlying factors. While general agreement would be found with the contention that habilitational and therapeutic efforts cannot wait until our assessment methods have reached a state of perfection, few would disagree with the necessity for continuing our efforts to understand the differential nature of psychological deficits associated with varying causes. Brain damage, while certainly not the only significant factor in mental retardation, may well be of critical importance in determining the character of psychological limitations in many more subjects than has presently been demonstrated. I n addition, the presence or absence of cerebral dysfunction, though bypassed by many in their development of habilitational and training programs, may well turn out to be significantly related to the interindividual variance in the results of such programs. These considerations are no less applicable to many children with higher general ability levels who are seen in psychoeducational, child guidance, and neuropediatric clinics. No attempt will be made to achieve closure regarding the relationships between brain damage, mental retardation, and psychological measurements, since closure is not appropriate considering our present state of knowledge. REFERENCES Andersen, A. L. The effect of laterality localization of brain damage on Wechsler-Bellevue indices of deterioration. J . d i n . Psychol., 1950, 6, 191-194. Apter, N. S., Halstead, W. C., Eisele, C. W., & McCullough, N. B. Impaired cerebral functions in chronic brucellosis. Amer. J . Psychiat., 1948, 105, 361-366. Apter, N. S., Halstead, W. C., & Heimburger, R. F. Impaired cerebral functions in essential hypertension. Amer. J. Psychiat., 1951, 107, 808-813. Armitage, S. G. An analysis of certain psychological tests used for the evaluation of brain injury. Psychol. Monogr., 1946, 60, No. 1 (Whole No. 277). Benton, A. L. Right-left discrimination and finger localization. New York: Harper (Hoeber), 1959. Birren, J. E., & Spieth, W. Age, response speed, and cardiovascular functions. J . Cerontol., 1962, 17, 390-391. Chapman, L. F., & Wolff, H. G. The cerebral hemispheres and the highest integrative functions of man. Arch. Neurol., 1959, 1, 357-424. Doehring, D. G., & Reitan, R. M. MMPI performance of aphasic and non-aphasic brain-damaged patients. J . d i n . Psychol., 1960, 16, 307-309. Doehring, D. G., & Reitan, R. M. Behavioral consequences of brain damage associated

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with homonymous visual field defects. J. comp. physiol. Psychol., 1961, M, 489492. (a) Doehring, D. G., & Reitan, R. M. Certain language and nonlanguage disorders in brain-damaged patients with homonymous visual field defects. Arch. Neurol., 1961. 5, 294-299. (b) Doehring, D. G., & Reitan, R. M. Concept attainment of human adults with lateralized cerebral lesions. Percept. mot. Shills, 1962, 14, 27-33. Doehring, D. G., Reitan, R. M., & Klgive, H. Changes in patterns of intelligence test performance associated with homonymous visual field defects. J. n e w . ment. Dis., 1961, 132, 227-233. Fitzhugh, K. B., Fitzhugh, L. C., & Reitan, R. M. Psychological deficits in relation to acuteness of brain dysfunction. J. consult. Psychol., 1961, 25, 61-66. Fitzhugh, K. B., Fitzhugh, L. C., & Reitan, R. M. Wechsler-Bellevue comparisons in groups with “chronic” and “current” lateralized and diffuse brain lesions. J. consult. Psychol., 1962, 26, 306-310. (a) Fitzhugh, K. B.,Fitzhugh, L. C., & Reitan, R. M. The relation of acuteness of organic brain dysfunction to Trail Making Test performances. Percept. mot. Shills, 1962, 15, 399-403. (b) Fitzhugh, K. B., Fitzhugh, L. C., & Reitan, R. M. Effects of “chronic” and “current” lateralized and non-lateralized cerebral lesions upon Trail Making Test performances. ]. neru. ment. Dis., 1963, 137, 82-87. Fitzhugh, K. B., Fitzhugh, L. C., & Reitan, R. M. Influence of age upon measures of problem solving and experiential background in subjects with longstanding cerebral dysfunction. J . Gerontol., 1964, 19, 132-134. Fitzhugh, L. C., Fitzhugh, K. B., & Reitan, R. M. Adaptive abilities and intellectual functioning in hospitalized alcoholics. Quart. J. Stud. Alcohol, 1960, 21, 414-423. Ghent, L. Developmental changes in tactual thresholds on dominant and non-dominant sides. J . comp. physiol. Psychol., 1961, 54, 670-673. Goldstein, K. Human nature. Cambridge, Mass.: Harvard Univer. Press, 1940. Halstead, W. C. Preliminary analysis of grouping behavior in patients with cerebral injury by the method of equivalent and non-equivalent stimuli. Amer. J . Psychiat., 1940, 96, 1263-1294. Halstead, W. C. Brain and Intelligence. Chicago: Univer. of Chicago Press, 1947. Halstead, W. C. Brain and intelligence. In L. A. Jeffress (Ed.), Cerebral mechanisms in behavior: T h e Hixon symposium. New York: Wiley, 1951. Halstead, W. C., & Rennick, P. Toward a behavioral scale for biological age. In C. Tibbitts, & W. Donahue (Eds.), Social and psychological aspects of aging. New York: Columbia Univer. Press, 1962. Pp. 866-872. Halstead, W. C., & Wepman, J. M. The Halstead-Wepman aphasia screening test. J. Speech Hearing Dis., 1949, 14, 9-15. Hathaway, S. R.,& McKinley, J. C. Manual f o r the Minnesota Multiphasic Personality Inventory. Minneapolis: Univer. of Minnesota Press, 1943. Heimburger, R. F., DeMyer, W., & Reitan, R. M. Implications of Gerstmann’s Syn. drome. J. neurol., neurosurg.. Psychiat., 1964, 27, 52-57. Heimburger, R. F., & Reitan, R. M. Easily administered written test for lateralizing brain lesions. J. Neurosurg., 1961, 18, 301-312. Holbourn, A. H. S. Mechanics of head injuries. Lancet 1943, 2, 438-441. Kimble, G. A. Principles of general psychology. New York: Ronald Press, 1956. Klpve, H. Relationship of differential electroencephalographic patterns to distribution of Wechsler-Bellevue scores. Neurology, 1959, 9, 871-876. (a)

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KIpve, H. T h e relationship of sensory suppression to distribution of Wechsler-Bellevue scores. Paper read a t Midwest. Psychol. Ass., Chicago, May, 1959. @) Klove, H. The differential relationships of psychological test results to electroencephalographic criteria in older and younger age groups. I n C. Tibbitw, & W. Donahue (Eds.), Social and psychological aspects of aging. New York: Columbia Univer. Press, 1962. Pp. 873-879. Klove, H., & Reitan. R. M. T h e effect of dysphasia and spatial distortion on WechslerBellevue results. A.M.A. Arch. Neurol. Psychiat., 1958, 80, 708-713. McFie, J., & Piercy, M. F. Intellectual impairment with localized ccrebral lesions. Bruin, 1952, 75, 292-311. (a) McFie, J., & Piercy, M. F. The relation of laterality of lesion to performance on Weigl’s sorting test. J. ment. Sci., 1952, 98, 299-305. @) Matthews, C. G., Guertin, W. H., & Reitan, R. M. Wechsler-Bellevue subtest mean rank orders in diverse diagnostic groups. Psychol. Rep., 1962, 11, 3-9. hlatthews, C. G., & Reitan, R. M. Comparison of abstraction ability in retardates and in patients with cerebral lesions. Percept. mot. Skills, 1961, IS, 327-333. Matthews, C. G., & Reitan, R. M. Psychomotor abilities of retardates and patients with cerebral lesions. Amer. J. ment. Defic., 1962, 66, 607-612. hlatthews, C. G., & Reitan, R. M. Relationship of differential abstraction ability levels to psychological test performances in mentally retarded subjects. Amer. J. ment. Defic., 1963, 68, 235-244. Matthews, C. G., & Reitan, R. M. Correlations of Wechsler-Bellevue rank orders of subtest means in lateralized and non-lateralized brain-damaged groups. Percept. mot. Jkills. 1964, 19, 391-399. Meyers, R. T h e relationship between “thinking” and language: An experimental approach using dysphasic patients. Trans. Amer. Neurol. Ass., 1947, 72, 65-69. Munn, N. L. Psychology (2nd ed.) New York: Houghton Mifflin, 1951. Reed, H. B. C., & Reitan, R. M. T h e significance of age in the performancc of a complex psychomotor task by brain-damaged and non-brain-damaged subjects. J. Gerontol., 1962, 17, 193-196. Reed, H. B. C., & Reitan, R. M. Intelligence test performances of brain-damaged subjects with lateralized motor deficts. J. consult. Psychol., 1963, 27, 102-106. (a) Reed, H. B. C., & Reitan, R. M. A comparison of the effects of the normal aging process with the effects of organic brain damage on adaptive abilities. 1. Gerontol., 1963, 18, 177-179. @) Rced, H. B. C., & Reitan, R. M. Changes in psychological test performance associated with the normal aging process. J . Gerontol., 1963, 18, 271-274. (c) Reed, H. B. C., Reitan, R. M., & Klgve, H. T h e influence of cerebral lesions on psychological test performances of older children. J . consult. Psychol., 1965, 29, 247-251. Reitan, R. M. Intellectual functions in myxedema. A.M.A. Arch. Neurol. Psychiut.. 1953, 69, 436-449. Reitan, R. M. Intellectual and affective changes in essential hypertension. Amer. J. Psychiut., 1954, 110, 817-824. (a) Reitan, R . M. Intellectual and affective functions in chronic brucellosis. Amer. 1 Psychiat., 1954, 110, 19-28. (b) Reitan, R. M. An investigation of the validity of Halstead’s measures of biological intelligence. A M . A . Arch. Neurol. Psychiat., 1955, 73, 28-35. (a) Reitan, R. M. T h e distribution according to age of a psychologic measure dependent upon organic brain functions. J. Gerontol., 1955, 10, 338-340. @)

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Reitan, R. M. The relation of the Trail Making Test to organic brain-damage. J. consult Pvchol., 1955, 19, 393-394. (c) Reitan, R. M. Certain differential effects of left and right cerebral lesions in human adults. j . comp. physiol. Psychol., 1955, 48, 474-477. (d) Reitan, R. M. Affective disturbances in brain-damaged patients: Measurements with the Minnesota Multiphasic Personality Inventory. A M A . Arch. Neurol. Psychiat., 1955, 73, 530-532. (e) Reitan, R. M. Investigation of relationships between “psychometric” and “biological” intelligence. J . n e w . ment. Dis., 1956, 123, 536-541. (a) Reitan, R. M. The relationship of the Halstead Impairment Index and the WechderBellevue total weighted score to chronologic age. /. Gerontol., 1956, 11, 447. (b) Reitan, R. M. The comparative significance of qualitative and quantitative psychological changes with brain-damage. Proc. 15th int. Congr. Psychol., Brussels, 1957, 1959, 214-215. (a) Reitan, R. M. Differential reaction of various psychological tests to age. Proc. 4th Congr. int. Ass. Gerontol., San Francisco, 1957, 1957, 4, 158-165. (b) Reitan, R. M. The comparative effects of placebo, Ultran, and meprobamate on psychologic test performances. Antibiot. Med. clin. Ther., 1957, 4, 158-165. (c) Reitan, R. M. The validity of the Trail Making Test as an indicator of organic braindamage. Percept. mot. Skills, 1958. 8, 271-276. (a) Reitan, R. M. Qualitative versus quantitative mental changes following brain-damage. /. Psychol.. 1958, 46, 339-346. (b) Reitan, R. M. Symposium: Contributions of physiological psychology to clinical inferences. Midwest. Psychol. Ass. Meeting, Detroit: May 1-3, 1958. (c) Reitan, R. M. The comparative effects of brain-damage on the Halstead Impairment Index and the Wechsler-Bellevue Scale. /. clin. Psychol., 1959, 15, 281-285. (a) Reitan, R. M. Effects of brain-damage on a psychomotor problem-solving task. Percept. mot. Shills, 1959, 9, 211-215. (b) Reitan, R. M. Impairment of abstraction ability in brain-damage: Quantative versus qualitative changes. /. Psychol., 1959, 48, 97-102. (c) Reitan, R. M. The effects of brain lesions on adaptive abilities in human beings. (Mimeo.) 1959. Pp. 1-133. (d) Reitan, R. M. The comparative behavioral effects of phenaglycodol, meprobamate and placebo. In L. Uhr & J. G. Miller (Eds.), Drugs and behavior. New York: Wiley, 1960. Pp. 365-367. (a) Reitan, R. M. The significance of dysphasia for intelligence and adaptive abilities. j . Psychol., 1960, 50, 355-376. (b) Reitan, R. M. Psychological deficit. Annu. Rev. Psychol., 1962, 13. 415-444. (a) Reitan, R. M. The comparative psychological significance of aging in groups with and without organic brain-damage. In C. Tibbitts, & W. Donahue (Eds.), Social and psychological aspects of aging. New York: Columbia Univer. Press, 1962. Pp. 880887. (b) Reitan, R. M. Symposium: Psychological function in cardiovascular disease. Paper read at Amer. Psychol. Ass. Meeting, Philadelphia, August, 1963. Reitan, R. M. Psychological deficits resulting from cerebral lesions in man. In J. M. Warren and K. A. Akert (Eds.), The frontal granular cortex and behavior. New York: McGraw-Hill, 1964. (a) Reitan, R. M. Relationships between neurological and psychological variables and their implications for reading instruction. In H. A. Robinson (Ed.), Meeting individual differences in reading. Chicago: Univer. of Chicago Press, 1964. PP. 1oo-110. @)

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Reitan, R. M., & Shipley, R . E. T h e relationship of serum cholesterol changes to psychological abilities. 1. Gerontol., 1963, 18, 350-356. Reitan, R. M., & Tarshes, E. L. Differential effects of lateralized brain lesions on the Trail Making Test. 1. n e w . ment. Dis., 1959, 129, 257-262. Ross, A. T., & Reitan, R. M. Intellectual and affective functions in multiple sclerosis: A quantitative study. A M A . Arch. Neurol. Psychiat., 1955, 73, 663-677. Russell, J . R., & Reitan, R. M. Psychological abnormalities in agenesis of the corpus callosum. I . new. ment. Dis., 1955, 121, 205-214. Rylander, G. Personality changes after operations on the frontal lobes. London: Oxford Univer. Press, 1939. Sarason, S. B., & Gladwin, T. Psychological and cultural problems in mental subnormality; a review of research. Amer. 1. ment. Defic., 1958, 62, 1115-1307. Semmes, J., Weinstein, S., Ghent, L., & Teuber, H-L. Somatosensory changes after penetrating brain wounds in man. Cambridge, Mass.: Harvard Univ. Press, 1960. Shure, G. H., & Halstead, W. C. Cerebral localization of intellectual processes. Psychol. Monogr., 1958, 72, No. 12 (Whole No. 465). Sinnott, E . W. Cell and psyche. Chapel Hill, Univer. North Carolina Press, 1950. Spieth, W. Abnormally slow perceptual motor task performance in individuals with stable mild to moderate heart disease. Aerospace Med., 1962, 33, 370. Spieth, W. Cardiovascular health status, age, and psychological performance. I . Gerontol., 1964, 19, 277-284. Talland, G. Deranged memory. New York: Academic Press, 1965. Teuber, H.-L. Some observations on the organization of higher functions after penetrating brain injury i n man. In The biology of mental health and disease, New York: Harper (Hoeber), 1952. Pp. 259-262. Teuber, H.-L., Battersby, W. S.. & Bender, M. B. Performance of complex visual tasks after cerebral.lesions. /. new. ment. Dis., 1951. 114, 413-429. Watson, J. B. Behaviorism. New York: People’s Institute, 1924. Wechsler, D. T h e measurement of adult intelligence. Baltimore, Williams & Wilkins, 1944. Weinstein, S. Tactile sensitivity of the phalanges. Percept. mot. Skills, 1962, 14, 351-354, Weinstein, S., & Sersen, E. A. Tactual sensitivity as a function of handedness and laterality. I . comp. physiol. Psychol., 1961, 54, 665-669. Weinstein, S., & Teuber, H:L. Effects of penetrating brain injury on intelligence test scores. Science, 1957, 125, 1036-1037. Wheeler, L. Predictions of brain-damage from an aphasia screening test; an application of discriminant functions and a comparison with a non-linear method of analysis. Percept. mot. Skills, 1963, 17, 63-80 (Monogr. Supplement l-Vl7). Wheeler, L. Complex behavioral indices weighted by linear discriminant function for the prediction of cerebral damage. Percept. mot. Skills, 1964, 19, 907-923 (Monogr. Suppl. 4-Vl9). Wheeler, L., Burke, C. J., & Reitan, R. M. An application of discriminant functions to the problem of predicting brain-damage using behavioral variables. Percept. mot. Skills, 1963, 16, 417-440 (Monogr. Suppl. 3-V16). Wheeler, L., & Reitan, R. M. T h e presence and laterality of brain-damage predicted irom responses to a short aphasia screening test. Percept. mot. Skills, 1962, 15, 783-799. Wheeler, L., & Reitan, R. M. Discriminant functions applied to the problem of pre. dicting cerebral damage from behavioral tests; a cross validation study. Percept. mot. Skills, 1963, 16, 681-701. Wilson, E . B. T h e cell in development and heredity (3rd ed.). New York: Maanillan, 1925.

Long-Term Memory in Mental Retardation JOHN M. BELMONT DEPARTMENT OF PSYCHOLOGY, UNIVERSITY OF ALABAMA, TUSCALOOSA, ALABAMA

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Development of the Problem Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. Methodological Considerations . . . . . . . . . . . . . . . . . A. Measures of Retention . . . . . . . . . . . . . . B. Methods of Original Training . . . . . . . . . . . . . . . . . . . . . C. Conclusions . . . . . ......................... IV. Retention Research with Retarded Subjects . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Discussion . . . ................................. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1. INTRODUCTION

This chapter is a summary and critique of research relevant to longterm memory (LTM) in the mentally retarded. T h e emphasis is upon L T M rather than short-term memory (STM). It should be clear from the outset, however, that the LTM-STM distinction is equivocal, involving both methodological and theoretical difficulties. Keppel (1965) has dwelt at length on the problems of method inherent in both L T M and STM studies, his work implying the possibility of defining three operationally distinct concepts of memory. First, measuring immediate memory ideally involves no time lapse between original learning and the moment of memory testing. Indeed, for some research, the immediate memory test is the measure of learning. T h e second, STM, is. measured a few seconds or minutes after the immediate test. This research normally involves attempts to control or manipulate S’s retention interval behavior. For instance, S may be required to fill the retention interval with irrelevant activity, such as counting, color naming, etc.. or he may be required to engage in behavior similar to that of the original learning task. T h e latter 219

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case would be a retroactive interference paradigm. In the L T M paradigm, generally involving retention intervals of hours, days, or weeks, no attempt is made to control behavior within the retention interval, but Ss may still be required to learn other materials, more or less similar to the original learning task, in attempts to systematically influence LTM. Generally, then, the paradigms for STM experiments involve short retention intervals, during which control and sometimes manipulation of retention interval behavior is attempted, whereas for LTM experiments, retention intervals are relatively long, and usually do not involve control. These distinctions are sometimes rather vague and arbitrary (e.g., length of the retention interval as a defining property). Nonetheless, several authors have proposed theoretical distinctions between STM and LTM which have far-reaching implications for research with retarded Ss. One outstanding example is Hebb’s (1949) familiar dual-trace model, in which an immediate reverberatory trace serves to mediate structural changes upon which LTM may ultimately rely. Ellis (1963) cited this model among others, along with widely varied research findings, in support of the notion that retardates suffer a significant STM deficit. No similarly comprehensive, critical summary of LTM research has been done. Two reviewers (Denny, 1964; Lipman, 1963) examined some of the LTM research, intending to determine the relative importance of a possible retention deficit, compared to several alternative performance and learning defects, any of which may contribute to overall intellectual disability (e.g., attention span, incidental learning, inhibition, etc.). T h e wide scope of these reviews, however, permitted scant criticism of the LTM studies per se. T h e reviewers seldom questioned the methodological adequacy of a retention study, especially with reference to specific issues peculiar to research on retention. Yet the research cannot be adequately evaluated independently of such criticism. It is the purpose of this chapter to review these studies of LTM in mental retardates, with major attention paid to the extent to which these works cope with problems of method. The chapter comprises three sections. The first deals with the historical development of the problem of studying retention in fast and slow learners. In the second section studies are presented whose principal goals were to raise and test methodological issues peculiar to retention research involving fast and slow learners. On the basis of these works, a set of criteria is then proposed for the evaluation of comparative studies which have actually involved samples from populations of retarded and normal individuals. The third section presents an examination and evaluation of these studies, with the ultimate aim of assessing

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the current status of knowledge about LTM capacities of the mentally retarded. 11. HISTORICAL DEVELOPMENT OF THE PROBLEM

The first LTM study in which retardation was specified as an independent variable was conducted relatively recently by Lott (1958). Prior to Lott’s work, research on memory had enjoyed a long and prolific life, having had its origins in late nineteenth century German psychology, including Ebbinghaus’s monumental work (with an N of 1). This history is encouraging, but its lack of impact upon research with retardates is baffling. Lott’s research was quickly followed by other enthusiastic workers, yet the studies emanating from their laboratories hardly reflected the considerable sophistication which had evolved out of 50 years of research with fast and slow learners from normal school and college populations. Henderson (1903) appears to have made the first large-scale, reasonably clear-cut study of the relationship of speed of learning to amoun’t of retention. T o 212 normal Ss, from fifth grade through graduate school, he gave one or several passages of English prose averaging 150 words. The Ss were instructed to read through the passage at least twice and to memorize as much as possible. Three min were given to complete this task. The test of learning, which required S to write the passage from memory, immediately followed the 3-min study period. Henderson gave retention tests, again requiring written reproduction, after intervals of 2 and 28 days. Criterion scores were number of “ideas” and number of words recalled. Words were scored correct if they a p peared within their original context. With various age groups, there appeared a weak, positive correlation between original learning and both absolute and “percent loss” retention scores. Henderson (1903, p. 53) concluded that “those who learn quickest retain . . . a greater percentage of what they have learned,” especially over the 28-day interval. His study clearly anticipated several later versions which accompanied the advance of “a small army of investigators” (Whipple, 1915, p. 150), indefatigable educators laboring at intercorrelating tests of memory and minutely examining the effects of individual differences reflected in these tests. Following Henderson’s lead, Gamble (as cited in Lyon, 1916) read lists of words or letters four or five times to 350 college students, after which the Ss wrote down as many as they could remember. Five or 6 weeks later, Ss were first asked for free written recall of the material. The list was then reread once, and a second recall elicited. Finally, the list was presented several times, after which a third reproduction was

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required. The top quartile of the first retest scores contained about 45% of the original top quartile Ss, a “marked correlation between quickness of learning and tenacity of impression” (Lyon, 1916). In relative amount retained, as measured by this first recall, however, Gamble noted a methodological artifact. Since slow learners had achieved low original scores, any retention would appear as a relatively high percentage of the original score. The second retention test, after one rereading, showed a high correlation between original and relearning scores. Gamble’s comments were that the first measure, free recall without re-presentation, was inappropriate because some Ss may remember little spontaneously, but they may show considerable “subliminal” retention on the relearning task; that is, relearning may be better than original learning, evincing partial retention, although the free recall test might show little or no retention. Of the relearning task she remarked, however, that it is impossible to distinguish partial memory of old items from genuine new learning. Intra-S variability might, therefore, have significant effects on the original learning-relearning correlation. These points, made very early in the history of memory research, contain the kernals of methodological problems still very much alive today. Pyle (1913) extended Gamble’s work by administering the Marble Statue Test of Memory (Whipple, 1915) to two groups, each containing about 300 grammar school children. The test requires a written reproduction of an orally presented paragraph comprising 166 words and 67 “ideas.” Pyle found correlations between original learning (as measured by immediate recall) and 5-week deferred recall of .76 and .70for the two groups, thus extending Gamble’s findings to connected, logical material. Patterning her work after Thorndike (1908),Norsworthy (1912) tested the hypothesis “easy come, easy go” with 83 college psychology students, using Thorndike’s 1200 German-English word pairs. The Ss were first given a pretest for knowledge of any German-English equivalents; they were then given the 1200 pairs, ordered in numbered groups of 10, to be studied 20 min per day for 5 days. The Ss were told to memorize a certain group of 40 words per day, and as many more as they wished. Each daily session was followed by a test of the English equivalents of the words studied that day, S being given a list of all 1200 German words, numbered in lo’s, but randomized within groups of 10. At week’s end, therefore, all Ss had studied at least the first 200 words. There followed two identical repetitions of this 5-day procedure, with weekends given as rest days. T w o days after the last study period, E gave a preannounced test (TI) containing 50 German words from the required 200. A retest (T2) comprising another 50 words from the 200, was given unannounced a month later. Original learning (OL) was defined as

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the total number of different words remembered (during the last week of study) minus the number of these words known on the pretest. Retention scores were taken as the absolute number of words remembered of the 50 administered. OL-T,. OL-T2, and T,-T, correlations were .41, .50, and .60, respectively. There was also a strong positive correlation between OL and percent retained of those pairs actually learned of the 200 required pairs. Norsworthy’s procedure and results strongly resemble those of Henderson (1903), Gamble (cited in Lyon, 1916), and Pyle (1913), in that the Ss were given a fixed time for OL, and those who scored high on OL scored relatively high on the retention tests. However, Gamble and Henderson did not corroborate Norsworthy’s high correlation of OL and percent retained. As Gamble had indicated, anything retained by her slow learners would constitute a high percentage of OL; the same would hold to a lesser degree for Henderson’s study. The extended range of Norsworthy‘s OL scores (up to 200) was apparently sufficiently large to dissolve this artifact. Other early investigators who employed essentially the same methods as those described were Thorndike (1908; 1910), J. Peterson (1916), H. A. Peterson (1925), and Gordon (1925). All reported high positive correlations between OL and deferred recall. J. Peterson added that these correlations are much higher when Ss have purposely learned the material than when learning was incidental. Gordon found that OL-retention correlations are higher when OL involves spaced rather than massed practice. With the data pointing toward a reliable, general phenomenon, researchers progressively acknowledged the need for parametric studies of factors likely involved in the relation of speed of OL to amount of retention. Length of retention interval was first observed by Lyon (1916) as influencing these correlations. Although he had given the matter no systematic study, he noted that in some of his work, the OL-retention correlations had actually gone from positive to negative as the interval increased; in any case, he reasoned, the correlation should diminish at least to zero, concomitantly with the fast and slow learners’ absolute retentions going to zero. Brown (1924) also found a diminution of the OL-retention correlation as the interval increased. He read a list of 48 words to 18 groups of college students, giving a phrase containing each word. A written recall (index of OL) followed immediately; this was followed by either 8 or 16 min of memorizing irrelevant nonsense syllables. Nine groups received each interval (1,). Another written recall of the 48 words (T,) immediately followed I,. Groups then waited from 3 to 7 days before a T2 was given. Brown observed no differences between

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average recall scores at 8 and 16 min, but he did find a steady drop in average recall scores over longer intervals. The OL-TI correlations were .86 and .83 for 8 and 16 min, respectively. He also found significantly different OL-T2 correlations of .74 and .64 for the 8- and 16-min groups, respectively; the longer the 11, the weaker the relation of OL to deferred memory. The OL-T2 correlations for 3, 4, 5, 6, and 7 days, respectively, were .74,.70,.63, .68, and .65. For T,-T2 the correlations were, respectively, .83, .82, .78, .72, and .71. These diminutions were associated with correlations of -34 and -.53 between length of I2 and correlations for OL-T2 and T1-T2. quite in keeping with Lyon’s predictions. Since Brown did not carry I2 far enough to bring these correlations clearly to asymptote, it is indeterminate whether they would actually have become negative, as Lyon had informally reported. Luh (1922) was the first to demonstrate experimentally the shift of OL-retention correlations from positive to negative as the interval increases. His 10 Ss learned lists of nonsense syllables to one perfect recitation by the serial anticipation method, with memory drum presention. Each S learned two lists for each retention interval, which ranged from 20 min to 48 hr. Three retention measures were used: (a) free recall: (b) recognition of learned syllables intermingled with previously unseen similar items; and (c) reconstruction of the serial order, given the original items. Luh (1922, p. 81) found virtually no relation between free recall scores and trials to OL; for recognition and reconstruction, however, “the correlation between speed of learning and amount of retention tends to change from positive to negative as the (interval) is lengthened.” Slow learners actually performed better than fast learners after a 48-hr rest. Luh’s failure to find positive OL-retention correlations using recall scores seems to contradict all previous findings, but Luh’s training procedures may account for this. His Ss were required to learn to a specified level of performance (one perfect recitation of the list), whereas in previous studies Ss were given equal opportunity to learn as much as possible. The OL score in the first case would be speed of learning, while in the second case it would be amount learned. The OL-retention correlations therefore would be between speed of learning and amount recalled for equated performance vs. amount learned and amount recalled for equated opportunity. The only other early studies involving equated performance were Lyon (1916) and Vlai’cou (1914-1919). Lyon supported Luh’s finding of negligible OL-retention correlations, not only for nonsense syllables, but for words and digits as well. Vlai‘cou, who recorded free recall data, unfortunately did not report them, favoring instead percent OL saved in relearning to original criterion. The clearest evidence for the progressive shift of OL-retention correla-

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tions from positive to negative with increasing intervals was provided by Leavitt (1945). Four groups of 12 Ss each learned a list of 15 nonsense syllables by serial anticipation. All Ss were given ten 30-sec presentations of the list. Each S also had ten 30-sec practice periods on a pursuit rotor. The OL scores for these two tasks were (a) nonsense syllables correctly anticipated, and (b) time on target, during the last 30-sec trial on each task. The four groups returned for memory tests after 1, 7, 28, or 70 days, a different group returning at each interval. Retention scores were number of correct anticipations and time on target during the first SO-sec relearning period. For nonsense syllables, Leavitt found OL-retention correlations of 34, .67, -26, and -.17 for 1, 7, 28, and 70 days, respectively. The corresponding correlations for the motor task were .54, --.06, -.68, and -.73 for the four intervals, respectively. Since the training method involved equal opportunity to learn, and the memory test was recall without retraining, the correlations may be compared with those of Brown (1924). Brown's OL-retention correlations for 16 min and 7 days ( 2 3 and .67, respectively), and Leavitt's correlations for 1 and 7 days (34 and .67, respectively) show parallel trends suggesting that Brown's correlations would have diminished as much as Leavitt's had Brown sufficiently extended his retention intervals. Summary The research reviewed in this section represents about 40 years of work on the question of the relation of speed or amount of original learning to the amount retained. Dichotomizing the studies according to original training procedures, it will be noted that three (Luh, 1922; Lyon, 1916; Vlaicou, 1914-1919) required S to reach a specified level of proficiency, while the remaining nine researchers (Brown, 1924; Gordon, 1925; Henderson, 1903; Leavitt, 1945; Norsworthy, 1912; Pyle, 1913; H. A. Peterson, 1925; J. Peterson, 1916; Thorndike, 1908, 1910) gave Ss equal o p portunity to learn. The equal opportunity studies generally showed that amount originally learned (as measured most frequently by immediate free recall) correlated fairly highly with amount retained (also generally measured by free recall). For connected meaningful materials, these correlations held up for as long as 6 weeks. For nonmeaningful, or disjointed materials, the correlations were generally found to diminish slowly over time when multiple retention tests were administered. If single measurements were taken, the correlations for non-meaningful materials were found to be smaller than those for meaningful materials at equal retention intervals. Of the three equal proficiency studies, VIaicou's (19141919) cannot be compared with the equal opportunity works because,

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as will be seen in the following section, Vlaicou's relearning data are incomparable with recall scores. The two equal proficiency studies which did provide comparable retention data did not agree with the equal opportunity works. Neither Lyon (1916) nor Luh (1922) found positive OL-retention correlations, using disconnected or nonmeaningful materials. This picture is fursther complicated by results of several studies involving extended retention intervals. The positive OL-retention relationship not only broke down over time, but actually became negative, with poorer learners showing significantly better retention at relatively long intervals. From the preceding discussion, it appears that at least four independent procedural variables may bear strongly upon the outcome of a memory study involving comparisons of fast and slow Ss: (a) nature of the materials learned: (b) method of original training; (c) length of retention interval; (d) method of measuring retention. But despite the complexity of the problem, and the lack of comprehensive methodological studies, and sometimes even in the face of obviously weak empirical support, the early researchers concluded, with rare exception, that the fast learner showed better retention than the slow learner. 111. METHODOLOGICAL CONSIDERATIONS

In the preceding review the author omitted most of the details of Lyon's study (1916) and altogether ignored three others (Gilette, 1936; Underwood, 1954; 1964). These four studies are distinguished by a common concern, not for showing how speed of learning relates to retention, but rather for the problem of how procedures directed toward answering that question may influence the answers obtained. A. Measures of Retention

T o Lyon (1916) we are indebted for two contributions: his scholarly appraisal of a large and multilingual literature and his demonstration that the answer to the differential retention question may vary with the method used to measure retention. He based his report largely upon data obtained from 41 female college students. At various times Ss studied lists of 20 digits, nonsense syllables or English nouns, and passages of prose and poetry containing about 100 words. The OL score was the time necessary for S to study the material until she felt confident that she could recite it perfectly. The E checked this proficiency by listening to the recitation directly after OL. Lyon did not report the sequence or temporal spacing of the learning sessions for various materials. The re-

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tention interval for digits and nonsense syllables was 1 week; that for nouns and connected material was 10 weeks. T h e retention test always consisted of three consecutive parts: (a) free recall; (b) free recall after E had read the list or passage once; and (c) time to relearn to the prior level of proficiency, using the OL method (cf. Gamble, cited in Lyon, 1916). Although Kjerstad (1919) marshalled damaging criticisms of Lyon’s scoring procedures for nonsense syllables, Lyon’s overall results may usefully be compared to other studies involving his procedures: spontaneous free recall without rereading showed relatively strong correlations of OL and percent retained for the connected materials; free recall also showed positive but weak correlations for nonsense syllables and words, but zero-order correlation for digits; for recall after one oral presentation, strong positive OL-percent retained correlations obtained for all materials except digits, for which positive correlations were small. For relearning, Lyon reported savings scores, i.e., the difference between OL and relearning times, divided by OL time. T h e OL-percent savings correlations were strongly negative for digits, weakly negative for words and poetry, and zero-order for nonsense syllables and prose. In summary, free recall yielded positive correlations, free recall after one rereading gave somewhat stronger ones, and relearning gave negative or zero-order correlations. I n view of Lyon’s results, the question will naturally arise, which of his retention measures best shows the relation of speed of learning to amount retained? T h e relearning method, which yielded generally negative or zero-order OL-savings correlations, regrettably disqualifies. Irrespective of the theoretical significance one may wish to ascribe to the speed of relearning relative to that of OL, the relearning method is inappropriate because it may be strongly biased against fast learners. If the materials originally learned are too easy, the fast learner must generally find his OL zeal rewarded by failure to better his OL time significantly a t relearning. T h e faster the OL, the less opportunity for improving on OL time. T h e slow learner, on the other hand, statistically stands to gain a great deal on the relearning task because he has room to greatly reduce his OL time. That is what happened for most of Lyon’s materials. For example, on a list of 20 words learned by 24 girls, the fastest OL was 4.40 min, the slowest 28.50 min, and the intermediate times fell normally around a mean of 11.88 min. T h e average relearning time was 5.62 min, for an average savings of about 50%. T h e upper half of the OL scores were improved on the average by only 40%; this is not surprising since the fastest Ss would need almost total spontaneous recall to be able to recite the list perfectly after the extremely short relearning

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time they could afford if they were to better their O L times. But, as was shown by free recall test performance, the fast Ss did not have total recall. T h e top 25% of the OL times were associated with an average of only 26% recall without further exposure to the words. T h e bottom OL quartile showed only 18% recall. T he foregoing analysis is not intended to suggest that the percent savings score is merely a function of recall and original learning speed. It approaches that function, however, as the lowest scores in the O L time distribution approach zero. When they do, the OL-relearning correlation is biased against the fast learners, increasingly reflecting the absolute level of recall of these Ss. Another bias, perhaps stronger even than level of recall, is the learning-to-learn phenomenon. If anyone gained new methods of learning during OL, it would be the slow learners. These new learning methods would serve to reduce their relearning scores, further decreasing the OL-relearning correlations. T h e proper experimental control for this error would be a group who learned an equally difficult list of new items while the experimental Ss relearned the original list. Lyon’s method (b), recall after one rereading, showed generally strong positive OL-retention correlations. Unless his slow Ss had shown much better spontaneous recall than the fast Ss, however, it could not have been otherwise. Even if all Ss had had equal, imperfect spontaneous recall, the faster learners, by whatever virtue they were originally faster, would relearn materials, on the basis of one rereading, faster than the slow learners. If faster Ss also had better spontaneous recall, which they did, method (b) would serve only to enhance the differences. It might be argued that OL and relearning involved different processes, since OL was S-paced in Lyon’s study, and OL speed probably reflected many more personality variables than would be involved in his method (b) relearning. It is nevertheless assumed that the two measures of learning are highly related, and, therefore, that the moderate positive OL-retention correlations of method (a), free recall, spawned the large positive correlations of method (b). But Lyon’s purpose was not merely to reaffirm the fast learner’s learning ability: it was to describe the relation of this ability to retention as clearly as possible. Of the three methods of measurement he used, the spontaneous recall method would thus be the method of choice, given the OL methods. Free recall at least measures retention without the myriad disadvantages accruing to relearning, or the spuriously inflated measures of recall following a refresher presentation. Postman and Rau (1957) have recently lent support to this argument against relearning methods, by demonstrating with serial anticipation

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of nonsense syllables that performance on the first relearning Vial adequately predicts relearning scores. 8. Methods of Original Training

The preceding discussion was directed at the adequacy of measures of retention. Gillette's (1936) study suggests that the burden of methodological weakness in retention studies rests not in the measures, but instead in the original training procedures, of which she considered three: (a) equal learning; (b) equal opportunity to learn; and (c) adjusted learning. The equal learning procedure requires all Ss to study material until a criterion of mastery is reached, OL score being in terms of time or trials to criterion; retention scores are expressed either in time or trials to relearn, or, preferably, number of units recalled. Gillette pointed out that equal learning involves overlearning of that segment of the materials which were learned early. For example, of the items in a list to be learned by serial anticipation, some will be anticipated correctly almost from the beginning. By the time OL criterion is reached, correct anticipations to these items will have been reinforced more frequently than will correct anticipations to items learned later in the session. Likewise, slow learners will generally receive more exposure to material, and will receive more reinforcements on some of the items than will the fast learners. This observation led Gillette to predict that for equal learning, correlations of OL and recall should be negative, or at least highly suppressed, even though fast learners might actually retain more relative to the number of reinforced anticipations. Her criticisms of relearning as a measure of retention are similar to those presented above, with the additional remark that relatively large savings scores by slow learners would probably result from their original o p portunity to overlearn. It will be recalled that the equal opportunity procedure differs from equal learning in that the former permits OL proficiency to vary, while the latter fixes proficiency, permitting learning time or trials to criterion to vary. Gillette noted that equal opportunity does not admit of a straight units-recalled memory measure, since slow learners have less to recall than do fast learners, who are therefore favored in OL-retention correlations. She also argued against correlations of OL scores with percent OL retained, or percent OL lost, centering her complaints on Thorndike's (1924) demonstration that with uncorreluted data, random error tended to produce negative Pearson correlations between initial scores and gain scores, and positive correlations between initial and loss scores. Gillette did admit, however, that the deficiencies inherent in

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OL-loss correlations may be overcome by making noncorrelational comparisons of losses, with T scores replacing raw OL scores, for fast, average, and slow subgroups. Of these various statistical and practical problems, Gillette considered overlearning the least formidable. She concluded that if equal learning could be achieved while avoiding overlearning, the procedure would definitely settle the issue. Woodworth (1914) had proposed a method by which items were dropped from the list as soon as one correct anticipation had been elicited. All items would therefore be learned to a criterion of one correct recitation (equal learning) without overlearning. Gillette noted that by this method of dropping items, the list soon becomes quite small, the final items being tested immediately after criterion is reached. If this fault were corrected, she felt, adjusted learning would provide the adequate memory test. Her study was actually a comparison of the three training procedures. T h e equal learning Ss were 54 college psychology students. Learning materials were 15 word-word pairs, 10 form-number pairs, and 10 color-letter pairs. T h e Ss first learned the word-word pairs by successive presentations of the list of pairs and then the list of stimulus words only, until all response words had been written correctly on one test run through the stimulus list. Following learning of this word-word list, the form-number pairs were learned by the same method. Similarly, the color-letter pairs were learned after the form-number list. Total combined learning time for all three lists was about 45 min. Criterion measures were trials to OL, correct responses recalled, and trials to relearn. T h e retention interval was 5 days. In accordance with the Lyon (1916) and Luh (1922) studies, Gillette found zero-order correlations of trials to O L and pairs retained for all lists. She viewed this as indirectly reflecting poorer retention in slow learners because their overlearning would tend to reduce the positive correlation necessary to directly demonstrate differential retention. T h e OL-relearning correlations were, as expected of the analysis, reliably positive, yet revealed nothing about memory. Gillette then divided her Ss in terms of z scores, fast Ss defined as those scoring better than one standard deviation above the OL mean, average scoring from minus one to plus one, and slow falling below minus one. She found that the fast group generally lost significantly fewer pairs over the retention interval than did the other two groups, which showed equal losses. These differences were computed by the method of multiple t’s, with obviously skewed O L distributions, and very small extreme groups (fast N = 3; slow N = 9). Gillette’s equal opportunity Ss were 149 fourth, fifth, and sixth grade

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children. Learning materials were comparable to those used in the equal learning problem, with adjustments made for the age differences between the two samples. T h e pairs were printed on cards for group testing procedures. Each card was shown for 4 sec. T h e deck was shuffled and shown in the same way three more times. Next followed the OL test, on which immediate memory was measured by having S write the response items, shown only the stimulus items, at the rate of 6 sec per card. T he retention interval was 48 hr. T h e memory test was a repetition of the OL test procedure. Gillctte’s three criterion scores were: (a) number of pairs recalled in OL; (b) number recalled at retest: and (c) number lost at retest. Three weeks after the first session, an identical OLretention test sequence was run, with new, comparable materials. Estimated true scores, based upon the reliability coefficient for the two tests, were computed for OL, and then transmuted into z scores as was done in the equal learning study, with fast, average, and slow groups identified as before. Correlations of OL and restest (number recalled) were generally high and positive, in agreement with previous studies. Absolute loss scores also correlated positively with OL. Gillette remarked that the fast learners, having learned more, had more to lose, however, which accounted for both these results, independent of memory. Analysis of the z scores for loss corroborated these findings; for fast, average, and slow groups, the slow learners tended to lose less absolutely, and more relative to their OL scores than the fast learners, with the average group generally falling between fast and slow, or equal to the fast group. These findings agree with previous research; but the problem of floor effects again enters to bias the results in favor of the fast learners. With average OL scores of 5 out of 20 items, slow learners were handicapped in the percent-loss comparisons. In addition to this difficulty, not all materials yielded the biased differences expected on the basis of these methodological errors. With T scores for OL and retest, in three out of five lists there were no differences between fast and slow learners on percent-loss. Because of the biases inherent in the equal learning and equal o p portunity methods, Gillette adopted and refined Woodworth’s (1914) method of adjusted learning. T h e procedure is strictly an equal learning method modified to protect against overlearning by slow learners. Twenty-five of the equal opportunity Ss were chosen on the basis of their OL in the previous experiment. Selection was random, with the restriction that the group be representative of the OL distribution which had been most nearly normal; picture-number pairs had yielded this distribution, hence the same type of materials was used with adjusted

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learning. Testing was individual. Twenty S-R cards were shown for 4 sec each. Following this exposure series, the S cards alone were shown

at the rate of 4 sec each, S being required to respond with the associated

R number. Pairs whose stimulus items had elicited the correct response numbers were immediately removed from the deck, and the exposuretest sequence repeated. Learning was terminated when S had correctly responded to about 10 cards, the average number learned in the equal opportunity study. Th e learning score was trials to reach this 10 criterion. T h e retention interval was 48 hr, after which the S cards previously learned were first shown alone as a retention test; then the S-R cards were presented according to a nonadjustment procedure until S reached a criterion of one perfect run ,through the deck. Three scores were considered: (a) trials to OL; (b) number of pairs retained on the retention test; and (c) trials to relearn. T h e analysis compared fast (N = 7), average (N = l l ) , and slow (N = 7) groups by t tests. Significant differences were found for absolute number retained (fast > slow), percent retained (fast > slow), and trials to relearn (fast < slow; average < slow). Because the adjusted learning method had overcome the biases of the equal learning procedure, yet had still supported the differential retention hypothesis, Gillette concluded that “the fast learner is the better retainer.” T h e Gillette study seems to admit of little methodological criticism beyond that raised in view of earlier studies. T h e differential retention observed in the adjusted learning series may have resulted from an interaction of practice and initial ability (it will be recalled that Ss had learned two previous lists of comparable materials). Assuming no such interaction, however, it seems reasonable to accept Gillette’s solution of the overlearning difficulty. Thus experimentally based upon Gillette’s finding, the differential memory notion was immediately crystalized and securely endorsed by several textbook citations. Boring, Langfeld, and Weld (1939, p. 343) pointed out that when the methodological difficulties were overcome, there remains a high positive relation between measures of learning and retention. T h e ‘slow’ learner gains no retentive advantage from his slowness, and the ‘fast’ learner suffers no disadvantage for his fastness. There is no benign law of compensation.” Hilgard (1948) and Munn (1951) accepted Gillette’s work as finally establishing, popular superstition to the contrary notwithstanding, that fast learners are the better retainers. McGeoch (1952) saw Gillette’s work as supporting the theoretical notion that learning and retention are continuous processes. Gillette had accepted this idea as self-evident, even to the somewhat prenat ur e point of justifying sigma transformations of OL and retention

“. . .

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test scores to the same scale because “delayed memory scores are really estimates of the same function measured in the initial memory tests” (Gillette, 1936, p. 40). Underwood (1949) expanded and clarified this principle of learningforgetting continuity by asserting a two-process theory. He contended that learning, as measured by increments in response tendency, is simultaneous with forgetting. During the learning period, the increases in response tendency reflect both processes, but obviously the learning process is greater. Following OL, however, the learning process is no longer active, and forgetting is unhindered. Therefore “from slow learning we may infer a forgetting process of greater magnitude than we infer from fast learning” (Underwood, 1949, p. 510), and, because forgetting is continuous, it would be predicted that rapid learning will be associated with slow forgetting, and the converse. Five years later, Underwood (1954) rejected his idea in deference to an analysis which rocked the foundations of Gillette’s hitherto unchallenged findings. He recognized an apparently erroneous, yet crucial implicit assumption in the adjusted learning method. Gillette’s solution to the problem of overlearning simply prohibited S from making more than one correct response to any one stimulus item, thus presumably equating OL on all items for all Ss. If this assumption were tenable, Gillette’s research would have held. If, however, it could be shown that a reinforced correct anticipation of a response item resulted in differential associative strength for fast and slow learners, the method of adjusted learning would have no advantage over other methods; learning would not have been equated for all Ss at the beginning of the retention interval, and measures of retention would again be distorted. Armed with the “very reasonable hypothesis that the essential difference between fast and slow learners is that a reinforcement does result in more associative strength for a fast S than for a slow S’ (1954, p. 278), Underwood proposed a “successive probability analysis of learning,” a determination of the probability of correct response following various numbers of reinforcements for individual items. To 90 fast and 90 slow Ss he presented three lists of 10 paired associates (nonsense syllables), yielding 2700 items per group. The analysis consisted of noting whether the reponse item was correctly named on the trial following that on which it was first correctly named: then, again, on the trial following the second correct response, etc. From the resulting graphs of number of previous reinforcements plotted against probability of correct response on the next trial (see Fig. l), it is evident that a reinforcement does not yield equal probabilities of correct responses on the following trial for fast and slow learners. In fact, fast learners apparently gained about twice

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as much associative strength per reinforcement over the initial rising portion of the curve. Underwood determined the lines of best fit for the fast and slow data, and then equated the resulting scales by superimposing them on a common abscissa (number of reinforcements during learning necessary to produce a given probability of correct response). He then found the proportion of items recalled by the separate groups for various values along the abscissa and plotted these proportions (probability of correct response at recall) on the ordinate. T h e resulting curves showed

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(a) that for both groups, probability of recall uniformly increased with increases in final associate strength, and (b) the curves were essentially identical. Underwood concluded that there is no differential memory apparent after 24 hr when original learning (initial associative strength) is equalized for fast and slow learners. Further pursuing his methodological criticisms, Underwood (1964) examined the situation in which original learning is carried to a specified criterion, but acquisition curves approach the common criterion level at different rates. If differences on a retention test are to be validly ascribed to a retention interval effect, it must first be shown that no differences would have been found in an immediate test of memory. One method of assuring equality of original learning has already been described

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above as the “successive probability analysis of learning” (termed “multiple-entry projection” by Underwood, 1964). Another method, which is statistically far less involved than the multiple-entry projection method, would be to maintain immediate memory control groups. These would receive one trial beyond the criterion trial, thus constituting a measure of immediate retention against which the long-term memory scores would be compared. Since the learning curves approach the criterion level at different rates, it is assumed that performance on one trial past criterion would be higher for the steeper curve. This is what was found. Furthermore, Underwood found that when statistically different mean retention scores are compared to means for immediate memory control groups, rates of long-term forgetting were not significantly different for easy and difficult materials. I n view of these results, it seems imperative that research involving criterion performance employ either the multiple-entry procedure or the super-criterion control groups in assessing level of original learning. The method of equal opportunity to learn also requires special procedures for equating or evaluating original learning. Underwood (1964, p. 114) points out that “. . . determination needs to be made of the number of correct responses which would have been given had there been another trial.” This specifies that long-term retention must be measured against an immediate test which is not actually administered to Ss who will eventually contribute scores on a long-term memory test. To satisfy this condition there are again two procedures available. Control groups receiving one trial beyond the limit imposed on experimental Ss would yield point estimates of immediate memory similar to those derived from the super-criterion controls described above. The alternative is a method of extrapolating the acquisition curves beyond the levels attained when learning was terminated. The advantages of this “singleentry projection” method are the savings in laboratory time and the possibility of predicting not only average scores, but individual scores as well. The procedure requires the computation, based on all items for all Ss, of the probability of correct response on the projected trial following various numbers of previous correct responses. T h e individual S’s score is then predicted by examining his item-by-item performance and assigning probabilities according to the group standards. This procedure results in an accurate prediction of performance on later trials; and, incidentally, forces the conclusion that “characteristics of S, other than those involved in producing differences in degree of learning, are of relatively minor importance in forgetting” (Underwood, 1964, p. 117), a finding consonant with Underwood’s (1954) equal criterion study. The major difficulty of the single-entry projection technique is in

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coping with asymptotic performance. Predicted scores are the same for all items reaching asymptote. Underwood has shown, moreover, that recall of items which reached asymptote is dependent upon the number of trials on which an item was given at asymptote. T h e projection technique is thus insensitive where complete learning occurs under equal opportunity training conditions. The solution suggested to meet this problem was to determine in a pilot study the different learning rates involved, and then to adjust the difficulty of the task to the point where all Ss could be stopped at a point of equal, yet imperfect learning, with mean projected values roughly equated over groups. The retention data would then be compared with projected scores, with the detemination of forgetting being based on percent loss. Underwood concluded that this method of single-entry projection with equated learning is the method of choice in retention research, with the major reservation that, since no assessment can be made of gains in associative strength accruing to overlearning, the method must be applied at equal levels of imperfect learning. Keppel (1965) reported Shuell’s ongoing research in which this method of equated, imperfect learning was being used to study short-term memory in fast and slow learners. Shuell first administered a pretest in which 30 words were presented at the rate of 2 sec per word to 99 fifth graders. Free recall was then elicited with a 4-min time limit imposed. Four and a half weeks later, the 36 highest and lowest Ss were given a new list at either 1-, 2-, or 5-sec presentation rates. Recall scores revealed that the mean number of words retained by the fast group after 1-sec presentations was equal to the mean following the 5-sec rate for slow learners. The third stage involved presenting lists to fast learners at the 1-sec rate and to slow learners at the 5-sec rate, and tapping free recall at various retention intervals. Keppel (1965, p. 8) noted that “since . . . these two rate-group combinations would be equal immediately following presentation . . . any differences in retention functions would be attributed to differences in subject ability.” Although this procedure attempts to equate learning by manipulating rate of presentation, it is not free of alternative interpretations. T h e initial selection procedure, as described by Keppel, appears to have been based upon performance following learning. I t may be that the high and low Ss had all entered the initial 4-min retention test with equal learning, and had then been selected for their different retentive capacities over this period, which was relatively long in view of the intention to study short-term memory. Were this so, the two groups would later be tested for the very capacity for which they were originally selected. Since Shuell seems to have provided no safeguard against this

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contingency, a finding of poor “slow” group performance o n the memory test could not be interpreted clear!y. Keppell reported that neither fast nor slow learners showed forgetting over the short retention intervals used by Shuell. Thus, unfortunately, short-term memory functions could not be assessed. Despite Shuell’s attempt to equate learning, her research does not seem to satisfy Underwood’s requirements because no clear assessment of immediate memory appears to have been achieved. To the author’s knowledge, no study of memory using Ss of different ability levels as the principal independent variable has been done according to Underwood’s suggestions, except Underwood’s own work (1954). T h a t single study showed that Ss of high and low learning ability show no retention differences after 24 hr. Moreover, reinforcement for a correct response was found to result in unequal increments in probability of a correct response for the fast and slow learners. Although he favored the interpretation that reinforcement adds different amounts of associative strength, Underwood was quick to acknowledge an alternative possibility. Reinforcement may indeed add equal associative strength for all Ss, but slow Ss may have a short-term memory deficit which asserts itself between successive presentations of an item, lowering the slow learner’s probability of correct response despite initial equality of associative strength among all Ss. Of course, a reasonable choice between these options will be available only after careful study of the short-term memory functions of fast and slow learners has been accomplished. C. Conclusions

I t seems appropriate to conclude this section on methodology in long-term memory research with the discussion of Underwood’s work. He has crystallized several operating principles which resulted both from careful consideration of his data and keen awareness of problems which have long plagued the field. These principles may be abstracted as follows: (a) level of learning, defined as probability of performance, must be equalized for all Ss, especially where S variables are being studied independently; (b) the optimum level of learning must be less than maximal at the beginning of the retention interval; and (c) there must be a criterion against which retention test performance will be judged. This criterion should take the form of a reliable evaluation of what Ss would have done had there been no retention interval, thus permitting an evaluation of the retention interval effect per se. Implied in these statements are other problems critical to retention 1

Keppel, G., personal communication, 1965.

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research: (a) the original learning phase must be regulated to yield sufficient acquisition data for all Ss before asymptotic performance is reached, yet asymptotic performance should be avoided. Shuell’s attempt to provide carefully selected tasks graded to S ability illustrates the application of this principle; and (b) the retention test conditions must be identical to the conditions prevailing at the time of immediate memory assessment. This requires that retention be measured by administration of the same task, or at least by a task on which performance does not rely upon factors other than those influencing original learning. T h e focus of the following section is upon critical examination of research on memory in the mentally retarded. It seems fitting to point out here that only one of these studies has operationally acknowledged Underwood’s modernization of the classical concepts of retention research as they are epitomized in Gillette’s (1936) report. For this reason the criticism of these studies will seldom be found to reflect directly the criteria for memory research suggested above. An attempt has nonetheless been made to relate the problems encountered by each study to the critical framework established here. IV. RETENTION RESEARCH WITH RETARDED SUBJECTS

Lott’s (1958) study was the first to explore long-term memory using separately identified mentally retarded subgroups. Her purpose was to establish a standardized series of learning tasks with which to distinguish objectively between normals and defectives. T h e basic hypothesis was that in learning, generalization, and memory, superiors would exceed normals, and normals would exceed retarded Ss. Lott established three groups of 23 Ss each, with mean IQs of 68, 99, and 123, and mean chronological ages (CA) of 14-5, 14-3, and 13-4, respectively. T h e Ss were given a seven item paired-associates learning task (pictures of common objects) with stimuli presented for about 8 sec. All Ss were brought to a criterion of four perfect trials. Immediately following original learning, pictures similar to the stimulus items were shown as a test of generalization. One week later 12 Ss from each ability group were given the original learning task as a test of memory. Following one nonreinforced run through the list, Ss relearned to a criterion of one perfect trial. T h e remaining 11 Ss from each group were given this memory test after 1 month. Lott’s X2 analyses yielded no significant differences among the groups on original learning, generalization, or 1-week or 1-month relearning. Several problems of method in this study may be cited in addition

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to those which Lott acknowledged. A generalization test, involving stimuli similar to those of the original learning task, was introduced directly after original learning. This procedure may have had retroactive interference effects which could not, however, be evaluated independently of the retention interval effect because all Ss received the interpolated task. A t test analysis of Lott’s original learning data (Lipman, 1963) showed significant differences in trials to criterion, and 1 week retention scores. The X 2 had not shown these differences. Whether or not they differed significantly, the mean trials to criterion for superior and retarded groups (5.3 and 7.5, respectively), indicate that all Ss found the task very easy. The superior Ss, who performed perfectly after an average of about one trial, were thus liable to a floor effect. Relearning differences would therefore be difficult to interpret. Cantor and Ryan (1962) employed Lott’s basic designed, but increased the number of paired associates to 12. Their Ss were 20 retarded children (mean IQ: 72; mean CA: 9-2) and 24 normal kindergarten children (mean CA: 6-5). Each stimulus was presented alone for 6 sec followed by a 5-sec S-R exposure, with a 2-sec inter-item interval. Practice was continued to a criterion of two perfect runs through the 12-item list. The retention intervals were again 1 week and 1 month. Half of each group was tested (relearning to original criterion) at each retention interval. Prior to relearning S went through the list, naming stimuli and responses. All anticipations given during this trial were reinforced, but no record was kept of such reinforcements. Although the task was much more difficult than Lott’s, the results corroborated the earlier findings in that no significant original learning differences were observed. Mean trials to criterion were 13.5 and 15.1 for retardates and normals, respectively. Mean trials to relearning (and SDs) for retardates and normals were, respectively, 5.00 (4.83) and 4.92 (5.73) at 1 week, and 3.70 (2.36) and 4.50 (2.75) at 1 month. Although there were no significant differences between the two samples at relearning, it is clear from the means and SDs that floor effects were operating, especially in the normal sample, to obscure the meaning of these relearning scores. Further work on memory of paired associates was done by Jensen and Rohwer (1963b). In an earlier study (Jensen & Rohwer, 1963a), these authors found that having S make sentences involving both stimulus and response terms greatly facilitated paired associates learning. In the next study (Jensen & Rohwer, 1963b) the authors emphasized the effects of verbal mediation of this sort upon memory. The Ss were 20 male and 10 female retardates located in a sheltered workshop setting. Experimental and control groups of 15 Ss were selected such that mean IQs were 55 and 54, respectively: mean CAs were both 27-6. The learning

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materials comprised six boxes and six pairs of models of common objects. All Ss first memorized the six response objects, separate from the stimulus objects. The control Ss were then shown the stimulus and response objects as pairs, and were required to name ,the objects of each pair. They then learned the paired-associates, stimulus objects being fixed to the box lids, and response objects remaining hidden within the boxes. The E lifted the lid, exposing the stimulus, and S was required to name the hidden response object. T h e experimental group learned in the same manner, with the modification that during the S-R naming period S repeated a sentence containing the names of both objects (e.g., “the cup wore glasses”). Both groups learned to a criterion of one perfect run through the boxes. Memory was tested 1 week later by relearning to the original criterion, without reintroduction of mediation sentences for the experimental group. Original trials to criterion were 3.53 and 16.33 for experimental and control groups, respectively; relearning scores were, respectively, 4.93 and 7.40, a nonsignificant difference. This is an example par excellence of a floor effect operating to the disadvantage of the experimental group. Even if the original task were made considerably more difficult for this group, as the authors suggested, this paradigm would still not yield clear information about the retention functions of mediation and nonmediation groups. Because no mediation instructions were delivered at the beginning of relearning, the retention interval effect was confounded with the effects of varying instructions. If the purpose of the research is to determine the effects of verbal mediation upon retention of the materials, then every effort must be made to provide constant testing procedures at each stage of the study. This is not to disparage either the intent or the original learning findings of the Jensen and Rohwer study, however. I t has been shown elsewhere (Underwood, 1954; Underwood, 1964) that some variables which affect learning do not affect retention. It may be that mediation does affect both processes, and possibly interacts with ability level as well. Since it has been established that mediation facilitates learning, the logical next step would seem to be to equate original learning performance for four groups, mediation and nonmediation normals and retardates, and to observe the resulting effects upon memory. O’Connor and Hermelin (1963) studied the effects of frequency and intensity of presentation of high and low associates in a paired-associates paradigm, using normal and severely retarded Ss with equal mean MAS. Samples of 40 normals (mean CA: 6-10) and 40 retarded adults (mean IQ: 46.4; mean CA: 22-0) were each divided into four groups of 10. Each group received one of the fous combinations of either high or low intensity of aural presentation (55 or 90 db on a 4 0 4 5 db ambient back-

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ground level) and either 10 or 20 presentations. T w o lists of six wordpairs were tape-recorded. T h e stimulus terms, common to both lists, were Dark, Man, Table, Deep, Soft, and Mountain. List I had high associate response terms (Night, Work, Eat, etc.). List I1 had low associate response terms (Light, Woman, Chair, Shallow, etc.). It should be noted that “high” associate refers to free association responses commonly given by children, while “low” associates are those commonly given by adults. Five Ss from each group were exposed to each list, which was simply played over the tape recorder with 5-sec inter-pair intervals and 1-sec S-R intervals. T h e presentation intensity was controlled by having S sit a t one of two distances from the tape recorder. T h e Ss were instructed to learn the words as pairs, but S did not actively participate, having only to listen and remember. Retention intervals were 1 min, 2 days, and 1 month. All Ss were tested at all retention intervals. T h e retention test involved the presentation of the stimulus words with 15-sec inter-word intervals, during which S was required to supply the appropriate response word. Stimuli were presented at original intensities. T h e four major findings were: (a) there were no significant differences between lists on original learning; or (b) between IQ levels on original learning; or (c) over retention intervals; however, (d) it was found that 20 presentations were significantly more conducive to learning than 10 presentations, and the 90 db-20 presentations combination was better than 55 db-10 presentations. T h e authors noted that since frequency of presentation did not interact with the retention interval effect, frequency appears to affect original learning, but not recall. And, since no normalretardate differences were observed, it was concluded that “provided material is learned well it is relatively well retained by (severely retarded), compared with normal children of like sex and mental age” (O’Connor & Hermelin, 1963, p. 84). I t is interesting to speculate what conclusions would have been drawn had O’Connor and Hermelin run separate analyses for each intensity level while maintaining the frequency of presentation dimension. T h e authors had noted the normals’ tendency to reminiscence, and the retardates’ tendency to forget over retention intervals. These trends are clearly present under both 10 and 20 presentations in the 90-db group, yet they are absent in both frequency conditions under 55-db intensity. T h e repeated measurements may well have differentially affected successive test performances in normals and retardates, even though no feedback was given. Also, with so few items, a floor effect may have been operating. T h e indication was that frequency of presentation does not affect retention. With immediate memory equalized by appropriately varying frequencies of presentation, however, it is nonetheless possible that different retention interval effects

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will be seen with normals and retardates; and these effects may interact with original intensity of presentation, or intensity of presentation relative to ambient noise level. T h e paired associates method was used by Heber, Prehm, Nardi, and Simpson (1962) to study the effects of varying task difficulty and degree of learning. Their Ss were 72 normal elementary school children (mean CA: 9-7; mean MA: 10-8; mean IQ: 110) and 72 public school special class children (mean CA: 12-0; mean MA: 8-4; mean IQ: 70.4). T h e learning materials were nonsense figure-CCC trigram pairs, arranged in three lists comprising 3, 5, and 8 pairs, respectively. List length determined task difficulty. Degree of learning was varied by having half the Ss in each ability group-task difficulty combination learn (by adjustment procedures) to a criterion of three correct anticipations of each trigram (3-criterion); the other half learned to a gaiterion. Retention was tested by relearning 24 hr and also 6 months after original learning. T h e experimenters found that normals originally learned the task significantly faster than the retarded Ss, even when MA was partialed out in a covariance analysis. Retention was evaluated by covariance analysis of trials to relearning, with trials to original learning as the predictor. This procedure purportedly measured retention directly by partialing out original learning performance. At 24 hr, normals relearned significantly faster than retardates. This difference did not interact with task difficulty, but it did interact with original level of learning, being wholly contained in the minimal learning (3-criterion) groups. T h e 6-month retest gave similar results, suggesting the conclusion that “these findings, therefore, highlight the importance of retention as a deficit in the performance of the mentally retarded” (Heber et al., 1962, p. 9). In view of the criteria set forth in this chapter, however, these conclusions are unjustified. Although the covariance technique is appropriate in evaluating relearning independently of original learning speed, this kind of analysis does not guarantee equal levels of original learning for retarded and normal Ss, even when used in conjunction with an adjusted learning procedure. Interpretation of later relearning is obscured without appropriate control Ss, or some other independent assessment of original learning. Vergason (1964) also used paired associates to study the effects of varying level of original learning. His Ss were 64 retardates (IQ: 60-75) and 64 normals (IQ: 90-110); all Ss fell without a CA range of 12-0 to 16-5. Half the Ss of each ability group learned a list of 13 paired pictures of common objects to a 1-criterion by adjusted learning. T h e other half of each group learned the same list to a 5-criterion. Half of each of these original learning level groups then relearned to original criterion

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after either one or 30 days. Criterion scores were: (a) original trials ‘to criterion; (b) trials to relearn; and (c) percent savings. Vergason found no ability level difference on original learning. He did find, however, that the l-criterion was achieved significantly faster than the 5-criterion, even with original learning adjusted by subtracting one and five respectively from the 1-criterion and the 5-criterion scores. For the one day reten tion groups, normals were significantly superior to retarded on percent savings in both the 1- and 5-criterion groups, and the 5criterion bettered the l-criterion. For trials to criterion, normals were still superior, but there wa5 no difference between levels of learning groups. At 30 days, percent savings scores showed that the 5-criterion was still superior to the 1-criterion, for both ability groups, but the normals no longer surpassed the retarded Ss. Trials to criterion, on the other hand, showed a significant interaction of level of learning and ability group. With percent savings scores, this interaction reflected better learning in the normal groups with the I-criterion, but n o differences between ability groups with the 5-criterion. Several difficulties arise in interpreting Vergason’s results. First, if original learning trials to criterion had really been equal for ability groups, he should have found no differences between analyses of percent savings and trials to criterion on relearning. It is therefore difficult to understand the contradictions between percent savings and trials to criterion scores at 30-day retention. Vergason discovered a nearly significant interaction with percent savings, confirmed its significance by analysis of trials to relearning, and then sought the source of the interaction by reexamining percent savings scores. Such a statistical practice is hardly justifiable. Second, the differences between analyses of 24-hr percent savings scores and trials to relearning for the two levels of learning probably reflect no more than the original learning differences between the two groups. Third, in view of the original learning trials to criterion (about 6 trials on the average for all groups), a floor effect appears to be working against both ability groups. Fourth, the adjusted learning procedure is intended to equalize original learning, but its success cannot be guaranteed without appropriate immediate memory control groups. It would be predicted from Underwood’s (1954) work with normal fast and slow learners that bringing all Ss to a common original learning criterion would not result in equal learning for normals and retardates. Ellis, Pryer, and Barnett (1960a) have confirmed one of Underwood’s findings, demonstrating that normals and retardates d o indeed show differential probabilities of correct response accruing to equal numbers of reinforcements. Moreover, they found that the difference in the probability of a correct response diminishes over successive

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reinforcements. Several problems of method confound the interpretation of Vergason’s findings. However, if overlearning is defined by extended numbers of reinforcements in a paradigm such as that of Vergason or of Heber et al. (1962), and overlearning is found to reduce retention differences between ability groups, the reduction would likely reflect the Ellis et al. (1960a) finding of a decreasing difference in probability of correct response with increasing reinforcements. Such a decrease would reveal nothing about retention. Lance (1965) added a meaningfulness dimension to Vergason’s basic design. The Ss were 64 retardates (IQ: 60-80) and 64 normals (IQ: 90-110). The CAs for all Ss fell within a range of 12-0 to 16-5. Learning materials were two lists of CVC-digit pairs, with high associate (high meaningful) CVCs in one list, and low associate (low meaningful) CVCs in the other. The Ss spelled the low associates and named the high. Like Vergason, Lance brought separate subgroups to either 1- or 5criterion by an adjusted learning method. A 30-day retention interval was used with all Ss. Relearning was to the original criterion. On original learning, there were significant differences on all dimensions and no interactions. Normals learned faster than retardates, the high meaningful list was learned faster than the low, and the 1-criterion was achieved sooner than the 5-criterion. On trials to relearning the same relations held, again with no significant interactions. The analysis of percent savings, however, revealed no ability or level of meaningfulness differences, leaving only the difference between the two levels of original learning. But the difference now favored the overlearning group. This difference is ascribable to bias against the minimum learning group because of the floor effect. And, since the differences found in trials to relearning directly reflect those found for original learning, Lance’s study appears to have yielded no direct information about the effects of overlearning or meaningfulness upon memory. Pryer (1960) used a serial anticipation procedure to study retroactive interference as a function of temporal position of the interpolated task. Although this study focused only indirectly upon memory, Pryer maintained retarded and normal control groups which received no interference task. For these groups, the procedure approximated a straightforward memory study. The Ss were 75 institutionalized retardates (mean CA: 22-1; mean IQ: 59.5) and 75 high school students (mean CA: 16-1; mean 1Q: 102.7). All Ss learned an initial list of 10 common words to a 1-criterion by serial anticipation with memory drum presentation (2 sec exposure rate). At four later times (30 sec, 5 min, 30 min, or 2 hr) 15 Ss from each ability group learned a second list comparable to the first. T w o control groups of 15 Ss received no second task. All Ss returned

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24 h r after original learning to relearn the original list. Pryer found large mean differences between ability levels on original learning (8 VS. 18 trials to criterion). For normal controls the mean 24-hr relearning score was 2.9; the mean for retarded controls was 6.1. T h e percent savings for normals and retardates were thus 63.6 and 65.9, respectively. Analysis of covariance, with original trials to criterion as the predictor, yielded no significant differences between these percent savings scores or among those of any of the interference groups. It should be clear from previous critiques that, for present purposes, the study is weak in at least two respects. First, there appears to be a floor effect, biasing the results against the normal Ss and impairing interpretation of the observed nonsignificant differences. Second, since original learning was not equated, differences at relearning would be inconclusive, regardless of floor effects, It will be noted that the analysis of covariance was used to evaluate the influence of original learning differences, and, indeed, the authors concluded from this analysis that differences in relearning did not reflect a memory phenomenon. I t should be reemphasized here, however, that the covariance technique is a statistical control, and by no means represents an equation of original probabilities of correct responding. Johnson (1958) also studied serial learning and retention. T h e Ss were 30 normals (mean CA: 9-4; mean IQ: 100) and 30 retardates (mean CA: 13-6; mean MA: 9-4). All Ss were carried to a 2-criterion on a list of 6 nonsense syllables presented by memory drum. Recognition recall, anticipation, trials to relearn, and savings were tested following retention intervals of 1 and 2 weeks. These scores derived from two memory tasks: first, S was shown 72 nonsense syllables and asked to underscore the ones he had learned on the original learning task. Then he was given the original task to relearn. No significant IQ level differences were found on original learning, mean trials to criterion being 18.7 and 22.2 for retarded and normal Ss, respectively. After 1 week, the retardate’s anticipation recall scores (number of items anticipated correctly on first relearning trial) averaged 1.83; the normals remembered about 2.57. T h e difference was not significant. Trials (and SDs) to relearning a t 1 week were 6.57 (3.26) and 6.30 (4.32) for retardates and normals, respectively. These 1-week relearning scores suggest a floor effect in the normal group which may have biased the memory test against them. This effect is especially evident when it is noted that the minimum possible relearning score is 2.0, indicating that the mean for normals fell only one SD above the minimum. Another problem, arising uniquely in this study, is that of assessing the effects of presenting the recognition task just prior to relearning. Griffith (1960) has shown a positive relation

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between IQ and recognition ability. Johnson noted a nonsignificant difference in recognition scores favoring the normal Ss. T h e effect of this exposure to learning materials along with highly similar irrelevent materials, is uncertain, and therefore presents a possible contamination. This clearly illustrates the desirability of providing a retention task which is essentially identical to the original task. Ellis, Pryer, and Barnett (1960b) reviewed Gillette (1936), Leavitt (1945), and Underwood (1954), and concluded that “variables other than learning rate may influence amount retained” (p. 83), suggesting retroactive inhibition and reactive inhibition as variables which may be operating on retention and learning, respectively. Their study was intended to explore learning and retention phenomena which might reflect the operation of variables like these. Their Ss were 80 institutionalized retardates (mean CA: 16-5), and 80 high school students (mean CA: 16-5). All Ss received 20 20-sec trials on a pursuit rotor. Inter-trial interval was 20 sec. After a 5-min rest, this procedure was repeated. Half of each ability group returned after 24 hr; the other half returned after 28 days. T h e retention task consisted of 10 more trials on the pursuit rotor. Forgetting was defined as a loss in performance (time on target) from the last trials of the first session to the first trials of the retention session 1 or 28 days later. N o forgetting was observed in any group after any rest interval, except for a slight effect on the first trial at 28 days. This loss was equal for retardates and normals, but greater for retardates relative to amount learned. Typical of motor learning experiments of this kind, was a reminiscence effect in all groups after the 5-min rest and the one day rest. When postrest gains were compared across ability groups, it was found that normals were superior to retardates after all rests. This suggests that normals suffer greater buildup of reactive inhibition during learning. Because it was too closely bound to the complex of reminiscence and warm-up effects, Ellis et al. (1960b) were reluctant to interpret the slight loss at 28 days as clear forgetting. T h e authors recommended future use of longer retention intervals and experimental designs in which inhibition (a learning phenomenon) would not be confounded with forgetting. I t might be added that one way of achieving such an equation of learning would be to adjust the speed of rotation or the size of the target of the pursuit rotor until ability groups were equated on time-on-target, given the same amount of practice. Wischner, Braun, and Patton (1962) used object-quality learning set as a unique approach to retention in retarded Ss. Their Ss were 32 retarded school children sampled from three CA ranges: 7-4 to 9-5 ( N = 10); 9-6 to 11-7 (N = 10); and 12-4 to 13-11 ( N = 12). Mean IQ was 67.7; mean MA was 7-5, and ranged from 4-5 to 11-5. T h e equipment

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consisted of a modified Wisconsin General Test Apparatus used with laboratory-fabricated objects of varying shape and color. T h e S was presented with two distinct objects, one of which was arbitrarily designated as correct. If S chose the correct object, he was rewarded with candy. T h e pair was presented twice more, with the position of the correct object randomized. T h e three presentations of a pair constituted a problem. Each new problem involved a new pair of objects. Twelve problems were given each day for 10 days, or until S solved all the problems given on any one day. Solution involved making correct choices on the second and third trials of each problem. After a retention interval ranging from 5 to 7 months, and averaging 6 months, all Ss returned for 2 more days of testing (25 new problems). Evidently Ss were not required to remember concrete information (i.e., specific solutions to specific problems) but rather a general conceptual mode of attacking all problems involving one correct and one incorrect stimulus. Retention scores (problems solved) for Ss who had met the original learning criterion showed an average loss of 18% (2 problems out of 12) on the first day of retention testing. By the second day these Ss were again making 100% correct responses on trial three. T h e authors concluded that “in view of certain attitudes about the poor retention capacity of retarded Ss generally, the rather excellent retention of the object-quality (learning set) after 6 mo. deserves emphasis” (p. 522). A normal comparison group showing equal losses over 6 months would have lent considerable support to this conclusion. T h e problems of method in this study are clearly similar to those involved in other techniques used to evaluate retardate retention. Learning set formation is nonetheless a powerful tool, and one which has been greatly neglected. It has the advantage of requiring the acquisition of a learning principle, yet can be tested with discrete trials (problems), and it yields classic learning curves. T h e problem of asymptotic performance may be evaded by regulating the difficulty of the principle involved (i.e. task complexity) to give similar growth curves at several ability levels, with learning discontinued short of perfect performance. Those interested in the retention of problem solving skills (vs. concrete knowledge) may find that this technique permits good control over extraneous variables which might influence retention. T h e last study to be reviewed in this section was actually one of the first published in the area. It also appears to represent a model which will appeal both to the educator, with his interest in the retention of practical knowledge, and to the experimentalist whose interest lies in developing methodology. This study is also far and away the most complex in the field, and may be the best as well. For these reasons

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Klausmeier, Feldhusen, and Check‘s report (1959) will be discussed at some length. The study’s two hypotheses relevant to retention were: “. . . high IQ children learn rapidly and forget rapidly whereas low IQ children learn slowly and forget slowly” . . . (and) . . . “Retention . . . is the same among children of low, average, and high intelligence when the original learning task is graded to the learner’s achievement level” (Klausmeier et al., 1959, p. 3). T h e Ss were 40 low IQ students (range: 55-80), 40 average IQ students (range 90-110) and 40 superior IQ students (120+). At each point in the study (which lasted 2 years) the CAs were equal across ability groups, starting at an average of 8-6. A common problemsolving task was used to test the first hypothesis. All Ss were given a pile of pennies and required “to divide (them) so that there are the same number of pennies for each of your seven friends” (p. 26). T h e Ss were given help at specified intervals during the 20-min maximum learning period. This help was graded in such a way that increasing hints ultimately resulted in a solution given, even if by rote, by all Ss. T h e acquisition score was time to solution (20 min maximum). Immediately following this learning period was a 5-min rest, during which Ss looked at pictures or conversed with E. Five-min retention was tested, using identical materials and instructions. Help was again given to permit all Ss to finish. A 7-min maximum performance time was imposed. Six-week and 12-week retention were tested in the same way. The retention score was taken as the ratio of time of original learning to time of relearning. It will be noted that the maximum possible learning and relearning score (in seconds) would be 1200 and 420, respectively. A retention ratio of 3:l would therefore be expected of all nonlearners. Similarly, a ratio of 1:l would be expected of all Ss whose learning and relearning times were both a flat 2 min. The actual learning and 5-min relearning times (and SDs) were 631 (235) and 297 (126), 235 (161) and 116 (58), and 238 (175) and 88 (55) for the low, average, and high I& groups, respectively. Average ratios would be about 2:1, 2:1, and 3:1, respectively. T h e authors found no significant differences among ability groups for the 5-min, 6- or 12-week retention tests. Because (a) there was no way to evaluate the effects of varying degrees of help at each test, (b) learning was unequal across ability groups at the outset, (c) a very high learning-relearning ratio is expected of nonlearners because of the time limitations imposed, and (d) very fast learners are penalized by the ratio measure, it seems clear that the work with the common problem-solving task yielded no data clearly appropriate for testing the hypothesis of differential forgetting rates in high and low ability groups. T h e authors generally shared this opinion.

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The tests of the second hypothesis sharply contrasted with the methodological nai’vetk of the common problem-solving task. Four types of arithmetic problems were used: (a) counting (as by 2’s, S’s, etc.); (b) problem solving; (c) addition; and (d) subtraction. The methods of presenting these materials varied slightly, but the general practice involved a pretest to determine S’s existing ability level, the pretest being followed by a learning-retention sequence with materials one grade more difficult than S’s achievement level. For counting, E first established the level at which S made two consecutive errors in counting up to the tenth step (e.g., 2, 4, . . . , 18, 20, 22). The S then spent 19 min learning to count at this level. At the end of 19 min, S was required to perform the counting, his original learning score being total correct out of 10 possible. After a 5-min rest, similar to that used in the common problem-solving task, Ss were given unlimited time to recall the same 10 items. The retention score was taken as number correct, counting being terminated if two successive errors were made. The same unaided testing procedure was used for 6- and 18week long-term retention tests. The authors daim that Ss received no formal instruction on any of the experimental tasks during the long retention intervals. On the original counting acquisition test, the mean scores were 7.55, 9.52, and 9.65 for low, average, and high I Q groups, respectively. T h e low group was found to be significantly inferior to the other two. T h e 5-min retention score showed no change. At 6 weeks all groups showed a mean loss of about two items. At 18 weeks there was no further loss. Considering the relatively large correlations of OL and all retention scores, the authors used OL as the predictor in a covariance analysis of retention data. There were no significant differences at 5 min, 6 weeks, or 18 weeks. The counting task thus upheld the hypothesis of no differences in forgetting rates when materials were graded to S’s ability. The meaning of this lack of differences is clouded, however, by (a) the obvious ceiling effect working against the true assessment of average and high acquisition, and (b) the demonstration that OL was not equal at all ability levels. The procedure used with problem-solving was roughly equivalent to that used with counting. First, a pilot series of problems (e.g., make 23 cents using 7 coins) was tested on children whose IQs were comparable to those of the experimental Ss. From this pretest a set of problems was established representing the narrow range of achievement for each ability group. During acquisition S was first given an easy demonstration problem followed immediately by the problem to be learned. If S succeeded in less than 3 min, a second, slightly more difficult problem was

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posed. Maximum learning time was 15 min. Increasing levels of help were given at 3-min intervals. Following correct solution, S listened to 5 min of recorded music and stories. He then received either the same task, or another of comparable difficulty (test of transfer). Half of the Ss in each ability group received the transfer problem. Help was given on all occasions. Criterion scores were: (a) time to original solution and (b) time to relearn. T h e maximum possible score was 900 sec, the minimum 180 sec. On acquisition all three IQ levels scored around 550 with SDs around 250. Transfer Ss found OL only slightly more difficult. After 5 min, all retention Ss scored around 100, with SDs around 300. T h e differences between transfer and retention groups were significant, but those within the two methods were nonsignificant, as shown by covariance analysis with OL time as the predictor. T h e same relations held at the 7-week retention and transfer tests, with all retention groups showing increases in learning time, and transfer Ss showing consistent decreases. These results are encouraging on two counts. First, the OL scores fell at least one and a half SDs from the possible maxima and minima, suggesting that no ceiling or floor effects were operating to confound the assessment of OL. Second, task difficulty was manipulated successfully: there were no OL differences among ability levels. These achievements met two essential criteria for a proper evaluation of later retention. Unfortunately, the retention data revealed marked floor effects. This defect is not as obvious in the transfer data, however, which nonetheless showed significant gains by all groups over each rest interval. Although the IQ effect on retention of concrete knowledge is unclear, it seems reasonable to conclude that IQ did not influence the retention of methods of problem solving (transfer). T h e addition task involved a pretest to determine the level of complexity at which S made two consecutive errors. H e was then given a maximum of 17 min to learn 10 items at that level. Overlearning was not permitted. Help was systematically given on each item. Immediately following the study period, S was given the same 10 items to work without help. Then, following a 5-min rest in which S was again occupied, the same unaided test was readministered. This test procedure was repeated 6 weeks later. A 5-min time limit was imposed on all tests including that of acquisition. Mean acquisition scores (and SDs) for low, average, and high IQ groups were 6.28 (2.78), 5.70 (2.36) and 7.38 (1 .go), respectively. T h e difference between high and average was significant. T h e 5-min retention means (and SDs) were 6.18 (2.92), 6.0 (2.57) and 7.58 (1.81) for low, average and high groups, respectively, and the means at 6 weeks were 4.80 (2.83) 3.15 (1.59) and 5.23 (3.25). From these means and SDs it is clear that no appreciable floor effects were operating

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except for the average group at 6 weeks. Covariance analyses of these retention data, with OL as the predictor, showed no significant differences among ability levels at either 5 min or 6 weeks. It is difficult to evaluate the effects of the OL difference between the average and high groups. If the average group is ignored, however, it is once again clear that the study succeeded in equating OL and in avoiding floor and ceiling effects. T h e conclusion of equal retention for high and low IQ groups over a 6-week interval seems warranted. On the subtraction test, which was quite similar to the addition task, no forgetting appeared in any of the IQ groups after 14 weeks, and all scores were equal, with possible ceiling effects appearing at various times in various groups. T h e Klausmeier et al. (1959) study appears to have come much closer than other studies to satisfying the requirements of adequate retention research. I n addition to equating OL without ceiling or floor effects, and later observing no differences in retention, it is important that retention decreased over time in all groups. This is so because unchanging retention scores might merely be reflecting an insensitive retention measure. In the two most successful subtests of this study, problemsolving and addition, forgetting was demonstrated following retention intervals of several weeks. T h e statistics used to study differences were, however, inadequate to judge the significance of forgetting. A repeated measurements design might have picked u p an interaction of IQ level and retention interval in the problem-solving task: the average group may well have lost more than the others between the 5-min and 7-week tests. Also, the effect of repeated exposure to the same materials is not assessable. Fortunately, the degree of contamination from details such as these is probably far less than that controlled by the careful attention paid to adjusting the task difficulty to S’s ability. Summary

T h e present author found 12 studies of retention in mentally retarded Ss. These studies have ranged widely and differed greatly in terms of the variables under consideration, S populations, and the materials and methods employed. T h e present summaries and criticisms have focused largely upon the degree to which these studies satisfy certain methodological criteria. It was found, by and large, that most suffered, in varying degree, frgm one or many weaknesses which cloud interpretation. Failure to demonstrate equal original learning, or even to evaluate degree of original learning, was a principal source of weakness. Floor and ceiling effects were also found to be critical limitations in several studies. Failure to demonstrate retention was another shortcoming. T h e single study

John M. Belmon which seemed to overcome these problems found that normals and retardates were equal in long-term memory. V. DISCUSSION

In reading recent studies on long-term memory in mental retardation, one can detect a feeling of great confidence in the reliability of procedures and measures. This is partly conveyed by an eagerness to go well beyond ability level in the study of variables which might influence retardate memory, such as meaningfulness of the learning materials, degree of learning, and length of retention interval. T h e attitude appears to be that a catalogue of such variables would give a wide and meaningful picture of retardate limitations. Elaborate experimental designs have evolved parallel to the current tendency to discount simple paradigms which, after all, are supposed to yield little generality. In one sense the workers have kept abreast of developments outside their area, viz., in a vague way they seem to appreciate the value of statistical precision. In other ways, however, most studies have remained surprisingly unsophisticated. Unfortunately, in this field, which has evolved in the brief period since 1958, researchers have labored in ignorance of important developments outside their area: developments that represent potent tools for studying retardate memory. This technological lag places the field about 25 years behind the times. Between 1958 and 1962, with one notable exception (Klausmeier et al., 1959), most problems were researched in the fashion of t5e 1920’s. Since 1962, memory research has acknowledged Gillette’s (1936) refinement of Woodworth’s (1914) adjusted learning procedure. But, with the exception noted, investigators have paid no more than lip service to the stiff criticisms and strong principles voiced by Underwood (1954). Recently, these have been elaborated (Underwood, 1964) and applied to research with fast and slow learners (Keppel, 1965). Ellis et al. (1960a) have shown that learning rates in normals and retardates confirm Underwood’s (1954) findings for fast and slow normal Ss. Therefore, at least until other methods are shown to work better, i t appears that those who would compare retardate memory with that of normals are obliged to operate under the rules that Underwood prescribed. Because these rules have not been applied, the research on retardate memory has been singularly unfruitful. There is almost no solid evidence either to support or contradict the classic hypothesis of a retardate memory loss. T h e conclusion has been drawn, contrary to this hypothesis, that retardates show no memory deficit; but reliable findings are rare. Two steps are here proposed to alleviate this unsatisfactory status of

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current knowledge. T h e first would be a proper and concerted effort to compare retardates and normals within simple experimental designs. Next would be the systematic appraisal of variables which have been identified as potentially influencing retardate memory, but have not yet been adequately tested. If Underwood’s work is to be taken seriously, these studies will involve considerable pilot work to find appropriate tasks for normals and retardates. Without such tasks, memory research is bound to fail outright because strictly statistical treatments such as those used in the past cannot insure an adequate equation of original learning level. When there has been sufficient replication to warrant faith in the basic procedures (nobody has reported a single replication of a study of retardate memory), consideration might be turned to an impressive list of variables which is already long enough to hold considerable interest: difficulty and meaningfulness of materials; degree of learning; frequency and intensity of presentation; length of retention interval; ability level (as well as etiological factors); type of task (motor vs. verbal; concrete vs. abstract); relative distribution of learning; and degree of verbal mediation. ACKNOWLEDGMENTS T h e author is grateful to William H. Smith and Dr. Paul S. Siege1 for their very generous and helpful criticism of the manuscript. REFERENCES Boring, E. G., Langfeld, H. S., & Weld, H. P. Introduction to psychology. New York: Wiley, 1939. Brown, W. Effects of interval on recall. J. exp. Psychol., 1924, 7 , 469-474. Cantor, G. N., & Ryan, T. J. Retention of verbal paired associates in normals and retardates. Amer. I. ment. Defic., 1962, 66,861-865. Denny. M. R. Research in learning and performance. In H. Stevens, & R. Heber (Eds.), Mental retardation. Chicago: Univer. of Chicago Press, 1964. Ellis, N. R. The stimulus trace and behavioral adequacy. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill; 1963. Ellis, N. R., Pryer, Margaret W., & Barnett, C. D. Note on habit formation in normal and retarded subjects. Psychol. Rep., 1960, 6, 385-386. (a) Ellis, N. R., Pryer, Margaret W., & Barnett, C. D. Motor learning and retention in normals and defectives. Percept. mot. Shills, 1960, 10, 83-91. (b) Gillette, Annette L. Learning and retention: a comparison of three experimental procedures. ,drc/t. Psychol., N . Y . , 1936, 28, No. 198. Gordon, Kate. Class results with spaced and unspaced memorizing. J. e r p . Psycho/., 1925, 8, 337-343. Griffith, Ann H. T h e effects of retention interval, exposure interval and IQ on recognition in a mentally retarded group. Amer. J. ment. Defic., 1960, 64, 1000-1003. Hebb, D. 0 . The organization of behavior. New York: Wiley, 1949. Meber, R. F.. Prehm, H., Nardi, G., & Simpson, Nancy. Learning and retention of

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retarded and normal children on a paired associates task. Paper read a t the annual meeting. Amer. Ass. Ment. Defic., New York, May, 1962. Henderson, E. N. A study of memory for connected trains of thought. Psychol. Monogr., 1903, 6, No. 23. Hilgard, E. Theories of Learning. New York: Appleton, 1948. Jensen, A. R., & Rohwer, W. D. Verbal mediation in paired-associates and serial learning. J. verb. Learn. verb. Behav., 1963, 1, 346-352. (a) Jensen, A. R., & Rohwer, W. D. The effect of verbal mediation on the learning and retention of paired associates by retarded adults. Amer. J. ment. Defic., 1963, 68, 80-84. (b) Johnson, G. 0. Comparative studies of some learning characteristics in mentally retarded and normal children of the same mental age. Syracuse, N.Y.: Syracuse Univer. Press, 1958. Keppel, G. Problems of method in the study of short-term memory. Psychol. Bull., 1965, 63, 1-13. Kjerstad, C. L. The form of the learning curves for memory. Psychol. Monogr., 1919. 26, No. 116. Klausmeier, H. J., Feldhusen, J.. & Check, J. An analysis of learning eficiency in arithmetic of mentally retarded children in comparison with children of average and high intelligence. Madison: Univer. of Wisconsin Press, 1959. Lance, W. Effects of meaningfulness and overlearning on retention in normal and retarded adolescents. Amer. J . ment. Defrc., 1965, 70, 270-275. Leavitt, H. J. The relation of speed of learning to amount retained and to reminiscence. 1. exp. Psychol., 1945, 35, 134-140. Lipman, R. S. Learning: Verbal, perceptual-motor and classical conditioning. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Lott, Bernice E. Paired associate learning, generalization, and retention as a function of intelligence. Amer. J . ment. Defic., 1958, 63. 481-498. Luh, C. W. The conditions of retention. Psychol. Monogr., 1922, 33, No. 3. Lyon, G . 0. The relation of quickness of learning to retentiveness. Arch. Psychol., N.Y., 1916, 5, No. 34. McCeoch, J. A. The psychology of human learning. New York: David McKay, 1952. Munn, N. L. Psychology. (2nd ed.) New York: Houghton MiWin, 1951. Norsworthy, Nancy. Acquisition as related to retention. 1. educ. Psychol., 1912, 3, 214-218. O’Connor, N., & Hermelin, Beate. Recall in normals and subnormals of like mental age. J . abnorm. SOC. Psychol., 1963, 66, 81-84. Peterson, H. A. A class experiment on individual differences in memory. J. educ. Psychol., 1925, 16, 247-250. Peterson, J. The effect of attitude on immediate and delayed reproduction: a class experiment. J. educ. Psychol., 1916, 7 , 523-532. Postman, L., & Rau, Lucy. Retention as a function of the method of measurement. Berkeley: Univer. of California Press, 1957. Pryer, R. S . Retroactive inhibition in normals and defectives as a function of temporal position of the interpolated task. Amer. J. ment. Defic., 1960, 64, 1004-1011. Pyle, W. H. Standards of mental efficiency. J. educ. Psychol., 1913, 4, 61-70. Thorndike, E. L. Memory for paired associates. Psychol. Rev., 1908, 15. 122-138. Thorndike, E. L. The relation between memory for words and memory for numbers, and the relation between memory over short and memory over long interval. Amer. J. Psychol., 1910, 21, 487-488.

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Thorndike, E. L. T h e influence of the chance imperfections of measures upon the relation of initial score to gain or loss. J. exp. Psychol., 1924, 7 , 225-232. Underwood, B. J. Experimental psychology. New York: Appleton, 1949. Underwood, B. J . Speed of learning and amount retained. A consideration of methodBull., 1954, 51, 276-282. 0 1 0 ~ Psychol. . Underwood, B. J. Degree of learning and the measurement of forgetting. J . verb. Learn. verb. Behav., 1964, 3 , 112-129. Vergason, G. A. Retention in retarded and normal subjects as a function of amount of original learning. Amer. J. ment. Defic., 1964, 68, 623-629. Vlaicou, 0. Capacite d’apprehension, rapidite d’acquision et puissance de retention d e souvenirs bruts. Recherches de correlation. Annie psychol., 1914-1919, 21, 171-189. Whipple, G. M. Manual of mental and physical tests. 11; Complex processes (2nd ed.) Baltimore: Warwick & York, 1915. Wischner, G. J., Braun, H. W., & Patton, R. A. Acquisition and long-term retention of a n object-quality learning set by retarded children. J. comp. physiol. Psychol., 1962, 55, 518-523. Woodworth, R. S . A contribution to the question of “Quick Learning, Quick Forgetting.” Psychol. Bull., 1914, 11. 58-59.

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The Behavior of Moderately and Severely Retarded Persons' JOSEPH E. SPRADLIN2 A N D FREDERIC 1. GIRARDEAU3 BUREAU OF CHILD RESEARCH, UNIVERSITY OF

KANSAS,

LAWRENCE, KANSAS

I. Introduction .......................................... 257 11. Respondent Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 A. Unconditioned Reflex Behavior . . . . . . . . . . . . . . . . . . . 259 B. Conditioned Reflex Behavior . . . . . . . . . . . . . . . . . . . . . . 26 1 111. Operant Behavior ..................................... 262 A. Development of Behavior 262 B. Establishing Stimulus Con 272 C. Shifting Stimulus Control 277 D. Reducing the Frequency o 28 1 E.

Practical Applications of Behavioral Principles in the Development of Adaptive Behavior ................ F. Some Perennial Problems . . . . . . . . . . . . . . . . . . . . . . IV. Conclusion ..... ................................ References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1. INTRODUCTION

The present chapter will discuss the behavior of retardates who score below IQ 50 on a standardized test. Those who score below IQ 25 will be designated as severely retarded. Those who score between 25 and 50 will be designated as moderately retarded. While the definition's of 1 This chapter is primarily concerned with research published since 1960. Articles prior to that date have been included when they are especially relevant to the topic being discussed. T h e writing of this chapter and some of the research reported were partially supported by National Institute of Child Health and Human Development grant HD 00870 01. 2 Field Director, Parsons Research Center. Parsons State Hospital and Training Center, Parsons, Kansas. 8 Field Director, Bureau of Child Research Laboratories, Children's Rehabilitation Unit, University of Kansas Medical Center, Kansas City, Kansas.

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severe and moderate retardation are based on IQ scores, there are rather typical deficits in behavior which are correlated with low IQ scores. Severely retarded persons, especially those in residential centers, most frequently do not dress themselves, are not totally toilet trained, and in many instances do not even feed themselves. Their social reactions to people vary a great deal. Some approach adults in a clinging manner, some pay little attention to adults, and some avoid contact with the adults in their environment. Their interaction with peers and their verbal behavior frequently are quite limited. Some say a few isolated words and phrases but many exhibit no intelligible speech. Their communication with other persons is more often than not limited to crying, screaming, crude gesturing, and tugging at the person as a small child would do. Their responses to the speech of other persons are quite limited, and many do not even respond to their own names. Imitation of children or adults is often extremely limited or nonexistent. Severely retarded persons also exhibit a variety of responses to physical objects in their environment. For example, they may not respond to a toy or they may mouth the toy, attempt to rip it apart, or perhaps throw it. They spend much time engaged in such repetitive behavior as rocking, rolling their heads from one side to the other, flicking their fingers in front of their eyes, masturbating, hand wringing, and thumb-sucking. The category “severe retardation” includes people who exhibit varied behavior; however, the above behavior’s are frequently found among persons labeled severely retarded. Moderately retarded persons frequently are able to dress themselves partially, to take care of most of their own toilet needs, and to feed themselves without assistance. The social reactions of moderately retarded children to adults are somewhat more varied than those of the severely retarded, and they usually exhibit a more extensive verbal repertoire. They are frequently able to imitate rather wide ranges of adult or peer activities. They use toys more nearly like normal children and engage somewhat less frequently in stereotyped activities. In brief, they have a wider range of appropriate behavior (socially defined) which is under the control of both physical and social stimuli. Nevertheless, they fail to meet community norms. They usually do not read, and they speak with poor syntax and articulation. Arithmetic and writing skills are quite limited. Although they may dress themselves, their dress is often substandard or inappropriate. Other types of behavioral deficits which are associated with the labels of moderately and severely retarded could be listed. However, this brief description should suffice to orient the reader to the types of persons being discussed in this chapter. Estimates of the number of severe and moderate retardates range from

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.36 to .50% of the population. If these estimates are correct there is a world population of 10-15 million severe and moderate retardates, including a United States population of approximately 800,000. For clarity of presentation and usefulness to the reader, behavior has been classified into two general categories: (1) respondent behavior; and (2) operant or instrumental behavior. This classification system for behavior is based primarily on procedures used to control the behavior. Respondent behavior is elicited by antecedent events or stimuli (e.g., a light flash, a tap on a tendon). Operant behavior is controlled by its environmental consequences (Skinner, 1938). II. RESPONDENT BEHAVIOR

Respondent behavior refers both to simple reflexive behavior and to behavior developed with a classical (Pavlovian) conditioning procedure. Both unconditioned and conditioned reflexes are included under the label of respondent behavior. Examples of unconditioned reflexes are salivation to food and pupillary contraction to an increase in illumination. To establish a conditioned reflex, a neutral stimulus (e.g., a flash of light which does not elicit salivation) is presented immediately preceding an unconditioned stimulus (e.g., food) which elicits an unconditioned response (e.g., salivation). After some training trials the previously neutral stimulus (now a conditioned stimulus) reliably elicits the conditioned response of salivation. There have been very few studies regarding the respondent behavior of moderately and severely retarded persons. The studies summarized by Lipman (1963) will not be discussed in the present chapter. A. Unconditioned Reflex Behavior

Systematic descriptive studies of the reflexive behavior of moderately and severely retarded persons are noticeably lacking in the literature. The most recent book on the medical aspects of mental retardation (Carter, 1965) does not have an index entry for “reflex” and systematic data regarding reflex behavior for the clinical medical syndromes are scant. General observations that “deep tendon reflexes are sluggish” are reported for some medical syndromes (Carter, 1965). Wall, Umlauf, and Geppert (1964) stated, “Since there are no data available in the pediatric literature on muscle reflex patterns, our initial objective was to determine the feasibility of such testing in the pediatric age group.” Prechtl (1961) has discussed some neurological sequelae of prenatal and paranatal complications. In some babies born in breech presentation, he reported abnormal flexion and extension reflexes of the leg. Another

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abnormality reported by Prechtl was the "hyperexcitability syndrome." After complications which probably included disturbances in oxygen supply, he found infants to be hyperactive and easily startled, with a very low threshold for the Moro reflex. A tremor of low frequency and high amplitude was also reported. Prechtl stated that this "hyperexcitability syndrome" can have serious consequences for the mother-child interaction. Bowers, Gordon, and Segaloff (1959) reported gross observations of the myxedema reflex4 of 11 infants and children. T h e group was composed of six nongoitrous cretins, three goitrous cretins, and two children with hypothyroidism after a thyroidectomy. In all 11 cases the myxedema reflex was strongly present prior to therapy. With therapy, the reflex returned to normal before many of the other clinical signs of cretinism disap peared. Bowers et al., suggested using the Achilles reflex since the muscle is larger and longer and the prolonged relaxation is more readily a p parent. They did not report any quantitative data on the relaxation time, and they pointed out that the force applied to the reflex hammer has an effect on the resulting reflex. With a refined procedure using a Kineometer developed by Lawson (1958), Wall and associates (1964) recorded the free Achilles reflex for 3100 normal children varying in age from 20 minutes to 13 years. Fifty children were studied longitudinally, i.e., muscle reflex patterns were obtained within 24 hr of birth and repeated monthly for 15 months. T h e group data and the individual longitudinal data revealed a reliable, progressive lengthening of the muscle contraction time. The contraction time lengthened from 120 to 182 msec from birth to 13 months and stabilized at 182 msec from 13 months to 13 years. Achilles reflex contraction time for 11 hypothyroid infants and children was lengthened three standard deviations over the normal mean. With eight hyperthyroid patients the muscle contraction time was greatly decreased, i.e., 40 msec or more, faster than three standard deviations from normal. With thyroid treatment, the reflex contraction time of the hypothyroid children returned to normal and correlated we11 with improving cIinica1 status and . . have not seen a laboratory data. These investigators stated they proved case of hypothyroidism that did not have an abnormally slow reflex." Wall, et al. (1964) also studied the Achilles reflex of 276 mongoloid persons, 125 persons with spastic cerebral palsy, and 20 patients with a diagnosis of meningitis. In the mongoloid group, 200 had normal mean

".

4 The myxedema reflex can be elicited from any deep tendon and is characterized by apparently normal contraction of the muscle followed by an abnormally slow reaction time and is typically associated with hypothyroidism.

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contraction times (mean = 191.1 msec), 4 showed typical reflex patterns of hypothyroidism, and 2 had contraction times associated with hyperthyroidism. T h e diagnoses of hypothyroidism and hyperthyroidism, respectively, were confirmed later by laboratory procedures. T h e cerebral palsy group and meningitis group showed similar patterns which included three characteristics: (1) a contraction time in 85% of the cases that was shorter than two standard deviations from the normal mean; (2) a relaxation time that was shorter than the contraction time; and (3) an extremely peaked relaxation phase. McIntire and Dutch (1964) reported that 84 of 86 mongoloids examined by them showed generalized hypotonia which was manifested in all the major muscle groups. Th e hypotonia was best demonstrated when the muscle was in the resting state. B. Conditioned Reflex Behavior

According to C . M. Franks (1964), the literature regarding classical conditioning with retardates is sparse, especially in the languages of Western Europe. There are also very few studies reported in the American literature. Razran (1961) reviewed several studies from the Russian literature and apparently the “new look” in conditioning is semantic conditioning studies of the type done by Luria and his associates. According to the classification system used in this chapter, many of these are instrumental, or operant, rather than classical conditioning. C. M. Franks (1964) reported that the conclusions regarding respondent conditioning are conflicting for retardates in general. Cromwell, Park, and Foshee (1961), using retardates with an IQ range of 15-68, found n o relationship between IQ and eyelid conditionability.6 Behrens and Ellis (1962) found simultaneous eyelid conditioning to be superior with retardates, when compared with normals. There were no differences between normals and defectives with a trace conditioning procedure. There is fair agreement, according to C. M. Franks (1964), ‘‘. . . that congenital idiots form conditioned responses with great difficulty if at all (Franks, V., 1959).” In reporting a recent series of studies, C. M. Franks (1964) pointed out that conditionability is related, not to intellectual differences, but to neurological differences as far as the conditioned eye blink is concerned. Brain-damaged retardates conditioned significantly more poorly than nonbrain-damaged Ss whereas nonbrain-damaged normals and retardates conditioned and extinguished equally well. 5 Whether the eyeblink response is a respondent or operant escape response which is learned at an extremely early age is open to question. However, in this chapter it will be discussed as respondent behavior.

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Grings, Lockhart, and Dameron (1962) reported that moderately retarded Ss conditioned as well as mildly retarded Ss. The usual optimal interval of .5 sec between conditioned stimulus (CS) and the unconditioned stimulus (US) was not found by these investigators. and they reported that a 5-sec interval was as efficient as the .Bsec interval. Baumeister, Beedle, and Urquhart (1964) found no evidence for differences in Galvanic skin response conditioning between a group of normals and a group of retardates with a mean IQ of 49. Differences in conditioning as a function of CS-US interval were reported, but there was no evidence for an interaction between intelligence level and CS-US interval. It is rather clear that data are limited regarding the unconditioned and conditioned reflexive behavior of moderately and severely retarded persons. 111. OPERANT BEHAVIOR

A. Development of Behavior

Operant behavior is behavior which is initially brought under control by its consequences. The behavior is not elicited (as is respondent behavior); instead, once it is emitted, it operates on, or changes, the environment. It is instrumental in producing a consequence and frequently is labeled instrumental behavior. In contrast to respondent behavior, no eliciting stimulus can be specified for operant behavior. One can, however, arrange the environment so that the response is likely to be emitted. Once the response is emitted, it is reinforced thus increasing the probability that similar responses will occur in the future. Reinforcement refers to a stimulus change which results in an increase in the frequency of the class of behavior on which it is contingent. Reinforcement may be either positive or negative. Positive reinforcement refers to the presentation of a stimulus which increases the frequency of a response. The presentation is contingent on the response. Positive reinforcers, in general, refer to those events which people describe as rewarding, pleasant, desirable, and are often referred to as “goals” or “incentives.” For example, presentation of candy to a child who has just said, “I’m hungry,” will increase the frequency of “I’m hungry” responses under similar conditions in the future. The prompt comfort and attention of an adult to a child who makes loud cries when slightly injured may increase both the frequency of loud cries and mild injuries. This is even more probable if the child does not receive attention and comfort on other occasions. Negative reinforcement refers to the increase in the withdrawal of an aversive stimulus as a consequence of the subject’s response. The with-

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drawal is contingent on the response. Negative reinforcers (or aversive stimuli) refer to those events which people describe as unpleasant or noxious. They are frequently spoken of as things to avoid. For example, a child’s finger gets caught in a door or drawer and he calls for his mother. If his mother comes, releases the finger, and there is a subsequent reduction in pain, then on future occasions when his finger is caught, he will probably call for his mother. Two common examples of behavior developed by negative reinforcement are the covering of the ears when loud noises are presented and going into a warm house following periods of exposure to extremely low temperature. Many everyday situations include both positive and negative reinforcement procedures, and they certainly can be combined in a laboratory or practical application situation. The behavior of a child, who comes in from the cold during the winter and is given a piece of cake, is maintained by both positive reinforcement (cake) and negative reinforcement (escape from cold). For the mother who has several young children, the hiring of a babysitter so that she may go bowling may involve both positive and negative reinforcement. Not only is she praised for her bowling skills but her behavior terminates aversive stimulation arising from the simultaneous care of several children (e.g., screaming, nagging, etc.). If one is having trouble establishing a response, such as sitting in a chair, using positive reinforcement, the process might be speeded up by adding negative reinforcement to the procedure. This can be done by having a loud noise present in the room when the child enters. Sitting in the chair terminates (withdraws) the negative reinforcer (loud noise) and results in the presentation of a positive reinforcer (candy). Such a procedure is probably more effective than either reinforcer alone, providing the aversive stimulus is not sufficient to elicit strong emotional responses such as crying, screaming, and refusing to enter the room. 1. TYPES OF REINFORCERS

One of the first steps in the modification of behavior is the determination of an effective reinforcer. Most of the earlier operant studies of severely and moderately retarded children used nutritive or unconditioned reinforcers. Fuller (1949), used warm milk delivered by a syringe to condition a nonambulatory, untestable 18-year-old male to raise his right arm, Even earlier, Mateer (1918), who interpreted her work in terms of Pavlovian conditioning, reported that she had conditioned anticipatory mouth opening, using bits of sweet chocolate and sweetened water. Sweet chocolate (M & M’s) has become one of the favorite reinforcers for use with moderately and severely retarded persons (Bijou & Orlando, 1961; Ellis, Barnett, & Pryer, 1960; Orlando & Bijou, 1960; Spradlin, Girardeau.

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& Corte, 1966). While M & M’s are reinforcing for many retardates, there

are some for whom they are not. This same comment, however, could be made about any other single nutritive. For this reason, some experimenters use a mixture of candies and other nutrients as reinforcers (Bijou & Orlando, 1961; Orlando & Bijou, 1960; Spradlin et al., 1966). The use of a mixture of nutrients has the advantage of increasing the chances that an effective reinforcer will be included. However, it has a disadvantage. While the feeder delivers something on a specified schedule, the S may be reinforced on some very different schedule. For example, suppose the equipment is wired to deliver a reinforcer after every 25 responses (FR-25). An equal mixture of four types of candy is used. Suppose further that the S rejects two of the four types of candy. I n this case, the effective schedule is not a simple FR-25, but presentation of the conditioned reinforcers (houselight dim, relay click, etc.) on an FR-25 schedule and presentation of the effective food reinforcer on a variable ratio 50 (VR-50) schedule. In other words, every 50 responses (on the average) is followed by a reinforcer which the S consumes. For a short term study involving few reinforcements, it is possible to simply present various foods to a child until you find one which reinforces. This is a fairly easy discrimination for the E . If the S eats the food, smiles and reaches, begs, or sticks out his tongue for more, you probably have an effective reinforcer. Hollis (1962) used a limited version of the above procedure to select a reinforcer for use in training severely and moderately retarded persons to work a bent-wire problem. Hollis offered each S Coca-Cola or mints and used the one which the S responded to more appropriately. This procedure was generally effective; however, there were Ss for whom this procedure (or reinforcement selection) was inadequate. Watson, Lawson, and Sanders (1965) studied the edible (candy and food) and manipulable (movies, sounds, mechanical toys) reinforcement preferences of 14 moderately and severely retarded children (mean CA = 11-0 years and mean IQ = 23). Ss were given poker chips which could be exchanged for any one of five types of candy or the operation of a tape recorder, movie projector and screen, or any one of five mechanical toys. One poker chip would produce either a piece of candy or 10 sec of music, viewing a movie, or movement by a mechanical toy. Initially there was a preference for the manipulables but, over 13 sessions, there was no evidence for a difference between the two classes of reinforcers. Among the manipulables, music was preferred significantly more than the other six alternatives. Spradlin et al. (1966) compared six types of food reinforcers (grapes, maraschino cherries, corn chips, cheese sticks, M & M’s, and mints) for

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five severely retarded Ss. Each S received five 20-min sessions on FR-25 with each food. As a group, these Ss did not show food preferences; however, it should be remembered that the fixed-ratio schedule is a powerful, controlling schedule which is not affected greatly by moderate variations in amount of reinforcement. Moreover, variability in deprivation might mask any type of reinforcement effect. Most of the studies using nutrients as reinforcers have not controlled deprivation or have used extremely mild deprivation puller (1949) used 15 hr]. Spradlin et al. (1966) studied the effects of mild deprivation (17 hr) on the response frequency of three severely retarded boys. Frequency of response increased for two of the Ss but did not for a third S until the reinforcement was shifted from corn chips to M & M’s. Work has been conducted at Parsons with two severely retarded children who, when they received their meals in the regular dining hall, would make few, if any, responses for candy, milk, and other nutrients.6 However, these Ss would respond for prolonged periods of time when the major portion of their daily diet was obtained by performing in the experimental setting. The first S was simply given her regular diet of milk, potatoes, meat, etc., in the experimental setting. The S performed rather well for regular food. However, regular food has two major disadvantages: (1) it is not easily dispensed; and (2) more importantly, the caloric intake per meal is difficult to determine. Furthermore, there is no way to insure a balanced diet. In order to overcome these problems, Metrecal cookies and liquid were substituted for the regular meal and vitamin supplements were given. The first S was shifted to Metrecal. The second S was started on Metrecal at the beginning of the experiment. For the first few meals both Ss were somewhat slow in responding to Metrecal. With one S a Wisconsin General Test Apparatus (WGTA) was used in presenting a variety of stimuli. In this situation, the E delivered either one-fourth of a Metrecal cookie (6+ calories) or about one-fourth ounce of liquid Metrecal (7 calories) per correct response. The S lost some weight on this regimen at first but then maintained a high rate of performance and a stable weight condition for over 3 months on this diet. A second S was in a typical operant conditioning setup in which she pressed a key in the wall for reinforcement. Initially, one-fourth of a Metrecal cookie was delivered to her; however, performance remained low and she ate very few cookies unless she was periodically given liquid. After several sessions, she was shifted to a moist mixture of Metrecal liquid and crushed cookies 6 This work has been conducted by John Hollis, Research Associate, at Parsons Research Center; John Kane, Research Trainee at Parsons Research Center; and the first author, 1965.

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(1 oz liquid to nine cookies). These were mixed in the morning, rolled into small balls, and placed in the refrigerator 2-8 hr before using. These Metrecal balls were rather easily dispensed by a Gerbrands Universal Feeder with only an occasional ball sticking to the feeder. This problem was totally solved by making sure a period of 4-6 hr elapsed during refrigeration of the balls. As was the case with the first S, there was an initial slight loss in weight. However, the S ate the Metrecal balls well and responded for periods of time up to 3 hr per day. Interestingly, when the Ss were taken off Metrecal and placed on a regular diet, they went back to eating the regular diet immediately. Moreover, after several days on regular meals they would eat Metrecal even when satiated with food from their regular diet. One S, on a regular diet, frequently walks off the cottage and goes to the experimental room where Metrecal is delivered. Moreover, when this S was placed in a hearing experiment where Metrecal was used as a reinforcer, she responded well on Metrecal balls. She was on ad lib regular food. Apparently the taste for Merrecal can be acquired. Baer, Peterson, and Sherman (1965) used the children’s regular meals as reinforcement in developing discriminated imitative behavior by three moderately and severely retarded children. The meal was delivered a spoonful at a time by the experimenter, contingent on imitative behavior by the child. Other reinforcers have been suggested and used with severely retarded children. For example, Hollis (1965~)found that performance on a bentwire problem could be maintained for some Ss by social reinforcement (gentle pat on the head and a verbal statement, “Good girl, Susie”). Meyerson and Michael (1960) have worked with vibratory stimulation as a reinforcer for severely retarded persons. Petre7 is exploring the use of battery-operated toys as reinforcers for some children. The toy is remotely operated for 10 sec when a correct response is made in a matching-to-sample reading readiness program. One particular S who rejected candy and trinkets performed at a much higher rate for the movement of the mechanical toy. Several researchers have used generalized conditioned reinforcers in operant studies with human Ss. A generalized conditioned reinforcer is a discriminative stimulus which sets the occasion wherein responding will yield any one of several types of reinforcers (e.g., food, water, toys, termination of an aversive condition, etc.). Money is a prime example of a 7 Information of this study was obtained through personal communication with Richard Petre, Research Associate, Bureau of Child Research Laboratories, University of Kansas Medical Center, Kansas City, Kansas. 1965.

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generalized conditioned reinforcer and has been used in a variety of human operant studies (Lindsley, 1964; Schwitzgebel & Schwitzgebel, 1961; Slack, 1960). Tokens have been used by researchers dealing with retarded persons (Ayllon & Azrin, 1965; Birnbrauer & Lawler, 1964; Girardeau &. Spradlin, 1964; Heard, 1964; Watson, Lawson & Sanders, 1965). These tokens are redeemable for such merchandise as trinkets, toys, candy, fruit, articles of apparel, pop music, etc. They are established as reinforcers rather quickly even with moderately and severely retarded children (Girardeau & Spradlin, 1964; Watson et al., 1965). I n general, tokens have been used primarily in executing rather gross demonstrations of procedures based on operant techniques; however, work has been done by Hom and Kanes using tokens as reinforcers for studying schedule effects with moderately retarded children. These tokens show extremely powerful control over the behavior of moderately retarded children in the laboratory situation. Still other persons (Heard, 1964; Long, Hammack, May, & Campbell, 1958; Meyerson & Michael, 1960) have used a mixture of trinkets as reinforcers in various kinds of operant experiments using normal and retarded children as Ss. Using a mixture of trinkets is subject to the same criticism as the use of a mixture of foods; however, most of these writers report that trinkets, or trinkets and candy, maintained behavior quite well. Social consequences also have been used in operant and instrumental studies with retarded persons (Barnett, Pryer & Ellis, 1959; Hollis, 1965a; Hollis, 1965b; Locke, 1962). Harris, Wolf, and Baer (1964) have demonstrated that the attention of certain adults can serve as a n effective reinforcer for several types of behavior emitted by nursery school children. Although such systematic studies have not been done with the moderately retarded, the implications of the Harris et al., work are that social reinforcers can be powerful with selected children particularly in an institution where adult attention is not often gained by the child. Our casual observations indicate that its effects with severely retarded children are quite unpredictable. This is not to say that social reinforcers will not work with some severely retarded children. Rather, they will work only with selected children and, even then, their effects may be limited or unpredictable. Social comments have limited value as reinforcers due to the fact that they depend so much on the unique history of the child. If a n adult’s comments have, in the past, set the occasion where responses were reinforced, it is quite likely that comments by adults now will be rein8 Information of these studies was obtained through personal communication with George Horn and John Kane, Research Trainees at Parsons Research Center. 1965.

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forcing, at least for a while. However, if such comments have not been positively backed up or have been associated with aversive conditions, it is quite likely that they will have either no effect or an aversive effect. Thus, comments by adults can be neutral or conditioned aversive stimuli. There have been a few systematic studies of the effects of the termination of an aversive stimulus on the behavior of moderately or severely retarded children. However, Lovaas, Freitag, Kinder, Rubinstein, Schaeffer, and Simmon (1964) has reported on the use of an aversive electrical stimulus with behaviorally limited autistic children. Lovaas’ procedure involved placing the autistic child in a small room with electrical grids. Two adults were in the room with the child. Initially, when the electricity was turned on, one adult pushed the child into the arms of the other adult. The child thus escaped the electrical stimulation. After relatively few shocks, the child was shaped to sit on the adult’s lap and hug, touch his cheeks, etc. This behavior extinguished when shock was discontinued for long periods of time; however, one noncontingent shock was enough to reestablish the behavior. Ward0 brought the behavior of a severely retarded mongoloid child under the control of an intense auditory stimulus. The S had been shaped previously to pull a knob using positive reinforcement. Then white noise which could be terminated by pulling the knob was introduced. Moreover, each response delayed the onset of white noise a specified amount of time, 5 sec, 10 sec, or 15 sec. Highly reliable escape behavior developed. However, the child did not learn to avoid the stimulus. The experiment was terminated due to the development of emotional behavior by the S.

2. SCHEDULES OF REINFORCEMENT A reinforcer may be delivered following every response; such a schedule is usually termed continuous reinforcement (CRF) or fixed ratio 1 (FR-1). Reinforcers also may be delivered intermittently. When a reinforcer is delivered after a predetermined number of responses have been emitted, the term “fixed ratio” (FR) schedule is used. “Fixed interval” (FI) shedule is the term used when a reinforcer is delivered for the first response following a fixed time interval. When a reinforcer is delivered following a variable number of responses (e.g., on the average every 10 responses but varying between 1 and 20), the term “variable ratio” (VR) is used. The term “variable interval” (VI) schedule describes a procedure in which the reinforcer is delivered following a response after varying time intervals. “DRL” refers to a schedule in which low rates of responding are rein9 Information concerning this study was obtained through personal communication with James Ward, Research Trainee at Parsons Research Center. 1964.

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forced but not high rates, i.e., differential reinforcement of low rate. A discussion of other schedules can be found in Ferster and Skinner (1957). Ellis et al. (1960) studied the fixed ratio behavior of 12 adult Negro males with IQs less than 30. These 12 Ss were selected from a total of 22 Ss. The other 10 Ss were excluded from the major part of the study because they failed to respond, cried, wanted out, or responded only when told to do so. Later, informal study of the 10 who were excluded indicated that all but 3 or 4 could be trained to respond and adapt to the situation. The behavior studied was responding on a Lindsley manipulandum. The Lindsley manipulandum consists of a knob which, when pulled, trips a microswitch so that the response may be recorded. The Ss were seen for 30 sessions. M & M's were used as reinforcers and a 5-sec time-out period (in which the goal box light was on and the house light was off) occurred with the delivery of each reinforcer. Ss were on FR-10 for 11 days. Then they were shifted successively to FR-SO, VI-1, FI-1, FR-10, and to FR-100. Each session lasted 30 min. Ss exhibited quite varied behavior under all schedules. Under the fixed ratio schedules, most Ss exhibited high rates; however, at least one S exhibited low rate behavior and finally ceased responding. On the variable interval schedule the rates for 3 of the 4 SS, whose cumulative records were presented, were high. The rate of the fourth was quite low. Scalloping on FI-1 appeared infrequently. In general, Ss did not show typical FI low rates. However, it should be remembered that Ss had been on ratio schedules previously and were on interval schedules for only a few hours at most. In a subsequent study reported in the same article, Ellis et al. (1960) studied the fixed ratio behavior of 26 teenage and adult Negro males with IQs between 30 and 70. The Ss were switched from a candy reinforcer to cigarettes on the twelfth day. There were more pauses in responding by the lower mental age Ss but behavior was maintained quite well for most Ss on fixed ratio schedules as high as 1024. Orlando and Bijou (1960) studied the effects of single and multiple schedules on the behavior of retarded children with IQs between 23 and 64 who ranged in age from 9 to 21 years. They used Hershyettes, candy corn, M & M's, and mints as reinforcers. The response was pressing the handle from the squeezer of an O'Cedar mop. A small bulb high over the reward box was dimmed for 3 sec as a conditioned reinforcer. Sessions lasted from 15 to 60 min and were typically scheduled twice each week, Orlando and Bijou studied VR, FR, VI, FI, and DRL schedules. FR schedules of 10-25 and VR schedules of 100 generated high stable rates of behavior. VR schedules yielded fewer and aperiodic pauses, while FR schedules yielded pauses primarily after reinforcement before the beginning of a run. Orlando and Bijou report that VI schedules yielded rates

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which were quite like those obtained by VR schedules with the exception of greater amounts of course grain. The results under FI conditions were the most variable. Some Ss emitted “runaway” rates similar to those obtained under VR and FR conditioners, while others emitted paced rates. However, with additional sessions most Ss adopted low rates with an occasional scallop. Headrick (1963) studied the effects of instructions on the behavior of 24 retarded persons (IQ range = 31-76, mean IQ = 51) on FI schedules. The experimental setting and apparatus were similar to that reported by Ellis et al. (1960). Four types of instructions were given. Nine Ss were told to pull the knob and reinforced on an FR-1 for 3-8 responses or on an FI-.5 for a while, then shifted to an FI-2 schedule. Seven of the nine Ss in this group emitted high-rate response patterns; only two emitted low rates. Nine Ss were told simply that they could get some pennies, candy, or cigarettes and started immediately on an FI-2 schedule. Only one S in this group emitted a high-rate pattern; the other eight emitted low rates with some scalloping. Three Ss were told to pull the knob and started immediately on FI-2. Two of the Ss had high-rate patterns and one a moderate rate pattern. Three Ss were instructed that they could get candy, pennies, or cigarettes. They were reinforced for eight responses on FR-1, and then shifted to FI-2. Two of the three Ss emitted high-rate patterns and one a low-rate pattern. In summary, Headrick’s data indicate that the rate of responding one obtains on fixed interval schedules is a function of instructions and experience on previous schedules. Spradlin et al. (1966) studied the effects of FR and FI schedules on the behavior of severely and moderately retarded children. The basic procedures were also quite similar to the Ellis et al. (1960) procedures. They found that under FR schedules, most of the Ss developed high rates of responding, with pausing confined primarily to periods right after reinforcement. Once an S began to respond, he rarely stopped before completing the ratio. When Ss were placed on FI schedules for about 10 hr, their rates were low but only two of six Ss on these schedules showed distinct scalloping. Kane’o has studied the behavior of two moderately retarded girls on DRL schedules (schedules in which a certain amount of time must pass since the S’s last response for a response to be reinforced). Kane used tokens backed up by merchandise as reinforcers. The schedules used have been DRL 20 sec and DRL 45 sec. On DRL schedules the rates were quite low as expected. One S on DRL 20 sec showed short bursts of responding during the first 5 sec after reinforcement. Responses showed a sharp drop 10

Personal communication. 1964: see Footnote 9.

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during the next 5 sec and then gradually increased during successive 5-sec periods through the 15-sec to 19-sec interval. Then-there was a decrease of responding. The other S overshot DRL 20 sec most of the time; in other words, she did not respond until after the 20 sec had passed. When put on a DRL 45 sec this S undershot and showed a pattern similar to the first S on DRL 20 sec. Kane found that when he increased the amount of spring tension on the manipulandum, both Ss showed a decrease in responses immediately after reinforcement and a general increase in efficiency. However, when tension was set low, the Ss undershot to a greater degree than the baseline. In general, observations of the girls’ performance on DRL schedules were interesting. An S might repeatedly exhibit certain chains, such as pulling the manipulandum, looking in the goal box, walking to the opposite side of the room, tapping the wall and then slowly walking back to the panel and pulling the manipulandum again. Kane and Spradlin studied two severely retarded children on short variable interval schedules, VI-10 sec. The reinforcers were Metrecal balls (as described in the section on types of reinforcers). One S developed steady moderate-rate responding on this schedule while a second S developed extremely low rates which looked more like the behavior usually obtained by DRL schedules. These low rates were maintained on the VI-10 sec schedule in spite of the fact that the S received all of her daily food intake in the experimental session during the time she was on a VI-10 sec schedule and her weight was reduced to approximately 93% of normal. During the long pauses (approximately 30 sec after reinforcement) the S would engage in stereotyped behavior almost continually. It seems quite likely that a long superstitious chain of behavior was being reinforced. Later, a 5-sec limited hold was placed on the VI-10 sec schedule. (That is, if the S did not respond within 5 sec after reinforcement became available, she simply missed that reinforcement.) This resulted in more responses; however, it did not totally eliminate long pauses after reinforcement. When the limited hold was reduced to 1 sec, local rates went even higher; however, there were still long pauses after reinforcement. Horn11 studied the effect of amount of reinforcement on responses made by moderately retarded Ss on a concurrent schedule. Tokens were used as reinforcers. During baseline sessions, both responses were reinforced on an independent VI-2 schedule. The reinforcement on each schedule was two tokens until responses on each manipulandum were stable. Reinforcement was then shifted so that response to manipulandum 1 paid off one token on a VI-2 schedule while responses to manipulandum 2 paid off 11

Personal communication. 1964: see Footnote 9.

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three tokens on a VI-2schedule. Amount of reinforcement showed initial clear-cut effects on time spent and number of responses made on each manipulandum. However, with further sessions the difference became much less stable. That is, amount of reinforcement had a strong initial effect on preference; however, the behavior became unstable with additional sessions.

3. OTHERREINFORCEMENT VARIABLES Within the past 3 decades latency of reinforcement and amount of reinforcement have been studied extensively at several phyletic levels. I n general, these studies have shown that immediate reinforcement is much more effective in developing behavior than delayed reinforcement and that larger amounts of reinforcement (within limits) are more effective than smaller amounts. These variables have not been studied systematically with moderately and severely retarded persons. However, beginning efforts have been made by Ellis (1962) and Hom’s study reported above. 4. CHANGES IN REINFORCER VALUES It is quite important to point out that (1) what serves as a reinforcer at one time might not be effective at another time, and (2) what will serve as a reinforcer for one person might not be effectivewith a different person. The first point is most clearly illustrated by the fact that food will serve as a reinforcer for a deprived person but not for a satiated one. Physical contact might be a reinforcer on some occasions but not on other occasions. Regarding the second point, one should be aware that what might be positively reinforcing for one child could be aversive to another. In working with moderately and severely retarded persons, both points are important. These are two major reasons why generalized conditioned reinforcers (such as tokens, money, etc.) are useful when one is working with the retarded for extended periods.

B.

Establishing Stimulus Control (Discrimination)

Stimulus control means that an organism responds differently when a given stimulus is present than when it is absent or that the organism responds differently to one stimulus in its environment than i t does to another. DISCRIMINATION 1. FREEOPERANT The traditional method of establishing stimulus control over a single operant in a free operant experiment has been first to increase the rate of the responding in the presence of the positive stimulus (SD) through

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positive reinforcement and then simply to extinguish the response during the time when the negative stimulus (SA) is present and the SD is absent. This procedure can be used to establish discrimination with some moderately and severely retarded persons, However, the procedure will not inevitably lead to discrimination. The present writers ran one severely retarded child for over 200 sessions. When the S was placed in the room, the houselight was off as was a white noise generator. The S was never reinforced until the houselight and noise generator were turned on. At the end of the session the houselight and noise generator were turned off and the S was no longer reinforced. This S continued to respond both prior to the onset of the noise and light and after the noise and light had been turned off at the end of the session. In short, he did not learn the discrimination. This is in marked contrast to a moderately retarded adolescent boy who came under control of both the light and the noise. This S, who was on an FR-75 schedule, came to respond only when the light and noise were on. If, during the final sessions, either the light or noise were terminated, the S stopped responding immediately and did not respond again until the light and noise were again both present. This was true whether the light or tone was off 20 sec or 10 min. In fact, stimulus control was so precise that the casual observer might speculate that knob pulling was elicited rather than operant behavior. The failure to discriminate in a free operant situation is not totally unique to severely retarded persons. Sidman (1960) reports that when the presentation of the SD is made on a time schedule independent of the S’s behavior, failure to discriminate frequently occurs. He attributes this to superstitious chaining due to the adventitious reinforcement of responding during the SA period by the presentation of SD. He suggests that one can preclude this problem by making the presentation of the SD contingent on a second kind of response during SA. Thus, during SA the S makes one response to present the SD and, once the S D occurs, the S makes a second response to obtain the reinforcer. One may also overcome superstitious chaining in discrimination learning by making presentation of the S D contingent on a fixed time interval of not responding during the SA. Bijou and Orlando (1961) have used a modified form of this procedure in developing discrimination by moderately retarded children. Bijou and Orlando first established a specified rate of responding in the presence of the SD by reinforcing the response on an FR-1 schedule-then they introduced the SA. The S D was then presented again whenever the S paused for a specified amount of time. After pauses of this amount of time were occurring quickly during the SA, the pause time was increased. The pause time was gradually increased until the S was pausing for 30 sec during the SA period. During the next

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phase, the Ss were placed on either a ratio or temporal intermittent schedule with times or ratios gradually being increased to either an FR-50 or an FI-1 min schedule during the SD period. This procedure resulted in rather precise multiple schedule discrimination by eight moderately retarded children with IQ’s between 30 and 42. The above described procedures for establishing discrimination in a single response free operant situation are traditional. That is, they rely on strengthening the response during the SD period and extinguishing it during the SA period. There has been much speculation that this is the only way that discrimination can be learned (Keller & Schoenfeld, 1950). However, Terrace (1963a) has recently reported data on pigeons which lead to questioning such assumptions. Terrace, by presenting the SA for short periods of time when the pigeon was not in a position to respond, was able to establish a high rate of responding to the SD and almost no responses to the SA. In other words, the S did not go through an extinction process with the SA. These procedures have not been investigated with severely retarded persons but they would seem to hold promise. Barrett and Lindsley (1962) have investigated discrimination in an experimental situation where two stimulus patterns and two responses are available to the Ss. Their Ss were retardates whose IQs ranged from 33 to 72. They used candy and pennies as reinforcers. The contingencies involved FR-10 reinforcement for the left manipulandum when the light above i t was on. When the light over the left knob went off, the light over the right knob was presented. No reinforcement was delivered for any response on the right knob, and responses on the left were reinforced on an FR-10 schedule only when the light was on above it. Barrett and Lindsley reported a variety of behavior. Some Ss showed neither discrimination nor differentiation. That is, they pulled either knob equally often regardless of which light was on. Other Ss learned to discriminate the light on-light off condition, but overgeneralized the response to the nonreinforced knob. One S developed both discrimination and differentiation but correct performance went down during subsequent sessions. Orlando (1961) ran two moderately retarded adolescents (IQ 34-40) on a two-choice operant discrimination task. The operant chamber included two response panels spaced four feet apart, separated by a chute for delivering reinforcers (small pieces of candy). On each panel there was a Lindsley plunger-type manipulandum with two stimulus lights (red and blue) mounted above it. For each S one of the stimulus lights was designated the SA and the other the S D . For example, when SD occurred on one panel, SA was occurring on the other. The SD and SA shifted from one panel to the other after a short interval. Correct responses were designated as those which were made on the panel with the SD, while errors were

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responses made on the panel with the SA. During the interval session, SS were reinforced on a VR-25 schedule for correct responses until they reached a correct response rate of 20 responses per min, then they were shifted to a VR-100 for correct responses. The criterion for discrimination was 90% correct response for a 32-min session. During the six sessions following realization of the criterion, each S received two 4-min tests for positive-cue (SD) removal, negative cue (SA) removal, and reinforcement removal. One test of 4 min was given per session. These tests were given in a counterbalanced order in the 20-40-min interval of each session. Removal of reinforcement for 4 min showed no effect on discrimination. One S’s percentage of correct responses dropped from 99.7 to 56.5 when the S D was removed but showed no decrement when the SA was removed. The other S dropped from 99.1 to 32.4 when the S A was removed but showed little loss when the SD was removed. The data indicate that either S D or SA may control responding and the effective controlling stimulus may vary from S to S. Investigations have been initiated by Spradlin and Kane to develop the free operant discrimination of severely retarded children. The initial attempts to develop discrimination involved a multiple FI-1:FR-50 schedule. The FI-1:FR-50 schedule involved a single manipulandum. When one stimulus light was on, reinforcement was delivered on an FR-50 schedule. When the other light was on, reinforcement was delivered on an FI-1 schedule. None of the three severely retarded Ss showed any evidence of discrimination under these conditions, nor did they when the multiple schedule was shifted to FR-50:extinction. More recently, Spradlin and Kane have been using a two-manipulanda situation. With one severely retarded S, plastic keys on the panel were used as the manipulanda. Responses to a key resulted in reinforcement only if a red light behind it was on. When the light behind one key was off, the light behind the other was on. Prior to discrimination training, the S had been on a variable interval 10-secschedule with a limited hold of 1 sec. During initial discrimination training, the S was on this same schedule whenever she was responding on the lighted key. Responses to the unlighted key were never reinforced. After approximately 15 hr of training on this schedule, the S made very few errors (i.e., less than 57, of her responses were to unlighted keys). However, when the S was shifted from this two-response discrimination situation to a single response discrimination, she responded both to the right key (key which was lighted part of time, S D ) and to the left key which was now unlighted (extinction) at times when the right key was off. Discrimination on the right key broke down as a function of no alternative correct response. However, after 21 hr the S was making few responses to the unlighted left key and less

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than 5% errors on the unlighted right key. In other words, this severely retarded child had formed nearly perfect discrimination. After seeing the relative ease with which discrimination was established with this severely retarded child with a two-response system, the Es attempted a two-response discrimination with one of the previous Ss who had failed to discriminate on a one-response system. This S was a severely retarded adolescent male with a left temporal lobectomy. The simple tworesponse discrimination procedure was not adequate to establish discrimination by this S, so a variety of techniques were used in an attempt to establish discrimination. The last technique used involved turning off the houselights and making the stimulus light flicker in an attempt to control observing responses. This technique was only partially successful insofar as the S continued to make about 20% errors (i.e., responded to the unlighted stimulus).

2. EXPERIMENTER-PACED DISCRIMINATION The most frequent type of discrimination studied with moderately and severely retarded children has been multi-choice simultaneous discrimination (Stevenson, 1963; Zeaman & House, 1963). This type of discrimination usually is a two-choice one in which a positive stimulus (SD) and a negative stimulus (SA) are presented to the S simultaneously. If the S responds to the positive stimulus, he is reinforced; otherwise, he may be allowed to make a second response (correction procedure) or both stimuli may be removed and set up for the next trial (noncorrection procedure). Unlike the free operant situation, the arrangement of the physical environment by the experimenter usually precludes the S from making a response except at specified times called trials. Zeaman and House (1963), as well as others, have used the simultaneous procedure for studying the effects of pretraining variables and stimulus variables on the performance of moderately retarded persons. Seventeen retarded Ss (IQ range = 30-68, mean IQ = 49) were given three trials on each of 64 two-choice visual discrimination problems by Zeaman, Thaller, and House (1964). Half the problems had a constant irrelevant dimension and half had a variable irrelevant dimension. Superior performance was found on the problems with the constant irrelevant dimension. Eimas (1964) studied the visual discrimination learning of retardates (IQ range = 38-67, mean IQ = 49) as a function of compound and component cues. Performance was attributed to the utilization of both “types” of cues, and the statement was made that retarded children appear to be able to utilize a considerable amount of the stimulus information provided.

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Ellis, Girardeau, and Pryer (1962) investigated the development of learning sets by severely retarded adolescents and young adults (IQs less than 25). The task involved learning a series of “junk-type” two-choice simultaneous discrimination tasks with a noncorrection procedure. Ss were reinforced with a mixture of reinforcers such as grapes, M & M’s, crackers, etc. Ten Ss showed no improvement over 200 problems. Ten Ss achieved near perfect performance by the 17th day (98% correct) and 10 Ss achieved roughly 75% correct responses. This study indicates that some severely retarded persons are able to learn a simple simultaneous discrimination and, second, that for some Ss, performance on this task improves with successive training on a series of discrimination problems. C. Shifting Stimulus Control

While it is sometimes necessary to establish a new or basic discrimination, this is frequently not the case. Often behavior is already under stimulus control; the problem is how to bring the behavior under the control of other stimuli. Terrace (1963b) studied three ways of shifting stimulus control from one SD to a second SD in a fixed trial experiment. Pigeons had been trained by errorless discrimination techniques to respond when the red light S D appeared. The pigeons were then shifted to a discrimination situation in which a vertical line was the SD and a horizontal line was the SA. Three procedures for shifting were used. The first technique (abrupt shift) involved an abrupt shift from the red-green discrimination to the vertical horizontal discrimination. This procedure appeared no more effective than if he had never learned the initial discrimination. The second technique (superimposition only) involved superimposing the vertical line on the red key and the horizontal line on the green key for five 60-trial sessions and then presenting the horizontal and vertical lines above. This procedure was superior to the abrupt shift procedure. The third procedure, superimposition and fading, involved superimposing the vertical line on the red key and the horizontal line on the green key for five sessions, and then during the following session, the red and green light were progressively diminished until only the vertical and horizontal lines remained. This procedure resulted in a shift in discrimination without errors. After Ss reached criterion for learning the vertical-horizontal discrimination, they were shifted back to the red-green discrimination. Ss who had only the abrupt shift and the superimposition treatments now made errors on the original discrimination, while the Ss receiving the superimposition and fading treatment did not. Meyerson and Michael (1960) reported a fading procedure for establish-

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ing tone control over responding in a two-manipulanda operant situation. Their Ss were moderately retarded children on whom they were attempting audiometric evaluation. Their experimental situation included a Dalrymple panel with two Lindsley manipulanda. Above each manipulandum was a stimulus light. They found that there was a high probability of an S responding to the manipulandum if the light above it was on. Thus, they first established a twu-response light discrimination through reinforcement of responses to the manipulandum with the light on above it. Then they paired the tone-on stimulus with the light under one manipulandum and tone-off with the light on under the other manipulandum. They, then, gradually faded the light. Soon their Ss were responding to one manipulandum when the tone was on and to the other manipulandum when the tone was off. This allowed for an evaluation of hearing. Gove, Lawson, and Watson (1964) have found that moderately and severely retarded children, who did not exhibit differential responding when a single four inch black disc was used as an SD and its absence as an SA, did respond differently when the black disc was associated with a bright white background light as the SD condition and a tone plus a dim blue background light as the SA condition. Once stimulus control was well established, the extra stimuli could be gradually withdrawn until only the presentation of the black disc controlled responding. Sidman12 has used the procedure of gradually changing the controlling SD, while gradually introducing SA stimuli in a multiple choice discrimination task, to train a severely retarded microcephalic adult to make rather fine discriminations between a circle and an elipse. A second general situation where the shifting of stimulus control is useful is in teaching the person to make the same response in the presence of several different stimuli. A good example is the shift from saying “car” in the presence of the object to saying “car” in the presence of a picture of a car and finally in the presence of the printed word. A study by Hermelin (O’Connor & Hermelin, 1963) demonstrated that the control over a verbal response could be shifted rather rapidly from a picture to a word when the Ss were 10 moderately retarded children. His treatment was somewhat analogous to Terrace’s superimposition only treatment. Four words-“bed,” “corn,” “dog,” and “cup”-were taught individually. The procedure was as follows. The S was asked to tell the experimenter what was on the card each time it was presented on a screen. All correct responses were rewarded with a sweet plus the verbal response “good.” The picture was presented first. When the S had named it cor12 Personal communication with Dr. Murray Sidman, Neurology Research, The Massachusetts General Hospital, Boston, Massachusetts. 1964.

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rectly on five consecutive trials, the word and picture were presented simultaneously. When these had been named five times correctly the word alone was presented and five correct naming responses were required. When this criterion had been reached, the card with the word and picture was withdrawn and an additional five consecutive correct responses to both the picture and the word was required. This same procedure was followed with the remaining three words. It took an average of 4.7 presentations to reach criterion on the first word, 1.9 for the second, 1.3 for the third, and 1.1 for the fourth. Each of the four words was then presented with two similar ones and the S had to select the correct word. Trials were repeated until the correct word was selected on 10 consecutive trials. It took 10.7 trials to reach criterion on the first word discrimination, 1.4 for the second, 1.8 for the third, and 2.8 for the fourth. Finally the S was presented the four learned words on cards and was asked to name each card for three trials. The average number of errors out of a possible 12 was 2.6. O’Conner and Hermelin (1963) reported a study which illustrates the process of gradually shifting the control of a response from one stimulus to other stimuli. Their Ss were 24 moderately retarded children between 9 and 15 years of age with IQs below 40. Experimental and control Ss were matched on the basis of IQ. The experimental task was that of training Ss to recognize four words“panda,” “horse,” “fish,” and “swan.” For the experimental group, the following treatment was applied. One of the words, such as “horse,” was selected for training. This “cue” word was presented in large print (10 mm letters) on a card along with three cards on which the three other words appeared in small print (3 mm letters). The S was shown a picture of a horse and asked to name it. Then he was asked to select the card with the word horse. If the S responded correctly, he was given a reward. If not, he was told which printed word was correct. Then the four cards were again rearranged and the procedure repeated until the S made 10 consecutive correct responses. This ended the first stage. In successive trial stages the size of the correct word was gradually reduced in five additional stages from 10 mm to 8 mm, to 6 mm, to 5 mm, to 4 mm, and finally to 3 mm. The same training procedure was used successively for the remaining three words. The control group received the same treatment except that the cue word was always the same size as the other three words (3 mm). The Ss receiving the experimental treatment learned to recognize the words in significantly less trials than did the control group. Retention tests yielded no significant differences between experimental and control

ss.

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1. IMITATION Imitation is a class of behavior under the control of stimuli which result from another person’s behavior and has been studied within the framework of discriminated operant behavior. The occasion for reinforcement is simply that s’s behavior matches the other person’s behavior. Bandura and Walters (1963) have pointed out the importance of imitative behavior in the development of social behavior in human Ss. However, these authors did not specify how imitative behavior develops. Recently, Baer et al. (1965) have demonstrated that imitative behavior by severely retarded children can be established using reinforcement procedures. Baer, et al. (1965) observed several severely retarded children extensively for several days and found no spontaneous imitation. An E then engaged them in play and asked them to imitate some simple responses he demonstrated. Imitative behavior did not occur. The subsequent training procedure involved telling the child, “Do this,” giving a demonstration, and following the s’s response with food reinforcement. With the S who had the most extensive training, 130 discriminated operants were taught using food as the reinforcer. Physical assistance by the experimenter was used at first to get the imitative behavior started. During the training program, generalized imitation occurred, i.e., responses were imitated the first time they were presented. Several of these were not reinforced by E but remained strong (although never reinforced) when they were included with imitations that were reinforced. Chains of imitative behavior of a rather complex nature were developed. Furthermore, new behavior could be included in the chain and they were imitated. With one S at least, the imitative behavior also generalized to new Es. Another important aspect of the study was the development of verbal imitation whereby one S was slowly taught 10 usable words. Finally, an extinction procedure resulted in greatly decreased imitative performance, but the behavior was reinstated by reinstating the contingent reinforcement. Metz (1964) has reported the use of a similar procedure in establishing generalized imitative behavior with two autistic children. The results of these studies hold a great deal of promise for the training of severely retarded persons. 2. GENERALIZATION Any discussion of discrimination involves generalization. I n fact, witho u t generalization the gradual shift of stimulus control discussed above would not occur. Lane and Curran (1963) studied auditory loudness gradients of three moderately retarded blind children. The reinforcer

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used with al! three Ss was 3 sec of recorded music. One S was given twomanipulanda training. He was trained to press the left button when a low intensity (56 db) 500 cps tone was presented. He was trained to press the right button when a high intensity (76 db) 500 cps tone was presented. The other two Ss were given single-manipulandum training. They were trained to respond to a 74-db tone but not to a 56-db tone. All Ss were given 10 test presentations at each of 11 loudness intensities ranging from 50 to 80 db. Reliable generalization gradients were obtained with both the one-manipulandum and the two-manipulanda procedures. Gradients were asymmetric and nonmonotonic. D. Reducing the Frequency of Behavior 1. EXTINCTION

Extinction refers to a decrease in performance as a function of withholding or discontinuing reinforcement. Extinction processes have been widely studied with animals. However, studies of extinction with human Ss have been limited primarily to short term group studies. Moreover, most of these studies have investigated only the initial phases of extinction due to reliance on a rather arbitrary criterion for extinction. For example, Spradlin (1962) used as a criterion for extinction, 30 sec without a response. Spradlin did find, however, that 24 intermittently reinforced responses led to a greater number of responses during extinction than did 24 continuously reinforced responses, when moderately retarded children were Ss. Moreover, most Ss reached criterion for extinction within the first 10 min after reinforcement was discontinued. This finding is in line with the results of both human and animal extinction studies. Ellis (1962) studied the effect of amount of reinforcement on time and number of responses to extinction. The Ss of his first experiment were retarded persons with I@ ranging between 11 and 80 with a mean IQ of 46.2. The reinforcers were cigarettes. Twenty reinforcements were programmed according to an increasing ratio of 1, 4, 8, 12, 16, 32, 48, 64, 96, and 128 for the last 10 reinforcements. If an S completed the acquisition phase, he made 1585 responses for 20 reinforcements. Two different amounts of reinforcement were used-three cigarettes and one cigarette. There were no significant differences between groups in reaching criterion for extinction (10 min without a response or leaving the room). However, responses to extinction, time to extinction, and responses during conditioning all showed an absolute difference in favor of the low reinforcement group. I n a second experiment, Ellis studied extinction with 56 institutionalized severely retarded males between 8 and 27 years of age. The pro-

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cedure was the same as the first study except that the ratios were 1, 4, 12, 16, 24, 32, 40, 48, 56, and 64 for the last 10 reinforcements. Cigarettes and penny candy were used as reinforcement. There was no significant effect as a function of amount of reinforcement. However, absolute differences in extinction time and responses to extinction were in the opposite direction from the first study. In both studies a majority of the Ss reached criterion for extinction. In summary, the studies yielded no evidence that amount of reinforcement had a significant effect on performance during extinction. Hollis studied the effects of extinction on the bent-wire performance of a single severely retarded child over several experimental sessions. Prior to extinction the child was given either a bite of Metrecal cookie or a drink of Metrecal liquid after each correct response. For several sessions the S had made 40 correct responses in 40 trials. The S was then fed prior to the session and no more food was given during the session. After four sessions of extinction under satiation conditions, the S’s correct responses went to near zero. When the S was not fed prior to the session and reinforcement was delivered, performance recovered completely. Later Hollis ran extinction series of 40 trials under deprivation conditions and fed the S after the fortieth trial. Performance remained quite high. I t seems likely that this procedure is somewhat like reinforcing behavior on an FR-40. I n an earlier study Hollis (1965~)studied the bent-wire performance of severely and moderately retarded children under nutrient reinforcement and extinction. In general, performance was decreased under both social reinforcement and extinction conditions. However, this was not true for all Ss. Fuller (1949) increased the frequency of arm raising by a “vegetative human organism” from .67 to 3 responses per min by delivering warm milk as a consequence. Extinction occurred when Fuller quit delivering milk. The results of the above studies indicated that complete elimination of reinforcement did result in a reduction of performance, that intermittent reinforcement led to greater resistance to extinction than did continuous reinforcement, and that resistance to extinction was not significantly affected by varying amounts of reinforcement within limited ranges. 2. PUNISHMENT Research and training efforts with moderately and severely retarded children have been spasmodic and unsystematic. Only in the last 10 years have researchers begun to consider the moderately or severely retarded an adequate S for behavioral research. Thus, it is not surprising that vast gaps exist in experimental research on behavioral processes

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with such Ss. One area of investigation which has been especially neglected with retarded Ss, is punishment. The control of retarded persons’ behavior with aversive techniques is generally in disrepute among professional psychologists today. This is especially true concerning the use of punishment, e.g., making the delivery of an aversive stimulus contingent on a response. I t is true that aversive techniques have been applied quite ineffectively in the past. Moreover, the widely publicized studies of Estes (1944) seem to indicate that punishment is ineffective in eliminating behavor. However, the recent animal data on punishment, as well as everyday observations, suggest that punishment should be given a more careful analysis before concluding that it is ineffective as a procedure for modifying the behavior of retarded persons. Researchers at Anna State Hospital have analyzed the effects of punishment on both human and animal &. The results of their work indicate the following. 1. Mild and moderate punishment (shock or intense noise) have little effect on the rate of responding if there is no alternate response which will deliver reinforcement (Azrin, 1960; Herman & Azrin, 1964). 2. Severe punishment will suppress a response totally and for long periods of time (Holz & Azrin, 1963). 3. When severe shock is administered, its results may be nonspecific. That is, the pigeon does not peck the key, but may also not eat grain when presented (Holz & Azrin, 1963). 4. Mild punishment will result in a marked decrease in responses if it serves as an SA. That is, it sets the occasion when a response is not reinforced (Holz & Azrin, 1961; Holz & Azrin, 1962). 5. Punishment will increase the frequency of responding if it sets the occasion for reinforcement. That is, pigeons will peck a key when they are shocked on each response if the shock indicates that grain will be forthcoming (Holz & Azrin, 1961; Holz & Azrin, 1962). 6. Even mild punishment is effective in reducing the frequency of behavior if an alternative response is available which will deliver the same reinforcer (Herman & Azrin, 1964). Some questions for further research with retarded children suggested by this literature are the following. 1. Does punishment reduce the frequency of a reinforced response if no alternative response will obtain reinforcement? 2. Does it make a difference whether punishment is applied early or late in acquisition? 3. Can punishment be established as an SD for responding if it sets the occasion for reinforcement?

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4. Is punishment effective in reducing the frequency of responses by retarded children if an alternative response is available? 5. What kinds of stimuli are effective as punishment? Lovaas et al. (1964) has reported preliminary work using shock to eliminate self-destructive behavior. The presentation of a painful stimulus (electric shock) was contingent on the self-destructive behavior of two autistic children. The behavior was suppressed within minutes and remained so for 11 months. When it reoccurred, a single noncontingent shock resuppressed the behavior for the remainder of the study. Previous attempts to use noise as a punishing stimulus had proved unsuccessful in reducing the self-destructive behavior. The following conclusions can be drawn from the experimental literature concerning moderately and severely retarded persons. 1. Both moderately and severely retarded persons do learn under appropriate reinforcement conditions. 2. Food is a n effective reinforcer for most moderately and severely retarded persons. This is especially true if the S is on dietary control. 3. Music, movement of mechanical toys, vibrations, and social contact are effective reinforcers for some moderately and severely retarded persons. 4. Tokens can be established as powerful generalized reinforcers for moderately and severely retarded persons. 5. The behavior of both moderately and severely retarded children can be brought under stimulus control in the experimental laboratory. 6. Stimulus control may be established by making SD and SA conditions quite different, by presentation of SD only after a short pause in responding on SA, or by providing an alternative reinforced response during the time that one response is under S A conditions. 7. Stimulus control is most likely to be shifted from an SD to another stimulus if the change in stimulus conditions is made gradually rather than abruptly. 8. The behavior of moderately and severely retarded persons decreases in frequency if it is not reinforced. However, this decrease may not be immediate. This is especially true if the behavior has been maintained on an intermittent schedule. 9. Experimental work on the effects of punishment on the behavior of moderately and severely retarded children is extremely limited.

E.

Practical Applications of Behavioral Principles in the Development of Adaptive Behavior

There are admittedly great gaps in the laboratory operant research with mentally retarded persons and other human Ss. These should be

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filled. However, many persons feel that treatment programs need not wait until all of the principles established on lower animals have been tested with human Ss in laboratory situations. Moreover, early reports by persons who have applied these principles to treatment problems seem to uphold this opinion (Staats, 1965; Ullmann & Krasner, 1965). The results to date indicate that operant principles are amenable to application in everyday situations. With relatively few principles, one can make changes in the behavior of moderately and severely retarded persons. 1. PERSONAL SELF-CARE SKILLS The lack of simple self-care skills is a major problem of severely retarded children. The development of the motor requirements for such skills can be established through shaping (reinforcing successive approximations of the desired behavior). Numerous investigators (Bensberg, Colwell, & Cassel, 1965; Blackwood,, 1962; Hundziak & Maurer, 1963; Pursley & Hamilton, 1965; Spradlin, 1964) have reported success in training severely retarded persons to feed themselves. Self-feeding, once established, generally maintains itself since it is continuously reinforced in the natural environment. The general procedure for training self-feeding involves partial support by a trainer at first. The trainer assists by helping the retarded person fill his spoon and then helping him move it toward the mouth. The person then makes the last part of the movement himself. The trainer then reduces the assistance in very small steps (fades the stimulus control) until the retarded person is finally making the entire chain of behavior himself. The procedure, including the carrying of trays, is described in more detail by Spradlin (1964). Food throwing, if it occurs, can be eliminated by reducing the amount of food served and providing a time-out period as a consequence of the behavior. The training of dressing behavior has been reported by Bensberg et al. (1965). Each step of dressing was evaluated and ranked from least difficult to most difficult. Beginning with the most simple step, sequences were developed and food rewards were given following successful completion of each step. As training progressed, more and more was required of the person before he was reinforced. In the last stages, they were required to completely dress before receiving a reward. The program was begun with simple clothing and new, more difficult clothing was introduced gradually with appropriate training. Perhaps it should be mentioned here that the development of motor skills, such as dressing, can probably be assisted by changes in the materials ordinarily used by average persons. In other words, planning

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for the retarded should probably include changes in the physical environment as well as the shaping of behavior. For example, in terms of training dressing behavior, simpler clothes could be used a t first. Changes to ordinary clothing could be made in small steps, if the wearing of ordinary clothes is the desired behavior. Lindsley (1964) has discussed the development of prosthetic environments for these children. Michael (1963) and Ellis (1964) also have discussed certain changes in the physical environment which should improve the retardate’s interaction with his environment. Gove et al. (1964) have designed a commode which might prove quite useful in shaping toilet behavior. Toilet training of moderately and severely retarded persons has been attempted by Bensberg et al. (1965), Blackwood (1962), Dayan (1964), and Hundziak, Maurer, and Watson (1963). Blackwood (1962) and Hundziak et al. (1963) were able to shape toilet behavior but were unable to maintain it when rewards were withdrawn. These investigators speculate that the behavior was not under appropriate stimulus control. I n other words, the toilet behavior was under the control of the attendant’s telling the child or leading him to the bathroom rather than under the control of a full bowel or bladder. Bensberg et al. (1965) and Dayan (1963) report success with a behavioral approach described by Ellis (1963). Bathing, teeth brushing, hair combing, hair setting, ironing, mopping, cutting fingernails, proper sitting, and other skills have been taught with the same procedures (Bensberg et al. 1965; Girardeau & Spradlin, 1964). Wolf, Risley, and Mees (1964) trained a moderately retarded autistic child to wear glasses and reduced such undesirable behavior as temper tantrums through the systematic application of operant techniques. Once these skills are developed using a positive reinforcer delivered after nearly every response, the behavior can be maintained by requiring more and more responses before a reinforcer is given. Social reinforcers can then be used to maintain the behavior for many children. 2. SOCIALSKILLS Operant principles have not only been useful in the development of motor skills of a self-care nature, but also appear quite promising when applied systematically in programs designed to develop social and educational skills. Moreover, the acquisition of personal skills leads to increased opportunity for social behavior to occur and be reinforced. T h e child who is relatively clean and properly dressed is more likely to be responded to by adults. Thus, there are more opportunities for the child to be reinforced socially. I n fact, the development of rudimentary self-

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care skills is probably a prerequisite for the development of social and educational skills. Ayllon and Michael (1959) were among the first to suggest the systemitic application of behavioral principles to ward management and the training of groups of behaviorally deficient persons. Although their work, as well as the subsequent programs reported by Ayllon and Haughton (1962) and Ayllon and Azrin (1964), was primarily with adult schizophrenics, the general procedures which they used have proven to be effective with moderately and severely retarded persons. Birnbrauer and Lawler (1964) have reported work with a class of moderately and severely retarded children in an educational setting. In this study, operant principles were used to establish social and studying behavior of 37 moderately retarded children (all below IQ 40). By positively reinforcing approximations to desirable social and studying behavior, extinguishing inappropriate and incorrect behavior, and punishing dangerous behavior, these children were able to accomplish a great deal in one year. With four exceptions, they learned to hang up their coats upon entering the classroom, take their seats quietly, and wait for their assignments with only an occasional reminder. Eleven advanced to the point of working persistently on programmed multiplechoice prereading assignments which required from 10 to 30 min to complete. Candy (M & M’s) was used at first as a reinforcer, but there was a systematic shift to poker chips. Plans were reported to shift the reinforcers to grades and social approval as quickly as possible. Also, a classroom for moderately and mildly retarded children has been operated by Birnbrauer, Bijou, Wolf, and Kidder (1965). A beginning effort has been made at Parsons State Hospital and Training Center in the development of a comprehensive program designed to train moderately retarded children to live adequately in their home community (Girardeau & Spradlin, 1964). A cottage of 28 adolescent girls (IQ range = 20-50) was selected and two 21-year-old girls were hired as additional personnel. After a gross evaluation period, bronze tokens approximately the size of a half-dollar were established as generalized conditioned reinforcers by allowing the girls to trade them for candy, fruit, cosmetics, soda pop, lace underwear and numerous other articles. In addition to purchasing items with the tokens, there were rental materials available, such as watches, record players and records, bicycles, and transistor radios. After about 10 days a shaping procedure was introduced, i.e., the girls were required to make slight improvements in their behavior before tokens were given to them. One of the most immediate problems was

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that of devising constructive activities for these girls. Pets (goldfish, parakeet, turtles) were introduced on the cottage, and the girls were taught how to care for pets. The rewarding of self-care activities was a major part of the program for the first year but many other activities were included in the program. The activities listed in Table I are illustrative of the variety of skills which are being developed. The elimination of undesirable behavior is being accomplished primarily TABLE I WHICH ARE REWARDED A SAMPLE OF THE BEHAVIORS A N D APPROXIMATE REWARDAMUUNTS Behavior Making u p bed Dressing for meal Brushing teeth Taking shower properly Helping clean cottage Setting hair Straightening bed drawer Trimming and filing nails Combing hair Washing hair Group play (30 min) Coloring Work placement in institution Cleaning goldfish bowl Feeding goldfish Cleaning bird cage School readiness tasks Being on time at work or speech therapy Shining shoes General proper use of leisure time (20-min period)

Approximate reward amount 1 token 2 tokens 2 tokens 2 tokens Quite variable 4 tokens 2 tokens 2 tokens 1 token 2 tokens 5 tokens Quite variable 10 tokens/day 5 tokens 1 token 5 tokens Quite variable 4 tokens 5 tokens 4 tokens

by using an extinction procedure (e.g., totally ignoring tantrum behavior) and by rewarding behavior which is incompatible with the undesirable or maladaptive behavior. When it has been necessary to reduce the frequency of behavior quickly, a combination of mild punishment (time out from earning tokens) of the undesirable behavior and reward for other desirable behavior has been used. Gross observations indicate that desirable behavior is increasing in frequency and that undesirable behavior is decreasing in frequency.

3. VERBALSKILIS One of the frequently cited problems of the moderately and severely retarded is the lack of verbal behavior or an impoverished verbal repertoire. Schiefelbusch (1965) has pointed out some of the essential aspects involved in the development of language by the retarded.

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For the child without any communicable vocal behavior, the first step might be to train him to respond vocally to a vocalization of the trainer by the procedure used by Kerr, Meyerson, and Michael (1965) with a retarded three-year-old girl of approximate IQ 25. Initially, the child was reinforced for any vocalization and then the requirements were gradually increased. Later in the study, the child was reinforced for vocalizations only if they occurred within 5 sec of the trainer’s vocalization. Echoic behavior (matching the experimenter’s vocalization) was not required. As Kerr et al. (1965) point out, a shaping procedure could probably be used throughout but it is highly impractical and time consuming. The procedure in the usual environment probably involves a great deal of echoic behavior. In the imitation study by Baer et al. (1965) a child was given 10 words through imitative training. These were echoic, i.e., the controlling stimulus was the sound made by the experimenter. Following echoic training, control of the vocalizations of retarded children can be shifted to objects and pictures (Risley, 1965). Heard (1964) trained four moderately retarded children to recognize and respond phonically to letters of the alphabet with diacritical marks. His procedure involved a variety of verbal training including establishing an echoic response, shifting the response from echoic to textual control, and pointing out matching symbols in a matching-to-sample task. He used social comments and tokens redeemable in edibles and toys as reinforcers. Heard’s techniques and accomplishments are too complex for an adequate review in this chapter. However, the person interested in teaching reading will find many suggestions concerning techniques in Heard’s dissertation. Petrel3 is developing a program for the training of concept formation by language impaired children. This program can be used by the moderately and severely retarded, as well as the deaf, aphasics, etc. The procedure is a matching-to-sample one in which a word (e.g. hat) is presented and several pictures of different hats are presented below the word. On different trials the child is reinforced for responding to different hats. In this manner the child learns to respond to different hats in the presence of the same word, hat.

F.

Some Perennial Problems

Much of the behavior of the moderately and severely retarded is aversive to many people. Other prevalent behavior, though not aversive, is incompatible with the development of adaptive behavior. There have 18

Personal communication. 1965: see Footnote 8.

1. E . Spradlin and F. L. Girardeau been few systematic attempts to solve such problems as self-destructive behavior, stereotypies, tantrums, aggressive behavior, drooling and nasal discharge, excessive clinging to others, abnormalities of posture (including sitting), and excessive masturbation. The following remarks regarding some perennial problems are, for the most part, speculative. However, the principles used in the speculations are based on research with both children and lower animals. 1. INSTITUTIONAL MALADAPTIVE BEHAVIOR

There is some maladaptive behavior which is typically found in institutions. This behavior is developed and maintained by the institutional environment. For example, the institutional environment provides very little adult attention for the child. However, when the child has a tantrum, is aggressive with others, breaks a window, or exhibits self-destructive behavior, he usually receives a great deal of attention from the attendant and professional personnel. Probably the most effective procedure for reducing the frequency of these behaviors is to withhold reinforcement when they occur, i.e. extinguish them. However, in a field situation if one withholds reinforcement for one undesirable response, the person may make an even more objectionable response which cannot be ignored. For example, if adult attention is withheld when a tantrum occurs, then aggressive behavior toward the adult may occur. If this goes unreinforced, then selfdestructive behavior may develop which forces the adult to reinforce by giving attention. Thus, prior to the initiation of extinction for maladaptive behavior, the retarded person should be given the reinforcer for adaptive responses. When selfdestructive behavior occurs, it is often possible to handle the situation adequately and not provide some of the usual adult attention of a positive nature that customarily accompanies such a situation. Pursley and Hamilton (1965) have described a typical situation and suggested an appropriate procedure for the personnel involved. Lovaas, Freitag, Gold, and Kassorla (1965) have been interested in self-destructive behavior and have reported work using shock to eliminate self-destructive behavior. The presentation of a painful stimulus (electric shock) was contingent on the selfdestructive behavior of two children. The behavior was suppressed within minutes and remained so for 11 months. When it reoccurred, a single noncontingent shock resuppressed the behavior for the remainder of the study. T h e present writers would speculate that the punishment would be most effective if the self-

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destructive child were reinforced for behavior incompatible with selfdestruction. Clinging or hugging of both friends and strangers is a behavior which is exhibited in high frequency in institutions for retarded persons. Yet this kind of behavior is generally unacceptable in a community and might even reduce the probability of weekend visits home if the child embarrasses the parents by clinging to neighbors or visitors. This behavior is not an innate characteristic of retarded persons but is generated by the social reinforcements of an institutional environment. The persons in the institutional environment are apt to overlook a retarded person if the person is playing with blocks, drawing, or merely talking to them in a conversational voice. However, it is most difficult to overlook a patient who is clinging to you. Moreover, most visitors of an institution have no particular behavior goal for the child other than to make him smile for the moment. Thus, even though clinging is temporarily mildly aversive, they socially reinforce it by talking to the child and perhaps even hugging the child in return. If asked why they don't ignore the child or push him away they usually respond that they do not want him to "feel rejected." Yet they are reinforcing the exact behavior which will preclude acceptance by a normal peer or adult. Clinging can be reduced rather quickly with no bad side effects if the personnel and visitors are instructed to ignore clinging and to direct attention to the child while he is not clinging. Moreover, if social or verbal 'reinforcement of other behavior (such as walking beside a person without clinging) does not reduce the clinging then reinforcers such as tokens, candy, and money may be used initially to establish nonclinging behavior. Poor posture is a characteristic which quickly identifies many institutionalized retarded children as different from their peers in the community. Correct posture can be developed by reinforcing approximations to the desired posture and ignoring deviations from the desired behavior. Such a procedure is being used in the cottage program reported by Girardeau and Spradlin (1964). 2. AGGRESSIVE BEHAVIOR Aggressive behavior may be under the control of numerous variables. First, aggressive behavior may be a positively reinforced operant. When a child obtains another child's toy, food, or other reinforcers by striking, biting, or kicking, such behavior is reinforced by positive consequences. Moreover, a child who obtains little adult attention may be reinforced by adult attention when he is aggressive toward another child. It is not unusual for the aggressor to be taken aside by the adult and asked why he hits other children, asked to resolve to do better in the future, and

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finally assured he is loved. Such a procedure may be a powerful reinforcer for the child who infrequently receives adult attention on other occasions. Aggressive behavior may also be reinforced by the termination of an aversive situation. For example, counter-aggressionmay terminate another child’s hair pulling, biting, or pinching. Bandura and Walters (1963) have found that normal children will imitate the aggressive behavior of peers and adults. Thus aggression may occur as a form of generalized imitation. Finally, research on animals (Ulrich & Azrin, 1962) suggests that certain forms of aggression or attack may be pain-induced. That is, presentation of a painful stimulus such as shock and intense heat will result in attacks on other organisms. Such pain-produced aggressive responses are short lived in white rats and usually stop immediately after the painful stimulus is terminated; however, with monkeys these aggressive responses are vicious and will continue even after the termination of the painful stimulus. There is no scientific evidence for pain-produced aggression in human Ss. However, the phenomenon is so widespread among lower species and seem so in line with casual observations that it seem likely that it does occur with the human organism. The procedures for reduction of aggressive behavior by retarded children necessitates the analysis of the variables controlling the behavior. If aggressive bkhavior is being maintained by positive reinforcement, one can reduce such behavior simply by changing the contingencies so that aggressive behavior goes unreinforced while nonaggressive behavior is reinforced. Close supervision may prevent the aggressive child from profiting from striking, kicking, or biting. That is, if he uses these devices to take a toy, the toy i s immediately taken from him. However, if he makes some sort of nonaggressive request the supervisor would be very quick to provide the toy or one which is similar. Counter-aggression or aggression which terminates an aversive consequence may not present a problem unless the counter-aggressive responses become too severe, In this case one may have to reduce counteraggression by controlling the initial aggressive responses of the other person. Counter-aggression may be closely related to pain-produced aggressions and thus may be very difficult to reduce through control of the consequence variables. Finally, one may reduce aggressive behavior by providing nonaggressive adult and peer models. Numerous investigators have reported that a large percentage (over 50%) of institutionalized moderately and severely retarded persons exhibit stereotopies (Berkson & Davenport, 1962; Hollis, 1965b; Kaufman

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& Levitt, 1965). These stereotopies include such repetitive acts as body swaying, head rolling, and flicking the fingers in front of the eyes. Kaufman and Levitt (1965) found that head rolling and body swaying occurred more frequently right before lunch and at 3:OO p.m. when the attendant shifts changed. Levitt and Kaufman (1965) found that rocking increased with increased intensities of white noise. Davenport and Berkson (1963) and Hollis (1965a; Hollis, 1965b) has found that availability of objects reduced stereotyped behavior. The present writers would speculate that rocking and head rolling are superstitious behavior developed in an impoverished environment in which reinforcement is noncontingent. Rocking and head rolling are responses which occur with high frequency among normal persons; however, they are usually under very tight stimulus control. For example, normal persons rock in rocking chairs and turn their heads back and forth in looking for objects or in following conversation. When a child has no toys, objects, or other controlling stimuli, head rolling and rocking are no doubt probable. Suppose that while the child is rocking he is called to lunch, to a bus ride, or any one of several noncontingent reinforcers. The probability that he will rock or head roll the next time he is hungry, thirsty, or bored is now higher. The increased stereotyped behavior now increases the probability that reinforcement will occur during the time the person is stereotyping. Under such conditions stereotyping may become extremely frequent and persistent. If rocking and head rolling are superstitious behavior they could be reduced in frequency by arranging the environment so that reinforcements are delivered primarily when the patient is engaged in behavior which is incompatible with stereotyping. Excessive and indiscreet masturbation is a problem which often perplexes those who manage retarded persons. It is unlikely that masturbation can be completely eliminated. However, one may reduce the frequency of masturbation in public by providing the person privacy. Moreover, the general frequency of masturbation may be decreased by reinforcing activities that are incompatible with masturbation. The use of a handkerchief or tissue in handling excess saliva or nasal discharge is a skill which moderately and severely retarded children often lack. We have found several techniques useful in eliminating this problem. First, the child was provided with an apron in which to keep tissues. Then an adult would demonstrate how to use the tissue or might possibly move the child’s hand with the tissue so that the nose or mouth was cleaned. During the early stages the child was given a token (reinforced) for cleaning her nose or mouth even if it was with help. Later a token was given if the child used the tissue without help and sometimes merely

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for having a clean mouth or face. Gradually the support of the adult and the frequency of reinforcement was reduced. IV. CONCLUSION

The last portion of this chapter has been devoted to the solution of practical problems through the use of operant techniques. In cases where operant techniques have been applied, the reported results are encouraging. One might hope that these advances would lead to the development of training and educational programs which one day would allow these persons to live in and contribute to the noninstitutional community. The extent to which such a goal is accomplished depends primarily on the ingenuity and effort of interested workers. The present writers believe that if the principles and techniques discussed in this chapter were consistently applied, Butterfield’s (1961) case of overachievement by a mongoloid might be considered “typical” rather than a “provocative case.” REFERENCES Ayllon, T., & Azrin, N. H. Reinforcement and instructions with mental patients. J . exp. anal. Behav., 1964, 7 , 327-331. Ayllon, T., & Azrin, N. H. The measurement and reinforcement of behavior of psychotics. J . ex$. anal. Behav., 1965, 8, 357-383. Ayllon, T., & Haughton, E. Control of the behavior of schizophrenic patients by food. I. exp. anal. Behav., 1962, 5, 343-352. Ayllon, T., & Michael, J. L. The psychiatric nurse as a behavioral engineer. J . exp. anal. Behav., 1959, 2. 323-334. Azrin, N. H. Effects of punishment intensity during variable-interval reinforcement. J . exp. anal. Behau., 1960, 3, 123-142. Baer, D. M., Peterson, R. F., & Sherman, J. A. Building an imitative repertoire by programming similarity between child and model as discriminative for reinforcement. Read at biennial meeting of the SOC.for Res. in Child Develpm., Minneapolis, Minn.. March, 1965. Bandura, A.. lk Walters, R. H.Social learning and personality development. New York: Holt, 1963. Barnett, C. D.. Pryer, Margaret W., & Ellis, N. R. Experimental manipulation of verbal behavior in defectives. Psychol. Rep., 1959, 5, 393-396. Barrett, Beatrice H., & Lindsley, 0. R. Deficits in acquisition of operant discrimination and differentiation shown by institutionalized retarded children. Amcr. J. ment. Defic., 1962, 67, 424-436. Baumeister, A. A., Beedle, R., & Urquhart, D. GSR conditioning in normals and retardates. Amer. J. ment. Defic., 1964, 69, 114-120. Behrens, R. F., & Ellis, N. R. Simultaneous and trace eyelid conditioning in normals and defectives. In R. L. Cromwell (Ed.) Abstracts of Peabody studies in mental retardation, 1960-1962. George Peabody Coll. for Teachers, 1962, Vol. 2 (Abstract No. 20). Bensberg, C. J., Colwell, C. N., & Caapel, R. H. Teaching the profoundly retarded

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self-help skill activities by behavior shaping techniques. Amer. J . ment. Defic., 1965, 69, 674-679.

Berkson, G., & Davenport, R. K. Stereotyped movements of mental defectives: I. Initial survey. Amer. J . ment. Defic., 1962, 66, 849-852. Bijou, S. W., & Orlando, R. Rapid development of multiple-schedule performances with retarded children. J. exp. anal. Behav., 1961, 4, 7-16. Birnbrauer, J. S., Bijou, S. W., Wolf, M. M., -& Kidder, J. D. Programmed instruction in the classroom. In L. Ullmann & L. Krasner (Eds.), Case studies in behauior modification. New York: Holt, 1965. Birnbrauer, J. S., & Lawler, Julia. Token reinforcement for learning. Ment. Retard., 1964, 2, 275-279. Blackwood, R. 0. Operant conditioning as a method of training the mentally retarded. Unpublished Ph.D. dissertation, Dep. of Psychol., Ohio State Univer., 1962. Bowers, C. Y., Gordon, D. L., & Segaloff, A. The myxedema reflex in infants and children with hypothyroidism. J. Pediat., 1959, 54, 46-49. Butterfield, E. C. A provocative case of over-achievement by a mongoloid. Amer. 1. ment. Defic., 1961, 66, 444-448. Carter, P. H. (Ed.) Medical aspects of mental retardation. Springfield, Ill.: Thomas, 1965. Cromwell, R. L., Palk, B. E., & Foshee, J . G. Studies in activity level: V. T h e relationships among eyelid conditioning intelligence activity level, and age. Amer. J. ment. Defic., 1961, 65, 744-748. Davenport, R. K., & Berkson, G. Stereotyped movements of mental defectives: 11. Effects of novel objects. Amer. I . ment. Defic., 1963, 67, 879-882. Dayan, M. Toilet training retarded children in a state residential institution. Ment. Retard., 1964, 2, 116-117. Eimas, P. D. Components and compounds in discrimination learning of retarded children. J. e x p . child Psychol., 1964, 1, 301-310. Ellis, N. R. Amount of reward and operant behavior in mental defectives. Amer. J. ment. Defic., 1962, 66, 595-599. Ellis, N. R. Toilet training the severely defective patient: an S-R reinforcement analysis. Amer. J . ment. Defic., 1963, 68, 98-103. Ellis, N. R. Experimental approaches to behavioral engineering: considerations in establishing more adequate behavioral patterns and response repertoires in the retarded. Paper delivered at the Ameri. Psychol. Ass. Meeting, Los Angeles, 1964. Ellis, N. R., Barnett, C. D., & Pryer, Margaret W. Operant behavior in mental defectives: exploratory studies. J . exp. anal. Behav., 1960, 3 , 63-69. Ellis, N. R., Girardeau, F. L., & Pryer, Margaret W. Analysis of learning sets in normal and severely defective humans. J . comp. physiol. Psycho[., 1962, 55, 860-865. Estes, W. K. An experimental study of punishment. Psychol. Monogr., 1944, NO. 57. Ferster, C. B.,& Skinner, B. F. Schedules of reinforcement. New York: Appleton, 1957. Franks, C. M. Individual differences in conditioning and associated techniques. In J. Wolpe, A. Salter & L. J. Reyna (Eds.), The conditioning therapies. New York: Holt, 1964. Franks, V. An experimental study of conditioning and learning in mental defectives. Unpublished Ph.D. dissertation, Univer. of London. 1959. Fuller, P. R. Operant conditioning of a vegetative human organism. Amer. J . Psychol., 1949, 62, 587-599. Girardeau, F. L., & Spradlin, J. E. Token rewards o n a cottage program. Ment. Retard., 1964, 2, 345-351. Cove, R. M., Lawson, R., & Watson L. S., Jr. Operant conditioning with severely and profoundly mentally retarded children. Unpublished manuscript, Columbus State Sch., 1964.

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Gnngs, W. W., Lockhart, R. A., & Dameron, L. E. Conditioning autonomic responses of mentally subnormal individuals. Psychol. Monogr., 1962, 76, 1-35. Harris, Florence R.,Wolf, M. M., & Baer, D. M. Effects of adult social reinforcement on child behavior. Young Child, 1964, 20, 8-17. Headrick, Mary W. Effects of instructions and initial reinforcement on fixed-interval behavior in retardates. Amer. J . ment. Defic., 1963, 68, 425-432. Heard, W. G. Extension of the method of the laboratory study of reading acquisition to retarded children. Unpublished Ph.D. dissertation. Arizona State Univer., 1 W . Herman, R. L., & Azrin, N. H.Punishment by noise in an alternate response situation. J . exp. anal. Behav., 1964, 7, 185-188. Hollis, J. H. Solution of bent-wire problems by severely retarded children. A n e r . J. ment. Defic., 1962, 67, 463-472. Hollis, J. H. T h e effects of social and nonsocial stimuli on the behavior of profoundly retarded children: Part 1. Amer. J. ment. Defic., 1965, 69, 755-771. (a) Hollis, J. H. T h e effects of social and nonsocial stimuli on the behavior of profoundly retarded children: Part 2. Amer. J . ment. Defic., 1965, 69, 772-789. (b) Hollis, J. H. Effects of reinforcement shifts on bent-wire performance of severely retarded children. Amer. J . ment. Defic., 1965, 69, 531-535. (c) Holz, W. C., & Azrin, N. H. Discriminative properties of punishment. J. exp. anal. Behav., 1961, 4, 225-232. Holz, W. C.,& Azrin, N. H. Interactions between the discriminative and aversive properties of punishment. J. exp. anal. Behav., 1962, 5, 229-234. Holz, W. C., & Azrin, N. H. A comparison of several procedures for eliminating behavior. 1. exp. anal. Behav., 1963, 6, 399-406. Hundziak, M., & Maurer, R. A. A comparison of nursing care for profoundly mentally retarded boys in large and small groups. Unpublished manuscript, Columbus State Sch., 1963. Hundziak, M., Maurer, R. A., & Watson, L. S., Jr. Operant conditioning in toilet training of severely mentally retarded boys: a controlled study. Unpublished manuscript. Columbus State Sch., 1963. Kaufman, M. E., & Levitt, H. A study of three stereotyped behaviors in institutionalized mental defectives. Amer. J . ment. Defic., 1965, 69, 467-473. Keller, F. S., & Schoenfeld, W. N. Principles of psychology. New York: Appleton, 1950. Kerr, N., Meyerson, L., & Michael, J. L. A procedure for shaping vocalizations in a mute child. In L. P. Ullmann & L. Krasner (Eds.), Case studies in behavior modificatiott. New York: Holt, 1965. Lane, H., & Curran, C. Gradients of auditory generalization for blind, retarded children. J . exp. anal. Behav., 1963, 6, 585-588. Lawson, J. D. T h e free Achilles reflex in hypothyroidism and hyperthyroidism. New Engl. J . Med., 1958, 259, 761-765. Levitt, H., & Kaufman, M. E. Sound induced drive and stereotyped behavior in mental defectives. Amer. J. ment. Defic., 1965, 69, 729-734. Lindsley, 0. R. Direct measurement and prosthesis of retarded behavior. J. Educ., 1964, 147, 62-81. Lipman, R. S. Learning: verbal, perceptual-motor, and classical conditioning. In N. R. Ellis (Ed.), Handbook of mental deficiency: psychological theory and research. New York: McGraw-Hill, 1963. Locke, B. J. T h e effects of examiner, role, and reinforcement variables on the modification of verbal behavior in institutionalized retardates. Unpublished Ph.D. dissertation, Oklahoma State Univer., Stillwater, 1962.

MODERATELY AND SEVERELY RETARDED PERSONS

297

Long, E. R.,Hammack, J. T., May, F., & Campbell, B. J. Intermittent reinforcement of operant behavior in children. J. exp. anal. Behav., 1958, 1, 315-339. Lovaas, 0. I., Freitag, G., Kinder, M., Rubenstein, B., Schaeffer, B., & Simmon, J. Developing social behaviors in autistic children using electric shock. Paper delivered at the Amer. Psychol. Ass. Conv., Los Angeles, 1964. Lovaas, 0.I., Freitag, G., Gold, Vivian J., & Kasmrla, Irene C. Experimental studies in childhood schizophrenia: 1. Analysis of self-destructive behavior. J. exp. child Psychol., 1965, 2, 67-84. McIntire, M. S., & Dutch, S, J. Mongolism and generalized hypotonia. Amer. /. ment. Defic., 1964, 68, 669-670. Mateer, Florence. Child behavior: a critical and experimental study of young children by the method of conditioned reflexes. Boston: Badger, 1918. Metz, R. Imitation in autistic children. Paper read at Amer. Psychol. Ass. Conv., Los Angeles, 1964. Meyerson, L., & Michael, J. L. The measurement of sensory thresholds in exceptional children: an experimental approach to some problems of differential diagnosis and education with special reference to hearing. Cooperative Res. Proj. No. 418. U.S.Office of Educ., 1960. Michael, J. L. The relevance of animal research. In R. L. Schiefelbusch & J. 0. Smith (Eds.), Proceedings of a conference on research in speech and hearing for mentally retarded persons. A report to the U.S.Office of Educ., 1963. O’Connor, N., & Hermelin, Beate. Speech and thought in severe subnormality: an experimental study. New York: Macmillan, 1963. Orlando, R. The functional role of discriminative stimuli in free operant performance of developmentally retarded children. Psychol. Rec., 1961, 11, 153-161. Orlando, R., & Bijou, S. W. Single and multiple schedules of reinforcement in developmentally retarded children. J. ex#. anal. Behav., 1960, 3 , 339-348. Prechtl, H. F. R. Neurological sequelae of prenatal and paranatal complications. In B. M. Foss (Ed.), Determinants of infant behavior. Vol. I. New York: Wiley, 1961. Punley, N. B., & Hamilton, J. W. The development of a comprehensive cottage-life program. Ment. Retard., 1965, 3, 26-29. Razran, G. The observable unconscious and the inferable conscious in current Soviet psychophysiology: Interoceptive conditioning, semantic conditioning, and the orienting reflex. Psychol. Rev., 1961, 68, 81-147. Risky, T. K. The establishment of verbal behavior in deviant children. Unpublished Ph.D. dissertation, Univ. of Washington, 1965. Schiefelbusch, R. L. A discussion of language treatment methods for mentally retarded children. Ment. Retard., 1965, 3, 4-7. Schwitzgebel, Ralph, & Schwitzgebel, Robert. Reduction of adolescent crime rate by a research method. J. SOC. Ther., 1961, 7, 212-215. Sidman, M. Tactics of scientific research. New York: Basic Books, 1960. Skinner, B. F. The behavior of organisms. New York: Appleton, 1938. Slack, C. W. Experimenter-subject psychotherapy: a new method of conducting intensive office treatment for “unreachable” cases. Ment. Hyg., N.Y.,1960, 44, 238-256. Spradlin, J. E. Effects of reinforcement schedules on extinction in severely mentally retarded children. Amer. J. ment. Defic., 1962, 66, 634-640. Spradlin, J. E. T h e Premack hypothesis and self-feeding by profoundly retarded children: a case report. Parsons Res. Center, Working Paper #79, 1964. Spradlin, J. E.,Girardeau, F. L., & Corte, E. Fixed ratio and fixed interval behavior of severely and profoundly retarded subjects. J. exp. child Psychol., 1966, in press.

298

J. E . Spradlin and F. L. Girardeau

Staats. A. W. (Ed.) Human learning. New York: Holt, 1965. Stevenson, H. W. Discrimination learning. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Terrace, H. S. Discrimination learning with and without “errors.” J. exp. anal. Behau., 1963, 6, 1-27. (a) Terrace, H. S. Errorless transfer of discrimination across two continua. J. exp. anal. Behau., 1963, 6, 223-252. (b) Ullmann, L., & Krasner, L. (Eds.) Case studies in behavior modification. New York: Holt, 1965. Ulrich, R. E., & Azrin, N. H. Reflexive fighting in response to aversive stimulation. J. exp. anal. Behau., 1962, 5 , 511-520. Wall, R. L., Umlauf, H. J., & Geppert, L. J. hfuscle reflex patterns in infancy and childhood: normal patterns and patterns in thyroid disorders, cerebral palsy, and meningopathies. J. Pediat., 1964, 64, 701-710. Watson, L. S., Jr., Lawson, R., & Sanders, C. C. Generalized or token reinforcement with severely and profoundly retarded children. Paper read a t the 89th annual meeting of the Ameri. Ass. o n Ment. Delici., Miami, Florida, June, 1965. Wolf, M. M., Risley, T. R., & Mees, H. L. Application of operant conditioning procedures to the behavior problems of an autistic child. Beliciv. Res. Ther., 1964, 1, 305-312. Zeaman, D., & House, Betty J. T h e role of attention in retardate discrimination leaming. In N. R. Ellis (Ed.), Handbook of mental deficiency. New York: McGraw-Hill, 1963. Zeaman, D., Thaller, C., & House, Betty J. Variability of irrelevant stimuli in discrimination learning of retardates. J . exp. child Psycho[., 1964, 1, 89-98.

Author Index Numbers in italics refer to pages on which the complete references are listed. Ader, R., 114, 119, 145 Alderdice, E. T.. 70, 74 Alpert, M., 142, 143, 148 Andersen, A, L., 177, 214 Anokhin, P. K., 138, 139, I45 Apter, N. S., 205, 214 Arima, R. K., 142, 151 Armitage, S. G., 164, 214 Atkinson, J. W., 97, 105 Atwell, A. A., 71, 76 Avakian, S. A., 71, 74 Ayllon, T., 267, 287, 294 Azrin, N. H., 267, 283, 287, 292, 294, 296, 298 Badt, M. I., 130, 145 Baer, D. M., 2, 18, 18, 266, 267, 280, 289, 294, 296 Baker, C. T., 5, 19 Ball, Rachel S., 59, 60,70, 74, 76 Bandura, A., 280, 292, 294 Barnett, C. D., 243, 244, 246, 252, 253, 263, 267, 269, 270, 294, 295 Baron, A,, 116, 145 Barrett, Beatrice H., 274, 294 Bartlett, C. J., 67, 71, 74, 75 Battersby, W . S., 163, 218 Baumeister, A. A., 67, 71, 74, 75, 262, 294 Bayley, Nancy, 5, 18 Beedle, R., 262, 294 Behrens, R. F., 261, 294 Beier, D. C., 12, 18 Bell, R. W., 116, 128, 136, 145, 146 Bender, M . B., 163, 218 Benjamin, J. D., 142, 150 Bennett, E. L., 120, 143, 145,148 Bensberg, G. J., 285, 286, 294 Benton, A. L., 160. 214 Berkowitz, H., 93, 105 Berkson, G., 292, 293, 295

299

Bernstein, L., 114, 128, 142, 146, 150 Bijou, S. W., 1, 2, 18,18,263, 264, 269, 273, 287, 295, 297 Bingham, W.E., 113, 114, 119, 146 Birch, D., 26, 52 Birnbrauer, J. S., 287, 295 Birren, J. E., 205, 214 Bitterman, M. E., 47, 52 Blackwood, R. O., 285, 286, 295 Boring, E. G., 232, 253 Bossio, V., 130, 149 Bowers, C. Y., 260, 295 Brackbill, Yvonne, 4, 18 Braun, H. W., 246, 255 Broadhurst, P.L., 115, 135, 146,148 Brookshire, K. H.,116, 135, 145, 146 Brown, W., 223, 225, 253 Burke, C. J., 188, 218 Burke, R. E., 50, 52 Burlingham, D., 93, 105 Butler, A. J., 70, 74 Butterfield, E. C., 88, 93, 97, 105, 294, 295

Campbell, B. J., 267, 297 Cantor, G. N., 239, 253 Carlson, D. C., 71, 75 Carlson, P. V., 116, 127. 146 Carr-Saunders, A., 89, 90,106 Carter, P. H., 259, 295 Cassel, R. H., 285, 286, 294 Cattell, R. B., 58, 59, 61, 75 Chapman, L. F., 181, 214 Check, J., 248, 251, 252, 254 Chevalier, J. A., 116, 136, 148 Clark, L. P., 83, 105 Clark, W. E. L., 142, 146 Clarke, A., 89, 105 Clarke, H., 89, 105 Clausen, J., 71. 75

Author Index

300 Coate, W. B.,47, 52 Cohen, B. J., 113, 120, 146 Colwell, C. N., 285, 286, 294 Conklin, P. M., 119, 145 Cooley, J. A., 4, 13, 19 Cooper, R. M., 114, 119, 146 Corte, E., 263, 264, 265, 270, 297 Cox, Catherine M., 10, 18 Cox, F., 93, 105 Cromwell, R. L., 97, 105, 261, 295 Cruse, D., 103, 105 Curran, C., 280, 296 Dameron, L. E., 29, 53,262, 296 Davenport, R. K., 292, 293, 295 Davidson, K., 97, 107 Davis, A., 96, I05 Davis, K., 14, 18 Dayan, M.. 286, 295 delabry, J., 90, 95, 108 DeMyer, W., 195, 215 Denenberg, V. H.,114, 116, 118, 119, 121, 127, 128, 135, 136, 137, 140, 142, 145, 146,148,149 Dennis, W., 11, 18, 19, 131, 138, I46 Denny, M. R., 21, 30, 49, 52, 113, 150, 220, 253 Diamond, M. C., 143,145 Dingman, H.F., 69, 71, 73, 75, 76 Dobzhmski, T., 5, I8 Doehring, D. G., 179, 180, 181, 182, 184, 195, 214, 215 Douvan, E., 96, 105 Dubanoski, R. A., 125, I51 Duffy. Elizabeth, 135, 146 Dunn, L. M., 134, 147 Durkin, K., 95, 107 Dutch, S. J.. 261, 297 Dye, H. B., 132, 150 Eells, Janet F., 114, 118, 147 Ehrlich, D. J., 121, 142, 149 Eichorn, Dorothy H.,131, I50 Eimas, P. D., 276, 295 Eisele, C. W., 205, 214 Eleftherion, B. E., 115, 148 Elliott, 0..125, I47 Ellis, N. R., 67, 71, 75, 77, 105, 220, 243, 24,246,252. 253, 261, 263, 267, 269, 270, 272, 277, 281, 286, 294, 295

Erickson, M., 96, 105 Erlich, Annette, 114, I47 Estes, W. K., 283, 295 Fahel, L. S., 87, 107 Faltin, J., 113, I49 Feldhusen, J., 248, 251, 252, 254 Ferster, C. B., 10, 11, 18 Fitzhugh, K. B., 178, 185, 186, 187, 195, 215 Fitzhugh, L. C., 178, 185, 186, 187, 195, 215 Flanders, V., 113, 149 Fleishman, E. A., 60, 75 Forgays, D. G., 114, 128, 147 Forgays, J. W., 114, I47 Forgus, R. H.,119, 120, 128, 147, 149 Foshee, J., 77, 78, 107 Fourment, A., 141, I50 Franks, C. M., 29, 52, 261, 295 Franks, V,.29, 52, 261, 295 Freedman, D. G., 125,147 Freitag, G., 268, 284, 290, 297 French, J. W., 60, 61, 65, 75 Freud, A., 93, 105 Freud, S., 109, 147 Frommer, G., 114, I49 Fuller, P. R., 263, 282, 295 Ganz, L., 113, I47 Gardner. W. I., 97, 105, 106 Garrard, S. D., 6, 18, 18 Garrett, H. E., 62, 75 Geppert, L. J.. 259, 260, 298 Gesell, A., 10, 18 Gewirtz, J. L., 4, 19 Ghen't, L., 160, 215, 218 Gillette, Annette L., 226, 233, 238, 246, 252, 253 Girardeau, F. L., 263, 264, 265, 267, 270, 277, 286, 287, 291, 295, 297 Gladwin, T., 88, 90, 107, 207, 218 Gold, Vivian J., 290, 297 Goldfarb, W., 93, 106 Goldstein, H., 103, I06 Goldstein, K., 77, 106, 175, 176, 180, 215 Goodnow, J. J., 98, 106 Gordon, D. L., 260, 295 Gordon, Kate, 223, 225, 253 Gove, R. M., 278, 286, 295 Gray, Susan, 134, I47 Green, C., 86, 99, 100, 102, I06

Author Index Griffith, Ann H., 245, 253 Griffiths, W. J., Jr., 113, 114, 119, 146 Grings, W. W.,29,53, 262, 296 Grossman, H. J., 73, 76 Grota, L. J., 135, 146 Guertin. W. H., 89, 106, 206, 216 Guilford, J. P., 58, 59, 61, 75

Halstead, W. C., 158, 164, 168, 172, 17i, 180, 181, 205. 206, 214, 215, 218 Hamilton, J. W., 285, 290, 297 Hammack, J. T., 267, 297 Harburg, E., 114, 151 Harmon, H. H., 56, 75 Harris, Florence R.. 267, 296 Hartman, T. F., 29, 38, 39, 53 Hathaway, S. R., 164, 215 Haughton, E., 287, 294 Haywood, H. C., 123, 124, 125, 126, 147 Headrick. Mary W.,270, 296 Heal, L. W., 31, 32, 42, 43, 44, 53, 54 Heard, W. G., 267, 289, 296 Hebb, D. 0.. 119, 135, 137,147,220,253 Heber, R. F., 97, 106, 242, 253 Heimburger, R. F., 183, 195, 205, 214, 215 Hellmer, L. A., 118, 147 Henderson, E. N., 221, 223, 225, 254 Henderson, N. D., 127, 147 Herman, R. L., 283, 296 Hermelin, Beate, 78, 106, 240, 241, 254, 278, 279, 297 Heron, W., 112, 151 Herrick. R. M., 50, 53 Hess, E. H.. 123, 147 Hilgard, E., 232, 254 Hilgard, Josephine R.,10, 18 Hirsch, E. A., 90, 106 Hodgden, L., 83, 91, 99, 102, 108 Hoepfner, R., 58, 75 Hofstaetter, P. R., 70, 75 Holbourn, A. H. S., 205,215 Hollis, J. H., 264, 265, 267, 282, 292, 293, 296 Holz, W. C.. 283, 296 House, Betty J., 29, 42. 53, 54, 98, 107, 276, 298 Hubel, D. H., 141, 148 Humphreys, L. D., 59, 75

So1 Hundziak, M., 285, 286, 296 Hunt, J. McV., 116, 117, 128, 136, 148, 150 Hutchings, D. E., 118,148 Hymovitch, B., 119, 120. 127. 148 Irvine, E.,93, 106 Ison, J. R.,26, 27,552, 53 Jensen, A. R., 239, 254 Johnson, G. O.,245, 254 Jones, D., 89, 90,106 Kanner, L., 12,18 Kantor, J. R.. 2, 19 Karas, G. G., 127, 136, 146 Kass, N., 97, 106 Kassorla, Irene C.,290, 297 Katz, I., 97, 106 Kaufman, M. E.. 292, 293, 296 Kebbon, L., 71, 75 Keller, F. S., 274, 296 Kelley, T. L., 70, 75 Kendler, H. H., 29, 34, 42,53 Kendler, T. S., 29, 34, 42, 53 Keppel. G., 219, 236, 237, 252, 254 Kerr, N., 289, 296 Kidder, J. D., 287, 295 Kimble, G. A., 182, 215 Kinder, M., 268, 284, 297 King, J. A., 115, 125, 147, 148 Kirk. S. A., 58, 71, 75, 133, 148 Kjerstad, C. L., 227, 254 Klaus, R. A.. 134, 147 Klausmeier, H. J.. 248, 251, 252. 254 Kline, N. J.. 127, 128, 135, 136, 146, 148 K10ve, H., 178, 179, 195, 215, 216 Koldovsk$ 0..113, 149 Korchin, S. J., 116, 136, 148 Koski, C. H., 36, 39, 40,54 Kounin, J.. 77, 78, 79, 91, 95, 106 Krasner. L., 285, 298 Krech, D.,120, 141, 143, 145, 148 Kugelmass, I. N.. 5, 19 Lachman, R.,22,25, 53 Lance, W..244, 254 Lane, H., 280, 296 Langfeld. H. S.. 232, 253 Langworthy, 0.R., 142, 148

302 Lawler, Julia, 287, 295 Lawson, J. D., 269, 296 Lawson, R., 264, 267, 278, 286, 295, 298 Leavitt, H.J., 225, 246, 254 Levine, S., 114, 115, 116, 118, 121, 122, 125, 128, 135, 136, 137, 142, 143, 148 Levitt, H.,292, 293, 296 Lewin, K., 77, 78, 106 Lewis, G. W., 128, 142,148 Lighthall, F., 97, 107 Lindholm, B. W.,128, 135, 149 Lindsley, 0. R.,267, 274, 286, 294, 296 Lipman, R. S., 21, 29, 53, 220, 239, 254, 259, 296 Lipsitt, L. P., 29, 53 Littman, R. A.,116, 145, I46 Locke, B. J.. 267, 296 Lockhart, R. A., 29, 53, 262, 296 Loeffler, F. J., 71, 75 Long, E. R.. 267, 297 Lorenz, K. Z., 122, 149 Lott, Bernice E., 221, 238, 254 Lovaas, O:I., 268, 284, 290. 297 Luchins, A. S., 120, 149 Luh, C. W.,224, 225, 226, 230, 254 Luria, A. R.,78, 106 Lyon, D. O., 221, 222, 223, 224, 225, 226, 227, 230, 254 McCandless, B. R., 128, 132,149 McCarthy, J. J., 58, 71, 75 McCartin, Sr. Rose Amata, 71, 75 McClelland, W. J., 142, 149, 151 McCoy, N.. 93, 106 McCullough, N. B., 205, 214 McFie, J., 180, 216 McGeoch, J. A., 232, 254 McGraw, Myrtle B., 10, I9 McIntire, M. S., 261, 297 McKinley, J. C., 164, 215 McKinney. J. P., 57, 75 McMichael. R. E., 136, 149 McNemar, Q., 60,61, 65, 70, 75 Maher, B. A., 114, 118, 121, 150 Makmo, R. B., 135, 149 Margulies, S., 50, 53 Markowitz, H.,143, 151 Mateer, Florence, 263, 297 Matthews, C. G.. 179, 206, 207, 216 Maurer, R. A., 285, 286, 296

Author Index May, F., 267, 297 Mees, H.L., 17, 19, 286, 298 Meier, G. W.,142, 143. 149 Melzack, R., 112, 149 Merrill, M. E., 65, 76 Metz, R.,280,297 Meyer, W.J.. 118, 127, I49 Meyers, C. E., 69, 71, 73, 75, 76 Meyers, R., 182, 216 Meyerson, L., 266, 267, 277, 289, 296, 297 Michael, J. L.. 266, 267, 277, 285, 287, 289, 294, 296, 297 Michener, R.,71, 76 Miller, N. E., 22, 53 Mogenson. G. J., 121, 142, I49 Moltz, H., 123, 124, 149 Monkman, J. A., 116, I50 Morison, R. S., 52, 53 Morton, J. R. C., 114, 121, 135, 142, 146, 149 Mosier, H.D., 73, 76 Munn, N. L., 182, 216, 232, 254 Myers, B., 93, 107 Najarian, P., 11, 18 Nardi, G., 242, 253 Neff, W. S., 134, I49 Nelson, V. L., 5, 19, 70, 76 Norsworthy, Nancy, 222, 225, 254 Notterman. J. M., 50, 53 NovAkovi, V., 113, I49 Nunnally, J., 67, 76 O’Connor, N.. 78, 106, 240, 241, 254, 278, 279, 297 Oden, M., 10, 19 Orlando, R.. 263, 264, 269, 273, 274, 295, 297 Orpet, R. E., 69, 71, 73, 76 Osborn, W., 96, 106 Otis, L. S., 114, 121, 128, 149 Ottinger, D. R., 119, 146, 149 Palk, B. E., 261, 295 Patton, R. A.. 246, 255 Peterson, H.A., 223. 225, 254 Peterson, J., 223, 225, 254 Peterson, R. F., 266, 280. 289, 294 Piercy, M. F., 180, 216 Plenderleith, M.,81, 106

303

Author Index Postman, L., 228, 254 Prechti, H. F. R., 259, 297 Prehm, H., 242, 253 Pringle, M. L. K., 130, 149 Pryer, Margaret W., 243, 244, 246, 252, 253, 263, 267, 269, DO, 277, 294, 295 Pryer, R. S., 244, 254 Pryor, G. T., 143, 150 Pursley, N. B., 285, 290, 297 Pyle, W. H., 222, 223, 225, 254 Ramor. S. C., 113, 150 Rau, Lucy, 228, 254 Razran, G., 261, 297 Read, Janet, 128, 147 Reed, H. B. C., 179, 195, 206, 216 Reitan, R. M., 164, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 190, 191, 194, 195. 196, 201, 205, 206, 207, 214, 215, 216, 217, 218

Rennick, P., 206, 215 Rheingold, Harriet L., 4, 13, 19 Richards, T. W., 70, 76 Richmond, J. B., 6, 18, 18 Riesen, A. H., 113, 141, 147, 150 Risley, T. R., 17, 19, 286, 289, 297, 298 Rohwer, W. D., 239, 254 Rosennveig, M. R.. 120, 143, 148, 150 Ross, A. T., 195, 218 Ross, Helen W., 4, 19 Ross, L. E., 29, 31, 36, 37, 38, 39, 40.42, 43, 53, 54

Rotter, J. B., 97, 106 Rubenstein, B., 268, 284, 297 Ruebush, B., 97, 107 Ruegamer, W. R., 142, 150 Russell, J. R., 195, 218 Ryan, T. J., 239, 253 Rylander, G., 180, 218 Salama, A. A,, 116, 117, 136, 150 Sanders, B., 31, 42, 43, 54 Sanders, C. C., 264, 267, 298 Sarason, S. B., 11, 19, 83, 88, 90, 97. 106, 107,207, 218

Satter, G., 65, 70, 76 Sayegh, Yvonne, 11, 19 Schaefer, T., 118, 126, 128, 150

Schaeffer, B., 268, 284, 297 Schiefelbusch, R. L., 288, 297 Schoenfeld, W. N:, 274, 296 Schwitzgebel, Ralph, 267, 297 Schwitzgebel, Robert, 267, 297 Scott, J. P., 125, 150 Scott, T. H., 112, 149 Segaloff, A,, 260, 295 Seigle, D., 103, 106 Semmes, J.. 160, 218 Serrano, L. J., 113, 120, 146 Sersen, E. A., 160, 218 Shallenberger, P., 92, 107 Sherman, J. A., 266, 280. 289, 294 Sherrer, J., 141, 150 Shipley, R. E., 195, 218 Shure, G. H.,181, 218 Sidman, M., 273, 297 Siege!, P., 77. 78, 107 Silfin, C. K., 34, 53 Simmon, J., 268, 297 Simpson, Nancy, 242, 253 Sinnott, E. W., 191, 218 Sitkei, E. G., 69, 76 Skeels, H. M., 83, 107, 132, 133, 150 Skinner, B. F., 2, 3, 8, 9, 19, 259, 269, 295, 297

Slack, C. W., 267, 297 Smith, S. A., 116, 135, 146 Snygg, D., 130, 150 Soddy, K.,4, 6, 19 k n ta g , L. W., 5, 19 Speer, C. S., 130, 150 Spence, Janet, 114, 118, 121, 150 Spence, K. W., 38, 54 Sperling, S. E., 26, 52 Spieth, W., 205, 214, 218 Spiu, H. H., 77, 107 Spitz, R. A., 88, 93, 107 Spradlin, J. E., 263, 264, 265, 267, 270, 281. 285, 286, 287, 291, 295, 297 Staats, A. W., 285, 298 Staats, S. R., 114, 149 Stanley, W. C., 4, 13, 19, 116, 150 Stedman, D. J., 131, 150 Stephens, M. W., 116, 119, 127, 146, 149 Stettner, L. J., 123, 124, 149 Stevenson, H. W., 21, 54, 81, 83, 91, 95, 97, 98, 99. 102, 106, 107, 108, 276, 298 Stewart, C. N., 116, 146

304 Stott, L., 59, 60, 70, 76 Strong, R. T., Jr., 71, 76 Stuant, H. L., 142, 149 Talland, G., 163, 218 Tanner, M., 130, 149 Tapp, J. T., 143, 151 Tarshes, E. L., 179, 187, 218 Tedeschi, J. T., 114, 151 Terman, L. M., 10, 19, 65, 76 Terrace, H. S., 274, 277, 298 Terrell, G., Jr.. 95, 107 Teuber, H.-L., 160, 163, 218 Thaller, C., 276, 298 Thompson, Helen, 10. 10 Thompson, W. R., 112, 151 Thorndike, E. L., 222, 223, 225, 229, 254 Thurstone, L. L.,56, 59, 62, 70, 76 Thurstone, Thelma G.,70, 76 Towne, J. C., 118, 150 Tredgold. R. F., 4, 6, 19 Turnure, J., 99, 100, 102, 107 Ullmann, L., 285, 298 Ulrich, R. E.,292, 298 Umlaut, H.J., 259, 260, 298 Underwood, B. J.. 226, 233, 234, 235, 237, 240, 243, 246, 252, 255 Unell, E., 95, 108 Updegraff, R., 83, 107 Urquhart. D., 262, 29# Vergason, G. A., 242, 255 Vla'icou, O., 224, 225, 255 Waite, R.. 97, 107 Wall, R. L., 259, 260, 298 Walters, R. H., 280, 292, 294 Watson. J. B., 182. 218

Author Zndex Watson, L. S., Jr.. 264, 267, 278, 286, 295, 296, 298 Watts, C. A., 69, 76 Wechsler, D., 164, 218 Weingarten, F. S., 118, 150 Weininger, O.,114, 142, 151 Weinstein, S., 160, 163, 218 Weld, H. P.,232, 253 Wellman, B. L., 83, 90, 107 Wepman, J. M., 168, 215 Wetzel, A., 115, 149 Wheeler, L., 174, 185, 188, 189, 201, 218 Whimbey. A. E.,118, 119,146 Whipple, G. M., 221, 222, 255 Wiesel, T. N., 141, 148 Wiesley, M., 95, 107 Williams. H. M., 83, I07 Williams, J., 88, 108 Wilson, E. B., 190, 218 Wischner, G. J., 246, 255 Wittenborn, J.. 93, 107 Wolf, K., 93, 107 Wolf. M. M., 17, 19, 267, 286, 287, 295, 296, 298 Wolff, H. G., 181, 214 Woods, P. J., 114, 120, 151 Woodward, M., 90, 107 Woodworth, R. S.. 230, 231, 252. 255 Yaeger, J., 36, 39, 40, 54 Zarrow. M. X.,142, 149 Zeaman, D., 29, 42, 53, 54, 77, 98, 107, 276, 298 Zigler, E.,25, 54, 78, 81, 83, 85, 86, 87, 88, 90,91, 92, 93, 94, 95,97, 98, 99, loo, 102, 105, 106, 107, 108 Zimmerman, D. W.. 8, 19, 124, 125, 147 Zubek, J. P.,114, 119, 146

Subject Index Ability, factor studies of, research models for use in, 59-61 Adaptive behavior, age and, 111 dependent variables of, 110 human research and, 129-135 independent variables of, 110-111 Age, 70, 111 Aggressive behavior, 291-294 Anatomical structure, abnormal, 6-9 Aversive behavior, reinforcement of, 16-17 Aversive stimulation, retardation through, 14-16 Behavior, adaptive, age and, 111 dependent variables of, 110 human research and, 129-135 independent variables of, 110-111 aggressive, 291-294 aversive, 16-17 operant, 262-294 development of behavior and, 262-272 establishing of stimulus control, 272277 perennial problems of, 289-294 practical applications of behavioral principles and, 284-289 reducing the frequency of behavior and, 281-284 shifting stimulus control and, 277-281 reducing the frequency of, 281-284 extinction and, 281-282 punishment and, 282-284 respondent, 259-262 conditioned reflex behavior, 261-262 unconditioned reflex behavior, 25926 1 Behavioral variables, 111-129

critical periods and, 122-129 effects of environmental deprivation and, 111-113 effects of environmental enrichment and, 113-115 preweaning vs. postweaning stimulation and, 121-122 quality of early stimulation and, 115-121 Brain lesions, cerebral, 177-182 Halstead’s test and, 180-182 trail making test and, 179-180 Wechsler-Bellevue lateralization studies and, 177-179 interpretation of results for individual patients and, 195-213 patient W.B., 202-205 patient W.C., 196-202 relationships to mental retardation, 205-213 methodological approach to, 162-164 research results and, 170-195 acute vs. chronic brain lesions, 185187 aphasic and related sensory-perceptual deficits, 182-185 differential effects of left and right cerebral lesions, 177-182 linear discriminant function analyses, 187-189 qualitative vs. quantitative psychological effects of cerebral lesions, 174-177 relating neurological and psychological variables in individual patients, 189-195 Children, factor study and, 61-64, 70-71 age scales and, 70 factor hypothesizing studies and, 71

305

306

Subject Zndex

historical aspects, 70 Wechsler tests and, 70-71 Classical conditioning, current research involving, 35-42 discrimination learning and, 22-35 problems in research with retardates and, 30-35 role of in investigations of retardate learning, 27-30 trends in and implications for retardation, 24-27 Computers, factor analytic processes and, 64 Conditioning, classical, see Classical conditioning Contingent aversive stimulation, retardation through, 14-16 Controls in experiments, use of factored measures as, 67-68 Critical periods, behavioral variables and, 122-129 Deprivation, social, 85-90 Discrimination, experimenter-paced, 276-277 free operant, 272-276 inadequate history of, 9-14 infrequent reinforcement and, 11-13 opportunities restricted and, 13-14 withheld or noncontingent reinforcements and, 13 Discrimination learning, classical conditioning and, 22-35 problems in research with retardates and, 30-35 role of in investigations of retardate learning, 27-30 trends in and implications for retardation, 24-27 current research involving, 42-51 Disturbances, sensory-perceptual, 169-170 fingertip number writing perception and, 170 sensory imperception and, 169 tactile finger recognition and, 169 tactile form recognition and, 170 Environmental deprivation, variables and, 111-113

behavioral

Environmental enrichment, behavioral variables and, 113-115 Expectancy of failure, 97-99 Experience, early, theories of the effect of, 135-143 Experimental control, use of factored measures as, 67-68 Factor@), identifying and naming, 57-59 Factor analysis, availability of computers and, 64 uses of, 64-68 analysis of existing data, 65 controls of experiments, 67-68 hypothesizing and seeking structure, 65-66 program planning, 68 use of factor scores, 67 utilization of findings, 66 Factor scores, use of, 67 Factors established at preliterate levels. 71-73 Factor study, preliterate normal and retarded children and, 70-71 age scales and, 70 factor hypothesizing studies and, 71 historical aspects, 70 Wechsler tests and, 70-71 problems of applying to young and retarded children, 61-64 problems of investigation of subgroups and, 68-70 Factor study(ies) of abilities, research models for use in, 59-61 analyses of conventional tests, 59-60 structure of intellect model, 60-61 Failure, expectancy of, 97-99 Halstead’s neuropsychological test battery, 165-168 category test, 165-166 critical flicker frequency, 166 finger oscillation test, 167 Halstead’s impairment index, 168 rhythm test, 167 speech sounds perception test, 167 tactual performance test, 166-167 time sense test, 167-168

Subject Index Halstead's tests, 165-168, 180-182 Halstead-Wepman aphasia screening test, 168

Human research, adaptive behavior and, 129-135 lnadcquate reinforcement and discrimination histories, 9-14 infrequent reinforcements and, 11-13 opportunities restricted and, 13-14 withheld or noncontingent reinforcements and, 13 Institutionalization, 85-90 Learning, discrimination, see Discrimination learning Lewin-Kounin Formulation, 78-82 Long-term memory, historical development of, 221-226 methodological considerations, 226-238 measures of retention and, 226-229 methods of original training and, 229-237 Memory, long-term, historical development of, 221-226 methodological considerations, 226238 Models for use in factorial study of abilities, 59-61 analyscs of conventional tests, 59-60 structure of intellect model, 60-61 Motivational hypothesis, 82-84 Neuropsychological assessment, selection of tests for, 160-161 Neuropsychological examination, patients and, 196-205, 208-213 aphasic symptoms and sensory-perceptual deficits and, 196-198, 202205 comment on interpretation of, 198202 Neuropsychological tests, description of, 164-170 Halstead's neuropsychological test battery, 165-168 sensory-perceptual disturbances and, 169-170

307 Operant behavior, 262-294 development of behavior and, 262-272 changes in reinforcer values and, 272 reinforcement variables, 272 schedules of reinforcement, 268-272 types of reinforcers, 263-268 establishing of stimulus control, 272-277 experimenter-paced discrimination. 276-277 free operant discrimination, 272-276 perennial problems of, 289-294 aggressive behavior, 291-294 institutional maladaptive behavior, 290-291 practical applications of behavioral principles and, 284-289 personal self-care skills and, 285-286 social skills and, 286-288 verbal skills and, 288-289 reducing the frequency of behavior and, 281-284 extinction, 281-282 punishment, 282-284 shifting stimulus control and, 277-281 generalization and, 280 imitation and, 280 Opportunities, restricted, 13-14 Outer-directedness. 99-103 Patients, report of neuropsychological examination and, 196-205, 208-213 aphasic symptoms and sensory-perceptual deficits and, 196-198, 202-205 comment on interpretation of, 198202 Physiological functioning, 6-9 Program planning, use of factor batteries in, 68 Reaction tendencies, positive and negative, 90-94 Reinforcement, inadequate history of, 9-14 infrequent reinforcements and, 11-13 opportunities restricted and, 13-14 withheld or noncontingent reinforcements and, 13 infrequent, 11-13

308

Subject Index

operant behavior and, 263-272 withheld or noncontingent, 13 Reinforcement and discrimination histories, inadequate, 9-14 infrequent reinforcements and, 11-13 opportunities restricted and, 13-14 withheld or noncontingent reinforcements and, 13 Reinforcement of aversive behavior, retardation through, 16-17 Reinforcer hierarchy, 94-97 Respondent behavior, 259-262 conditioned reflex behavior, 261-262 unconditioned reflex behavior, 259-261 Retardation, dilTiculties of conceptualizing, in biological terms, 5-6 in hypothetical terms, 3-5 Retention, see also Memory, long-term Retention, retarded subjects and, 238-252

Tests for neuropsychological assessment, selection of, 160-161 Trail making test, 168, 179-180

Sensory-perceptual disturbances, 169-170

Wechsler tests, 70-71, 177-179

fingertip number writing perception and, 170 sensory imperception and, 169 tactile finger recognition and, 169 tactile form recognition and, 170 Skill(s), personal self-care, 285-286 social, 286-288 verbal, 288-289 Stimulation, aversive, 14-16 early, 115-121 preweaning vs. postweaning, 121-122 Structure, hypothesizing and seeking, 6566 Subgroups, problems of factorial investigation of, 68-70

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