ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR
VOLUME 15
Contributors to This Volume Jiiri All& Richard N. Aslin John M...
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ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR
VOLUME 15
Contributors to This Volume Jiiri All& Richard N. Aslin John M. Belmont Earl C. Butterfield Susan T. Dumais William Fowler Fred Rothbaum Dennis Siladi Jaan Valsiner
ADVANCES
IN CHILD DEVELOPMENT AND BEHAVIOR
edited by Hayne W. Reese
Lewis P. Lipsitt
Department of Psychology West Virginia University Morgantown, West Virginia
Department of Psychology Brown University Providence, Rhode Island
VOLUME 15
@
1980
ACADEMIC PRESS A Subsidiary of Harcourt Brace Jovanovich, Publishers
New York London Toronto Sydney San Francisco
COPYRIGHT @ 1980, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITINQ FROM THE PUBLISHER.
ACADEMIC PRESS,INC.
111 Fifth Avenue, New York, New York 10003
Uniied Kingdom Edition published by ACADEMIC PRESS, INC. ( L O N D O N ) LTD. 24/28 Oval Road, London N W l
LIBRARY OF
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CONGRESS CATALOG CARD
NUMBER:63-23237
ISBN 0-12-009715-X PRINTED IN THE UNITED STATES OF AMERICA 80 81 82 83
9 8 7 6 5 4 3 2 1
Contents ..........................................................
vii
Preface.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ix
List of Contributors
visual Development in Ontogenesis: Some Reevaluations J-I ALLIK AND JAAN VALSINER .......... I. Introduction ................................... 11. A Conceptual Framework for Infant Visual Preferen Discrepancy Hypothesis . . ......... 111. Acuity and Spatial Modulation Transfer Function ............................ IV. Conceptualizationof the Relative Functions of Environmental and Organismic Influences .................................................. V. Perception of Flicker and Movement ...................................... VI. Binocular Vision . . . . . . . . . .... ................... VII. Conclusions .................................... ......... References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 4 7
23 25 28
39 42
Binocular vision in Infants: A Review and a Theoretical Framework RICHARD N. ASLIN AND SUSAN T. DUMAIS I. Introduction
..........................................................
II. Levels of Binocular Function ............................................ 111. IV. V. VI.
Developmental Constraints on Binocular Vision ............................. Empirical Findings on Infant Binocular Vision .............................. Early Experience and Binocular Function .................................. Concluding Remarks ................................................... References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
54 54 62 68 79
90 90
Validating Theories of Intelligence EARL C. BUTERFIELD, DENNIS SILADI, AND JOHN M. BELMONT I. Introduction
..........................................................
11. A Strategy for Studying Intellectual Development
...........................
111. Illustration of the Strategy for Studying Intellectual Development. .............. IV. A Strategy for Studying the Generality of Cognitive Processes ................. V. Illustration of the Research Strategy for Testing Process Generality . . . . . . . . . . . . . VI. Concluding Considerations .............................................. References ...........................................................
V
% % 102 124
131 153 159
vi
Contents
Cognitive Differentiation and Developmental Learning I. I1. 111. IV . V.
VI.
WILLIAM FOWLER Introduction .......................................................... Biases Limiting Scope of Developmental Theory ............................ Integrating the General and Individual in Developmental Theory . . . . . . . . . . . . . . . Mechanisms of Cognitive Change and Development ......................... Developmental Phases of Concept Learning ................................ Summary and Conclusions . . . . . . . . ................................. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Children's Clinical Syndromes and Generalized Expectations of Control FRED ROTHBAUM I . Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1. Factor Analytic Research on Syndromes in Children ......................... III . Support for the Helplessness-Reactance Model ..............................
IV . Toward a Helplessness-Reactance Explanation of Syndromes .................. V . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References ...........................................................
Author Index Subject Index
................................................................ ............................................................
Contents of Previous Volumes
..................................................
163 164 170 188 195 199 201
207 209 211 220 234 241 247 257 261
List of Contributors Numbers in parentheses indicate the pages on which the authors' contributions begin.
JURI ALLIK Department of Psychology, Tartu State University, Tiigi 78,202400 Tartu, Estonian SSR, USSR ( I )
RICHARD N. ASLIN Department of Psychology, Indiana University, Bloomington, Indiana 47405 (53) JOHN M. BELMONT Kansas Mental Retardation Research Center, University of Kansas Medical Center, Kansas City, Kansas 66103 (95) EARL C. BUTTERFIELD Kansas Mental Retardation Research Center, University of Kansas Medical Center, Kansas City, Kansas 66103 (95) SUSAN T. DUMAIS' Indiana University, Bloomington, Indiana 47405 (53)
WILLIAM FOWLER* Ontario Institute for Studies in Education, Toronto, Ontario M5S 1 V6, Canada (163) FRED ROTHBAUM Eliot-Pearson Department of Child Study, Tufts University, Medford, Massachusetts 02155 (207) DENNIS SILADI O&e of Research and Development, Stamford Public Schools, 195 Hillandale Avenue, Stamford, Connecticut 06902 (95) JAAN VALSINER Department of Psychology, Tartu State University, Tiigi 78,202400 Tartu, Estonian SSR, USSR (1)
'Present address: Bell Laboratories, Murray Hill, New Jersey 07974. Tresent address: Laboratory of Human Development, Graduate School of Education, Harvard University, Cambridge, Massachusetts 02138. vii
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Preface The amount of research and theoretical discussion in the field of child development and behavior is so vast that researchers, instructors, and students are confronted with a formidable task in keeping abreast of new developments within their areas of specialization through the use of primary sources, as well as being knowledgeable in areas peripheral to their primary focus of interest. Moreover, there is often simply not enough journal space to permit publication of more speculative kinds of analyses which might spark expanded interest in a problem area or stimulate new modes of attack on the problem. The serial publication Advances in Child Development and Behavior is intended to ease the burden by providing scholarly technical articles serving as reference material and by providing a place for publication of scholarly speculation. In these documented critical reviews, recent advances in the field are summarized and integrated, complexities are exposed, and fresh viewpoints are offered. They should be useful not only to the expert in the area but also to the general reader. No attempt is made to organize each volume around a particular theme or topic, nor is the series intended to reflect the development of new fads. Manuscripts are solicited from investigators conducting programmatic work on problems of current and significant interest. The editors often encourage the preparation of critical syntheses dealing intensively with topics of relatively narrow scope but of considerable potential interest to the scientific community. Contributors are encouraged to criticize, integrate, and stimulate, but always within a framework of high scholarship. Although appearance in the volumes is ordinarily by invitation, unsolicited manuscripts will be accepted for review if submitted fmt in outline form to the editors. All papers-whether invited or submittedreceive careful editorial scrutiny. Invited papers are automatically accepted for publication in principle, but may require revision before fiial acceptance. Submitted papers receive the same treatment except that they are not automatically accepted for publication even in principle, and may be rejected. We wish to acknowledge with gratitude the aid of our home institutions, West Virginia University and Brown University, which generously provided time and facilities for the preparation of this volume, We benefited as well from the facilities of the Center for Advanced Study in the Behavioral Sciences at Stanford, where one of us (LPL) was located during the final editing of the volume. We also wish to thank Daniel Ashmead, Eve V. Clark,Barry Gholson,
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Preface
Martin J. Hofmann, Marion Perlmutter, Philip H. Salapatek, Martin E. P. Seligman, Robert S. Siegler, Irving E. Sigel, and Billy Wooten for their editorial assistance. Hayne W. Reese Lewis P. Lipsitt
ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR
VOLUME 15
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VISUAL DEVELOPMENT IN ONTOGENESIS: SOME REEVALUATIONS'
Jiiri Allik and Jaan Valsiner DEPARTMENT OF PSYCHOLOGY TARTU STATE UNIVERSITY TARTU, USSR
I. INTRODUCTION ...................................................... 11. A CONCEPTUAL FRAMEWORK FOR INFANT VISUAL PREFERENCE AND THE DISCREPANCY HYPOTHESIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .
. ..
In. ACUITY AND SPATIAL MODULATION TRANSFER FUNCTION . . . . . . . . . . . A. FACTORS AFFECTING VISUAL RESOLUTION . . . . . . . . . . . , , , , . . . . . . . B. PERCEPTION OF ONE-DIMENSIONAL PA"ERNS . . . . . . . . . . . . . . . . . . .. . . . . . . C. PERCEPTION OF TWO-DIMENSIONAL PATTERNS . . . . . . . D. DEFICIENCY OF VISUAL RESOLUTION.. . . . . . . . . . . . . . . . . . . . .. .. E. EXPERIMENTAL VISUAL DEPRIVATION .. . . . . .. . . . . . . . . . . . . . . . ... .
.
. . . .. . .. .
IV. CONCEPTUALIZATION OF THE RELATIVE FUNCTIONS OF ENVIRONMENTAL AND ORGANISMIC INFLUENCES . . . . . . . . . . . . . . . . . . . .
..
V. PERCEPTION OF FLICKER AND MOVEMENT . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . A. INFANT RESPONSE TO FLICKER AND MOVEMENT . . . . . B. REARING IN STROBOSCOPICALLY ILLUMINATED AND UMDIRECI'IONALLY MOVING ENVIRONMENTS . . . . .. . . . . . . . . . . . . . .
. .. . .
VI. BINOCULAR VISION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. INFANT BINOCULAR VISION . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. DISPARITY . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . , , , . . , . . . . . . C. ABNORMALITIES OF BINOCULAR VISION.. . . . . . . . . . . . . . . . . . . . . . . . . D. DEVELOPMENT OF BINOCULAR VISION IN ANIMALS.. . . . . . . . . . . . . . E. MONOCULAR DEPRIVATION . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . .. . . .
2
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1 7 9 11 14 18
23 25 25
26 28 28 30 31 34 35
'The authors are very grateful to Philip Salapatek for his critical comments on the manuscript, and to Michael Kuskowski, Martin J. Hofmann and Daniel Ashmead (all from the Institute of Child Development, University of Minnesota) for their very valuable editorial assistance. However, the authors reserve for themselves the responsibility for all the shortcomingsof the present article. James Wertsch's organizational help in preparing the manuscript is also gratefully acknowledged. 1 ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR, VOL. IS
Copyrighl@1980 by Academic Press, Inc. All rights of RpodUctirn in any form reserved. ISBN 0-12-0(m15-X
Juri Allik and Jaan Valsiner
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VII. CONCLUSIONS. ...................................................... A. NEWBORNS’ VISUAL ABILITIES ................................... B. COURSE OF DEVELOPMENT ......................................
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REFERENCES
39 39
I. Introduction Probably everyone agrees that modem theories of visual perception tend to be far less metaphysical, less ideological, and more experiment-bound than in the past. There are, of course, theoretical differences within the field of perception, but they are more sophisticated and more devoted to specific issues than before (Dodwell, 1975). The same is entirely true concerning the subfield of infant visual perception. This area has progressed from sterile discussions regarding the relative importance of nature and nurture toward a field of serious science, with unique methodology, experimental skills, and research problems. Several overviews have given a fascinating and complete picture of that progress (see Bower, 1974; Cohen & Salapatek, 1975a,b; Haith & Campos, 1977). The aim of this article is to analyze the development of infant visual perception, trying to integrate the findings of that research field with those of the developmental neurophysiology of visual perception in animals. The logic of our presentation is based on the following data: 1. Comparisons between infant and normal adult vision. This comparative analysis is limited, largely because of the lack of data about infant visual perception. As a rule, some knowledge exists about general properties of infant vision-for example about spatial resolution and localization brightness, and color vision-but the fine structure, the exact operating routines of visual perception, has not yet been described. 2. Acquired abnormalities of visual perception. Acquired abnormalities are treated as an additional source of information about possible ways in which perceptual development might occur. We shall pay primary attention to the cases of total or partial monocular or binocular visual deprivation. The results of visual deprivation, which may be treated as an unfortunate natural experiment, show the weakening or failure of certain algorithms required for transformation of visual information. Such abnormalities, in some conditions, may reveal the mechanisms of perceptual development or the relationship between experience and the functioning of perceptual processes. 3. Animal studies. “Environmental surgery, “selective visual deprivation,’’ and other related expressions are terms coined for a very popular area in ”
Visual Development in Ontogenesis
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recent neurophysiological research. Although environmental modification of central nervous system structures has been convincingly demonstrated for some time, intensive study of such malleability has begun only since it has been shown that the properties of single visual cells can be altered by early visual experience. Although the enthusiasm of the first reports has waned, many important findings about the fine structures involved in the development of visual functions have been collected and many new controversies have arisen. We are very far from believing in the face value of metaphors such as “what the cat’s eye tells the human brain,” but it may be fruitful to look at animal studies, mainly on cats and partly on monkeys, for a possible model of neuronal modification in the human visual system. It is astonishing to note that although a very great number of studies have been devoted to infant perception, they allow us to deal with only some areas in the rich field of infant vision and rarely shed direct light on specific models of neural modification. There seems to be a certain “encapsulation” among scientists who study these delicate and perspicuous phenomena. They generally use only one method of study-for example, the visual preference technique-and interpret their findings along conceptual lines that are not nested in the contemporary terminology of visual psychophysics. As we try to show in Section 11of our analysis, it may even be argued that their interpretations do not follow from their experimental data in an unambiguous manner, and, because of this, many of the research efforts on infant visual perception (as well as many tears produced by the infants dragged into laboratories) must be classified as rather barren from the viewpoint of understanding infant perception. Our goal in analyzing the data on visual perception stems from our belief that much could be achieved if studies on infant vision were directed along the lines in which contemporary psychophysics is moving. One of the most interesting developments in contemporary psychophysics is the tightening of its ties with neurophysiology; such a development might be of similar value for infant researchers. Along this line, we have decided to analyze a very broad spectrum of data and concepts in this article. It may be difficult for researchers in infant perception to maintain close and continuous contact with the burgeoning area of animal vision research, especially as the number of experiments devoted to early visual ontogenesis in different species of animals is ever-increasing. Ow reading of the research literature concerning human infant perception certainly indicates that cross-species comparisons are very rare. Therefore, much of the reasoning in this article is based on animal data, with the hope that our ideas will intrigue the reader and lead to experiments on human infants to prove or destroy our hypotheses. To some readers, our presentation might seem to be a simple renaming of concepts. Indeed, we use the terminology developed in psychophysics and related disciplines instead of the idiosyncratic terminology that is currently being
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Juri Allik and Jaan Valsiner
used by infant vision researchers (especially in infant visual attention and memory studies), with the single aim that the reader will recollect t k old scientific truth that a conceptual framework is better if it gains breadth without sacrificing depth and clarity.
11. A Conceptual Framework for Infant Visual
Preference and the Discrepancy Hypothesis
Research that involves infant visual preference techniques modeled after the preliminary investigationsby Fantz (1956, 1961, 1963)is usually termed “infant attention research. ” As Kinney and Kagan (1976)noted, the studies concerning human infant attention are directed toward two different goals. The f i t is to study how physical stimulus parameters influence the infant’s attention and perception; this issue is treated at length in other parts of the present article. The second goal is to study the outcome of infant perception-an engram, or schema, or model of the stimulus. We shall examine the relationship between the perceptual outcome and infant attention here. Although it goes without saying .that different assumptions may be used as bases for alternative conceptual systems and that those assumptions are not to be studied within the framework of their own particular systems, it seems that very little attention has been given to developing alternative assumptions concerning the human infant’s visual attention. The overwhelming majority of studies are conducted within the framework of “schema development,” which in more operational terminology is deeply associated with the “discrepancy hypothesis” and, in experimental practice, with habituation paradigms. It is assumed that, in the course of development and visual experience, the infant acquires (or develops further on the basis of existing experience) a “schema” or model of some event. Piaget has had great influence on this type of thinking. He has tied “schema development” to the general principle of assimilation-accommodation as the process along which development works. It should be noted that Piaget suggests that any new developing schema will be based on already existing ones, which are modified in the process of assimilation (Piaget, 1970). Accommodation is the term coined by Piaget to denote any modification of an assimilatory schema by the elements it assimilates. Piaget stresses the necessity for studying assimilation and accommodation always together, viewing cognitive adaptation as an equilibrium of these two processes. It is certainly safe to speak about the development of schemata on such a high level of abstraction. However, if one begins to ask more particular questions about what the concrete schemata might be like in real infants, problems begin to emerge. How do we unambiguously tie the various measures of infant attention,
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measured quite precisely in the laboratory, to the high-level, abstract concept, “schema”? Habituation of infant attentional responses provides one possibility, When the infant is repeatedly shown the same stimulus, his “attention,” as measured by some index (e.g., fmation duration or frequency, heart rate changes), seems to decline. Therefore, it seems reasonable to assume that the infant has “assimilated” the stimulus into the schema and that this is why the infant pays less attention to it. However, here we must deal with some implicit assumptions that have not been (and possibly cannot be) based on anything except adult common sense. These may be roughly described as follows: 1 . The indices of an infant’s visual attention are linearly related to schema development; if the schema develops, the infant’s attention declines; 2. The decline in infant attention toward the stimulus is paralleled by an inner comparison process within the infant. The infant monitors the schema being formed to the stimulus. If the schema has become more similar to the stimulus, the infant’s attention declines, and if not, it does not decline. Here too a kind of linear relationship between observable habituation measures and a hypothetical schema assimilation process is presumed.
The difficulty with these implicit assumptions is that they leave open questions as to whether they provide a fair basis for developing a conceptual system of infant visual attention. Even if attempted, the form of the relationships between an observable objective phenomenon and a hypothetical construction may be more than impossible. One important aspect of infant attention research is the “discrepancy hypothesis. Many different models of infant attention are based on this hypothesis (see Cohen & Gelber, 1975, for review). The general principle they share is the experimentally demonstrated fact that after familiarization with a stimulus and habituation to it, infants show an increase in attentional parameters when exposed to a different, discrepant stimulus (Figurin and Denisova used habituation and dishabituation as a research method as long ago as 1929; see Zaporozhets, Venger, Zintchenko, & Ruzskaja, 1967). Very often an inverted U-shaped relationship is found between discrepancy of the familiarized from the novel stimulus and infant attention measures (McCall, 1971). In other words, infants appear to pay most attention to those stimuli that are within an optimal range of discrepancy from the habituated stimulus. If the discrepancy is too great and the stimulus too novel, then the infants do not pay more attention to it than to the former stimulus. From the viewpoint of the conceptual system of schema development, the findings on optimal discrepancy preferences in infants are valuable in that they may show in the following way how assimilation occurs: If an optimally discrep”
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Jiiri Allik and Jaan Valsiner
ant stimulus enters the infant’s visual field, he turns his attention toward it and assimilates it into his developing schemata. If the new stimulus is too discrepant to assimilate, no extra attention will be paid to it. The directing of attention on the basis of a discrepancy principle helps the infant organize his stimulus environment in the optimal way for a given developmental level. The conceptual problem with both schema development theory and the discrepancy hypothesis is the lack of specificity of the function of visual fixation in perceptual development. Specifically, visual preference for some environmental stimuli may be a necessary cause of “schema development,” may correlate only with schema development, or may be the motor result of some implicit schema development. It is not apparent that we can decide among these alternatives within the conceptual frameworks and methods currently used. Because of these multiple interpretations, the explanation of the infant’s visual system development as the progressive development of schemata of different kinds would not make a perspicuous explanatory paradigm for the data. A more exact specification of the role of different aspects of infant fixation in habituation has been provided by Cohen (1973), based on experimental data that show that the overall size and number of elements in a checkerboard have different effects on infant looking (Cohen, 1972). He found that the size of the checkerboard influenced the infant’s latencies of turning to the stimulus, but the number of checks had more influence on the duration of looking at the stimulus. Cohen (1973) has formulated a two-process model of infant visual attention in which the process of attention is divided into attention-getting and attentionholding processes, and he has attempted to demonstrate their independence. His success in discovering these two processes stemmed from his use of independent criteria of infant’s visual fixation-latency and fixation time. His success illustrates the point that much of our theorizing is very procedure-bound. Had he used only traditional measures of fixation, such as visual choice or total looking time, he could not have obtained data in support of the two-process model. The mechanisms Cohen has described can be considered mainly as means of regulating the visual input, that is, as mainly a way (overwhelmingly motor) by which an infant can regulate its visual experience. This mechanism is not, at least at the very beginning of life, intentionally controlled by the infant. It may be more of a specific evolutionary adaptation that allows the motorically very immature human infant to extract the kind of stimulation from the environment that is necessary for the functional development of the visual system at that particular developmentlevel. The tendency for the human infant (and other primate infants) to combine a precocial pattern of sensory development with an altricial pattern of motor development (Gottlieb, 1971) makes possible the presence of some adaptational mechanisms during this developmental asynchrony-and we propose that selective fixation and habituation are among them.
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111. Acuity and Spatial Modulation Transfer Function A. FACTORS AFFECTING VISUAL RESOLUTION
Discussions regarding theoretical confusions among the various measures of visual acuity have been presented elsewhere (see Thomas, 1975; Westheimer, 1972). Here, we note that the resolving power of the visual system is determined by the optical system of the eyes, the spatial packing of the receptors, and the neural integration of the peripheral and central visual areas. Visual acuity may be defined by means of the spatial frequency variable, in a most general way, as the highest spatial frequency the visual system is capable of differentiating. In this section, we examine the various factors that are related to the functioning of the visual system as measured through the Modulation Transfer Function (MTF), which provides a measure of the sensitivity of the visual system to all spatial frequencies, hence being a more general measure of the spatial organization of vision than is acuity. 1. Optical Factors The quality of the retinal image is largely determined by appropriate accommodation. It is well established that infants younger than 1 month of age do not appropriately accommodate to the changes in the distance of a test object. Haynes, White, and Held (1965) found that the focus of the alert newborn is locked at one focal distance. The median distance for the group of newborns investigated in their study was 19 cm. During the second month of life, the accommodative system began to respond, to some extent, to the changes in target distance. By 3 or 4 months, the infants’ accuracy of accommodation was found to be comparable to that of emmetropic adults (White, 1971, Fig. 15). Therefore, the very young infant is myopic at almost all of the target distances. It has usually been found that visual acuity in infants at and below 2 months of age is 20/400or worse-that is, limited to spatial frequencies not higher than 2-3 cycles per degree (Banks & Salapatek, 1976). In those studies in which it was examined, acuity was found to be independent of the distances at which test gratings were presented. Therefore, for the young infant, the optical defocusing that accompanies changes in viewing distance does not appear to affect visual acuity (Salapatek, Bechtold, & Bushnell, 1976). The optical system of the infant differs remarkably from that of the adult. Since the infant’s cornea is more spherical, the radius of curvature is about 1 mm shorter than in the adult (Maurer, 1975). Further, the sagittal length of the eye is approximately 24 mm in the adult, and only 17-17.5 mm in the neonate (see Maurer, 1975; Slater & Findlay, 1975). These measures allow an approximate
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Juri Allik and J M n Valsiner
calculation of the size of the retinal image corresponding to the size of a visible stimulus. Stimuli subtending equal visual angles will fall on a retinal area about 48 times smaller in the newborn than in the adult. Therefore, fewer receptors are involved in the analysis of the same stimulus in the infant’s vision (assuming that the receptor packing is the same as or less dense than in the adult), which may be one reason for the newborn’s poor acuity (Maurer, 1975). The MTF of the infant’s visual system is partly limited by the cut-off frequency of the infant’s optical system. The MTF of the human infant’s optical system has not been assessed with satisfactory measures such as the reflected fundus image (Westheimer, 1972) or interference fringes (Campbell & Green, 1965). These techniques allow a separate estimation of the spatial frequency attenuation resulting from the optics of the eye, and that resulting from the nervous system isolated from the optics. Salapatek et al. (1976) stated that considerable optical defocusing, up to about 5 diopters, does not seriously affect the infant’s visual acuity or cut-off frequency of the transfer function, since the infant is sensitive only to spatial frequencies lower than 3 cycles per degree. In addition, some theoretical methods for the computation of the effect of defocus on the optical transfer function are available (Hopkins, 1955). These equations were applied to the psychophysical contrast sensitivity function by Freeman and Thibos (1975a), who showed that the usual notion that defocusing attenuates only the high-frequency end of an optical transfer function continuum is incorrect. A careful examination of the defocusing effect shows that the middle and low ranges of spatial frequency are also significantly depressed (see Freeman & Thibos, 1975a, Fig. 8, for the theoretical effect of defocusing, computed for Gullstrand schematic eyes). Using a different approach, Krueger, Moser, and Zrenner (1973) experimentally determined the effect of defocusing on the optical transfer function of the frog eye. Because the transfer function of the frog eye is qualitatively similar to that of the human eye (Krueger & Moser, 1973), their results are valuable for the understanding of the human eye as well. Defocus affects the image formation process throughout the spatial frequency spectrum, and even for very low frequencies the attenuation is significant. 2 . Neural Factors Campbell and Green (1965) assessed the relative roles of optics and nervous system in the transmission of spatial frequency in the human adult. They found that over the range of 30-40 cycles per degree, optical attenuation increased by a factor of 1.25, while attenuation by the nervous system increased by a factor of 2.4. Therefore, high-frequency attenuation is mainly determined by some process in the nervous system of the human adult. In recent years, several studies have been performed to measure the infant’s responses to spatial frequency. Banks and Salapatek (1976) presented sine wave gratings to probe the infant’s
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frequency response. In other studies, rectangular distributions of light-gratings consisting of black and white stripes-were used (e.g., Leehey, MoskowitzCook, Brill, & Held, 1975; Salapatek et a l . , 1976). In spite of the infinite number of “higher order harmonics” in a rectangular grating, the response of the visual system is determined mainly by the amplitude of the fundamental frequency. The method for determining whether a particular spatial frequency has been detected by infants is another serious problem. The most popular response measure is visual preference for the modulated over the unmodulated field with the same average luminance. The degree of preference is assumed to be equivalent to “amplitude attenuation” in linear system engineering. In other words, we might say that “infant looking preferences are determined by visibility, ” or “the infant looks at something that is more clearly visible to him. ” This, of course, is a model picture of the infant’s visual preferences, which cannot be turned into an explanatory principle for the interpretation of the preference data obtained in purely behavioral experiments. B. PERCEPTION OF ONE-DIMENSIONAL PATTERNS
From the studies by Atkinson, Braddick, and Braddick (1974), Banks and Salapatek (1976), and Salapatek et al. (1976), one might conclude that there are few, if any, qualitative differences between infant and adult modulation transfer functions. The main similarity is in the band pass character of the transfer functions: An optimal spatial frequency exists at which the modulation attenuation is minimal and below and above which modulation suppression increases progressively. The same idea expressed in spatial terms states that the human eye is relatively insensitive to very slow and very fast spatial changes in luminance. Though the modulation transfer functions appear to be qualitatively similar for the infant and .adult, very remarkable quantitative differences exist between the two: 1. The transfer function of the infant eye is displaced toward the lower spatial frequencies (the peak frequency is below 1 cycle per degree). The corresponding peak value for the human adult eye is somewhere between 4 and 8 cycles per degree, depending on the average illumination and other conditions (Kelly, 1975; Kelly & Savoie, 1973). 2. The exact location of the peak value of the infant function has not yet been clearly determined, since the modulation transfer is relatively flat in the region of peak sensitivity. A measure more appropriate than peak frequency is the cut-off frequency, defined as the frequency at which amplitude attenuation is increased by a factor of 2, or at which, for example, the amplitude drops to l/e’’*compared to the maximum. However, even the criterion of cut-off frequency has limited application because of the questionable measures of infant transfer function collected so far.
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3. The cut-off frequency of the 1-month-old infant transfer function may be roughly estimated as about 1-2 cycles per degree. The comparable value for the human adult is 10-20 cycles per degree, or higher by a factor of 10. One should remember that this is only a very approximate estimate that does not take into account any differences in adaptation level or decision criteria. In ophthalmological terminology, the newborn infant is 10 times more defocused than the adult. The young infant’s visual transfer function is quantitatively very similar to the cat’s. Various investigators, using very different methods (e.g., microelectrode recording-campbell, Cooper, & Enroth-Cugell, 1969; evoked potential recording-campbell, Maffei, & Piccolino, 1973; behavioral training techniques-Blake, Cool, & Crawford, 1974), have found that the point of maximal sensitivity of the cat’s modulation transfer function is near .5 cycle per degree, and the high-frequency cut-off is between 3 and 5 cycles per degree. These values are comparable to the corresponding values of the 1-month-old human infant’s MTF.One possible reason for the cat’s poor visual resolution is the low density of visual cells in the cat’s retina. The cat’s area centralis contains only about 350 ganglion cells per square degree of visual angle, while in the human, the corresponding number is 6500 (Stone, 1965). Anatomical factorsthe dimensions of the infant eye and the density of visual cells in the retina-are probably the most important factors determining the young infant’s spatial resolution. Results mentioned so far in this section have been based on the use of gratings that are periodic in one dimension and constant in the perpendicular dimension. Using one-dimensional patterns implies a belief that the visual system is isotropic, that is, that the detection of unidimensional gratings is invariant to the absolute orientation of the patterns. However, a good deal of evidence indicates that the human visual system is more sensitive to gratings in vertical or horizontal orientation than to patterns in an oblique orientation (for a review, see Apelle, 1972). In other words, the human visual system is orientationally anisotropic. The orientational asymmetry of the visual system is perhaps an inherent feature that appears even at birth. Kessen, Salapatek, and Haith (1972) reported newborn anisotropy in visual scanning patterns along horizontal and vertical orientations. Leehey et al. (1975) found that infants prefer to look at horizontal or vertical rather than oblique gratings. This last result suggests that acuity for oblique orientations is worse than that for horizontal and vertical lines or edges. Orientational anisotropy suggests that the contrast sensitivity function for a twodimensional sine wave distribution cannot be predicted simply from a onedimensional contrast sensitivity function that assumes the applicability of the principle of linear superposition. Rather, it is necessary to measure the contrast sensitivity function of one-dimensional gratings in many orientations. However, as Carlson, Cohen, and Gorog (1977) have indicated, the anisotropy in the visual
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system is not large enough to invalidate the assumption of linear superposition. Nevertheless, it is evident that the operational transfer function of the human visual system is two-dimensional in principle. Hence, there has been an increased interest in determining the perception of two-dimensional patterns. The contrast threshold for many types of two-dimensional patterns is being studied: for circular targets (Kelly & Magnuski, 1975), for unstructured (noise) patterns (Mitchell, 1976; Mostafavi & Sarkison, 1976), for two-dimensional sine wave patterns (Carlson et al., 1977), and for checkerboards (Kelly, 1976). One of the most significant discoveries in child psychology is that infants prefer to fixate some visual stimuli longer than other ones (Berlyne, 1958; Fantz, 1958). However, the mechanisms that control these preferences are still unclear, in spite of much experimentation. The most popular explanation relates the total (or mean) looking time to the “complexity” of the stimulus pattern. However, the concept of “complexity” is ambiguous for the following reasons: (1) it is specifically related to the pattern used as the stimulus; there exists no universal scale of “complexity”; (2) although the units of “complexity” are often not defined, “complexity” is usually related to numerosity, density, or some other quantifiable measure. We should like to consider most of the recent pattern preference studies as empirical attempts to find a stimulus parameter that is coherently and monotonically related to fixation preferences. However, the concept of “complexity” has remained an abstract, “etic” entity (to use the “emic”-“etic” distinction introduced into social sciences by K. L. Pike), which has not been related to the infant visual system. Let us suppose that visual preferences in infancy are determined by the visual images formed in the perceptual system of the infant. The infant prefers visual features that match hidher own perceptual capacities. In the interpretations of the visual preference data, the other possible factors regulating the infant’s visual attention (e.g., general activation state) are usually a priori considered to be less efficient than the features of the stimulus-and are seldom controlled in the experimental paradigms themselves. Let us take an analogous case from the field of the matched filters theory (Rosenfeld, 1969). If one has some idea about the transfer function of a filter, then it is possible to discover the signal that optimally matches this filter. The peak response from such a filter occurs when the form of the stimulus matches the weighted function of this filter. Therefore, we may propose that the concept of stimulus “complexity” should be replaced by the concept of the stimulus that optimally matches the infant’s perception. C . PERCEPTION OF TWO-DIMENSIONAL PATTERNS
Karmel and Maisel (1975) have written an excellent review of studies of the infant’s perception of two-dimensional patterns. Karmel and his co-researchers expressed looking preference as a function of the amount of contour per square
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degree of visual angle. The empirical function has an inverted U-shaped form that is optimally fitted by quadratic or cubic equations (Karmel, 1969; Karmfl& Maisel, 1975). For any infant, there exists a most preferred contour density level. Looking times will drop for patterns with contour densities below and above that optimal contour density level (Kannel & Maisel, 1975, Table 2.2). It is important that there is a significant correlation between behavioral preferences and pattern-dependent evoked potentials (Harris, Atkinson, & Braddick, 1976; Karmel, Hoffmann, & Fegy, 1974). Using two-dimensional patterns, we can again see the inverted U-shaped curve appropriate to the band-pass characteristic of the transfer function. However, this comparison islimited, because the stimuli (e.g., checkerboards and random check patterns, also Julesz-patterns) do not correspond to the single spectral line of the basic function. The stimuli employed possess a complex energy distribution in the spectral domain. The regular checkerboard pattern has a two-dimensional Fourier spectrum. The spectmm of a normally oriented checkerboard with 10' squares has four fundamental frequency components, which are located on the diagonal meridians at 4.2 cycles per degree from the origin, while the other harmonics are widely distributed throughout the spatial frequency plane (compare this to the two fundamental frequencies found in the square-wave grating). The higher harmonics have a hyperbolically decreasing amplitude (Kelly, 1976, Fig. 5 and Appendix A). However, the thresholds for two-dimensional patterns, as with the thresholds for one-dimensional patterns, can be explained in terms of the maximum amplitude of the two-dimensional Fourier spectrum. In the case of the checkerboard, this is equivalent to the amplitude of the fundamental frequency (Kelly, 1976; Kelly & Magnuski, 1975). On the assumption that infant looking preference is governed by the fundamental frequency, the checkerboard results may be treated as a measure of the two-dimensional transfer function. A correspondence between one- and two-dimensional cases is obvious, though exact numerical comparison is difficult. Karmel(l969) used regular checkerboards and randomly scattered contour test Patterns in his studies. These two types of stimuli are related to each other by the amount of contour or by the length of the white-black luminance transitions in the pattern. However, in the Fourier frequency domain these patterns have very different energy distributions (spectra). The random patterns are produced by the Markov process 5' = +a, for a constant duration of the impulse 6.The autacorrelation function of this process is expressed by a2(1 - 17116). (1) It is not difficult, by applying the Fourier transforms, to reveal the spectral distribution of this stochastic process: The energy spectrum has the following form: g ( w ) = v ( a sin W V / W V ) ~ (2) +(7) =
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Thus, the random patterns have continuous spectra without any distinct fundamental frequency. Those patterns are the results of the low-frequency broad-band visual noise process with a peak at zero frequency (Rytoff, 1976). Random patterns contain considerable noise, which is fdtered out by a differentiation process in the visual system so that the amplitude of the useful signal is relatively weak compared to the redundant patkm having energy concentration at the fundamental frequency. It can be assumed that the difference between a regular checkerboard and random patterns does not result from the contour density difference. It may be that the description in terms of Fourier analysis is the optimal language for expressing the functioning of the mechanisms responsible for the visual processing of two-dimensional patterns. It is obvious that this kind of explanation is more powerful than the one using contour density (or “complexity”) as the basic stimulus parameter. The latter has a limited range of application; only a narrow class of visual stimuli having two levels of luminance may be described by this concept. Moreover, Fourier analysis has greater theoretical generalizability. In Fourier analysis, an arbitrary stimulus can be described in terms of the transfer function. The present argument on the usage of matched filters leads us to ask the following general question of the infant vision data: “What does the infant detect in different visual scenes?” Karmel and Maisel (1975) speculated about the relation between hypothetical receptive field properties and contour density. They assumed that the visual system responds to the average contour density value by integrating contour over area. They proposed that the image is analyzed by a set of receptive fields. The output of this system is determined by the convolution of the stimulus with the weighted function of the receptive fields in the spatial domain or by the multiplication of the Fourier spectrum of the stimulus with the transfer function. The complete modulation transfer function must be known in order to make predictions about the behavior of the system. Karmel and Maisel postulated the existence of an operation involving the “integration of the contour over area,” without any references to the properties of the receptive fields that would be able to perform that transformation. The authors prefer a phenomenological and qualitative description to a more exact and quantitative one. Karmel and Maisel (1975) proposed that the peak location of the inverted U-shaped preference function on the contour density axis would depend on the field size of the neurons, that is, the field size of the hypothetical processing routine. However, Kelly (1975) has shown that frequency selectivity depends not on variations in the size of receptive fields but on the regularity of their spatial distribution. Using fixation measures, Slater and Sykes (1977) presented evidence that the “amount of contour, ” even in a binary-luminance pattern, is ,not the primary determinant of the infant’s looking behavior. Different patterns (checkerboards, square wave gratings, etc.) having similar amounts of contour elicited remarkable differences in infant looking preferences.
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In summarizing the review of the studies conducted by Karmel and his associates, it is necessary to note their importance. Although the contour density measure of two-dimensional patterns has limited application and there are no processing routines specially tuned to this stimulus parameter, their formulation has helped to sharpen theoretical ideas in infant pattern perception. In terms of the spatial frequency approach, some conclusions can be drawn from the studies mentioned above: 1. The modulation transfer function of the newborn infant has a band-pass character and the entire transfer function passes frequencies about 10 times lower than those passed by the human adult visual system. Interestingly, there is great similarity between the quality of the visual systems of the human infant and of the cat in that both are myopic to a comparable degree. 2. With increasing chronological age, the modulation transfer function continuously shifts toward the higher end of the spatial frequency axis, approaching adult values by the middle of the first year of the infant’s life (see also Pirchio, Spinelli, Fiorentini, & Maffei, 1978). 3. There is fragmentary but quite impressive evidence that the infant’s transfer function behaves in a manner qualitatively similar to the adult modulation transfer function under conditions of light adaptation. With a decrease in luminance, the form of the transfer function becomes flatter and the peak shifts toward the lower spatial frequencies. These changes are usually interpreted as a weakening of inhibitory interactions in the visual system (see McCarvill & Karmel, 1970). 4. Karmel and Maisel (1975) advanced the very strong theoretical hypothesis that optimal stimuli, matching the properties of infant visual processing, elicit more active responses from the infant than do other stimuli. D. DEFICIENCY OF VISUAL RESOLUTION
Since the classic study by von Senden (1932), it has been widely accepted that restoration of sight following a cataract operation is not sufficient for efficient vision. However, early reports about postoperative visual functions were based mainly on phenomenological observation. Recently, some cases have been studied by means of experimental paradigms (e.g., Ackroyd, Humphrey, & Warrington, 1974; Gregory & Wallace, 1963; Umezu, Torii, & Uemura, 1975). How does early visual deprivation affect visual resolution ability? As a rule, the physical condition of the eye after surgery is sufficient to permit relatively good visual acuity. For example, Ackroyd et al. (1974) found that in the case of patient H. D., acuity was as good as 6/18 or 6/12. But the actual visual acuity was poorer than the acuity measure obtained from direct ophthalmological investigations of the eyes. More than 150 trials were required before H. D. was able to
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state the presence or absence of a -5-cm square placed directly in front of her. In another study, Umezu et al. (1975) used Landolt rings as the acuity measure. The patient was able to find five out of six gap positions correctly if the Landolt ring for acuity of. 1 was placed at a distance of 25 cm. Therefore, acuity was .005 (.l X 25/50). This value is in the range of human newborn acuity. Ackroyd et al. (1974) noticed certain striking similarities between the case in which primary visual cortex was removed in the monkey and the phenomenology described in H. D. ’s case. After the removal of the primary cortex, however, the monkey’s spatial resolution was, in fact, better than H. D.’s. The qualitative picture that emerged was very much the same. This kind of similarity and the fact that human patients of that kind have had normal optics of the eyes restored by means of surgery, have been the basis for the discussions about “cortical blindness”: If a person has his eyes’ optics restored after functioning as blind for some time but still cannot see in a normal way, some changes must have taken place in the higher levels of the visual system. Additional support for the idea of “cortical blindness” of persons whose vision was restored after some time comes from the body of data on scotomata patients, whose visual fields are impaired after cortical damage. The rudimentary functions of the visual system of these patients are very similar in character to those described for recovered vision. Patients can see luminance transients in scotomata and make saccadic localizations of targets in the scotomata even though these targets are not consciously perceived (Perenin & Jeannerod, 1975; Poppel, Held, & Frost, 1973; Poppel, Von Cramon, & Backmund, 1975; Richards, 1973). In the context of our discussion, the most interesting studies are those of Bodis-Wollner (1972, 1976). He measured the contrast sensitivity function of patients with cerebral lesions. In several cases, it was parametrically demonstrated that the greatest loss in the contrast transfer function occurred at high spatial frequencies, even though attenuation also occurred in the midfrequency range. This implies that the cortical lesions more deeply affect the higher end of the axis of spatial frequency transfer functions. Routines that process finer aspects of the visual image may need more sophisticated metabolic processes to support their activity. Bodis-Wollner (1976) suggested that cortical cells tuned to higher spatial frequencies are especially vulnerable to metabolic deficit. This hypothesis may contribute to an understanding of the effect of lasting visual deprivation. Well-documented experiments suggest that spatial frequencies having different orientations are processed by separate mechanisms; in other words, separate routines of analysis are used for the processing of gratings having different orientations (e.g., Campbell & Kulikowski, 1966). If this is the case, it is possible that one orientational channel can be damaged independently of other channels. Astigmatism is a condition in which the eye’s refractive power differs in various meridians. An astigmatic lens produces a bIurred image along a certain
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visual meridian and a sharp image along the meridian perpendicular to the first one. When severe astigmatism is present shortly after birth and remains uncorrected throughout childhood, the conditions for partial visual deprivation in the human are satisfied. Freeman, Mitchell, and Millodot (1972) proposed that abnormal visual experience in the form of ocular astigmatism can cause permanent changes in the visual system. These orientational differences in visual resolution remain after complete optical correction because of the deficiency of visual resolution owing to the altered properties of the neural network. If the retinal image of a developing visual system suffers from astigmatism that brings with it an extensive blur along the horizontal axis, the visual cortex might adapt to the discordant input from the retina by “tuning” itself to the features clearly imaged along the vertical axis. Obviously, the development of neural connections is involved in resolution. Hence, resolution of horizontally imaged details would be Kduced (Freeman et al., 1972). This psychophysical finding was confirmed by electrophysiological experiments (Freeman & Thibos, 1973). Subjects who exhibit reduced resolution for a pattern of a particular orientation also show a decreased evoked potential response for the same pattern. Again, since an optical explanation of the effect can be ruled out, the results are consistent with the hypothesis that partial visual deprivation of higher spatial frequencies along a particular visual meridian can alter or stop development of that portion of the visual system sensitive to the particular visual axis. There can be no doubt that this effect has a neural origin, since some measurements were made by sinusoidal interference fringes formed directly on the retina (Mitchell, Freeman, Millodot, & Haegerstrom, 1973). There is a close relationship between the amount of astigmatism, as an optical defect, and meridional amblyopia, as a neural defect, with the axes of astigmatism and amblyopia coinciding. These relationships between astigmatism and amblyopia indicate a causal relation between image quality and the development of spatial resolution during childhood. The effect of partial visual deprivation can be shown by estimating the modulation transfer function of the human with astigmatic visual experience. Freeman and Thibos (1975a, 1975b) investigated contrast sensitivities of the meridional amblyope for sinusoidal gratings of diffenent spatial frequencies and orientations. Results showed that the contrast sensitivities for gratings of a given orientation in meridional amblyopes are reduced along the entire spatial frequency domain. The extent of meridional amblyopia may be expressed as the ratio of the contrast sensitivities corresponding to the astigmatic axis to those corresponding to the axis free from astigmatic influence. As was shown, this ratio is nearly constant for most spatial frequencies, including the frequencies of .5 and 1.0 cycles/ degree. Freeman and Thibos also established some other very important features of developmentally acquired meridional amblyopia. One subject had pronounced
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oblique astigmatism and matching meridional amblyopia in one eye only. Another subject had very severe astigmatism in his left eye and required no refractive correction in his other eye. These two cases with monocular astigmatism suggest that visual experience can independently affect spatial resolution in each eye. Experience can selectively modify visual resolution along certain visual axes as well as visual resolution of monocular input. The simplest speculation is that cortical neurons tuned to a given orientation receive a normal monocular input from the normal eye, while at the same time the resolution in the astigmatic eye is highly abnormal. If we suppose that the meridional deficit is the result of defocusing, then it is possible to predict the amblyopic contrast sensitivity function by computing the attenuation factor for the appropriate defocused optics. In the case of the most severe sensitivity reduction, the experimental points are unlike any defocused curve, but, in moderate cases, the contrast reduction falls in the region of about .4 D defocus. Freeman and Thibos (1975a) concluded that the reduced contrast sensitivity functions can be equivalent to the theoretical effect of a small amount of defocus. This conclusion is very important in the context of our problem, since it allows us to connect the spectral content of the image on the retina with the perceptual capacities that are most likely predetermined by the spatial frequency spectrum available for the system. It was established that meridional amblyopia is not just a simple shift of the high-frequency cut-off. The modification of the contrast sensitivity function over the entire range of spatial frequencies suggests principal changes in the processing routines applied in the visual image analysis. It is possible to examine the properties of the transfer function in the spatial domain as one approach to the problem. By using the Fourier transform, one can convert data from the frequency domain into the spatial domain with the line-spread function (in the one-dimensional case) and point-spread function (in the twodimensional case). The resulting spatial weighting functions characterize the interaction of points of different spatial separation. As we mentioned above, the similarity between the forms of the neuropsychologically determined receptive field and the line- or point-spread functions have led to speculations about the functional similarity of the underlying phenomena. In the case of the amblyopic eye, it can be predicted that the weighting function in the spatial domain has broad character and lower values at the origin. This denotes decreased sensitivity in the case of merid-ional amblyopia compared with normal cases. The broadening of the weighting function or point-spread function can be considered to be a sign of increase in the integrative power in the neural network. In accordance with this suggestion, Beyerstein and Freeman (1976) found a drastic increase in summation distance, by a factor of two or three, along the amblyopic meridian. As the difference between the normal transfer function and the amblyopic one is diminished when the back-
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ground illumination is lowered, it seems that the differentiation operation (or lateral inhibition, which turns on at higher levels of illumination) has been lost. As a conclusion, it may be argued that the properties of the visual optics shape the form of perceptual functions. The young infant is highly myopic with fixed refraction. The growth of the visual optics increasingly improves the quality of the image formation process. A sharper, more finely detailed image is available to the infant as he grows older. If the growth of optical quality is stopped or limited early in life, the growth of visual capacities will also be limited. There can be no doubt that normal visual experience, without optical limitations, is a necessary requirement for the development of visual functioning. Specific visual deficit can cause corresponding deficits in perceptual functions. Both the visual optics and the visual environment affect perceptual development. The difference between horizontal-vertical and oblique grating resolution and contrast sensitivity is well documented for subjects living in a carpentered urban environment (Campbell, Kulikowski, & Levinson, 1966). The possibility that the visual environment associated with urban civilization can specifically shape the visual function is interesting. Annis and Frost (1973) provided some experimental evidence that orientational anisotropy, the oblique effect, depends upon a particular human visual environment. The oblique-horizontal difference is not as strong among Cree Indians as it is in the Euro-Canadian urban population. However, this evidence has some strong limitations in that no attention was paid to anisotropical effect not contributed by the environment, as Timney and Muir (1976) correctly pointed out. It is still risky to attempt a detaiIed formulation of how genetic preprogramming interacts with amounts and kinds of stimulation of the visual system in the system’s development. E. EXPERIMENTAL VISUAL DEPRIVATION
Although data on the human infant’s visual system development during the first months of life are scarce, evidence toward the understanding of this development can be obtained from the very wide and intense experimentation with animals, where fewer ethical considerations apply for scientific inquiry. Certainly, some problems emerge when we attempt to compare the ontogenetic development of the visual systems of different species, in the hope that some of these species can be comparable to the human infant as far as visual system development is concerned. However, in our overview, rather than concentrating on the problems of interspecies comparability, we try to utilize the different results of animal experimentation for the understanding of visual system development in general. Hubel and Wiesel(l962, 1965a) have shown that cats’ visual areas are highly organized for spatial orientation. The visual cortex consists of parallel slabs perpendicular to the surface of the cortex, within which cells have the same
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preferred stimulus orientation. The preferred orientation of a cortical slab changes from one slab or column to another. The functional architecture of the monkey’s striate cortex is, in the orientational domain, very similar to that of the cat (Hubel & Wiesel, 1968). The cat (Albus, 1975b) and the monkey (Hubel & Wiesel, 1974a) have a systematic arrangement of orientational slabs or columns. In oblique or tangential microelectrode penetrations, the preferred orientation changes continuously with a lateral shift of the electrode’s tip relative to the surface of cortex. Hubel and Wiesel(1974b) and Albus (1975a) have shown that there are spatial subunits within the visual cortex, having diameters of 2-3 mm. This cortical block or cylinder contains the units that function as routines needed to analyze a region of the visual field. As the area of the visual field being analyzed increases in retinal eccentricity and the ganglion cell density in the retina is reciprocally decreased, there must be a constant relationship between number of retinal ganglion cells and cortical cells. Maffei and Fiorentini (1977) presented evidence that the visual cortex of the cat is spatially ordered in the spatial frequency domain. In penetration parallel to the surface (i.e., parallel to the slabs of constant orientation) cells of the same parallel layer represent a variety of preferred orientations (from 0 through 180” rotation), with maintenance of the same spatial frequency preference over the whole electrode track distance. The most provocative finding in the area of experimental visual deprivation research during the last decade is the impairment of certain orientations in the cat’s cortex as a result of early selective visual stimulation. Blakemore and Cooper ( 1 970) reared kittens in an environment consisting entirely of horizontal or vertical stripes. They reported that most of the responses of the cortical cells were like those in a normal animal, but the distribution of preferred orientation matched the orientation experienced by the animal during development. Similar results were reported by Hirsch and Spinelli (1970, 1971), who exposed a horizontal grating to one eye and a vertical grating to the other eye of the kitten. Cats reared under these conditions had visual cortexes with monocularly driven neurons preferentially responsive to the experienced orientation. Later, Blakemore and Mitchell (1973) reported that an extremely short exposure can modify the distribution of preferred orientations within the cortical cell population. Uniorientational experience for 1 hour at a peak time of sensitivity (twenty-eighth postnatal day) was sufficient for the development of a strong cortical bias in orientation toward the orientation experienced. This rapid modification is an extreme one; the functional plasticity of the cortical circuits remains for a longer time and exists even in the adult animal (e.g.. Creutzfeldt & Heggelund, 1975). Pettigrew and Freeman (1973) and Van Sluyters and Blakemore (1973) found environmentally induced neural properties in kittens’ cortex. For example, Pettigrew and Freeman reared kittens in a “planetarium” that had no straight contours and was composed of light spots. Compared with normal cats reared in a
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contour-rich environment, the “dot cats” had fewer cells with normal properties. Atypical receptive fields, called “spot detectors,” appeared in the cortexes of these kittens. These findings were treated as clear evidence of a causal role played by early visual input in the determination of the functional properties of the visual system. The original enthusiasm of the first studies was weakened by data showing limited changes in brain structures under environmental pressure or without any visual experience at all. Leventhal and Hirsch (1975) showed a remarkably weaker adaptation effect when the horizontal or vertical stripes were replaced by oblique ones. In this case, visual stimulation did not restrict the development of cells with the preferred horizontal or vertical orientation; these cells did not require a specific visual input for maintenance or for development. Selective visual stimulation also failed to modify rabbits’ visual cortexes (Mize & Murphy, 1973). The most serious argument against environmental modification in the cat was reported by Stryker and Sherk (1975). They had not been able to replicate the strong effects of Blakemore and Cooper (1970). Using a more quantitative technique of investigation, they failed to find a bias toward the orientation of the environment the animals under study had encountered. This discrepancy poses many questions and highlights the difficulties of the field, beginning with the exhausting procedure of surgery and ending in difficulties with maintaining cats in colonies that are notoriously liable to obliteration by epidemics (Barlow, 1975). However, although Stryker and Sherk failed to replicate the results of Blakemore and Cooper, they reported results similar to those of Leventhal and Hirsch ( 1975). Muir and Mitchell (1973,1975) and Mitchell, Giffin, and Timney (1977) have subjected cats to selective visual exposure for different periods of time in the f m t 4 months of life. The cats were trained on stimulus discriminations between gratings of various orientations and a blank field of the same mean luminance. The spatial frequency of the gratings was then systematically altered and the contrast sensitivity functions of the selectively stimulated and normal cats were determined. Selectively deprived cats performed the discrimination tests as well as normally reared ones, except for poorer acuity for the gratings oriented orthogonally to the one the animals had been exposed to. This orientational deficit appeared throughout the spatial frequency domain. There are striking similarities between this attenuation of sensitivity functions and those described in astigmatic humans (Freeman & Thibos, 1975a). d u i r and Mitchell expressed the cat’s visual acuity in terms of a crossing point between high-frequency asymptote and a line representing chance performance level. The deficits in acuity for a grating perpendicular to the experienced orientation varied between .26and .87 of an octave with a mean value of .48. Careful examination showed that the deficit was not the result of optical astigmatism or lowered motivation in deprived cats. It was also shown that the orientational amblyopia was long-lasting. Therefore, orientational acuity deficit seems to be caused by selective visual stimulation and
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is located in the nervous system. Optical or other factors should be rejected as having no significance here. Hubel and Wiesel(1963), investigating receptive fields in very young kittens, reported that cortical cells in inexperienced kittens had all the specific properties of cells of the adult cat. This finding introduces new questions in visual development. First, do receptive field properties develop or does the kitten possess all the visual machinery of the adult cat just after eye-opening? Second, if some receptive field properties appear later during maturation, what is the role of visual experience in this progress? Contrary to the findings of Hubel and Wiesel, a lack of functional specificity in young kittens’ visual neurons was reported by Barlow and Pettigrew (1971). Supporting the view of Barlow and Pettigrew, several other studies failed to reveal orientational selectivity in the kitten’s visual cortex (Blakemore & Mitchell, 1973; Pettigrew, 1974). However, another study (Sherk & Stryker, 1976) provides support for the views of Hubel and Wiesel. Sherk and Stryker studied kittens that had not received visual experience because of a binocular lid suture performed before the age of natural eye-opening. They tested the kittens at 22-3 1 days of age, and found that most cortical cells preferred a bar stimulus over a moving spot. The data suggested that the cells closely approximated the selectivity found in the adult cat. Similar results were obtained in fur$er experiments by Wiesel and Hubel (1974) on visually naYve monkeys. Binocular lid suture was performed just after birth or at various ages after it, and the lids were kept closed for varying periods of time. Two visually inexperienced monkeys at the ages of 17 and 30 days showed the presence of a highly ordered sequence of orientation shifts that were in no obvious way different from those seen in adults. The main parameters were similar to adult values. It was concluded that the ordered columnar system was completely formed in early infancy and no visual experience was necessary for its development. The orientation tuning of the visual cells was also normal by adult standards, which indicates that the monkey’s visual cortex with respect to processing of orientational informationis innately determined and is not influenced by the lack of early visual experience. This conclusion is in agreement with anatomical observations showing that, compared to other species, the macaque is already well developed at birth-as far as the visual system is concerned. Experimental evidence suggests that the cat and rabbit are less mature at birth than the macaque. Many studies provide evidence for a gradual delayed appearance of specific properties in the visual neurons of the rabbit (e.g., Grobstein, Chow, Spear, & Mathers, 1973). The data suggest that the immature rabbit’s cortical neurons (Mathers, Chow, Spear, & Grobstein, 1974) and superior colliculus neurons (Makarova, 1974) are functionally different from those of the adult until at least 18 days after birth. It was found that simpler types of receptive fields were present near the time of eye-opening (10-1 1 days), while more complex functions, such as directionally selective and asymmetric receptive fields, did not
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appear until several days later (Makarova, 1974; Mathers et al., 1974). This picture of neural maturation is well correlated with the ability to form a conditioned reflex at different ages (Shilagina, 1974). Rapisardi, Chow, and Mathers (1975) detailed the maturation process in dorsal laterate geniculate neurons, suggesting that all parts of the rabbit visual system develop after eye-opening. Effects of prolonged visual deprivation have been the subject of many recent investigations. Imbert and Buisseret (1975) obtained results in agreement with those of Blakemore and Cooper (1970) that dark-reared 5- to 6-week-old kittens are totally nonspecific with respect to the functional properties of cortical cells. This is diametrically opposite to the finding of Stryker and Sherk (1975). A more multiple-sided picture was provided in a study by Singer and Tretter (1976). These authors found that the cells of 1-year-old dark-reared cats did not lack specific properties, but did lack the high selectivity for stimulus orientation characteristic of normal cells. The total number of orientation-specific cells was altered; the orientation selectivity loss in area 17 was about 39%, less than in area 18 (about 46%). One must certainly agree with Singer and Tretter that the main principles of cortical functional organization were not affected by deprivation. The structuresprobably became less specific than the normally reared cat’s cortical structure, but the basic outline was clearly stable. Light-deprivedcells lacked the sharp tuning for orientation and the sharp boundaries of the excitatory receptive field areas. Most of these changes can be accounted for by reduced efficiency in synaptic transmission. Intracortical inhibition is essential in the elaboration of the specific properties of cortical cells (Shevelyev, 1977). It appears that the absence of visual stimulation would freeze or impair the development of the intracortical specific connections. This would not be true if specific properties were already established at birth. In this case another explanation would seem to be more appropriate-that the specific properties of cortical cells become degraded without visual stimulation. In other words, lack of specificity results in degradation rather than in restriction of growth. Supporting this idea, Buisseret and Imbert (1 976) found that up to 3 weeks of age there were no significant differences in the proportion of the different types of cells in the dark-reared and normal kittens. Thereafter, in the dark-reared kittens, the specific cells tended to disappear while the nonspecific ones increased in number. Therefore, highly specialized neurons are present in the earliest stages of development, and specificity decreases gradually in the absence of visual experience. Garey and Pettigrew (1974) reported that visual deprivation causes a reduction in the density of synaptic vesicles in the axon terminals. Observable biochemical changes associated with light deprivation take place there (Pigareva, 1975; Uzbekov, 1976; Volokhov & Pigareva, 1975). Perhaps specific cells are vulnerable to deficits in metabolic processes. Conclusions It is difficult to draw definite conclusions from the studies analyzed above.
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There are many difficulties and controversies within the field of visual experience and brain development. Many of the problems are presented in a comprehensive review article (Barlow, 1975), but we would like to emphasize a few of them here. First, behavioral effects, as a rule, are less dramatic than changes in the functional structure of the cortex following long-lasting visual deprivation. Light-deprived cats show remarkable or even complete recovery of visuomotor behavior (Ganz & Haffner, 1974; Van Hof-Van Duin, 1976a). In addition, Mitchell, Giffin, Muir,Blakemore, and Van Sluyters (1976) reported that a cat with a surgically rotated eye behaviorally compensated for this rotation, and was able to discriminate vertical-horizontal coordinates using only the rotated eye. Postdeprivationalrecovery has been shown on the receptive field level (Cynader, Bennan, & Hein, 1976). Second, diametrically different results were reported in experimental conditions that had no obvious setback differences (Blakemore & Cooper, 1970; Stryker & Sherk, 1975). In addition, Maffei and Fiorentini (1974) reported that selective exposure to a certain spatial frequency reduces sensitivity to gratings of the exposed frequency independent of orientation. Further studies are necessary to make the picture clearer. A large amount of data support the view that the principial structure of the visual cortex is already formed at the time of birth. The plan of this structure is determined by innate factors. We think that genetic factors shape routines executing analysis of spatial structures in the visual scene. These routines may be incomplete. However, anatomical findings suggest the appealing answer that complete refinement and maturation takes place during the early period of infancy. The experiments that showed unusual receptive field properties based on selective experience allow for the hypothesis that the process of development can be modulated by visual stimulation. While questions about the extent of the modulation remain open, the principial architecture seems fixed. Visual deprivation causes a noticeable impairment of the contrast sensitivity function. The results are in good agreement with human data on the astigmatic person’s contrast sensitivity. Amblyopia is well evidenced in the case of selective exposure as well as in the case of total visual deprivation. Therefore, we conclude that early visual stimulation is of importance at least for the building of a neural mechanism having high visual resolution abilities.
IV. Conceptualization of the Relative Functions of Environmental and Organismic Influences The relationship between nature and nurture, ever present as a problem in the empirical studies mentioned earlier, seems to pose difficulties more on the conceptual than on the empirical level. The experiments outlined in the previous
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sections showed how a new scientific finding can stimulate a number of studies and speculations that, especially in the latter case, go their own way with little concern for the objects under study. For example, Blakemore and Cooper (1970) and Hirsch and Spinelli (1970) thought that the simple idea of environmental modifiability of the visual cortex was the main strategy of vision development. Now, after certain controversies pertaining to the data have appeared, the enthusiasm for attributing the prime cause of visual development to the organism’s environment has greatly waned. Things that seem simple soon turn complicated-until simplicity is again assumed in some other way. Among scientists doing research on visual neurophysiology, Grobstein and Chow (1976) have tried to make some conceptual refinements to account for the discrepant findings. They use two distinct concepts to denote the different degrees of environmental influence on nervous system development. Experience sensitivity denotes the milder degree of influence; it means merely that the neuronal connectivity is affected by the organism’s individual experience, while the framework of connections in general is determined by internal factors. Experience dependency is said to be present when the functional appropriateness of neuronal connections depends on visual experience. Experience is necessary to maintain a connection pattern that is elaborated on the basis of genetic information; without the experience the function does not develop in its full form. The most elaborate system of concepts applied to elucidate the nature-nurture controversy has been provided by Gottlieb (1976a, 1976b). At the lowest level of environmental influence-that of maintenance-experience can preserve the already developed state or end point (with no regard to how that point has been reached). Maintenance can occur by means of suppression of those nerve connections that are functionally unrelated to a certain kind of experience. This concept is in accord with the theory of Marcus Jacobson (1974) stating that the initial number of neuronal connections is selectively reduced by means of experience. Facilitation refers to cases in which some neuronal connections would in general be able to develop without any experience, but experience is necessary to give them fine functional tuning. The findings mentioned above on the role of experience in visual ontogenesis show either facilitative or maintaining effects but no inductive effects at all (which effects might have been assumed at the beginning of the 1970s). Induction is the experiential influence on neuronal C O M ~ C ~ ~ O ~ S that leads to the appearance of some functional structure in the organism. Inductive influence is unambiguous; if the organism is exposed to some environmental parameter, the necessary connections to cope with it are formed. Without exposure, the connections would not develop (Gottlieb, 1976a). This conceptual system treats the function of the environment in more detail than was done previously, but the problem of how these effects work at the level of neuronal connections (e.g., by suppression of nonfunctional connections, by selective rapid growth of the functional ones, by simple degeneration of the nonfunctional ones) remains to be soIved.
Visual Development in Ontogenesis
V.
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Perception of Flicker and Movement
A. INFANT RESPONSE TO FLICKER AND MOVEMENT
Our knowledge about infant responses to flicker is limited to the study by Karmel, Lester, McCarvill, Brown, and Hoffmann (1976). A parametric relationship was found between infant visual preferences and the occipital visual potential evoked by the temporal frequency of variation in test stimulus luminance. Both behavioral and electrophysiological response functions were best described by inverted U-shaped curves with a maximum response at 5-6 Hz. It is well documented that the temporal contrast sensitivity is determined solely by the amplitude of the fundamental frequency. Therefore, the quality (“sharpness”) of the subjective image regulates infant looking behavior. The infant’s response to flickering patterns depends on the flicker rate, just as with the adult’s response. We propose that the infant’s visual system processes the temporal modulation of luminance in a fashion qualitatively similar to that used by the adult visual system. Turning to movement, we must note that visual tracking occurs as early as several minutes after birth (Goren, Sarty, & Wu,1975). Clear movements measured by induced optokinetic nystagmus have been recorded on the fust day of postnatal life (Dayton, Jones, Aiu, Rawson, Steel, & Rose, 1964). Recordings of optokinetic nystagmus show that some newborns may possess a visual acuity of at least 20/150, which is remarkably better than static acuity. It was shown that newborn infants (from 8 hours to 10 days of age) were able to perform a visual task demanding the localization and maintenance of the image of a moving target on the general macular area (Dayton, Jones, Steele, & Rose, 1964). In the Russian literature, there are some early observations that the infant is able to localize peripheral moving stimuli (Figurin & Denisova, 1949), but this ability is considered to be not very accurate until 6-10 days after birth (Fonaryov, 1959, cited in Zaporozhets et al., 1967). The successful tracking of a moving object provides evidence of movement processing in the newborn infant’s visual system, but the optomotor effects are confounded with perceptual ones in this case. The studies cited above show that the newborn infant possesses routines for movement processing, but unfortunately they say nothing about the structure of these routines. Tauber and Koffler (1966) showed that optokinetic nystagmus is elicited in the infant not only by continuous moving stimulation but also by stroboscopic stimulation. Some attempts have been made to determine the threshold for visual motion detection in newborn infants. Ames and Silfen (1965) reported an increase in sensitivity to movement with age. If 75% looking time is taken as a criterion of movement threshold, then 7-week-old infants had a threshold of about 6.3 cm/ second and 20-week-olds, of about 2.8 cdsecond. Volkmann and Dobson (1976) investigated 1- to 3-month-old infants’ responses to a horizontal oscilla-
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tory motion. Consistent with the results of Ames and Silfen, an increase with age was found in the discrimination of the oscillating vs stationary patterns. The established function, relating looking behavior to rate of oscillation, resembles an inverted U-shape, with a peak at about 100 cycleslminute, independent of infant age. Therefore, infants show the highest sensitivity to movement with a midfrequency rate and/or moderate speed. Again, little can be said about the mechanisms of movement perception. The study by Harris, Cassel, and Bamborough (1974) can be regarded as evidence for the relative potency of relative movement (displacement of an object relative to a background) over absolute stimulus movement for infants as young as 8-28 weeks. A more complicated aspect of motion perception is reported by Bower, Broughton, and Moore (1970a), Ball and Tronick (197 1), and Ball and Vurpillot (1976). The defensive behavior of 1-week-old infants was evaluated in situations in which different objects were seen to approach by the infant. It was shown that the kinematic properties of a motion parallax field (see Koenderink & Van Doom, 1975) could be discriminated by the infant, and that defensive responses were appropriate for the direction of approach of objects. This selectivity obviously implies differential evaluation of the distribution of local movement over the visual field. Newborn infants certainly possess the processing routines for movement analysis, and these routines may even be rather complicated, as indicated by an appropriate evaluation of motion parallax. B. REARING IN STROBOSCOPICALLY ILLUMINATED AND UNIDIRECTIONALLY MOVING ENVIRONMENTS
Effective for the study of selective deprivation of movement information is a visual environment illuminated by a train of short flashes (say, with a duration of .01 second, and frequency of 2 Hz) visible as a sequence of static pictures. Such stroboscopic illumination “freezes” retinal displacements due to movement of either the visual environment or the perceiver. Cynader, Berman, and Hein (1973) reared cats in a stroboscopically illuminated environment (flash durations 10 psec, frequency .5 Hz).The number of both orientation and direction selective neurons observed was greatly reduced in the stroboscopically reared cats as compared to normal cats. A similar reduction of directionally selective neurons was observed in another study (Olson & Pettigrew, 1974). Flandrin, Kennedy, and Amblard (1976) demonstrated a more dramatic effect of stroboscopic rearing upon the cat’s superior colliculus;stroboscopicrearing significantly reduces directional preferences of the cortex, and it apparently almost completely eliminates directional preferences in the superior colliculus. Handrin et al. (1976) concluded that visual experience of motion constitutes an absolute criterion for the development of direction selectivity in the superior colliculus, while in the visual cortex it merely reduces the breadth of tuning. This conclusion
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implies that total visual deprivation affects the cell properties of the superior colliculus in a way similar to selective movement deprivation. This last conclusion is supported by an experimental observation of dark-reared kittens (Flandrin & Jeannerod, 1975). Another method for selective deprivation of movement information is the rearing of kittens or infants of other species in a unidirectional environment. Daw and Wyatt (1974) tried to modify the directional sensitivity in the rabbit’s retina after selective visual exposure to a moving visual environment. The rabbit’s retinal cells were not modified under the environmental pressure. This negative result is contradictory to many other results that show modification of directional selectivity in the cat’s visual cortex and superior colliculus due to selective movement deprivation. Tretter, Cynader, and Singer (1975) exposed cats to unidirectionally moving black and white stripes for a few hours per day for 1-4 days at about 4 weeks of age. They found a strong bias in neuronal specificity toward movement direction experienced during this exposure. Similar results were reported by Cynader, Berman, and Hein (1975). Cats were reared in a visual environment in which irregular patches of luminescent paint moved constantly leftward. It was shown that most of the cortical cells, simple as well as complex, had leftward components in their directional preferences. However, the collicular neurons studied in these cats did not differ strongly from those of normal cats in the distribution of their preferred directions of movement. Daw and Wyatt (1976) and Berman and Daw (1977) introduced an important method for measurement of a critical period for movement perception. Kittens were placed inside a drum rotating leftward until a certain age, when the direction of rotation was changed. If movement-sensitiveneural networks have plastic properties, then selective exposure to a unidirectionally moving environment should shape this network. Daw and Wyatt (1976) showed that the critical period for developing directionally sensitive cortical mechanisms was about the fourth week of age. The “time window” of the critical period is relatively narrowapproximately 1 or 2 weeks wide. Before or after this critical period (outside the “window ”), exposure to selective visual environments does not significantly alter the responses of directionally tuned cortical units. It Seems extremely interesting that the critical period for movement terminates earlier than does the critical period for binocularity (Berman & Daw, 1977). Berman and Daw proposed that more “peripheral” synapses (the geniculocortical ones) retain their plasticity longer than more “central ’* (intracortical) ones, on the assumption that intracortical synapses are involved in direction-sensitive networks. The common belief that movement perception is not vulnerable to environmental modification by means of binocular enucleation or rearing in a unidirectional environment is seriously threatened by the nemphysiological studies cited. However, case studies of recovery from long-lasting blindness have not included parametric measures of movement perception abilities. It seems that we
Jiri Allik and Jaan Valsiner
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have no information about the visual processing of temporal information after recovery from early blindness. The only thing we know from reported clinical observations is that patients are better able to answer “where” questions than “what” questions. However, this function is essentially different from the ability to process spatiotemporal luminance modulation, that is, two-dimensional timevaried visual patterns. Different kinds of spatiotemporal information are necessary to give satisfactory answers to the different questions. Therefore, the problem of processing movement information after prolonged deprivation is still open for future clarification.
VI. Binocular Vision A.
INFANT BINOCULAR VISION
Coordinated binocular fixation is a basic requirement for binocular vision. What do we know about the newborn’s ability to fixate objects binocularly at different distances from the perceiver? In a pioneering study, Ling (1942) showed that the infant’s ability to fixate binocularly is relatively poor during the first weeks of life. She gathered filmed records of vergence eye movements in response to target approach and recession along the median plane. The records, which permitted only qualitative analysis, showed an absence of systematic vergence movements until 7 weeks of life. Wickelgren (1967) measured infant scanning of two-dimensional patterns. He used the corneal reflection method (Haith, 1969; Maurer, 1975) to measure the area of the pattern that was scanned by each eye. The areas scanned by each eye overlapped only partly; for a centrally presented flickering light, the overlap was only about 9%. Wickelgren concluded that the two eyes were actually directed at different parts of the visual field. The neonate’s eyes were more divergent than is required for appropriate binocular fixation. This conclusion is limited by the accuracy of the corneal reflection technique. Moreover, other artifacts may make the corneal reflection technique invalid. One of these is due to projective distortion during reflection (Slater & Findlay, 1975a). Another is due to the anatomy of newborn’s eye; there is a disparity of about 8.5” between the newborn’s visual axis and the axis of regard (Slater L Findlay, 1972, 1975a). During binocular fixation, disparity between the recorded centers of the pupils and the actual axis of regard has a magnitude of 17”. Hence, the newborn baby’s divergent “squint” might be a result of an erroneous measuring technique. Binocular fixation can be estimated by two different methods: (1) measuring the vergence eye movement to the response of approaching or receding visual targets or (2) measuring the ocular responses to the target movement on the same plane of depth. In the latter case, conjugate eye movements (pursuit or saccadic)
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are required for the appropriate binocular fixation. Dayton et al. (1964) electrooculographicallystudied the fixation reflex in 45 newborn infants. They found that at least 17 subjects were able to perform a visual task demanding the placement and maintenance of the image of a moving target on the general macular area. A similar conclusion was reached by Hershenson (1964). Dayton et al. (1964) documented that the newborn's saccadic eye movements were closely conjugated, although relatively coarse and hypermetric compared with those of an adult. Other studies have confirmed these results in general ( A s h & Salapatek, 1975; Harris & MacFarlane, 1974). Aslin and Salapatek (1975) studied the ability of 1- to 2-month-old infants to localize saccadically targets presented parafoveally or peripherally. Contrary to the previous finding, the infants' saccadic movements were found to be highly hypometric, and corrective saccades occurred frequently. However, the main conclusion is the same: Conjugate eye movements are present at early stages of development, suggesting that very young infants possess binocular fmation ability. The presence of conjugate eye movements in young infants is accepted by the majority of investigators, but there is less agreement about vergence eye movements. Slater and Findlay (1975b) found clear differences in fixation of targets at distances of 25 and 50 cm in infants ranging from 10 hours to several hundred hours in age. The difference between convergence angles for the two distances was 2.6", close to the expected value (3.lo). Taking into account necessary correction of the recorded data, they concluded that the objects were fmated bifoveally . The bifoveal fixation and appropriate convergence angle were not found when the target distance was 12.5 cm. Slater and Findlay (1975b) proposed that the lack of appropriate convergence was caused by the absence of accommodation for near vision in the newborns. However, it is reasonable to assume that the newborn is well equipped to fixate binocularly, and will manifest this ability when a suitable stimulus is shown at a reasonable distance from the eye. It is possible that binocular fixation is infrequently observed simply because of crying and other infant behaviors that seem to be more important from the evolutionary point of view than training of the binocular system in the first hours of infant life. Slater and Findlay summarized their studies by concluding that there seems to be no reason why the newborn baby should not have binocular vision. The suggestion that the major characteristics of binocular vision are present at birth was presented in Slater's contribution to the International Congress of Psychology in Paris, July 1976. Aslin (1977) used a luminous target moving along a path on the infant's visual midline and measured the vergence eye movements of the infant from 1 to 6 months of age. The amplitude of the approaching and receding targets was 12 to 57 cm. The results indicated that the ability to converge and diverge the eyes in the appropriate direction is present as early as 1 month of age, but only for some infants. As the infant's age increases, the frequency of making correct vergence eye movements also increases. Although the direction of ver-
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Juri Allik and Joan Valsiner
gence movement is appropriate, the amplitude of vergence or divergence is erroneous. The convergence angle that is needed to maintain appropriate binoculrrr fixation as the target is moved is significantly below the expected value. The 1-month-old infants did not show changes in convergence sufficient to maintain binocular ftxation, but the 2-month-olds did. A s h (1977) noted that responses to the faster target movements improved with age (the speeds used in the study were 12 and 22 cdsec). Working with adults, Zuber and Stark (1968) realized that the vergence eye movements are relatively “lazy” movements and it would be predicted that a newborn baby’s vergence system is even more “lazy” than that of the adult. Therefore, it is quite possible that the slow speed (12 c d s e c in A s h ’ s experiment) nevertheless exceeds the resolution power of the system. In this respect the infant’s vergence eye movements need a more careful examination before any conclusions can be drawn. B. DISPARITY
Bower, Broughton, and Moore (1970) used a stemswpic device to create virtual objects at different distances in space. They claimed that the infants at the age of 1 week reached and grasped for the virtual object. The fact that the “object” had no tactual properties produced frustration and crying (although there might have been many other reasons for distress). This work provides evidence for stereoscopic vision in infancy as early as the first weeks of life. However, the experimental setup of this study is open to serious criticism. Appel and Camps (1977) presented a stereoscopic image of a toy rabbit to 7- to 9-week-old infants. Different groups were habituated to the particular disparity value of the image and after a period of habituation, the reactions (heart-rate deceleration) to the disparity changes were recorded. A sophisticated procedure was reported by Gordon and Yonas (1976). The subjects of this study were infants aged 20 to 26 weeks whose reaching behavior toward the position of stereoscopically presented virtual objects was videotaped. Analysis of the infants’ behavior showed that they discriminated between the far and near positions of the virtual object. When the virtual object was positioned out of reach, the infants tended to lean farther forward and to reach less frequently than when the virtual object was positioned within reach. As disparity was the only feature varied in these experimental conditions, the conclusion seems rather clear-5-month-old infants are sensitive to binocular information for depth. Similar results for older infants (18-32 months) were reported by Von Hofsten (1977). The infant’s reach was always directed toward the virtual position definqd by the angle of convergence. Atkinson and Braddick (1976) performed a study in which random dot stereograms were presented to the infant as stimuli. The ability to make discriminations based on binocular disparity was investigated
Visual Development in Ontogenesis
31
in 2-month-old infants by two methods: (1) fixation preference between patterns differing in the disparity they contained and (2) recovery from habituation of high-amplitude sucking when there was a change in disparity of the visual reinforcer. The results obtained with both methods indicated that at least some infants at the age of 2 months were sensitive to binocular disparity. As individual variation and differences in the methods are not important to the aims of the present discussion, we can conclude that the disparity-extracting system is developed by the age of 2 months. This ability to discriminate binocular disparities does not necessarily imply the perception of stereoscopic depth. It is quite possible that infants can detect disparity at an early age, but do not interpret this information as signifying a difference in distance. The interpretation of depth might be learned later, as a consequence of the correlation of disparities with sensory and motor events, as proposed by Atkinson and Braddick (1976). C.
ABNORMALITIES OF BINOCULAR VISION
About 2 to 4% of humans are stereoblind (Julesz, 1971; Richards, 1970). People who lack stereopsis are unable to use retinal disparity as a cue for depth. Richards (1970) found that genetic factors play an important role in this defect. However, stereoscopic vision is vulnerable to developmental influences as well. Therefore, acquired visual stereodefects are also frequent in the human population. There may be several reasons for impairment of the stereoscopic system: (1) binocular deprivation (blindness), (2) monocular deprivation, or (3) impairment of synchronous eye movements due to squint. Many perceptual defects involve the transfer of monocularly acquired information from one eye to another. For example, the magnitude of interocular transfer in the tilt aftereffect for normal vision is 70%. Interocular transfer implies the existence of binocular interaction, which probably takes place in the visual cortex. There must be binocular neurons that receive information from both eyes simultaneously. In other words, successful interocular transfer shows that the images presented to the left eye and to the right eye stimulate the same population of cortical neurons. Movshon, Chambers, and Blakemore (1972) were the first to demonstrate that humans who lack stereopsis also have little or no interocular transfer of the tilt aftereffect. Three groups of humans acted as subjects in this experiment. The fist group were normal subjects who were sensitive to depth cues in random dot stereograms. The second group were completely insensitive to depth cues in the tests; they had no clinical history of uncorrected or corrected strabismus, nor did they show strabismus on simple observation. The final group of subjects lacked stereopsis completely and also had a clinical history of strabismus; in some cases, the squint had been surgically corrected but in no case was the correction made
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Juri Allik and Jaan Valsiner
before the age of 2 years. The results for the three groups were as follows: The normal group showed 70% interocular transfer, the nonstrabismic group lacking stereoscopic vision had interocular transfer around 4 9 8 , and the strabismic group had only 12% interocular transfer. The reduction of interocular transfer for strabismic subjects compared with normal ones suggests that the cortical units were not sensitive to binocular influences. No integration of the information received from the left and the right eyes took place. The loss of binocularity in the case of strabismus is apparently caused by lack of conelation of ocular alignment and optical inequality in the two eyes. This point has an important implication for understanding the development of stereoscopic vision: Normal congruent visual input is a necessary condition for maintenance (or perhaps development) of stereoscopic vision. Mitchell and Ware (1974) confirmed and extended the previous results. They measured percentage of interocular transfer vs stereoacuity and found a strict linear relationship between these two measures: Persons who have a higher mean percentage of interocular transfer show better stereoacuity. Hohmann and Creutzfeldt (1975) studied the effect of the age at which the squint f m t appeared on interocular transfer of the tilt aftereffect. Twelve children ranging in age from 5 to 15 years served as subjects. Nine of them had suffered from strabismus in early life and had had corrective operations between the ages of 3 and 5 years. Results were quite impressive: The later a squint began in the child, the higher was his mean interocular transfer and the better his binocular vision. The authors hypothesized that about 2 to 2.5 years of age may be considered the end of the critical period for the development of binocular vision in humans. At the same time Banks, A s h , and Letson (1975) published a study of a larger population of isotropic persons whose ages at the onset of strabismic deviation were well established. The amount of interocular transfer of the tilt aftereffect was used as a measure of the normality of binocular vision. The age at which the greatest influence in determining the development of normal binocular functions was found was 1.7 years. Banks et af. (1975) concluded that the sensitive period for the development of binocularity begins several months after birth and reaches a peak between 1 and 3 years of age. The absence of normal binocular experience during some part of this critical period causes irreversible changes or occasionally total lack of binocular functions. It is well known from ophthalmological observations that squint significantly decreases visual acuity in the nondominant eye. Von Noorden (1973a) attempted to determine the critical period for the development of amblyopia ex anopsia. The effects of unilateral lid closure and artificial esotropia on the development of visual acuity were studied in visually immature rhesus monkeys. He found that irreversible amblyopia occurred in all animals whose lids were sutured between birth and 9 weeks of age. During this period, only a brief period of occlusion (2-4 weeks) was necessary to cause severe amblyopia. Results on experimental
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amblyopia in monkeys were compared with some cases of amblyopia in humans. Observation of patients with early unilateral visual deprivation showed that amblyopia ex anopsia can occur in children as old as 52 months. Therefore, the critical period in the human is much longer than that in monkeys. It is interesting that the only area where histological anomalies were noticeable was the lateral geniculate nucleus (von Noorden, 1973b; von Noorden & Middleditch, 1975). Hence, unilateral lid closure or esotropia causes unequal resolution power in the two eyes and at the same time results in an impairment of stereoscopic vision. The suppression of acuity in the nondominant eye can be seen even in an apparently normal visual system without obvious squint or refractive errors. Coren and Duckman (1975) studied cases of strabismic amblyopia and found that 57% were left-eye amblyopic. It is established that about 65% of the general human population is right-eye dominant and they therefore concluded that strabismic amblyopia occurs more frequently in the subdominanteye. Hence, the nondominant eye is chosen for functional expression more frequently than the dominant eye. In this respect, it is important to mention that ocular dominance is already developed at the age of 44 weeks, by which time the percentage of right-eye dominance is similar to that of adults (Coren, 1974). However, the situation is unfortunately complicated by the recent finding that there are at least three different types of ocular dominance: sighting dominance, sensory dominance, and acuity dominance (Coren & Kaplan, 1973; Porac & Coren, 1976). The binocular system is an example of extraordinary coordination between the oculomotor and perceptual systems. These systems are mutually dependent, in that exact binocular fixation requires an estimation of disparity of egocentric localization in both eyes and relatively good visual acuity from one side. Conversely, precise binocular fixation is required for normal binocular and stereoscopic vision. Various kinds of visual stimuli might serve as cues for vergence eye movements (Westheimer & Mitchell, 1969). For every vergence angle, there is an approximately constant error of binocular fixation (phoria). Richards (1969) showed that the fixation disparity changes with a change of wave-length of fixation stimuli. This furation disparity change may be the result of the different resolution capacities of the chromatic mechanisms. Therefore, the size of the operating receptive field determines the precision of binocular furation. The refractive error may cause a loss of stereoscopic vision by means of unwanted fixation disparity, For example, ophthalmologists have noted a correlation between the frequency of squint and the growthof visual acuity in infancy (Kogan, 1971). A large fixation error leads to a suppression of input from one eye. This is a possible cause of the frequent cases of diplopia. Richards and Miller (1969) found that about one-third of the whole population is not able to use convergence angle as a cue for depth. Those people who are unable to use convergence for depth estimation show an abnormal curve of fixation disparity with a tendency toward a greater error.
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Juri Allik and Jaan Valsiner
The binocular system is a complicated structure involving the coordination of the activities of many subsystems, A common activity of stereoscopic vision is the fusion of retinal images in the right and left eyes. This fusion is achieved by vergence eye movements that eliminate large fixation disparity. The releasing stimulus for vergence (fusional) eye movements is disparity in egocentric localization. Obviously, only mechanisms receiving information from both eyes simultaneously can perform thisjob. As we see from the study by Richards and Miller (1969), an impairment of the vergence system may have taken place when fusion breaks down. Jones (1977) reported similar findings showing that the total lack of stereopsis is not necessarily accompanied by apparent anomalies of vergence eye movements. Large fixation disparity causes a lack of fusion and diplopia of images. However, even crude diplopia does not prevent stereoscopic vision. The implication is that binocular fusion is not an absolute requirement for depth perception. However, diplopia has other consequences-for example, binocular rivalry. Images differing in relative egocentric space exhibit binocular competition and suppression of the input from one eye. This normal mechanism preventing image doubling operates effectively during development. As discussed previously , the nondominant eye becomes amblyopic more frequently than the dominant eye. Prolonged suppression of the nondominant images causes amblyopia ex anopsia in the suppressed eye. One mechanism that may be involved in the phenomenal suppression is a degradation of binocularity. Let us suppose that binocular units that received incongruent input from the two eyes resolve this confusing situation by disregarding one set of inputs. Herman, Tauber, and Roffwarg (1974) found that monocular deprivation for 24 hours remarkably impairs stereoscopic acuity, but binocular deprivation does not affect the stereoscopic capacities noticeably. Hence, the stereoscopic system is impaired not by the disuse of the mechanism, but by the absence of balanced stimulation from the two eyes. If that disequilibrium takes place at any time during the critical period for development of binocularity, then the consequences of that abnormal experience are irreversible. D. DEVELOPMENT OF BINOCULAR VISION IN ANIMALS
Hubel and Wiesel (1%2) established that the majority of cells in the visual cortex are binocularly driven. The cortical cells have receptive fields in both eyes. These fields are functionally very similar and have a relatively corresponding localization in the visual field. Although the majority of neurons are binocularly driven, they are not equally excited by both eyes. This inequality is called eye dominance, and Hubel and Wiesel proposed a system for classifying the different phenomena subsumed under that category. Cells were divided into seven groups. Groups 1 and 7 are monocular cells driven by contralateral and ipsilateral eyes, respectively; groups 2 to 6 show increasing shift of eye dominance from contralateral to ipsilateral dominance. It was found that mofe cells
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fall into groups 1 to 3 than into 5 to 7; that is, the majority of neurons are dominated by their input from the contralateral eye. Binocular cells stimulated through both eyes simultaneously respond best to an egocentrically located stimulus in both eyes. However, there are systematic deviations from an exact binocular correspondence. One of them, relative localization or binocular disparity, has been carefully investigated. Results lead one to conclude that there is disparity specificity in binocularly driven cells in the visual cortex of the cat (Barlow, Blakemore, & Pettigrew, 1967; Bishop, 1973; Nikara, Bishop, & Pettigrew, 1968; Pettigrew, Nikara, & Bishop, 1968). Hubel and Wiesel(l963) reported that the binocular system is present in very young kittens without visual experience. In later work, Wiesel and Hubel (1974) showed a similar state of affairs in a normal 2-day-old monkey, whose visual cortex had almost the same ocular dominance distribution as that found in the adult cortex. Similar to the organizationof visual cortex in the orientation domain, an ordered distribution of the ocular dominance column exists. Therefore, visual experience is not necessary for the development of cortical inputs from both eyes to a single neuron. However, prolonged binocular deprivation causes a decrease in binocularity in the visual cortex. Binocular deprivation of a few weeks duration in the monkey will bias the normal binocular distribution histogram remarkably, and there will be some shift toward monocularity (groups 1 and 7 become more dominant than others). Hence, binocular deprivation in both the cat and monkey results in deterioration of innate connections subserving binocular convergence in the visual cortex (Hubel & Wiesel, 1974). This finding has been extended by m a sures of the development of binocular disparity (Pettigrew, 1974). Disparity selectivity improved from birth until 30 days, when binocular neurons were seen approaching adult-like specificities. In the second and third weeks, there were no marked differences in cell specificity between normal and binocularly deprived animals. However, after the fourth and fifth weeks, significant differences become apparent between the experienced and inexperienced animals. Visually inexperienced cats do not have sharp binocular disparity tuning curves. These animals are less selective to binocular disparity in that they tolerate relatively large variations in the egocentric localization in each eye. One of the most stimulating findings in the field was the discovery that monocular eye closure or artificial squint is a more effective disturbing factor for the normal development of binocular vision than is total binocular deprivation (Wiesel & Hubel, 1965). This neurophysiological finding is in accord with the psychophysical demonstration reported above (Herman et al., 1974). E. MONOCULAR DEPRIVATION
Hubel and Wiesel (1970) discovered that monocular deprivation leads to almost total loss of binocular neurons. In the visual cortex of monocularly deprived
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kittens, most cells can be influenced through the opened eye. Behavioral examination confirms this neurophysiological finding; such an animal appears behaviorally blind when forced to use its deprived eye (Dews & Wiesel, 1970). However, some evidence suggests that behavioral defects after monocular deprivation result from deficiencies in the complicated visuomotor control rather than in pattern identification, that is, visual perception per se (Van Hof-Van Duin, 1976b). Hubel and Wiesel (1970) established the existence of a critical period during which the changes in cortical ocular dominance occurred. They found that changes in ocular dominance took place only if the deprivation occurred between about 3 and 15 weeks of age. A deprivation period as short as 3 days is sufficient to cause remarkable changes in the ocular dominance distribution. The same experiment showed that the reorganizationof the cortex persisted despite a period of full visual experience after the initial deprivation period. Olson and Freeman (1975) studied the time course of the reduction of binocular units after the monocular deprivation period. A severe reduction in the proportion of units responsive to the deprived eye occurred over the f i t few days of monocular vision. Functional abnormalities appeared in scattered cases after 1 day of deprivation, were marked after 3 days, and became complete after 10 days. Schechter and Murphy (1976) were able to show that even 3 hours of monocular deprivation are sufficient to cause a reduction in cortical binocularity. However, this period of deprivation is insufficient to cause a shift in ocular dominance favoring the experienced eye. Hence, this result may be an indication that there are two different processes underlying binocularity and ocular dominance. The principal findings of the previous authors seem to be confirmed in the studies performed by Colin Blakemore and his associates. Peck and Blakemore (1975) found that little visual experience was needed to cause changes in the visual cortex for binocularity. Twenty hours of monocular experience produced a distinct shift in ocular dominance toward the open eye, but this effect needed more time for consolidation. Recording immediately after the period of deprivation was less successful than recording 2 days later, when the deprivation effect was found. Blakemore, Van Sluyters, and Movshon (1976) reported experiments in which kittens were reared in normal conditions until the age of 32 days and then were monocularly deprived for 10 days. These monocularly deprived animals seemed to be very similar to those who had visual experience before the 10 days of deprivation. This result clearly shows that the “window” of sensitivity is restricted from both sides of the age axis. Monocular occlusion affects the functional architecture of ocular dominance columns in the cortex of monkeys. In the normal animal, ocular dominance columns occupy approximately equal areas in the visual cortex with the width of an individual column being about 400 pm. However, after monocular deprivation, the columns corresponding to the deprived eye decrease in width, and the
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width of the healthy eye’s columns expands at the expense of the deprived eye’s columns (Hubel, Wiesel, & LeVay, 1976). Hubel et al. (1976) concluded that the ocular dominance architecture of the monkey’s cortex changes markedly after monocular deprivation. This change is in contrast to the stability of orientation columns, which may collapse in an orientadonal domain but do not expand at the expense of other orientations. The response to monocular deprivation in the cat’s visual cortex is similar to the response found in the monkey’s visual cortex. Blakemore er al. (1976) showed in monocularly deprived animals that during long oblique electrode penetration, the sequential alternation between cells strongly dominated by one eye was similar to that found in normal animals. However, the electrode track distances in which the deprived eye dominated were drastically reduced. Therefore, cells dominated by the nondeprived eye expanded into the territory of the deprived eye, which resulted in an alteration of the entire functional architecture of the visual cortex of the cat. The majority of investigators working in the field of monocular deprivation accept the concept of competitive interaction between the pathways that go from the two eyes to the cortex. The existence of competitive interaction was proposed in its most explicit form by Murray Sherman. Sherman, Hoffmann, and Stone (1972) demonstrated that monocular deprivation causes a collapse of a specific cell type in the lateral geniculate nucleus (Y cells, the largest of the geniculate cells). This electrophysiological finding correlates well with the morphological demonstration of a reduction in the mean cell size in the layers of the geniculate nucleus that are innervated by the deprived eye. However, this change occurs only in the segments of the visual pathways that receive input from the binocular parts of the visual field; it has not been found in the parts of the visual pathways that receive their inputs from the monocular crescents of the visual field. Behavioral tests show that monocularly deprived animals respond to objects that result in input from the monocular crescent of the visual field (Sherman, 1973). The difference in behavior between the monocular and binocular segments of the visual pathways suggests that competitive interaction occurs between pathways that reach the cortex from each eye. Guillery (1972) and Sherman, Guillery, Kaas, and Sanderson (1974) developed a method for testing this proposal. The method consists of placing a lesion within the binocular segments of the opened retina. The most important and critical finding for the proposed theory of competitive interaction was that the damaged area in the opened eye can, to some extent, prevent deleterious effects of monocular deprivation. The morphological ground of this competitive interaction is a translaminal growth of axons from layers that are stimulated by the opened eye to the layers receiving no visual information (Hickey, 1975). Hence, changes in the representation of the normal eye in the visual cortex are extended at the expense of the deprived eye. Binocular competition occurs during a limited period of time, the “sensitive
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period. ” An appropriate method to demonstrate simultaneously the effects of binocular competition and the sensitive period is the procedure of reverse suturing. The lid of one eye is sutured until a certain age. After the sutured eye is opened, the other eye is closed. Movshon and Blakemore (1974) and Blakemore and Van Sluyters (1974) demonstrated that reverse suturing at 3-5 weeks caused a complete switch in ocular dominance. Reverse suturing at 14 weeks had almost no further effect on ocular dominance, because most cells were driven dominantly by the eye opened before the reversal of monocular deprivation. Therefore, results with reverse suturing are in good agreement with those of monocular deprivation: There are critical periods of sensitivity during which binocular competition occurs. As one might expect, artificial squint in animals leads to changes in the binocularity of the visual cortex very similar to those that occur in the case of monocular deprivation. For example, Yinon (1976) showed that the normal eye could drive twice as many cortical cells as the deviating eye. The period of susceptibility to the effect of squint is limited to the first 3 postnatal months; this finding, again, is in agreement with data on monocular deprivation. However, some data show that altered ocular motility per se is sufficient to affect cortical binocularity. Maffei and Bisti (1976) raised artificially strabismic kittens in total binocular deprivation and found a loss of binocularity in these cats. Moreover, there was a significant shift in dominance toward the normally moving eye similar to the shift that was experienced in strabismic animals with opened eyes. It was shown that the influence of the artificial strabismus on the cat’s visual cortex is specific: Only simple cortical cells are vulnerable to the immobilization of one eye (Fiorentini & Maffei, 1974). A significant reduction of binocularity in the visual cortex appeared after surgical rotation of one eye in the cat (Blakemore, Van Sluyters, Peck, & Hein, 1975; Yinon, 1975). In general, one can conclude that normal binocularity is maintained in the condition of visual and/or motor equality of the two inputs. The reduction of activity in one of these inputs causes reduction of binocularity because of competitive interaction between the two input pathways. The previously mentioned reduction seems to persist even in the adult cat, probably to a lesser degree and in a more reversible form (Maffei & Fiorentini, 1976). Severe reduction of binocularly driven cells in the cortex of monocularly deprived cats is accompanied by misalignment of the two eyes. Blake, Crawford, and Hirsch (1974) found that alternating monocular deprivation causes marked esotropia in the cat. In these animals, binocular convergence seems to be impaired as well. These results lead to the assumption that the loss of binocularity by means of monocular deprivation is a consequence of strabismus. In any case, disparity in the binocular system is only one of many stimulus cues that control vergence eye movement and binocular fixation. It is evident that binocularity is at least a necessary condition of appropriate eye alignment.
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Studies of albinos are closely relevant to the facts reported here. It is established that vertebrates with laterally placed eyes and panoramic vision have in the majority of cases complete decussation of optic fibers at the optic chiasma. However, in animal albinos, the number of decussated fibers is significantly reduced, leading to an abnormal visual mapping in the lateral geniculate body and visual cortex (Guillery & Casagrande, 1976; Guillery, Casagrande, & Oberdorfer, 1974; Shatz, 1977a, 1977b). The nondecussated optic system develops because of retinal hypopigmentation and apparently does not depend on species differences (Creel, Dustman, & Beck, 1973; Creel, Witrop, & King. 1974). The nondecussated visual system leads to serious problems in Siamese cats (albinos), because cortical representation of the visual field is ambiguous. The probable mechanism preventing ambiguous representation in the visual cortex is the suppresion of one monocular input, as in experimental strabismus. This possibility was confirmed and it is clear that Siamese cats solve this problem in the manner described for normally pigmented animals ’ responses to abnormal visual inputs. Balanced and approximately congruent stimulation of both eyes is a critical requirement for the normal development of the binocular system. Taking into consideration our knowledge about the Siamese cat’s visual system, the requirement can be reformulated in terms of the congruence of the two inputs at the level of the visual cortex: Visual mapping in the two eyes must be fairly equal. Hence, the degree of congruence or equality would be an important subject of investigation. Blakemore (1976, 1977) investigated this problem very carefully. He showed that contrast differences in the two eyes do not significantly change normal cortical binocularity.
VII.
Conclusions
A. NEWBORNS’ VISUAL ABILITIES
The situation in infant visual perception research is typical for a developing scientific area. primary interest is being directed toward disproving widespread “folk stories” that constitute the prescientific stage of knowledge. It seems indisputable that the field of infant visual perception is devoted mostly to demonstrating the existence of global visual abilities in the infant. Very little is known about the fine structure of the visual routines in infant vision. There is also a great shortage of data concerning quantitative comparisons between infant and adult. However, in spite of these difficulties, we can say that the long-lived myth about the functional “blindness” of the infant is dying out. The infant seems to acquire new visual abilities with each improvement in the ingenuity and methodology of the researchers.
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We feel that there are compelling reasons to believe that a complete set of global visual abilities exists in the infant at or closely following birth. Therefore, the newborn is far from being a “blind person” and can analyze the visual environment along the most important dimensions, such as pattern, movement, color, and depth. Moreover, the infant processes these aspects in a manner qualitatively similar to that of the adult. We can presume that there is a strict homology between newborn and adult visual routines for analysis of the following aspects of visual scenes: (1) the spatial distribution of light in the retinal image, (2) the spatial position of visual objects, (3) temporal changes in luminance contours, (4) the movement of visual objects, and ( 5 ) the binocular depth due to binocular disparity. This list is not complete with respect to either the exactness or the exhaustiveness of its categories. For example, nothing has been mentioned here regarding infant color vision. Color vision is one of the most advanced branches in the study of infant visual perception mainly because of Marc Bornstein’s studies, which have thrown considerable light on the underlying mechanisms for newborn color vision (Bornstein, 1976; Bornstein, Kessen, & Weiskopf, 1976a, 1976b). A recent review by him gives the most thorough and thoughtful account of the research in this somewhat more independent area of infant vision research (Bornstein, 1978). Adding these data on color vision to those reviewed in the present paper, we can conclude that the infant possesses very advanced structures for visual routines even at the moment of birth. However, since we have very poor knowledge about the exact properties of these routines, it seems preferable to assume that they are relatively immature. This immaturity, indeed, may be only quantitative rather than qualitative-the manner in which the newborn infant views his world is similar to that of the adult, although less differentiated. The infant’s subjective image of the external world is evidently more robust than that of the adult. The presence of certain routines at the very early stages of development leads us to hypothesize that the principal structure of the visual machinery is planned by genetic instructions and that visual experience plays a lesser role in the building of the general architecture of the perceptual system than was thought in the past. However, the exact degree to which the visual system, with its different functions, is modifiable by experience in the course of its ontogenesis remains to be settled (Mitchell, 1978). B. COURSE OF DEVELOPMENT
Experiments on the environmental modifiability of the visual system convincingly demonstrate that developing vision shows adaptive abilities to match the properties of the environment. The problem here is how to determine the degree of adaptive plasticity. It seems that deficiencies arising from some special kind of
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environmental input to the visual system may be caused by a process of degradation from the normal course of development, rather than by construction of special cortical mechanisms to adapt to the abnormal input. This hypothesis seems to gain support from the studies on binocular competition presented earlier. However, as far as the development of human infant vision is concerned, it is only a speculation. Experimental studies to date are not sophisticated enough to allow the people who like to “talk” about infants’ development (rather than study it) to put forward stronger propositions based on relevant data. It must be stressed that, despite intense interest and some considerable breakthroughs in infant vision during recent years, very little is known about the development of specific visual routines in human infants. Nevertheless, because it can be argued that there are similarities in the courses of visual development among human infants, monkeys, and cats (Mitchell, 19781, the prospects for relevant research are by no means poor. In studies of the environmental modifiability of the visual systems of young organisms, a methodological problem emerges, which may become a source of confusion in both research data and interpretations:Visual deprivation may cause impairment not only in the visual routines the investigator is most interested in unveiling, but also in the behavioral ways the organism makes use of the impaired visual input. This is especially the case in human studies; because of some environmental agent, understanding or interpretation of the visual representation may be impaired together with or instead of the routines of visual information processing. Although it is even more difficult to solve this problem in the case of infants, because of the difficulties of extracting visual routines from general behaviors in experiments, we feel that this kind of methodological difficulty needs to be considered. In general, we may conclude that although the general structure for vision is formed on the basis of genetic instructions, visual experience is necessary for elaboration of the system. Within certain limits, visual routines may adapt to the properties of the visual environment. The degree of this modifiability, however, varies with different visual routines. For example, binocular depth perception is more influenced by abnormal environmental stimulation than are other routines. It is natural to hypothesize that the criticalhensitive periods, if they exist, are also differently distributed for different visual routines along the age continuum. It can be hypothesized that all the “hardware” of the visual routines (e.g., specific pathways in the nervous system, age schedules for sensitive periods of different functions, the extent of modifiability by environmental stimulation) is preprogrammed by genetic factors, while the “software” of the organism’s functioning in real environments depends upon the nurturant factors-how effectively these factors can program the organism to behave in one way or another. In any case, it must be stressed that the general range of modifiability may itself be genetically programmed.
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BINOCULAR VISION IN INFANTS: A REVIEW AND A THEORETICAL FRAMEWORK'
Richard N . Aslin and Susan T . Dumais? INDIANA UNIVERSITY
I . INTRODUCTION ......................................................
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11. LEVELS OF BINOCULAR FUNCTION ................................... A . BIFOVEAL FIXATION ............................................. B. RTSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c. STEREOPSIS ..................................................... D . SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
54 55 55
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I11. DEVELOPMENTAL CONSTRAINTS ON BINOCULAR VISION . . . . . . . . . . . . . A. ACUITY AND CONTRAST SENSITIVITY ............................ B. ACCOMMODATION ............................................... C . FACIAL DIMENSIONS ............................................. D . SUMMARY .......................................................
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IV . EMPIRICAL FINDINGS ON INFANT BINOCULAR VISION . . . . . . . . . . . . . . . . . A . MULTIPLE-CUE DEPTH DISCRIMINATION STUDIES . . . . . . . . . . . . . . . . . B . BIFOVEAL FIXATION STUDIES .................................... C. FUSION STUDIES ................................................. D . STEREOPSIS STUDIES ............................................
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V . EARLY EXPERIENCE AND BINOCULAR FUNCTION ..................... A. THE ROLES OF EARLY EXPERIENCE ............................... B. BINOCULAR NEURAL MECHANISMS IN THE CAT .................. C . SENSITIVE PERIOD FOR HUMAN BINOCULAR FUNCHON ........... D . A MODEL OF HUMAN BINOCULAR DEVELOPMENT . . . . . . . . . . . . . . . .
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VI . CONCLUDING REMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REFERENCES
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'Preparation of this article was partially supported by grants from NSF (BNS-77-04580) and NICHD (HD-00309) to RNA . We gratefully acknowledge the helpful comments and criticisms provided by Martin Banks. Robert Fox. Conrad Mueller. Clark Presson. Sandra Shea. Linda Smith. and Davida Teller. *Present address: Bell Laboratories. Murmy Hill. New Jersey 07974.
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ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR VOL . 15
Cqyight 01980 by Academic F'ress. Inc. All rights of reproduction in m y form rcsrved.
ISBN 012-009715-X
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Richard N. Aslin and Susan T.Dumais
I. Introduction The study of how adults perceive the three-dimensional nature of the visual world has captured the interest of philosophers and psychologists for centuries (Boring, 1942; Pastore, 1971). Investigators studying the classic subject of adult spatial perception understand quite clearly that several types of visual information can specify the perception of object distance and depth, and that only a small proportion of that information is uniquely binocular (see Hochberg, 1971, and Kaufman, 1974, for general reviews). Surprisingly little study, however, has been made of the development of spatial perception, and even fewer attempts have been made to study binocular depth perception in young infants. Recently, several methodological and technical advances have enabled researchers to investigate systematically the visual capabilities of young infants, including binocular function. Despite these recent advances, empirical findings on the development of human binocular vision have been rare, and, as a result, theories concerning binocular development have been virtually nonexistent. The purpose of the present article is to provide a framework within which the empirical findings on binocular development can be organized. Moreover, we shall attempt to describe a rudimentary model to account for these data with the goal of suggesting directions for future empirical investigations.
11. Levels of Binocular Function In the past decade several researchers have attempted to study binocular depth perception in very young infants. In general, these studies have yielded inconclusive empirical findings. Moreover, the interpretation of these findings has often been made without a consistent guiding theoretical orientation. Much of the confusion and resulting controversy surrounding these studies of infant binocular vision centers on two factors: (1) the difficulty of operationalizing binocular abilities in nonverbal subjects, and (2) a basic misunderstanding of the different levels of binocular function. This misunderstanding has led several developmentalists to make inappropriate assumptions and inferences about infants’ binocular vision. A conceptual framework for the major levels of binocular function will now be discussed with the aim of clarifying the goals and conclusions that can be drawn on the basis of past and future empirical research. The levels of binocular function that appear to offer a simple yet complete categorization of binocularity were set forth by Worth (1915) in his clinical text on strabismus. Worth classified binocular function into three hierarchically related levels: (1) bifoveal fixation, (2) fusion, and (3) stereopsis. For example, Worth believed that in normal adults the presence of bifoveal fixation is a necessary prerequisite for fusion and stereopsis. However, Worth was well aware
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of the fact that bifoveal fixation is not a suficient condition for functional fusion or stereopsis abilities. Moreover, Worth's proposal that these three levels are hierarchically organized is strictly true only for normal adults. As we shall see later, this necessary but not sufficient hierarchy may be violated in the develop ing visual system. Nevertheless, tests of these three levels of binocular function are useful in characterizing both the developmental and the pathological state of the binocular visual system. We shall now consider each of these three levels of binocular function in some detail in an effort to describe the mechanisms underlying their development. A. BIFOVEAL FIXATION
The retinal locus of highest spatial resolving power (best acuity) is the fovea, a region of approximately 1-2", which in adults is coincident with the line of sight. Normal adults who fail to align the two foveas so that they are simultaneously directed toward a single object of regard typically perceive double images. Moreover, inaccurate bifoveal fixation results in a degradation in stereopsis (see Ogle, 1962, for a general review). Thus, it is of some importance to determine whether infants typically exhibit bifoveal fixation when presented with a visual target. Clearly, if one documented the presence of bifoveal fixation in infants, then only one of the criteria necessary for adult-like binocular vision would have been satisfied. If, however, one documented the absence of bifoveal fixation in infants, then, according to a hierarchical model of binocular function, fusion and stereopsis could not occur. Alternatively, it is possible that in the infant visual system, precise bifoveal fixation is not required for fusion and stereopsis. As we shall see, even this lowest level of binocular function, bifoveal fixation, has not as yet been satisfactorily described. B. FUSION
The second level of binocular function is fusion, or the combining of two retinal images into a single phenomenal percept. When viewing a single small object in space (see Fig. I ) , each eye receives stimulation on a particular retinal locus. If one considers only a single eye, the object of regard lies along a particular direction line (F,F in Fig. 1 for the left eye). If the object is moved to any other point along that direction line (i-e., at a different distance from the eye), the object's perceived direction remains invariant with respect to the single viewing eye. Since the two eyes are separated by approximately 6 cm, the direction line for an object is quite different for the opposite eye (F,F in Fig. 1 for the right eye). Under binocular viewing conditions, the conflict between the two direction lines is eliminated in the visual system of adults by a compromise directional judgment (e.g., CF in Fig. 1). This compromise judgment of the two
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Richard N . Aslin and Susan T . Dwnais F
Fig. I . Illustration of the two direction lines, FLF and FRF , for the two eyes, and an example of the combination of direction lines, CF,occurring during jksion.
retinal direction lines is accompanied by the subjective experience of a single object located at a particular position in three-dimensional space (Sheedy & Fry, 1979). Thus, the stimulation of two retinal loci can resuIt in a single or fused percept of an object in space, a percept which is in fact veridical. One potential explanation of the fusion mechanism is to propose the existence of retinal loci in the two eyes that are paired at some level of the visual system (Hering, 1868A977). In other words, stimulation of either or both members of the pair results in the registration of a single rather than a dual direction line. The theory that particular loci on the two retinal surfaces are paired is called the theory of corresponding retinal points. Perhaps the strongest evidence for the existence of corresponding retinal points is the phenomenon of peripheral fusion and the specification of the horopter (see Shipley & Rawlings, 1970, for an historical review). Fusion is not limited to those objects viewed by the two foveas. If an observer maintains bifoveal fixation on a target, fusion can occur also for objects presented in the peripheral visual field. However, peripheral fusion is limited to objects located at a particular distance from an observer. These locations constitute a surface called the horoptel3 that passes through the point of bifoveal fixation (see Fig. 2). Any object located in front of or behind the horopter does T h e concept of a horopter is considerably more complex than what we have described. There are at least three types of psychophysicalcriteria for empirically determining the location of the horopter (1) judging equivalent visual directions (nonius), (2) judging equivalent visual distances (apparent frontoparallel plane), and (3) judging the midpoint of the region of fusion. Although each of these three criteria results in a slightly different form of the horopter, all three assume a common underlying mechanism based on the theory of corresponding retinal points. Since the fusion criterion is the one most directly relevant to our presentation, we chose to bypass a more detailed discussion of the other two criteria for determining the horopkr.
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not stimulate corresponding retinal points and is therefore not fused. Stimulation of noncorresponding retinal points results in the perception of double images (diplopia). Although the foregoing description implies that the horopter is a very thin surface, there is in fact quite a large region surrounding the hypothetical horopter within which diplopia is not present. Figure 2 shows this region of single vision surrounding the horopter, a region called Panum’s fusion area. The functional significance of Panum’s fusion area becomes clear when one considers that the limit of spatial resolution (vernier acuity) is approximately 2-10 seconds of arc (Riggs, 1965) while the microsaccade and drift eye movements present in experienced adult observers who are fixating a very small target are typically in the 10-30 minutes of arc range (Nachmias, 1959). Thus, if the horopter itself defined the locus of fusion, then fusion would be very intermittent and of extremely short duration, given the comparatively large eye movements present during “steady” fixation. The extent of Panum’s fusion area (10-15 minutes of arc in central vision) maintains the phenomenal identity of objects in space despite the continual fluctuations in the position of the two retinas during binocular fmation. In addition, as shown in Fig. 2, the extent of Panum’s fusion area increases with increasing retinal eccentricity (more peripheral to the foveas). Although this broadening is at least partially the result of the decline in acuity with increasing eccentricity, it is also partially the result of a peripheral deficit in disparity resolution. However, regardless of its underlying mechanisms, the fact remains that fusion prevents the confusion (and diplopia) that would result if dual direction lines were not combined at some level of the visual system.
Fig. 2 . Representation of the horopter, the locus of corresponding retinal points, and Panum’s fusion area (the region of single vision surrounding the horopter). The subject isfmting point F with both foveas. Point P projects onto noncorresponding retinal points, creating retinal disparity. Retinal disparity, the angular measure of noncorrespondence. equals 6 , minus 8,.
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c.
STEREOPSIS
The final level of binocular function is stereopsis-the ability to a p p i a t e depth (or relative object distance) based on retinal disparity. Retinal disparity refers to the magnitude of mismatch between corresponding retinal points stimulated by an object located off the horopter. The discovery that slight differences in the input to the two eyes could result in the perception of depth was made by Wheatstone (1838). A very simple case of stereoscopic depth is shown in Fig. 3. Both eyes view an identical surrounding figure (the rectangle) to maintain a constant fixation distance and, in addition, each eye separately views a vertical bar. In this dichoptic viewing situation the angular distance separating the two vertical bars is a measure of retinal disparity. If the dichoptic targets stimulate the two temporal retinas, the retinal disparity is referred to as crossed and the target is perceived in front of the horopter. If the dichoptic targets stimulate the two nasal retinas, then the disparity is uncrossed and the target is perceived behind the horopter. The presence of retinal disparity for an object within Panum’s fusion area will result in a depth percept accompanied by fusion, a situation referred to as patent stereopsis. If the amount of retinal disparity exceeds the extent of Panum’s fusion area, however, a depth judgment can still be made, but diplopia is present and patent stereopsis is absent (Blakemore, 1970). These
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Fig. 3. Stimulus arrangement which presents slighily different information to the two eyes (dichopric viewing) and results in the perception of relative depth.
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I
Region of Diplopia
Region of Potent Stereopsis
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Region of Diplopio
Fig. 4 . Representation of an observerjkating a point in space and the resulting specifEation of the horopter, Panwn’sfusion area, the region of patent stereopsis. and the region of diplopia.
relationships between fusion, patent stereopsis, and gross (or diplopic) stereopsis are depicted in Fig. 4.4 Displays such as the one depicted in Fig. 3 are used to test for local stereopsis, i.e., stereopsis created by extended contours. Despite the simplicity and reliability of these stereoscopic displays, they suffer from one major drawback. An observer viewing such a display can detect the presence of retinal disparity by rapidly alternating fixation between the two eyes. When this alternation is performed, the observer will notice a shift in the location of the vertical bar relative to the fixed rectangular surround. Since this shift does not require simultaneous binocular fxation, it provides an obvious monocular cue to depth. Fortunately, most observers (unless trained) cannot correctly differentiate between crossed and uncrossed disparity using this monocular cue. However, in many *A simplification in the relationship between h u m ’ s fusion area and the region of patent stereop sis has been made in Fig. 4. Although under most conditions these two regions are coincident, one CM extend the region of patent stereopsisslightly beyond Panum’sfusion area if the amount of retinal dispnrity in the stereoscopic display is gradually increased (see Ogle, 1962). The mechanism that allows the normal adult visual system to fuse stereoscopic displays that contain relatively large amounts of retinal disparity is unknown and, fortunately, not germane to the basic relationships depicted in Fig. 4.
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psychophysical tasks designed to measure an observer’s disparity detection threshold (stereoacuity), the observer is required to indicate only whether the target is in the plane of the surrounding figure. Similarly, in clinical assessments of stereoacuity, the patient is typically required to pick from an array of targets the “one that looks different.” Obviously, displays that utilize a lateral displacement of the dichoptic target are subject to the criticism that monocular information mediated the observer’s “depth” judgments. A more complex stereoscopic display that does not contain monocular cues to depth is the random-element stereogram (Julesz, 1971). As shown in Fig. 5 , a random-element stereogram consists of an array of several hundred small, square-shaped elements that are viewed dichoptically so that each eye receives a separate random-element array. Both random-element arrays are identical except for a small region of one array that is offset with respect to the other array, thereby creating retinal disparity. This display differs from other stereograms in that no single element of the display creates or is sufficient to create retinal disparity. Rather, retinal disparity is defined by the region of elements that is displaced, and the resultant perception of stereoscopic depth is based on global disparity processing. Although the random-element stereogram provides an unambiguous measure of the presence of stereopsis, it has had limited application in the assessment of stereoacuity. For normal adults tested with displays containing contours (e.g., Fig. 3), stereoacuity values are typically in the range of 2-10 seconds of arc, a value comparable to that of vernier acuity (Berry, 1948). Stereoacuity values for random-element stereograms have not as yet been obtained because small random-element offsets are difficult to produce. Although several researchers have suggested that global stereoacuity is much poorer than local stereoacuity, this suggestion awaits a systematic empirical test. D. SUMMARY
The three levels of binocular function proposed by Worth provide a useful categorization scheme for assessing the development of binocular depth perception. The most important levels of binocular function, at least in terms of perceptual experience of the visual world, are fusion and stereopsis. Clearly, the absence of either level would result in a visual world for the infant quite different from that of the normal adult. Unfortunately, the study of fusion and stereopsis has been fraught with extremely difficult methodological problems. As a result, the level of bifoveal fixation has been addressed most often in empirical studies of binocular function in infants. It should be emphasized again, however, that the presence of bifoveal fixation in infants does not guarantee that fusion and stereopsis are present. Finally, it must be pointed out that the absence of bifoveal fixation in infants does not necessarily eliminate the possibility of fusion or stereopsis. For exam-
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Fig. 5. Schematic of the techniquefor generating stereopsis in a random-element display. The top panel illustrates rhe appearance of the display when viewed monocularly. The middle panels depict the horizontal displacement of a region in the two dichoptic displays which creates retinal dispariry. The bottom punel represents the appearance of the stereoscopic display to a normal adult observer. Note that the middle and bottom panels do not show all the random elements contained in the actual display, since these background elements would prevent a clear illustration of retinal disparity and depth.
ple, if Panum’s fusion area were very large during infancy, the accuracy of bifoveal fixation would be less critical than it is for normal adults. Similarly, stereopsis can occur under certain circumstances without the presence of fusion. Therefore, each level of binocular function must be investigated separately, yet in the context of the three interrelated levels, in order to understand the mechanisms underlying binocular depth perception during infancy. Although it is
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possible that the three levels of binocular function are hierarchically related and unfold developmentally in an invariant sequence, the possibility also exists that the three functions develop in parallel within a system of mutual constraints rather than a simple causal hierarchy.
111. Developmental Constraints on Binocular Vision A consideration of the mechanisms underlying the development of binocular function should not be attempted without considering the concurrent develop ment of other visual mechanisms that may influence the quality of binocular function. Few of these constraints have been systematically investigated in relation to binocular development, but they cannot be overlooked in explaining the status of a particular binocular function. The major constraints on binocular function are (1) acuity and contrast sensitivity, (2) accommodation, and (3) facial dimensions. Each of these will now be discussed with the goal of preventing unwarranted or premature theories of binocular development-theories that ignore the interrelationships among the complex subsystems involved in normal adult binocular vision. A.
ACUITY AND CONTRAST SENSITIVITY
The most obvious constraint placed upon the processing of binocular information is the availability of two monocular images of sufficient quality (size and contrast) to allow binocular information to be extracted. If the visual targets were too small (below acuity threshold) or of insufficient contrast (below contrast sensitivity threshold), then any observed binocular deficit would not necessarily imply the absence of some binocular function. Most researchers have been aware of the acuity constraint, but few have considered the possibility of degradations in image quality resulting from low target contrast (ratio of target luminance to background luminance). In normal adults, low target contrast results in poorer spatial resolution, which in turn (1) reduces the information available for accurate bifoveal fixation, (2) diminishes the stimulus for disparity, and (3) increases the area within which fusion is operative. Recent studies of acuity and contrast sensitivity in infants (Atkinson, Braddick, & Moar, 1977; Banks & Salapatek, 1978; Marg, Freeman, Peltzman, & Goldstein, 1976; see Dobson & Teller, 1978, for a general review) indicate that at maximal contrast (9096or greater), acuity thresholds improve from approximately 25 to 5 minutes of arc (20/500 to 20/100) during the first 6 months of life. Moreover, maximum contrast sensitivity shows a twofold increase between 1 and 3 months of age. Consequently, close attention must be directed to the monocular image quality of targets used in testing binocular vision in infants to ensure that acuity and contrast sensitivity thresholds are exceeded. A second issue related to monocular image quality is the balance of acuity in
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the two eyes. For at least two reasons, there may be differences in the quality of information processed from the two retinas. First, differential refractive error (anisometropia) leads to differences in image sharpness. This differential error can be eliminated by placement of appropriate lenses before one or both eyes. Unfortunately, this is not typically done in studies of infant binocular vision. Second, differential acuity of a nonoptical origin (amblyopia) can also produce a binocular imbalance. Amblyopia is a common result of periods of constant eye misalignment or anisometropia (Duke-Elder & Wybar, 1973). Amblyopia by definition cannot be overcome by a simple optical correction and is also not typically assessed in studies of infant binocular vision (see Thomas, Mohindra, & Held, 1979, for a recent exception). The presence of differential acuity reduces stereoacuity in adults (Matsubayashi, 1938) and therefore is of serious concern for the accurate assessment of infant binocular function. Although norms on the incidence of anisometropia or amblyopia have not yet been obtained for young infants, the rapid development of the visual system in the early postnatal months suggests that such anomalies are likely to occur. Both anomalies could mask the presence of good binocular function in young infants. A final issue relevant to monocular image quality is the anatomical development of the fovea during the early postnatal period. Mann (1964) has shown that the configuration of retinal layers characteristic of the adult fovea is not typically present until 4 months postnatally. Recent evidence from infant monkeys (Hendrickson & Kupfer, 1976) also documents a significant development in foveal anatomy during the early postnatal period. The implication of these anatomical findings is that any functional advantage gained by retinal receptors in the foveal area as a result of diminished image interference from other retinal cell layers may be absent in very young infants. Whether these anatomical developments per se improve acuity is not known at the present time. However, it seems likely that the developing anatomy of the retinal cell layers acts to constrain the quality of the retinal image and in turn may degrade the control of bifoveal fixation. B. ACCOMMODATION
1 . Accommodation and Acuity The second major constraint placed upon the integrity of binocular function is ocular accommodation, or the ability of the lens in each eye to change curvature so as to optimize the focus of the retinal image. In adults, failure to accommodate appropriately to targets presented at various distances results in a loss of acuity and contrast sensitivity (Green & Campbell, 1965). Hence, it is possible that while the potential for good acuity is present in the infant visual system, a motor control deficiency (inability to accommodate) prevents the retina from receiving an optimal retinal image. Inaccurate accommodation, because it degrades acuity, may result in the same types of degradation in binocular function discussed in Section II1,A.
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Until recently the only systematic study of accommodation in young infants was that of Haynes, White, and Held (1965). They employed dynamic retinoscopy to measure the infant’s far point (plane of fixation) as a target was presented at various distances. Their results indicated that infants do not begin to accommodate differentially to variations in target distance until 2 months of age and that adult-like accommodation, in which target focus is nearly optimized for all target distances, does not occur until approximately 4 months of age. A potential confounding factor in the study of Haynes et al. (1965) concerns the target stimulus used to elicit changes in accommodation. In the study of Haynes et al. (1965) a 3-in.-diameter bulls-eye pattern was attached to the retinoscope for use in attracting the infant’s fixation. Although this target may have been sufficient in size and contrast to engage the accommodative system at near distances, the target’s overall retinal size decreased as the target was moved away from the infant and the concentric target rings may have dropped below the younger infant’s acuity threshold. Therefore, the finding that young infants show little change in accommodation and a relatively fixed focal plane at a near distance may have been an artifact of the small size of the stimulus. Banks (1980) replicated and extended the study of Haynes et al. (1965) using a large (30”) checkerboard pattern that was altered to maintain a constant retinal size at all target viewing distances. He found that 1-month-olds show evidence of partial accommodation and 2-month-olds show a nearly adult-like accommodation response. Braddick, Atkinson, French, and Howland (1979), using a different measurement procedure, have reported quite similar results. Consequently, although the general conclusion reached by Haynes et al. (1965) was correct, they somewhat overestimated the age at which the accommodation system becomes operative. These studies of infant accommodation demonstrate that until at least 2 months of age, infants do not consistently receive a clear retinal image of targets presented at various distances. For normal adults, this failure of accommodation would create a retinal image that was nearly always out of focus (except at the fixed focal plane of 15-25 cm), and a resultant degradation in acuity and contrast sensitivity. Although this pattern of results is applicable to the normal adult visual system, it does not appear to hold for the visual system of young infants. Green and Campbell (1965) have shown that in adults the proportional loss in spatial sensitivity resulting from defocus is not equivalent at different spatial freq~encies.~ In other words, if the visual system is capable of resolving very small elements (as in adults), then slight errors in image focus lead to significant losses in spatial resolution. But if the visual system is capable of resolving only %patial frequency refers to the number of repetitive light-dark stripes per unit of visual angle. For example, a pattern containing 30 black and 30 white bars in an area one visual degree wide has a spatial frequency of 30 cycleddegree. The highest spatial frequency stimulus which can be reliably detected by an observer is an estimate of acuity.
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larger elements (as in infants), then image focus is less critical and results in little or no loss in spatial resolution. Salapatek, Bechtold, and Bushnell (1976), who assumed that little or no accommodation occurs in 1- and 2-month-old infants, showed that infants in this age range do not exhibit different acuity thresholds at different target viewing distances. This finding is consistent with the argument of Banks ( 1 980) that image focus is relatively unimportant to the spatial resolution of targets by infants under 2 months of age. The general conclusion to be reached from these studies is that measures of binocular function should employ targets that are well above the acuity and contrast sensitivity thresholds of infants, and that further losses of acuity and contrast sensitivity may occur in infants older than 2 months if the accommodative constraints on these abilities are not taken into account.
2. Accommodation and Convergence Another accommodative constraint on binocular function is the interaction between the accommodation and convergence systems. In normal adults, a synergistic link exists between changes in accommodation and changes in convergence (Muller, 1826/1943). As a target approaches a subject, the lens in each eye alters shape to maintain optimal image focus, and the angle formed by the two lines of sight (convergence angle) increases to maintain bifoveal fixation (see Morgan, 1968, for a general review). This link between accommodation and convergence is most impressively demonstrated under monocular viewing conditions. If a target approaches while one eye is occluded, then the binocular information for convergence (the extrafoveal location of the target’s image in the occluded eye) is absent. Yet adults consistently converge the occluded eye under these monocular viewing conditions, indicating that the accommodative change in the unoccluded eye is sufficient to activate an appropriate change in convergence. Anomalies in the accommodation-convergence relationship can lead to difficulties in maintaining bifoveal fixation under binocular viewing conditions (Duke-Elder & Wybar, 1973). If a young child is grossly hyperopic (farsighted), then the accommodation system is engaged even when the target is located at far distances. As the target approaches, the accommodation system saturates before the target reaches a near distance. Further approach by the target requires a further change in convergence to maintain bifoveal fixation, even though the target’s image begins to blur because accommodation is at a maximum. For some children, however, the strong link between accommodation and convergence induces a further change in convergence as more accommodative effort is exerted in an attempt to focus on the near target. As a result of this overacting accommodative-convergence, there is a breakdown of bifoveal fixation and a loss of fusion. Although the foregoing situation (accommodativeesotropia) is not common, there will be an imbalance between the accommodation-convergence link whenever an optical (refractive) error remains uncorrected. Since infants are
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rarely corrected for refractive errors prior to binocular testing, the accommodation-convergenceimbalance may create some difficulty in maintaining consistent bifoveal fixation and therefore bias the assessment of binocular function toward obtaining negative findings. One final issue relevant to the accommodation-convergence relationship is whether the synergistic link is present at birth, is acquired maturationally according to a genetic program, or is acquired as the result of early visual experience. To date, the only study that has provided data on the development of the accommodation-convergence link is the report by Adin and Jackson (1979). They demonstrated that accommodative-convergence, as measured under monocular viewing conditions, is present in infants as young as 2 months of age. However, the quantitative aspects of the accommodation-convergence link, in the absence of a dynamic recording technique, could not be determined. Obviously, the link must not be totally determined by early experience; if it were, any relationship between the two systems would be adapted to and conflicts would not occur. On the other hand, however, the link may not be totally determined by genetic factors since only gross refractive errors appear to lead to easily observable difficulties in converging appropriately. Clearly, the development of the accommodation-convergence relationship demands careful study in the near future. C. FACIAL DIMENSIONS
The last constraint to be considered is the configuration of the two orbits and related musculature. Although facial dimensions have not been discussed in the past as a possible reason for failures of binocular vision, two facial dimensionsare quite relevant to bifoveal fixation and stereopsis: orbital position and interocular separation. The position of the two orbits changes drastically during prenatal and early postnatal development. Zimmerman, Armstrong, and Scammon (1929) have shown that the orbits shift from a lateral to a frontal skull position during embryonic development. This shift is greatest during the prenatal period, but a significant postnatal shift also occurs (see Fig. 6). Therefore, a greater amount of rotation from a central orbital position is required for bifoveal fixation to occur in infants than in adults, and this additional requirement may prevent (or constrain) the convergence system from maintaining accurate bifoveal fixation to targets at all viewing distances during the early postnatal months. Zimmerman et al. (1929) also documented the large increase in interocular separation that occurs during fetal development. More recently, Krieg (1978) extended those findings by taking analogous measurements in infants between birth and 4 months of age. These two studies, plus additional normative data from adults, provide consistent evidence for a rapid increase in interocular sep-
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ot vorious periods d dewelopmml
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and early postnatal periods. Adaptedfrom Zimmerman, Armstrong, & Scammon. The Anatomical Record, 1929, 59, 119.
aration during prenatal development followed by an additional 50% increase between birth and adulthood. The importance of interocular separation for binocular function centers on the magnitude of retinal disparity. As shown in Fig. 7,the retinal disparity present in a display is inversely related to target distance and directly related to interocular separation. The 50% increase in interocular separation during postnatal development accounts for a 50% increase in disparity for an identical stereoscopic display, which means that a stereoscopic display containing retinal disparity that is just detectable by adults may be below an infant’s disparity detection threshold. Therefore, consideration of differences in interocular separation is crucial for the accurate assessment of infant stereopsis. D. SUMMARY
To conclude this section on developmental constraints, it should be clear that the size, contrast, viewing distance, and disparity of stimuli used to assess
binocular function must be taken into account when comparing the infant and adult visual systems. In addition, failures to demonstrate any given level of binocular function must be evaluated in light of other constraints, particularly those involving motor systems, to avoid possible underestimation of an infant’s
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6 cm
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Fig. 7. Illustration of the differences between a newborn (dashed) and an adult (solid)frxating point F with the foveas. Point P is an object that projects onto noncorresponding retinal points, thus creating retinal disparity. A measure of retinal disparity is the change in convergence angle needed to bring the two foveas onto point P.Retinal disparity in this figure equals a? minus atfor the adult and p1 minus PI for the newborn. The general formula for calculating retinal disparity is: 2 [arctan (IOSl2)lD minus arctan (IOSI2)lD D '1, where IOS = interocular separation.
+
binocular capability. In the literature review to follow, we shall see that conclusions reached in the past have rarely considered the constraints discussed in Section III.
IV. Empirical Findings on Infant Binocular Vision The study of depth perception in infants has involved four general lines of research. Three of these lines of research are closely related to the three levels of binocular function discussed in Section II. While the fourth line of research is not directly related to the specifically binocular aspects of depth perception, it represents the most extensive set of empirical findings on depth perception, and therefore deserves some attention in the following review. Our coverage of the literature on infant binocular function will begin with a very brief discussion of this fourth line of research, which we have called multiple-cue studies6 of infant Wur use. of the term multiple-cue refers to the fact that in many studies both mnwular cues to depth (shading, perspective, texture gradient, motion parallax, etc.) and binocular cues to depth (convergence, diplopia, disparity, etc.) are potentially available in the stimuli used to assess infant depth perception. Thus, it is often unclear which particular cue served either as the essential or sufficient condition for depth discrimination.
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depth perception. We shall then focus on the three less frequently studied levels of binocular function during infancy. A. MULTIPLE-CUE DEPTH DISCRIMINATION STUDIES
The first studies of depth perception in infants utilized stimulus displays that contained many types of depth cues. For example, the early studies of differential reaching to objects presented at different distances (Cruikshank, 1941) and the early visual cliff studies (Walk & Gibson, 1961) did not present infants with purely binocular depth information. Monocular cues such as linear perspective, texture gradients, and motion parallax were confounded with binocular disparity information. In all fairness, however, these early studies were not designed to assess only binocular depth perception in infants, since at the time any evidence for early depth perception was considered quite remarkable. Partly as a result of the difficulty encountered by these pioneering researchers, more recent studies of depth perception in infants have also failed to separate monocular and binocular cues to depth. These studies have employed a variety of stimulus displays and dependent measures, including locomotor, manual, and affective indications of visual cliff avoidance (Scarr & Salapatek, 1970; Walters & Walk, 1974; Campos, Langer, & Krowitz, 1970); postural and affective indicators of avoidance to impending collision (Ball & Tmnick, 1971; Bower, Broughton, & Moore, 1971; Yonas, Bechtold, Frankel, Gordon, McRoberts, Norcia, & Sternfels, 1977); discriminative conditioning and habituation measures of size and shape constancy (Bower, 1964, 1965, 1966a, 1966b; Caron, Caron, & Carlson, 1978); and visual fixation and reaching preferences for three-dimensional compared to two-dimensional objects (Fantz, 1961, 1966; Bower, 1972; Dodwell, Muir, & DiFranco, 1976). With regard to the binocular aspects of depth perception, however, no consistent conclusions from these studies can be drawn. All of the results described in the studies listed can be accounted for by the infant’s processing of monocular cues to depth and/or other methodological artifacts. Furthermore, even the clear and consistent demonstration of a difference between the infant’s behavior under monocular versus binocular viewing conditions would not indicate which particular binocular cue was responsible for this differential performance. Information about the relative depth of objects can be specified by one or more of the following binocular cues: convergence angle, diplopia (double images), and retinal disparity. In line with our classification of binocular vision into three levels of binocular function, it is perhaps more instructive to examine in detail the development of each of these potential binocular functions than to discuss further the more global, multiplecue approach used most frequently in the past.
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Our earlier discussion pointed out that in normal adults bifoveal fixation is a necessary but not sufficient condition for good binocular vision. Several investigators, operating under the assumption that bifoveal fixation is also important for infants' binocular vision, have attempted to measure the accuracy of binocular eye alignment in young infants. These studies of binocular eye alignment have employed corneal photography (see Haith, 1969, or Maurer, 1975b, for general reviews). The corneal photographic technique estimates the direction of gaze by a detailed measurement of the relationship between the pupil center and reflections on the cornea of fixed (and invisible to the infant) reference lights. Several studies (Wickelgren, 1967, 1969;Maurer, 1975a)have recorded the position of the two pupil centers in newborns and older infants who were presented with single visual targets. Both investigators reported that the pupil centers of young infants are generally divergent and typically straddle the location of the visual target. In add,ition,Maurer (1975a) reported that the degree of divergence of the pupil centers decreases during the first 2 to 3 months of life. Initially, these findings were taken as evidence that young infants do not have bifoveal fixation until some time after birth. There are, however, several problems with the corneal photographic technique that have cast serious doubt upon the conclusion of these original studies. Slater and Findlay (1972) pointed out that a line extending outward from the center of the pupil (optic axis) is not coincident with the line of sight, refmed to as the visual axis (line from target to fovea). They documented this optic axis-visual axis discrepancy (or angle alpha) in both adults and newborns and concluded that the angle alpha is greater in newborns than in adults (8-10" vs 4-5"). Therefore, the finding of divergence in newborns may be the simple result of an estimation error attributed to the corneal photographic technique. The corneal photographic technique is further complicated by the fact that there are wide individual differences in the angle alpha and potential differences between the two eyes within an individual. Therefore, the combination of a constant measurement error and a variable angle alpha error makes any statement about bifoveal fmation using targets presented at a single viewing distance quite ambiguous. For example, Slater and Findley (1975a) reported that after an average correction factor for the angle alpha was applied, newborns fixated within 2 1.5 in. of a vertical row of lights during 90% of the time period sampled. However, at the 10 in. viewing distance used in their study, 1.5 in. converts to 8 3 , a value several orders of magnitude greater than the accuracy needed to conclude that bifoveal fixation is or is not present. In fact there is no objective technique currently available that can measure binocular fixation with sufficient accuracy to conclude that bifoveal fixation is present. While these problems rule out the accurate assessment of bifoveal fixation by
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attempting to specify the absolute location of the two visual axes, several measurement techniques (including corneal photography) have sufficient resolution to measure the relative position of the eyes when viewing a target at different distances from the observer. Following this rationale, Slater and Findlay (1975b) presented visual targets to newborns at three viewing distances (5,10, and 20 in.) and recorded relative changes in eye alignment using corneal photography. They found that all newborns tested changed the relative position of the eyes (pupil centers) when the 10 and 20 in. distances were compared but not when the 5 in. distance was compared to the other two distances. Although this study provides evidence that newborns change their lines of sight appropriately as a target is presented at different distances, it is not clear which area of the retina is used as the line of sight, nor is it clear why the nearest target distance was not fixated appropriately. Another approach to the study of changes in binocular eye alignment is actually to move the distance of the target and record changes in eye alignment (convergent and divergent eye movements). An initial study of vergence in infants was conducted by Ling (1942), who tested infants from birth to 6 months of age. She moved a 2-in.-diameter black disk through a distance of 3 to 36 in. from the infant at a rate of 2 inhecond. On the basis of film records (not corneal photography), she concluded that binocular fixation (i.e., appropriate vergence) does not appear until 7 to 8 weeks of age. In a more recent study, A s h (1977) used corneal photography to measure changes in binocular eye alignment in 1-, 2-, and 3-month-dds as a luminous crosshair target moved along the midline from 57 to 15 cm at either 12 or 22 cdsecond. Results indicated that even the 1-month-olds converged and diverged appropriately, but only the 2- and 3-month-olds converged and diverged an amount indicative of bifoveal fixation. In general, both the amount of vergence and the speed with which these movements are executed appear to increase dramatically in the f i t 3 months of life. However, it is important to exercise caution in interpreting the presence of appropriate convergent eye movements as evidence of bifoveal fixation. Infants may consistently use a particular extrafoveal retinal locus in each eye to define the line of sight. Several researchers (Bronson, 1974; Lewis, Maurer, & Kay, 1978) have seriously considered this alternative of a nonfoveal newborn, and unfortunately it cannot be ruled out at the present time. In summary, the data on bifoveal fixation indicate that rudimentary binocular fixation (i-e., a consistent line of sight in the two eyes) may be present at birth. With increasing age, the infant is better able to maintain consistent binocular fixation, particularly to rapidly moving stimuli, and to change convergence over a larger range of target distances. It seems clear, however, that much of the young infant’s early visual experience is composed of misaligned images. Whether the images are ever in exact register bifoveally is also unclear, since no
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measurement technique used to date can unequivocally demonstrate bifoveal fixation. Nevertheless, it seems reasonable to conclude that by 3 months of age, infants are fixating targets with some area of the retina very close to the fovea and that together the two foveal areas are in fairly close alignment. C. FUSION STUDIES
The study of fusion is perhaps the most problematic of the three levels of binocular function because it involves a perceptual experience that is difficult to operationalize in preverbal infants. One technique that has been useful to the study of fusion in adults involves wedge prisms (Jampolsky, 1964; von Noorden & Maunamee, 1967). When an adult views a target with both foveas, introduction of a prism in front of one eye shifts the image of the target in that eye and creates diplopia. In normal adults, an eye movement is initiated to realign the two images and reattain fusion. The typical adult response during this prism test consists of a biphasic eye rotation including a saccadic and a convergent component. Usually, only the saccadic component is measured during the prism test. In some adults, however, the affected eye is being suppressed, so that no disparity is created by the prism and no realigning eye movement is present. To date, the only study that has collected data concerning the development of fusion in infancy is that reported by A s h (1977). In that study, binocular eye alignment was altered by placing a wedge prism in front of one eye in 3-, 4%-, and 6-month-olds. Three different wedge prisms were used: 0, 2.5, and 5". The 0" condition was used as a control for the presence of an eye movement associated with placement of any object in front of the eye. Each prism was introduced while the infant fmated the experimenter's face. Three-month-olds showed the saccadic refixation response only once among 120 trials. Four-andone-half-month-olds showed the refixation response on 2% of the 2.5" trials and 13% of the 5" trials. Six-month-olds refixated on 45 and 72% of 2.5 and 5" trials, respectively. These results indicate a marked improvement in performance on the prism test between 444 and 6 months of age. There are several reasons for infants not consistently showing refiation responses to the prism test until nearly 6 months of age. First, the stimulus for eliciting a refixation response on the prism test, i.e., diplopia, may be absent if the size of Panum's fusion area is large in early infancy. Hence, if the size of Panum's fusion area decreased during development, then the amount of prism displacement required to create diplopia would decline as the infant became older. This explanation is plausible but it demands further investigation. Second, young infants who do not respond appropriatelyon the prism test may experience diplopia but may fail to program an eye movement to re-fuse the target images. Third, infants may in fact realign their eyes by means of slow convergent eye movements, but, since the experimenter was scoring only the more easily ob-
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servable saccadic refixation movements, the slow convergent movements may have been missed. Clearly, more detailed measurements are needed to ensure that undetected refixation eye movements did not occur in the younger infants. Finally, poor monocular acuity may limit the young infant’s ability to detect the misalignment of the contours in the fixation target, making refixation eye movements unnecessary for the elimination of diplopia. As monocular acuity improved in subsequent months, the tendency to refixate would increase correspondingly. Variations in the characteristics of the fixation target used during the prism test are clearly called for in future research since certain types of targets may create more salient diplopic stimuli than others. In summary, there are no conclusive data on the presence of fusion in infants. Although the prism test results could be interpreted as evidence in support of fusion, they may also be accounted for by explanations involving measurement error, oculomotor immaturity, or deficits in spatial resolution. The study of fusion in infants awaits the development of an objective technique for the unambiguous measurement of the perception of single and double images. D. STEREOPSIS STUDIES
Although studies of the development of bifoveal fixation and fusion are of great interest, the classic question in binocular visual development is whether infants are capable of stereoscopic depth perception (and, if so, what mechanisms control its development). However, stereopsis, like fusion, has been difficult to study. In fact, only in the last 5 years has the presence of stereopsis been conclusively demonstrated in 2- to 4-year-olds (Reinecke & Simons, 1974; Romano, Romano, & Puklin, 1975; Walraven, 1975). Stereopsis, as defined previously, refers to the appreciation of the relative distance of objects based solely on retinal disparity. Since the percept of depth is a subjective experience and does not unequivocally result from the preseiice of an object in depth, it has been difficult to find an appropriate dependent measure of stereopsis in infants. For example, even though infants may be able to detect disparity (or other binocular cues), the perception of an object in depth may be absent. Nevertheless, the demonstration that infants can detect differences in retinal disparity is important, since disparity detection is a necessary prerequisite for stereoscopic depth perception. Our review of the infant stereopsis literature considers two major approaches to the study of stereopsis: (1) the development of spatially appropriate behaviors and (2) the development of disparity detection. 1 . Spatially Appropriate Behaviors
One approach to the study of the development of binocular depth perception in infants is to record the presence of spatially specific responses such as reaching or avoidance. Typically, studies of this type have employed a stereoscopic
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shadow-casting device to present disparate stimuli to the two eyes. The shadowcasting technique uses two horizontally separated point sources of light to cast the double shadow of an object onto a rear projection screen. By placing different chromatic or Polaroid filters in front of the two point sources and corresponding filters in front of the subject’s two eyes, it is possible to isolate each of the two double images of the stimulus and create a dichoptic viewing situation. The apparent distance of the fused images (for adult viewers) is proportional to the lateral separation of the stimulus images on the screen. If the left eye views the right image and the right eye the left image, then the stimulus object appears to be located in front of the screen. Conversely, if the left eye views the left image and the right eye views the right image, then the object appears in back of the plane of the screen. Thus, creation of a “virtual” object is based upon the extraction of binocular information for relative depth. Bower (1971, 1972) and Bower, Broughton, and Moore (1970) have reported that infants as young as 7 days of age reach appropriately to the location of a virtual object and become upset by the absence of tactual feedback from their intended reaching behavior. Unfortunately, both Dodwell, Muir,and DiFranco (1976) and Ruff and Hulton (1977) have failed to find evidence of either h s t r a tion or directed reaching in neonates under experimental conditions very similar to those reported by Bower and his colleagues (see also Bower, Dunkeld, & Wishart, 1979, and Dodwell, Muir, & DiFranco, 1979). In fact, the previously accepted norms on the development of reaching in infants (Gesell, Thompson, & Amatruda, 1934; White, Castle, & Held, 1964) report no directed (intentional) reaching toward real objects until 4 months of age. Furthermore, Gordon and Yonas (1976) have correctly noted that both binocular rivalry, which may result if the two stimulus images cannot be fused, and the conflict between accommodation and convergence, resulting from the large image separations used in the Bower studies, could account for the infant’s agitated behavior. Therefore, evidence from the reaching behavior of neonates that stereoscopic depth perception is present at birth must be seriously questioned. While the reaching behavior of neonates may be of questionable validity, the reaching behavior of older infants may provide evidence of appropriate target localization (cf. Bechtoldt & Hutz, 1979 and Gordon & Yonas, 1976). Gordon and Yonas (1976), however, found that 5- and 6-month-olds’ reaches were directed to approximately the same location in space regardless of the separation of the two stimulus images on the screen (and thus the presumed distance of the virtual object). This finding is difficult to interpret since even in their real object condition, reaches were often inaccurate and contact with the real object was often fortuitous. Three other measures (position of the infant’s head, number of reaches, and number of prehensile behaviors) did, however, vary with the apparent location of the virtual object. A follow-up study by Yonas, Oberg, and Norcia (1978) employed a virtual object display in which the separation of the two stimulus images increased rapidly during a trial, thus simulating the ap-
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proach of the object on a collision course with the infant's face. Twenty-weekolds showed more attentive furation, more reaching, more head withdrawal, and more blinking on these virtual object looming trials than on trials in which dichoptic viewing conditions were eliminated (by removing the filters from in front of the light sources). These results suggest that some aspect of the display that is present only under binocular viewing conditions mediates these behaviors. However, the specific type of binocular information mediating these behaviors remains unclear. For example, all studies that have used the shadow-casting technique appear to assume that binocular parallax (disparity) is responsible for depth-related behaviors in infants. However, one must recall that disparity is defined as the stimulation of noncorresponding retinal points by the same object (or part of an object). In the shadow-casting technique used in past studies, there are no contours on the display screen (except the outline of the screen's frame) to lock convergence onto the plane of the screen. Consequently, infants may simply maintain bifoveal fiation on the two stimulus images rather than bifoveally fiiating the screen plane. Although this cross convergence situation (left fovea fixating right image and right fovea fixating left image) maintains fusion, it does not result in retinal disparity. Therefore, infants may be relying on convergence angle as a cue to depth in studies employing the shadow-casting device. von Hofsten (1977)has provided some evidence that convergence angle may mediate distance-appropriate reaching in infants. He placed wedge prisms in front of both eyes, thereby altering the angle of convergence for infants viewing an object. Infants from 18 to 32 weeks of age provided some evidence of reaching for the virtual location of the object. Therefore, convergence, as well as other nonstereoscopic cues (binocular rivalry, alternation of fixation between the two eyes, diplopia) may be responsible for the differential behavior of infants presented with virtual objects. In summary, the studies that have employed spatially appropriate behaviors as an index of binocular depth perception suffer from three major difficulties. First, the frequency of reaching in neonates is low, suggesting that reaching is not a reliable measure of depth perception. Second, although reaching and avoidance behaviors are reliably present in older infants, the specific forms of these responses lack a consistent relationship to object distance. Third, the shadowcasting technique used to present binocular displays to infants provides cues other than retinal disparity. Thus, responses other than reaching and avoidance and displays other than the shadow-caster are needed to assess infant stereopsis more accurately. 2 . Detection of Disparity Another approach to the study of binocular depth perception in young infants is to determine whether differences in disparity can be detected. One method for assessing disparity detection is the habituation-dishabituation procedure. Bower
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(1968), in a very sparsely documented report, suggests that infants show a decline in fixation duration (habituation) over repeated trials of a stereoscopic display and recovery of fixation (dishabituation) upon a subsequent change to a nonstereoscopic display. Without further details on his procedures, however, Bower’s results are only suggestions. A more systematic study of disparity detection using the habituationdishabituation procedure has been reported by Appel and Campos (1977). They measured habituation of three indexes (heart rate, skin potential, and sucking rate) and subsequent dishabituation when a stereoscopic display was shifted to a nonstereoscopic display (or vice versa). A two-dimensional form (rabbit) composed of two images, each viewed separately by the two eyes (with polaroid goggles), was presented to 8-week-olds. The shift from the nonstereoscopic to the stereoscopic display was reliably discriminated, but the shift from stereoscopic to nonstereoscopic was not. Appel and Campos (1977) argued that a shift from a depth to a planar display must have been less salient than a shift from a planar to a depth display. Although these results suggest that young infants can detect some changes in disparity, the use of pictorial forms in their stereoscopic display is subject to a criticism similar to that raised in the case of the shadowcasting studies: that infants may detect a monocular cue (the relative position of the two stimulus images, an effect easily seen if one alternates fixation between the two eyes) or a binocular cue (rivalry, diplopia) not indicative of a depth percept. Consequently, use of the stimulus display employed in the Appel and Campos (1977) study leaves unclear whether infants actually detected differences in disparity. A stimulus display perfected by Julesz (1960, 1971) offers a more unambiguous method for the assessment of disparity detection in young infants. This stimulus display, a random-element stereogram (see Fig. 5 ) , is composed of hundreds of small square-shaped elements randomly arranged across a wide stimulus field. Under monocular viewing conditions, the random-element display appears to be devoid of any coherent contours. However, it is possible to displace a region of the display under dichoptic viewing conditions and thereby create retinal disparity. The primary advantage of the random-element display is that it effectively eliminates any monocular cue present in displays that have extended contours. The disparity present in a random-element display is defined with respect to a region of elements rather than with respect to a simple contour displacement. Of course, one could argue that any demonstration of detection of disparity in random-element displays by infants provides evidence only of the processing of a proximal cue to depth and does not provide conclusive evidence for the presence of a depth percept. However, strong evidence for infants’ detection of disparity would provide useful information concerning whether stereopsis is possible in young infants. To date there are only three studies that have employed random-dot stereo-
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grams to assess binocular function in young infants. Bower (1968),again in a very poorly detailed report, stated that when presented with a random-element display containing no form “the infant will frantically scan over the field” (p. 197). However, he stated that if the display contained a stereoscopic form, a majority of infants “will orient to the form with no rapid jumping at all” (p. 197). Very little detail was provided as to the infants’ ages or the method used to measure eye position, thus making this report very difficult to evaluate critically. Atkinson and Braddick (1976) have used both fixation preference and a habituation-dishabitation measure (high-amplitude sucking) to study disparity detection in four 2-month-olds. In the fixation preference procedure, a pair of random-dot displays (22” square) was presented side by side, separated by 11”. Pairings consisted of one stereoscopicdisplay (disparity = 26 minutes of arc) and one nonstereoscopic display. Only two of the four subjects showed differential fixation behavior to this paired comparison situation. In the habituationdishabituation procedure, each of the four subjects was habituated to a randomdot display containing either horizontal disparity (stereoscopic), vertical disparity (proximal cue without stereopsis), or no disparity (planar). After reaching a criterion of habituation, each subject received either a shift in disparity (horizontal to vertical, vertical to horizontal, planar to horizontal, or horizontal to planar) or a no-shift control. Two infants (only one of whom showed positive evidence of disparity discrimination on the fixation preference measure) showed reliable dishabituation to the disparity-shift condition compared to the no-shift control. The other two infants showed dishabituation to only one direction of disparity change (planar to horizontal and vertical to horizontal, but not the reverse). While these results suggest that some 2-month-old infants can detect changes in disparity, the fact that only four infants were tested, and only two showed positive evidence of disparity detection, leads one to question the reliability of disparity detection as measured in their two tasks. Fox, Aslin, Shea, and Dumais (1980) have recently reported the fiist compelling evidence for the existence of disparity detection in young infants. A key feature of their method was a system for generating random-element stereograms on-line by means of a rear projection color television display (Shetty, Brodersen, & Fox, 1979). The system presented red and green elements randomly arranged across the screen and in constant motion (Fox, Lehmkuhle, & Bush, 1977). Displacement of a small square-shaped region of red elements relative to the green elements created retinal disparity. Adults viewing this display while wearing a red filter over one eye and a green filter over the other report that the square-shaped region of elements appears to lie in front of the plane of the rear projection screen. The unique feature of the display system was its capability for moving the stereoscopic form within the entire field of random elements. Movement of the stereoscopic form capitalized upon the infant’s natural tendency to visually track moving stimuli. This dynamic random-element display (like static
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random-element displays) eliminated all monocular cues to detection of the stereoscopic form, and the continual motion of the elements eliminated all monocular cues to the movement of the stereoscopic form. Thus, the presence of visual tracking behavior that correlated with the lateral displacement of the stereoscopic form would provide strong evidence for the existence of disparity detection. Forty infants between 2 and 5 months of age were tested while wearing a pair of spectacle frames containing one red and one green filter. A variant of the forced-choice preferential looking technique (Teller, Morse, Borton, & Regal, 1974; see Teller, 1979, for a general description) was used to assess the presence of visual tracking of the stereoscopic form. On each trial the form was moved either to the right or left of screen center and an observer, blind as to the direction of stimulus movement, made a forced-choice judgment of the direction of stimulus movement based on the infant’s eye movements. Results indicated that the infants’ performance improved significantly with age and that infants over 3 months of age performed at a level significantly greater than chance. The negative finding for infants under 3 months of age was not the result of a simple attentional deficit since all infants were required to pass a 75% criterion on trials containing a real form (physical contour) before stereopsis testing began. In addition, the element size in the display (45 minutes of arc) was well above the acuity threshold typical of infants across all of the ages tested. Hence, it would appear that some other factor(s) accounted for the younger infants’ poor performance-for example, poor bifoveal fixation, inaccurate convergence, or a deficit in the central neural mechanism subserving disparity processing. The results for the infants older than 3 months of age demonstrated that the capability for disparity detection was present. Although this demonstration is important for an understanding of the development of binocular depth perception, disparity detection is only a necessary and not a sufficient condition for stereopsis. It is possible that in the study of Fox et al. (1980) the infants detected the presence of disparity (a proximal cue) without the perception of the stereoscopic form lying in front of the screen (the distal depth percept). To test this alternative, an additional group of 3- to 5-month-olds was tested on trials in which disparity was manipulated. For adults, very large values of disparity result in the loss of patent stereopsis even though disparity information is still present and can be reliably discriminated. Results from this second experiment indicated that the infants’ performance exceeded chance levels only at moderate disparity values-values that adults judge as easily fusable and resulting in the percept of depth. The results of the study of Fox et al. (1980) provide the first convincing evidence that stereopsis is present in young infants. However, many questions remain, including the accuracy of stereopsis (stereoacuity) at different ages and whether variations in early experience contribute to individual differences in
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stereoacuity. Moreover, it is clear that all of the constraints on stereopsis are sufficiently reduced by the fourth postnatal month to allow rudimentary stereopsis to occur. In Section V, we turn to the mechanisms responsible for the development of binocular function by considering how maturational and experiential factors interact to produce an adult level of binocular vision.
V. Early Experience and Binocular Function The preceding review of empirical research on infant binocular vision provides an up-to-date description of the three levels of binocular function-bifoveal fixation, fusion, and stereopsiAuring the first 6 months of life. However, those descriptions do not explain the mechanisms underlying developmental change in each of the three levels of binocular function. Although one cannot begin to understand how development is controlled until the basic abilities present at different ages are described, we feel that enough is now known about these basic binocular abilities to allow us to.propose a model of those factors influencing binocular development. Our goal in this final section, therefore, is to offer a model of binocular development that not only organizes the currently available descriptions of infant binocular abilities but also generates testable hypotheses to guide empirical research. A. THE ROLES OF EARLY EXPERIENCE
Perhaps the most basic question one can ask about the mechanism@) controlling binocular development concerns the relative influences of genetic and experiential factors during the early postnatal period. In the past, two dichotomous opinions have been raised regarding the basis of binocular development. In its most extreme form, the nativist position was that the mechanisms underlying binocular function are present at birth, although difficulties in measuring these abilities may prevent their accurate assessment. At the other extreme, the pure empiricist position was that the neural connections subserving binocular function and the sensory-motor coordination present in adults’ binocular vision are acquired solely as a result of postnatal experience. The preceding review of recent research on human infants strongly suggests that the three levels of binocular function undergo considerable postnatal improvement. In addition, these findings, along with related findings on the neural mechanisms underlying binocular function in nonhuman infants (see Grobstein & Chow, 1976, for a general review), suggest that the binocular visual system is significantly constrained by genetic factors. Therefore the simplistic (and extreme) forms of nativism and empiricism appear to be untenable as models of human binocular development.
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A more reasonable reformulation of the simple nativism-empiricism dichotomy is to ask (1) how severely do genetic factors constrain the plasticity of binocular functions, (2) what environmental manipulations influence binocular functions, and (3) when during development does the environment exert its greatest influence on binocular functions. A convenient method for addressing each of these questions is to consider the possible courses that binocular development can take as a result of the gene-environment interaction. A general scheme for illustrating these possible developmental outcomes has been proposed by A s h and Pisoni (1980). Although the scheme was originally applied to the developmental data on infant speech perception, it is based largely on the research and theorizing of Gottlieb (1976), a behavioral embryologist, and is generally applicable to a broad range of topics in sensory and perceptual development. The general scheme for describing the possible courses of infant binocular development is illustrated in Fig. 8. Although there are an unlimited number of developmental curves describing the possible progression of binocular develop ment, we have shown only three major alternatives that correspond to three degrees of genetic specification reached prior to birth. The first alternative describes a prenatal period during which the level of binocular function reaches the full adult status. The influence of postnatal experience is to maintain this mature binocular function. Failure to receive maintaining experience results in a loss of binocular function if that maintaining experience is absent during the particular postnatal period when the integrity of binocular function is susceptible to environmental influences (the sensitive period).
PRENATAL
POSTNATAL
A G E 4
Fig. 8 . Illustration of several possible roles that early visual experience might play in the development of binocular function.
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The second alternative developmental curve describes the partial specification of binocular development during the prenatal period. After birth, the level of binocular function either improves, declines, or remains the same as a result of the quality of binocular input received during the sensitive period. Binocular experience may facilitate, maintain, or decrease the partially specified (nearly adult-like) status of binocular function present at birth. The third alternative curve describes the absence of binocular function at birth. Postnatal improvement in binocular function is the result of an induction by environmental input received during the sensitive period. Both the qualitative and the quantitative aspects of binocular function are determined by early binocular experience. Finally, a postnatal improvement in binocular function might be determined by genetic constraints that are independent of any postnatal experience; that is, neural maturation may occur postnatally as well as prenatally, and this maturation may not depend upon any specific type of postnatal environmental input. In general, therefore, we can consider four major roles that postnatal experience might play in the development of binocular function. In the case of maintenance, the binocular ability is present at birth but must be consolidated during the sensitive period by visual experience that closely matches the genetically specified mechanism underlying a particular binocular function. For facilitation. the binocular ability is partially specified at birth but awaits postnatal experience to attune or align the mechanism underlying a particular binocular function to the specifics of the environment. For induction, the binocular ability is absent at birth and the path of postnatal development is primarily determined by the specific qualities of environmental experience. Finally, in the case of maturution, the binocular ability is either absent or only partially specified at birth and any postnatal improvement is determined primarily by genetic factors and not by the specifics of environmental input. One might infer that if postnatal improvement occurred, it would be impossible to choose among the three cases of facilitation, induction, and maturation. However, that inference is not correct provided that one can (1) vary the quality of visual experience during the early postnatal period and (2) measure accurately the integrity of binocular function at many postnatal ages. Although these two requirements are difficult to meet in the study of human binocular function, they have been met in the study of several nonhuman species. We shall now briefly consider two examples from the animal literature to highlight the importance of early experience in the development of binocular function. B. BINOCULAR NEURAL MECHANISMS IN THE CAT
Several experiments, including the pioneering reports of Hubel and Wiesel (1%5, 1970) and more recent replications (Blakemore & Van Sluyters, 1974, 1975; Movshon, 1976; Blakemore, 1976; Olson & Freeman, 1978), have
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documented four major aspects of neural functioning in the cat visual cortex. First, approximately 80% of single neurons in the visual cortex of the adult cat are responsive to visual input delivered to either or both retinas. Second, the newborn kitten has an adult-like distribution of binocular neurons. Third, these binocular neurons are absent in adult cats that have been deprived of normal binocular experience (e.g., having monocular occlusion). And fourth, a loss of binocular neurons occurs only if anomalous binocular input is received during a sensitive period extending from approximately 4 to 14 weeks postnatally. Therefore, the property of cortical neuron binocularity appears to be best described by a maintenance role for early experience. Adult-like binocularity is present at birth but is lost if abnormal binocular input is received during the cat's sensitive period. The property of cortical binocularity, however, does not provide a complete account of the cat's sensitivity to relative object distance, since binocularity indicates only that a neuron is responsive to input from both retinas. A further aspect of cortical responsiveness is the F i n g pattern of binocular neurons to the precise alignment of specific retinal loci. Barlow, Blakemore, and Pettigrew (1967) have shown that binocular neurons in the adult cat visual cortex are each optimally responsive to a particular value of retinal disparity. If the optimal disparity value is O", then that particular neuron represents a spatial location on the horopter. If the optimal disparity value is greater or less than O", then that particular neuron represents a location in front of or behind the horopter. Thus, the entire population of binocular neurons in the visual cortex of the cat can provide information on the relative depth of objects located in three-dimensional space. The property of cortical disparity specificity, unlike binocularity, does not appear to be present in an adult-like form in newborn kittens. Pettigrew (1974) has shown that at birth, individual binocular neurons are responsive to a broad range of disparity values. During early postnatal development, the range of disparities over which a particular binocular neuron will respond decreases, resulting in a population of binocular neurons each finely tuned to a particular disparity value. Obviously, if the kitten is binocularly deprived during the sensitive period, cortical binocularity will be lost, as will the property of cortical disparity specificity. More subtle manipulations of early visual experience may alter cortical disparity specificity. Shlaer (1971) found that the mean disparity value to which a particular neuron will become tuned is dependent upon the disparity values presented during the sensitive period and is not simply the result of innate or maturational factors. This plasticity in disparity tuning is apparently not unlimited, however, since large shifts in disparity (such as those resulting from gross eye misalignment) do not result in a shift in disparity tuning but rather in a loss of binocularity. Hence, the property of cortical disparity specificity appears to be best described by a facilitation role for early experience. The
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disparity responsiveness of individual neurons is partially constrained by genetic factors, but the fine tuning of these neurons is determined by the specifics of postnatal experience during the sensitive period. The behavioral implications of these findings on binocular neural development have been clearly demonstrated by Blake and Hirsch (1975) and Packwood and Gordon (1975), who showed that the accuracy of disparity detection in a local stereopsis task is greatly diminished if cats have been binocularly deprived during the sensitive period. These behavioral results strongly suggest that cortical binocularity is a necessary prerequisite for stereopsis. However, the specific correspondence between cortical disparity values and the quality of stereopsis remains unclear. Moreover, an understanding of the development of stereopsis in cats awaits the development of a behavioral technique that effectively measures stereoacuity in very young kittens.' C. SENSITIVE PERIOD FOR HUMAN BINOCULAR FUNCTION
The general principles discussed in the foregoing summary of the binocular neural mechanism in cats led two groups of investigators (Banks, Aslin, & Letson, 1975; Hohmann & Creutzfeldt, 1975) to search for analogous effects of early binocular experience in humans. Both studies employed a psychophysical technique (interocular transfer of the tilt-aftereffect)8to assess binocular function in children and adults who had received nonconcordant binocular input during some period of their early lives. This nonconcordant input resulted from a particular type of strabismus, esotropia, that consists of a constant cross-eyed condition. Each subject had been deprived during a different developmental period prior to receiving corrective surgery. Although all subjects had correctly aligned eyes after surgery, those who had been deprived during the first 3 years of life had a permanent deficit in binocular function. Figure 9.shows the estimated sensitivity of the human visual system to binocular deprivation at different ages. These results provide strong evidence that binocular function in humans is dependent upon the quality of binocular experience received during a sensitive period. The results from these two studies, despite their importance in delineating the characteristic form and timing of a sensitive period in humans, do not clarify the exact role that early experience plays in human binocular development. One knows from these studies only that a simple maturational model is untenable 'The fmt studies of stereopsis in cats were performed with a local stereopsis display. Subsequently, Lehmkuhle, Fox, and Bush (1977) have demonstrated stereopsis in cats using a randomelement display. A global stereopsistask, such as the one employed by Fox er al. (1980) with human infants, may provide a useful technique for assessing the presence of stereopsisin the developing cat. 8Mitchell and Ware (1974) and Movshon, Chambers, and Blakemore (1972) have shown that interocular transfer of the tilt-aftereffxt is highly correlated with stereoacuity values in adults.
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Fig. 9. An estimate of the relative importance of binocular deprivation to human binocular function during the first 10 years of life. (Adaptedfrom Banks, Adin. & Letson. Science, 1975, 190, 675477. Copyright 1975 by the American Association for the Advancement of Science.)
since binocular experience exerts some influence during the postnatal period. The only way of differentiating among the three remaining roles of experience-maintenance, facilitation, and induction-is to measure stereopsis in young infants to determine whether disparity responsiveness is completely specified at birth, partially specified, or not specified at all. The results of the study of Fox et al. (1980) suggest that experience is unlikely to play a maintenance role since infants did not show evidence of stereopsis until the fourth postnatal month. However, the negative findings from these younger infants must be interpreted with caution, since their poor performance may reflect deficits in one or more visual functions that limit disparity detection. Nevertheless, on the basis of currently available data, it appears that either a facilitation or an induction model offers the best description of the manner in which experience operates during the sensitive period for human binocular function. Based upon this conclusion and the previously reviewed findings on infant binocular function, we shall now propose a tentative model of human binocular development. D. A MODEL OF HUMAN BINOCULAR DEVELOPMENT
The model of binocular development we propose postulates that at birth, several factors constrain the integrity of binocular function. In the early postnatal period, the quality of visual experience tunes up those aspects of binocular
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function that are already partially specified by genetics. In general, therefore, we believe that the facilitation role for early experience best describes the mechanism underlying binocular development. In the discussion to follow, we shall consider each of the three levels of binocular function by describing the capacity of each level at birth, how that capacity changes postnatally, and the manner in which early experience modifies binocular capabilities.
I . Bifoveal Fixation Although the empirical findings on bifoveal fixation are not conclusive, it is quite clear that bifoveal fixation is at best intermittent at birth. Newborns may fixate bifoveally for targets located at certain distances, but the range of bifoveal fixation is limited and the speed with which changes in eye alignment occur to maintain bifoveal fixation is restricted. Two nonbinocular factors appear to offer the most significant detriments to consistent bifoveal fixation in newborns. First, monocular acuity and contrast sensitivity are quite poor at birth, degrading spatial resolution. As a result, a small high-contrast target is effectively increased in spatial extent and degraded in salience. Although measures of peripheral acuity have not been obtained in infants, their poor foveal acuity suggests that the gradient of acuity from fovea to periphery may be less steep in newborns than in adults. Consequently, the need for small eye movements to maintain optimum spatial resolution by keeping the target on the fovea@) is likely r e d ~ c e d .In~ addition, this shallower acuity gradient indicates a decreased likelihood of detecting a small shift in the target’s image on the retina. A second factor that degrades bifoveal fixation is the immaturity of the oculomotor control system. Much of this oculomotor control inefficiency is undoubtedly the result of deficits in image processing (acuity). In addition, however, the rapid development of the neuromuscular system, as evidenced by changes in motor reflexes (Peiper, 1963), suggests that the oculomotor system may be poorly organized at birth. In sum, currently available evidence strongly suggests that bifoveal fixation is not consistently present in early infancy. There is now convincing evidence that during the first 6 months after birth, there is a marked improvement in acuity (Dobson & Teller, 1978) and oculomotor control (Aslin, 1977, 1980; A s h & Salapatek, 1975; Dayton & Jones, 1964; Ling, 1942). These advances strongly suggest that bifoveal fixation also becomes more accurate and more consistent during this age period. The 9Weassume here that current infant acuity estimates (see Dobson &Teller, 1978) reflect the spatial resolving power of the most sensitive portion of the retina. However, one could argue that infants’ relatively poor acuity is in part the result of employing extrafoveal retinal areas that possess poor spntial resolving powers. If so, the apparent flatness of the infant acuity threshold across the entire retinal surface would be an artifact of the inefficient use of the fovea. Nevertheless, small eye movements would still fail to enhance spatial resolution since the fovea would not be consistently used as the line of sight.
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exact mechanism underlying improvements in the two subsystems of acuity and oculomotor control, however, is unclear. It would appear that unless a gross refractive error (myopia, hyperopia, anisometropia) is present, infants will show a nearly 10-fold improvement in acuity during the first 6 months of life. Although early deprivation degrades acuity in monkeys (von Noorden, 1973), it remains to be seen whether particular types of visual input are needed to facilitate acuity development in humans or whether acuity development occurs independently of early visual experience (i.e., according to a genetically specified maturational sequence). Similarly, the increase in oculomotor control might result from specific eye movement experience or general newomuscular maturation. However, regardless of the mechanism underlying development in these two subsystems, such development appears to be essential for accurate and consistent bifoveal fixation. In addition, it would appear that by 6 months of age, the major constraints of acuity and oculomotor control on bifoveal fixation are largely eliminated, since stereopsis is present. Any deficits in bifoveal fixation after this age can have long-term, often permanent effects on binocular function (Banks et al., 1975; Burian & von Noorden, 1974; Duke-Elder & Wybar, 1973; Hohmann & Creutzfeldt, 1975; Taylor, 1973). Finally, there are four other factors relevant to the question of bifoveal fixation that deserve brief mention. First, the absence of accommodation in newborns may create a conflict with the control of convergent eye movements and thereby prevent bifoveal fixation for targets presented at certain distances. Unfortunately, there are no data on the accommodation-convergence relationship in infants under 2 months of age. However, it appears that after 2 months of age, both systems are operating very well (Aslin & Jackson, 1979) although not necessarily as precisely as in adults. Second, the orbits are more divergent in newborns than in adults, hence demanding a greater degree of eye rotation to converge on fixation targets. This additional constraint on bifoveal fixation, however, is diminished by the third and fourth factors relevant to bifoveal development. The third factor is the increased optic axis-visual axis discrepancy in newborns compared to adults. The effect of this larger angle alpha is to demand less convergent eye rotation to near targets by newborns, since the visual axis in each eye is directed nasaliy from the optic axis. The fourth factor, interocular separation, also places less demand on convergent eye rotation. These last two factors raise an interesting point regarding the demand on the convergence system. In a newborn with a 40-mm interocular separation and an 8" angle alpha, the two optic axes (pupil centers) can be oriented in parallel (as if viewing an object at infinity), and the visual axes will-intersect at a point only 14.2 cm from the infant. In contrast, for an adult with a 60-mm interocular separation, a 4" angle alpha, and the two optic axes oriented in parallel, the point of visual axis intersection would be 42.9 cm away, thus requiring an additional 7.9" of convergent rotation for each eye in order to bring the visual axes to the
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14.2 cm viewing distance of the infant. In light of these facts, it is perhaps not surprising that very young infants often appear walleyed, especially if they are attempting to fixate an object beyond 14.2 cm. Consequently, the newborn’s visual system is apparently biased toward nearobject fixation by three factors: (1) the anatomical and geometrical factors involved in eye alignment, (2) the degraded image processing powers that make any distant object (unless very large) below acuity threshold, and (3) the absence of accommodation that biases image focus to near distances and may conflict with the control of convergence.10Although the period of early postnatal development may consist of intermittent bifoveal fixation, there appears to be a functionally advantageous bias for this intermittent bifoveal fixation to operate primarily during near-object viewing. In short, if early visual experience influences neural development during the first months of life, the resultant neural modification is biased toward receiving input from near, large, and in-focus objects.
2. Fusion The mechanism underlying this second level of binocular function is unfortunately not well understood. Moreover, little is known about the presence or absence of fusion in infants. However, it seems clear that the acuity deficit in newborns that degrades spatial resolution also reduces the need for accurate alignment of corresponding retinal points to guarantee fusion. That is, if fine spatial resolution is absent, then detection of spatial misalignment should be reduced. Nevertheless, it is impossible to state conclusively that fusion is present in young infants. They may very rapidly alternate viewing from one eye to the other and thereby exhibit few symptoms of the absence of fusion. In addition, they may have peripheral fusion without foveal (central) fusion, a fact that may not be functionally disadvantageous since in most normal viewing situations targets are quite large and scanning eye movements occur continuously. Although at present there are no conclusive data on infant fusion, our working hypothesis, based on the data from Aslin (1977) using the prism test and Fox et al. (1980) using random-element stereograms, is that infants have fusion by 4 to 6 months of age. We further hypothesize that the extent of Panum’s fusion area diminishes with age, and that this decrease is due both to an improvement in acuity and to an improvement in disparity resolution. Good monocular acuity is a necessary requirement for good disparity resolution, SO that disparity resolution must be built upon spatial resolution (Stigmar, 1970). However, good spatial resolution is not a guarantee of good disparity resolution, a fact borne out by the ‘ORecent estimates of the depth of focus in the infant eye (Banks, 1980; Green, Powers, & Banks, 1980) suggest that clarity of retinal image focus may not be critical for optimal acuity because the smaller infant eye, with a larger depth of focus, does not suffer a significant loss of acuity as the target becomes blurred.
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large number of stereoblind adults who have good acuity in both eyes. As disparity resolution improves during early life, the requirements of binocular eye alignment increase so as to maintain fusion. Clearly there are limits to the degree of inaccuracy this eye alignment can have without creating diplopia. Presumably, these limits are specified genetically such that slight deviations in eye alignment during the first few months of life do not permanently degrade fusion. However, as disparity resolution improves, the accuracy of binocular eye alignment must conform to these genetically specified limits. Failure to conform results in a permanent loss of the fusion mechanism, an effect clearly documented in the clinical literature on strabismus (Burian & von Noorden, 1974; Duke-Elder & Wybar, 1973). We conclude from these findings that either the induction or the facilitation roles for early experience best describes the development of fusion. That persons with crossed eyes from birth do not have fusion (unless surgically corrected early in life) suggests that maturation cannot account for its develop ment . 3 , Stereopsis The final level of binocular function, stereopsis, develops quite similarly to fusion. The only significant difference between our understanding of fusion and that of stereopsis is that we have evidence for the existence of stereopsis in very young infants (Fox er al., 1980). The evidence that suggests the absence of stereopsis in infants under 3 months of age may reflect the poor spatial resolution and lack of consistent bifoveal fixation in young infants. Although infants show good convergence by 3 months of age (both in range and speed), they may have difficulty maintaining consistent bifoveal fixation, thereby creating a difficulty in extracting from the display the corresponding and disparate points that provide the essential information for stereopsis. Apart from these constraints, however, the disparity resolution mechanism appears to undergo significant improvement postnatally, provided that bifoveal fixation is within genetically specified limits. Based upon the typical minimum eye misalignment that receives surgical correction and the accuracy with which surgical corrections are performed, this genetic limit in eye alignment is most likely 5-8". If bifoveal fixation is beyond this limit, then correspondingpoints cannot link up in the higher visual areas and both fusion and disparity detection break down. Consequently, early experience operates as a facilitator in that visual input during the sensitive period tunes up the disparity resolving mechanism, provided that early visual input conforms to the limits specified by genetics. Finally, the data on a sensitive period in human binocular development suggest that stereopsis is not significantly influenced by early experience during the first 4 months of life (see Fig. 9). Although we realize the following point is speculative, we would suggest that the visual system delays the period of experiential
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influence until the subsystems needed for all three levels of binocular function are at least minimally functional. This hypothesis, in concert with our previous discussion of the three levels of binocular function, suggests that the course of binocular development is characterized by a complex interaction between genetically constrained subsystems and early experiential effects. These genetic constraints place limits within which early experience must fall. Further development of binocular capabilities is directly dependent upon the quality of early experience. If that early experience conforms to the genetic constraints, then development proceeds normally. If the genetic limits are exceeded (i.e., producing binocular deprivation), then binocular abilities either fail to develop or show a permanent loss of function. 4. Summary
The general model of binocular development we have presented proposes that the basic mechanisms underlying bifoveal fixation, fusion, and stereopsis are present in rudimentary form at birth, but that they are constrained by various sensory and motor subsystems. These Constraints must be overcome for adult-like binocular functions to develop. During the first 4 to 6 months of life, as these constraints diminish, the three binocular functions become manifest. In addition, the postnatal period beginning at approximately 4 months after birth and extending at least into the second year of life is characterized by a heightened susceptibility to anomalous visual input. If the visual input during this sensitive period does not conform to the range of genetically specified limits for binocular functions, then the mechanism(s) underlying binocular functions fail to show further development and, in extreme cases of anomalous input, may become degraded or permanently impaired. The task for future research is to specify the precise relationship between the quality of early visual experience and the quantitative aspects of binocular function. This task will entail correlational studies linking the sensory (acuity) and motor (accommodative, oculomotor) subsystems with the integrity of binocular functions (Panum’s fusion area, stereoacuity). In addition to these correlational studies, attempts should be made to find naturally occurring variations in early visual input (crossed eyes, cataract, anisometropia) to determine the exact magnitude and timing of experiential influence on binocular function. Finally, the increasing study of genetic anomalies that affect visual functioning (e.g., albinism) may provide a useful insight into the limits placed by genetic factors upon experiential influence. The combined study of normal and clinical populations, as well as nonhuman primates, both during infancy and into adulthood, will eventually clarify the essential mechanisms and their time course in the development of binocular function.
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VI. Concluding Remarks In this article we have attempted to summarize the empirical findings on infant binocular vision within a coherent theoretical framework. This framework includes (1) a consideration of the multileveled nature of binocular function, (2) the constraints placed upon binocular function by other aspects of visual development, and (3) the role that early visual experience may play in binocular development. The goal of future empirical research, therefore, should be to provide (1) a more accurate description of the integrity of binocular functions at different postnatal ages, (2) an interpretation of those developmental descriptions that takes into account the several constraints on binocular functions, and (3) a search for new methods and clinical populations that will provide insight into the magnitude and timing of experiential influence in binocular development, REFERENCES Appel, M. A., & Campos, J. J. Binocular disparity as a discriminable stimulus parameter for young infants. Journal of Experimental Child Psychology. 1977, 23,47-56. A s h , R. N. Development of binocular fiiation in human infants. Journal of Experimental Child Psychology, 1977, 23, 133-150. Aslin, R. N. Development of smooth pursuit in human infants. Paper presented at The Last Whole Earth Eye Movement Conference. St. Petemburg, Florida, February 1980. Aslin, R. N., & Jackson, R. W.Accommodative-convergence in young infants: Development of a synergistic sensory-motor system. Canadian Journal of Psychology, 1979,33, 222-231. Aslin, R. N., & Pisoni, D. B. Some developmental processes in speech perception. In G. H. Yeni-Komshian, J. Kavanagh, & C. A. Ferguson (Eds.), Child phonology: Perception and production. New Yo& Academic Press, 1980. A s h , R. N., & Salapatek, P. Saccadic localization ofxisual targets by the very young human infant. Perception & Psychophysics, 1975, 17, 293-302. Atkinson, J., & Braddick, 0. Stereoscopic discrimination in infants. Perception, 1976, 5, 29-38. Atkinson, J., Braddick, O., & Moar, K. Development of contrast sensitivity over the first 3 months of life in the human infant. Vision Research, 1977, 17, 1037-1044. Ball, W..& Tronick, E. Infant responses to impending collision: Optical and real. Science, 1971, 171, 818-820. Banks, M. The development of visual accommodation during early infancy. Child Development, 1980, in press. Banks, M. S . , A s h , R. N., & Letson, R. D. Sensitive period for the development of human binocular vision. Science, 1975, 190,675-677. Banks, M. S., & Salapatek, P. Acuity and contrast sensitivity in 1, 2, and 3-month-old human infants. Investigative Ophthalmology, 1978, 17, 361-365. Barlow, H. B., Blakemore, C., & Pettigrew, J. D. The neural mech@sms of binocular depth discrimination. Journal of Physiology (London), 1967, 193, 327-342. Bechtoldt, H. P., & Hutz, C. S. Stereopsis in young infants and stereopsis in an infant with congenital eaotropia. Journal of Pediatric Ophthalmology, 1979, 16,49-54. Berry, R. N. Quantitative relations among vernier, real depth, and stereoscopic depth acuities. Journal of Experimental Psychology, 1948, 38, 708-721,
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207,323-324. Fox, R.,Lehmkuhle, S. W., & Bush, R. C. Stereopsis in the falcon, Science, 1977, 197,79-81. Gesell, A., Thompson, H., & Amatruda, C. S . Infant behavior: Its genesis and growth. New York: McGraw-Hill, 1934. Gordon, F. R., & Yonas, A. Sensitivity to binocular depth information in infants. Journal of Experimental Child Psychology, 1976,22,413-422. Gottlieb, G. The roles of experience in the development of behavior and the nervous system. In G.Gottlieb (Ed.), Studies on the development of behavior and the nervous system (Vol. 3). New York Academic Press, 1976. Green, D. G., & Campbell, F. W.Effect of focus on the visual response to a sinusoidally modulated spatial stimulus. Journal of the Optical Society of America, 1965, 55, 1154-1157. Green,D.G.,Powers, M. K., & Banks, M. S. Depth of focus, eye size and visual acuity, Vision Research, 1980. in press. Gmktein. P.. & Chow, K. L.Receptive field organization in the mammalian visual cortex: The role of individual experience in development. In G. Gottlieb (Ed.), Neural and behavioral specificity. New York: Academic Press. 1976. Haith, M. M a r e d television recording and measurement of ocular behavior in the human infant. American Psychologist, 1969,24, 279-283. Haynes, H., White, B. L.,& Held. R. Visual accommodation in human infants. Science. 1965,148,
528-530. Hendrickson, A., & Kupfer, C. Histogenesis of fovea in macaque monkey. Investigative Ophrhalntology, 1976, 15, 146-752. Hering. E. [The theory of binocular vision] (B. Bridgeman and L. Stark, Eds. and trans.). New York Plenum, 1977. (Originally published, 1868.) Hochberg, J. Perception II. Space and movement. In J. W. Kling Br L. A. Riggs (Eds.), Woodworth and Schlosberg’s experimental psychology (3rd Ed.). New York Holt, 1971. Hohmann, A., & Creutzfeldt, 0. D. Squint and the development of binocularity in humans. Nature (London) 1975, 254, 613-614. Hubel, D. H., & Wiesel, T.N. Binocular interaction in striate cortex of kittens reared with artificial squint. Journal of Neurophysiology, 1965. 28, 1041-1059. Hubel, D. H.,& Wiesel, T. N. The period of susceptibility to the physiological effects of unilateral eye closure in kittens. Journal of Physiology (London), 1970,206,419-436. Jampolsky, A. The prism test for strabismus screening. Journal of Pediatric Ophthalmology, 1964,
1, 30-34. JuIesz, B. Binocular depth perception of computer-generatedpatterns. Bell System Technical Journal, 1960,39, 1125-1162. Julesz, B. Foundawns of qclopean perception. Chicago: University of Chicago Press, 1971. Kaufman, L . Sight and mind. London and New York: Oxford University Press, 1974. Krieg, K. Tonic convergence andfacial growrh in early infancy. Unpublished senior Honors Thesis, Indiana University, 1978. Lehmkuhle, S. W.,Fox, R.,& Bush, R. C. Global stereopsis in the cat. Paper presented at the annual meeting of the Association for Research in Vision and Ophthalmology. Sarasota, Florida, 1977. Lewis, T. L.,Maurer, D., & Kay, D. Newborns’ central vision: Whole or hole? Journul of Experimental Child psycho lo^, 1978,26, 193-203.
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Ling, B. C. A genetic study of sustained fixation and associated behavior in the human infant from birth to six months. Journal of Genetic Psychology, 1942, 61, 227-277. Mann, I. The development of the human eye. New Yo& Grune & Stratton, 1964. Marg, E., Freeman, D. N.. Peltunan. P., & Goldstein, P. J. Visual acuity development in human infants: Evoked potential measurements. Investigurive Ophthalmology, 1976, 15, 150-152. Matsubayashi, A. Forschung iiber die Tiefenwiihmehmung.IX.Nippon G a n h GakkaiZasshi, 1938, 42, 1920-1929. (German abstract, Nippon Ganka GakkaiZasshi, 133; and Berichre ueber die Gesamte Physiologie und Experimentelle Pharmakologie. 1939, 112, 290-291 .). Maurer, D. The development of binocular convergence in infants. (Doctoral dissertation, University of Minnesota, 1974). Dissertation Abstracts Interncuional, 1975, 35, 6136-B. (University Microfilms No. 75-12. 121). (a) Maurer, D. Infant's visual perception: Methods of study. In L. Cohen & P. Salapatek (Eds.), Infant perception: From sensation to cognition (Vol. 1). New York: Academic Press, 1975. (b) Mitchell. D. E., & Ware, C. Intemular transfer of a visual aftereffect in normal and stereoblind humans. Journal of Physiology (London), 1974, 236,707-721. Morgan, M. W. Accommodation and vergence. American Journal of optometry and Archives of rhe American Academy of Optometry, 1%8,45,417-454. Movshon, J. A. Reversal of the physiological effects of monocular deprivation in the.kitten's visual cortex. Journal of Physiology (London), 1976, 261, 125-174. Movshon, J. A., Chambers,B.E. I., & Blakemore, C. Interocular transfer in normal humans and those who lack stereopis. Perception, 1972, I, 483-490. Muller, J. [Elements of Physiology] ( W . Baly trans.). Philadelphia: Lea and Blanchard, 1943. (Originally published, 1826.) Nachmias, J. Two-dimensional motion of the ntinalimage during monocular fixation. Journal of the Optical Society of America, 1959, 49, 901-908. Ogle, K. N. The optical space sense. In H. Davson (Ed.), The eye (Vol. 4). New York: Academic Press, 1%2. Pp.211-432. Olson, C. R.. & Freeman. R. D. Monocular deprivation and recovery during sensitive period in kittens. Journal of Neurophysiology, 1978, 41, 65-74. Packwood, J., & Gordon, B. Stereopsis in normal domestic cat, Siamese cat, and cat raised with alternating monocular occlusion. Journal of Neurophysiology, 1975, 38, 1485-1499. Pastore, N. Selective history of theories of visual perception: 1650-1950. London and New Yo& Oxford University Press, 1971. Peiper, A. Cerebralfunction in infancy and childhood. New York Consultants Bureau, 1963. Pettigrew, J. D. The effect of visual experience on the development of stimulus specificity by kitten cortical neurons. Jourml of Physiology (London). 1974, 237,49-75. Reinecke, R. D., & Simons, K.A new stereoscopic test for amblyopia screening. American Journal of Ophthalmology, 1974, 78,714-721. Riggs, L.A. Visual acuity. In C.H. Graham (Ed.), Vision and visualperception. New Yo& Wiley, 1965. Pp. 321-349. Romano, P. E., Romano, J. A., & Puklin, J. E. Stereoacuity development in children with normal binocular single vision. American Journal of Ophthalmology, 1975, 79,966-971. Ruff, H.A., & Hulton, A. Is there directed reaching in the human neonate? Developmental Psychology, 1977, 14,425-426. Salapatek, P., Bechtold, A. G.,& Bushnell, E. W. Infant visual acuity as a function of viewing distance. Child Development, 1976, 47, 860-863. Scarr, S., & Salapatek, P. Pattern of fear development during infancy. Mewill-Palmer Quarterly, 1970, 16,53-90. Sheedy, J. E . , & Fry, G. A. The perceived direction of the binocular image. VisionResearch, 1979, 19,201-212.
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Shetty, S. S., Brodersen, A. J., & Fox, R. System for generating dynamic random-element s t e w grams. Behavioral Research Methods and Instrumentation. 1979, 11, 485-490. Shipley, T., & Rawlings, S. C. The nonius horopter. I. History and theory. Vision Research, 1970, 10, 1225-1262. Shlaer, R. Shift in binocular disparity causes compensatory changes in the cortical structure of kittens. Science, 1971, 173,638-641. Slater, A. M., & Findlay, I. M. The measurement of fmation position in the newborn baby. Journal of Experimental Child Psychology, 1972, 14,349-372. Slater, A. M., & Findlay, I. M. The corneal reflection technique and the visual preference method: Sources of m.Journal of Experimenral Child Psychology, 1975, M, 240-247. (a) Slater, A. M., & Findlay, J. M. Binocular fixation in the newborn baby. Journal of Experimental Child Psychology, 1975, 20,248-273. (b) Stigmar, G. Observations on vernier and stereo acuity with special reference to their relationship. Acta Ophthalmologica, 1970, 48, 979-998. Taylor, D. M. Congenital esotropia: Management and prognosis. North Miami: Symposium Specialists, 1973. Teller, D. Y. A forced-choice preferential looking procedure: A psychophysical technique for use with human infants. Infant Behavior and Development, 1979, 2, 135-153. Teller, D. Y.,Morse, R., Borton, R., & Regal, D. Visual acuity for vertical and diagonal gratings in human infants. Vision Research, 1974, 14, 1433-1439. Thomas, J., Mohindra, I., & Held, R. Strabismic amblyopia in infants. American Journal of Optomeny and Physiological Optics, 1979, 56, 197-201. von Hofsten, C. Binocular convergence as a determinant of reaching behavior in infancy. Perception, 1977, 6 , 139-144. von Noorden, G . K. Experimental amblyopia in monkeys. Further behavioral observations and clinical correlations. Investigative Ophthalmology, 1973, 12, 721-726. von Noorden, G. K., & Maunamee., A. E. Atlas of Strabismus. St. Louis: Mosby, 1967. Walk, R. D., & Gibson, E. J. A comparative and analytical study of visual depth perception. Psychological Monographs, 1961, 75(15 Whole No. 519). Walters, C., & Walk, R. Visual placing by human infants. Journal ofExperimenta1 Child Psychology, 1974, 18,34-40. Walraven, J. Amblyopia screening with random-dot stereograms. American Journal ofOphrhalmo100,1975, 80, 893-899. Wheatstone, C . On some remarkable, and hitherto unobserved, phenomena of binocular vision. Philosophical Tmnsactions of the Royal Society of London, 1838, 128,371-394. White, B. L., Castle, R., & Held, R. Observationson the development of visually-directed reaching. Child Development, 1964, 35,349-365. Wickelgren, L. Convergence in the human newborn. Journal of Experimental Child Psychology, 1%7, 574-85. Wickelgren, L. The ocular response of human newborns to intermittent visual movement. Journal of Experimental Child Psychology, 1969, 8,469-482. Worth, C. Squint: Its causes, pathology, and treatment. Philadelphia: Blakiston, 1915. Yonas, A., Bechtold, A. G.,Frankel, D.,Gordon, F. R., McRoberts, G.,Norcia, A., & Stemfels, S. Development of sensitivity to information for impending collision. Perception & Psychophysics, 1977, 21, 97-104. Yonas, A., Oberg, C., & Norcia, A. Development of sensitivity to binocular information for the approach of an object. Developmental Psychology, 1978, 14, 147-152. Zimmennan, A. A., Armstrong, E. L., & Scammon, R. E. The change in position of the eyeballs during fetal life. The Anatomical Record, 1929, 59, 109-134.
VALIDATING THEORIES OF INTELLIGENCE'
Earl C . Butterjield. Dennis Siladi. and John M . Belmont KANSAS MENTAL RETARDATION RESEARCH CENTER
I . INTRODUCTION ......................................................
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I1. A STRATEGY FOR STUDYING INTELLECTUAL DEVELOPMENT .......... A . ANALYZE PROCESSES WITHIN AGE GROUPS ...................... B. CORRELATE PROCESS MEASURES WITH AGE ...................... C. ELIMINATE AGE DIFFERENCES WITH PROCESS INSTRUCTION . . . . . .
96 97 99 100
111. ILLUSTRATION OF THE STRATEGY FOR STUDYING INTELLECTUAL
DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. SELECTION OF AN INVESTIGATIVE DOMAIN ...................... B . PROBLEM SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C . CORRELATE PERFORMANCE WITH AGE ........................... D . ANALYZE PROCESSES WITHIN AGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E . RELATE PROCESSES TO AGE ..................................... F . TEACH CHILDREN TO PROCESS AS ADULTS ....................... G . TEACH ADULTS TO PROCESS AS CHILDREN .......................
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IV . A STRATEGY FOR STUDYING THE GENERALITY OF COGNITIVE PROCESSES .......................................................... A . IS THE PROCESS SUBORDINATE OR SUPERORDINATE? . . . . . . . . . . . . . B . DETERMINING THE GENERALITY OF SUBORDINATEPROCESSES ... C. DETERMINING THE GENERALITY OF SUPERORDINATE PROCESSES .
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V . ILLUSTRATION OF THE RESEARCH STRATEGY FOR TESTING PROCESS GENERALITY ........................................................ A . DECIDE WHETHER PROCESS IS SUBORDINATE OR SUPERORDINATE B. TESTING THE GENERALITY OF SUBORDINATE PROCESSES . . . . . . . . . C . TESTING THE GENERALITY OF SUPERORDINATEPROCESSES ....... VI . CONCLUDING CONSIDERATIONS ..................................... A . THE SEVERAL ROLES OF PROCESS ANALYSIS ..................... B . NONMETRIC COMPLETENESS CHECKS ............................
131 131 140
147 153 153 155
'The preparation of this paper and the research on which its ideas are based were supported by USPHS grants HD.00026. HD.00870. HD.08911. and HD.13029 .
95 ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR. VOL. 15
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C. INSTRUCIPJG AWAY AGE-RELATED DIFFERENCES IN PERFORMANCE .................................................. D. ECOLQGICAL VALIDITY ..........................................
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I. Introduction In this chapter we will describe and illustrate a research strategy for validating theories of intelligence. The strategy is dauntingly complex, but it is required by the wide acceptance of two simple ideas. The first is that intelligence develops: Behavior becomes increasingly complex and abstractly organized with age. The second idea is that individual differences in intelligence are general: People who perform relatively intelligently in one situation are likely to perform relatively intelligently in other situations. Even though some people use specialized forms of knowledge and specialized ways of thinking, a person must behave effectively in general to be termed intelligent. The idea that intelligence develops is accepted by process and structural theorists alike; it is accepted by continuity and noncontinuity theorists, by those who do and those who do not subscribe to stage theories, as well as by those who accept the atheoretical view that intelligence is only what IQ tests measure. The idea that intellectual differences are general can be seen in the functionalist argument that intelligence is adaptability, because adaptability amounts to performing well in diverse situations. It can be seen in the Piagetian argument that an instructional experiment has not influenced intelligence unless it has changed a wide range of uninstructed behaviors as well as the instructed ones. The idea can be seen in any standardized test of intelligence, since even the most factorially pure tests yield composite IQ or mental age scores. The wide acceptance of these two ideas makes their complex research implications fall on all who would test theories of intelligence, which is to say, on all who would test cognitive theory.
11. A Strategy for Studying Intellectual Development In cognitive theory, behavior is distinguished from processes that underlie it. The scientific goal is to explain behavior by reference to processes and (others would say) by reference to mental structures. By process, we mean any aspect of cognition that changes with age or can be changed by experience. This meaning includes most explanatory concepts invoked by cognitive theorists, including
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“structural” concepts. Since the goal is to explain performance by reference to processes, validating cognitive theory requires that one show relationships between performance and process, and this requires research designs and dependent measures that allow separate inferences about process and performance. It also requires process manipulations that influence performance. The belief that intelligence develops is based on the observation that as children age, their behavior becomes more complex and abstractly organized. The generic hypothesis of developmental cognitive theory is that at least some of the processes that underlie performance also become more complex and abstractly organized with age. The research strategy required to determine whether changes in underlying processes explain intellectual development must allow for the possibility that only some processes develop, and it must make provision for determining which processes do and which do not change with age. The fact of cognitive development and acceptance of the process/performance distinction require the use of the entire strategy outlined in Table I to validate a theory of intelligence. The strategy begins with three preliminary steps, the first two of which are judgmental. Step 1 is to choose an important intellective domain of investigation. As in all judgmental matters, importance lies in the mind of the investigator, but there are consensual constraints. Since Galton’s time, for example, few have supposed that sensory thresholds or simple reaction times reveal much about intelligence. Matters having to do with language, world knowledge, reasoning, or memory are now far more likely to be agreed upon as centrally important to intelligence. Having selected a domain of investigation, one must settle on some criterion problem(s). Most investigators settle on one, though the trend is toward the use of multiple performance problems. In part, this trend reflects an increased recognition that one should establish the generality of cognitive analyses (as will be discussed in the second half of this article). The third step is to establish that performance on one’s criterion problem(s) is correlated with age. Following these preliminaries, the research strategy begins in earnest at Step 4 (Table I) with a process analysis of criterion performance within narrowly restricted age groups. It continues, in Step 5 , with demonstrations that the processes identified in Step 4 change with age. In Steps 6 and 7, it moves to instructional experimentationdesigned to make the process theory meet the logical requirements of manipulative experimentation. A.
ANALYZE PROCESSES WITHIN AGE GROUPS
Even though one goal of cognitive theories must be to explain intellectual development, Step 4 calls for analyses performed within narrowly defined age groups. The purpose is to validate, independently of age, each process that accounts for any performance variability. Without such validity, no clear conclusions can be drawn from establishing procesdage relations, which is called for in
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TABLE I How to Validate a Process Explanation of Cognitive Development Step 1.
Choose an important cognitive domain.
Step 2.
Select criterion problem(s) that fairly represent performance in the chosen domain.
Show that performance on the criterion problem@)correlates with age. Step 3. So far, the work will have been judgmental (Steps 1 and 2) and descriptive (Step 3). Steps 4 through 7 are efforts after explanation. Step 4.
Step 5 .
Perform a process analysis of performance on criterion problem(s), within ages. A. Make process measurements that correlate with performance. B. Show correlations between independent measures of each process. C. Manipulate each process. D. Show that each process manipulation changes performance. E. Determine by multiple correlation whether the validated processes combine to account for all variance in criterion performance. If they do not, more process analysis will be needed (Steps 4A through 4D). Show that processes underlying performance change with age. Demonstrate correlations between age and each process measure. B. Using performance measures, demonstrate interactions between age and process manipulations. Collect concurrent process measurements. C. Determine by partial correlation whether the processes that correlate with age reduce the agelperformance correlation to zero. If they do not, more process analysis will be needed (Step 4).
A.
Step 6.
Teach children to process as adults, thereby raising their performance to the level of similarly instructed adults. If instructed children’s performance falls short of instructed adults’, check concurrently collected process measurements to see that instructions actually induced children to process as adults. A. If instructions failed to induce adult processing, revise them and try again. B. If instructions did induce adult processing, return to Steps 4 and 5 for further process analysis. C. If children’s and adults’ instructed performances are equal, but the instructions raised adult performance too, examine process measures to see that adults who contributed to the increase were using childish processing prior to instruction.
Step I.
Teach adults to process as children, thereby lowering their performance to the level of similarly instructed children. If the instructed adults’ performance lies above instructed children’s, use concurrently collected process measurementsto see that instructions actually induced adults to process childishly. A. If instructions failed to induce childish processing, revise them and try again. B. If instructions did induce childish processing, return to Steps 4 and 5 for further process analysis. C. If children’s and adults’ performance are equal. and the instructionslowered children’s performance, examine process measures to see that children who contributed to the lowering were using relatively mature. processing prior to instruction.
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Step 5 . Since age cannot be accelerated, reversed, or otherwise manipulated, ways must be provided to determine whether any process correlate of age arises from an unidentified confound of age. Step 4 calls for two such provisions: One is to establish the validity of each process within narrowly defined age groups; another is to produce and validate a process theory that accounts for all of the within-age variance in performance on the criterion problems used to study intellectual development. Having such a complete account allows, during Step 5 , determinations of which processes are directly correlated with age and which are correlated only because of their confounding with other processes. Such a complete account is also necessary to allow determination of which processes do not develop. A complete theory of intelligence will include concepts that are not developmental as well as those that are. Moreover, until a theory can account for all of the variance in its target performance measure(s), any other incomplete account can be claimed to be the basic account. Someone will always accept such counterclaims (Newell, 1973), although as long as any appreciable variance remains unaccounted, questions about which theory is basic or more general, elegant, or parsimonious can be given no disciplined answers. Only an exhaustive account of variance is immune to capricious challenge. An exhaustive account of variance is a basic account. Given two or more exhaustive accounts, disciplined considerations of elegance, generality, and parsimony become relevant. A complete accounting of performance variance within ages is necessary for full validation of a process theory, but it is not necessary to fulfill Step 4 before moving to Step 5 of the validation strategy. If it were a prerequisite, developmental studies could not yet be performed. Step 4 is included to emphasize that strong interpretations of developmental studies are possible only when all within-age variance has been explained. B. CORRELATE PROCESS MEASURES WITH AGE
The purpose of Step 5 is to determine whether a process changes with age. It also provides a test of the developmental completeness of a process theory. If the analysis upon which a theory builds is developmentally complete, then it will be possible to reduce performance/age correlations to zero by partialling out indices of processes that develop. Step 5 also provides information necessary to respond effectively to a question that inevitably arises in response to studies of the sort outlined in Steps 6 and 7. Such instructional studies have generally been done by investigators with a behavioral rather than a cognitive orientation. Usually, such studies have not been preceded by developmental process studies of the sort outlined in Step 5 . Rather, behavioral analysts take raising or lowering criterion performance as their goal, and they modify their instructional approach by intuition until the goal
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is reached. Regardless of the utility of the goal, cognitivists may ask whether the behavior analysts’ instructional routines mimic or can be taken as a model of the normal course of development. Thoughtful behaviorists will say that the instructions stand only as a model of how development might normally proceed, but they will not assert that it is a model of how development does proceed. Then, it will often happen that the behaviorists’ work will be dismissed by cognitivists as developmentally irrelevant, particularly if the cognitive critics can think of some developmental fact to suggest that the behaviorists’ instruction might not exemplify a good model of normal development. Step 5 provides data to justtfy the assertion that the processes described in Steps 6 and 7 do in fact change in the normal course of development. Thus, if behaviorists who have used instruction in generalized imitation as a prerequisite to teaching language to severely retarded children had also shown that generalized imitation precedes language development, and that it accounts for normal children’s language acquisition, their work could be less readily dismissed by cognitivists as irrelevant to normal development. It might still be dismissed on the ground that normal development cannot be mimicked, but that would amount to a rejection of the possibility of studying development experimentally. Step 5 is stated in terms of chronological age (CA), but mental age (MA) can be a more appropriate index of developmental level. The strategy allows the use of MA as well as CA. In fact, the strategy in Table I is applicable to any sort of comparative research: cultural differences, personality differences, and sex differences. Thus, the study of sex differences would begin, in Step 4, with analyses performed separately for males and females, and it would proceed, in Step 5 , to comparisons between males and females. A more general expression of the strategy can be found in Butterfield (1978). C. ELIMINATE AGE DIFFERENCES WITH PROCESS INSTRUCTION
Cognitive theory in general is vulnerable to the criticism that its empirical bases are weak. It can fairly be said that the ties between the concepts of basic cognitive science and its data are tenuous (Anderson, 1976; Chi, 1976; Schank, 1976; Townsend, 1972, 1974). Developmental cognitive theory is only slightly less immune to this criticism than basic cognitive theory (Butterfield, 1978; Butterfield & Dickerson, 1976). Some argue that it is impossible with empirical methods alone to affirm any theory satisfactorily (Lachman, Lachman, & Butterfield, 1979; Reese & Overton, 1970; Weizenbaum, 1976). Nevertheless, the premise of Steps 6 and 7 is that applying the logic of manipulative experimentation to process explanations will greatly strengthen the ties between cognitive theory and data. In the f m t place, process instruction that affects performance shows most directly that the process is plausible. Perhaps more importantly, applying the full instructional logic provides the strongest possible basis for claims about the normal course of cognitive development.
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The logic of Steps 6 and 7 is that instructed processes can be invoked as explanations of age or other group differences only if identical instructions are applied to various (age) groups, and then only if the instructions leave the groups performing at identical levels. The effect of the instructions can be to raise the performance of the younger group (Step 6) or to lower the performance of the older group (Step 7). However, if after instruction reliable differences remain between the age groups, then the processes affected by the instructions may not be responsible for differences between the ages under uninstructed conditions. In Step 6, where instructions are intended to improve poor performance, the notion is that older groups who naturally perform better are already using the instructed processes, but the younger groups who perform poorly are not. Therefore, the more accurate group should benefit little or not at all from the instructions, but the less accurate group should benefit greatly. Conversely, in Step 7, where the instructions are intended to eliminate the processing thought to account for adults’ accurate performance, the inaccurate children should be impaired relatively little, since they are presumably not using the target processes anyway. When the goal is to account for young children’s inaccurate performance, the instructional approach requires that older people be instructed along with the younger ones. In its most definitive form, which is not yet attainable, the instructional experiment leaves the performance of either the oldest (Step 6) or youngest (Step 7) group unchanged, and the performance of all groups identical. Implementing such an experiment would require a complete process understanding of the development of some intellectual performance, as well as accurate age norms specifying when the relevant processes have developed as completely as they will without special tuition. Given that there is no process analysis that completely accounts for any cognitive performance, producing identical group performance is improbable: Older groups will likely perform better than younger ones even after instruction, unless ceiling or floor effects are encountered. Moreover, there is ample evidence that fully mature individuals do not process optimally, so that older groups will almost always benefit from process instructions that are not carefully constrained by a knowledge of how far development carries people toward optimal processing. As long as the oldest group benefits, the process account of development is incomplete, even if the process analysis of within-age performance is complete. For these reasons, there must be a constant interplay and recursiveness between the various steps in the research strategy, and rules to guide this interplay are given in connection with Steps 6 and 7 (see Table I). Instructional experiments cannot be interpreted clearly unless unobtrusive measures are taken of the instructed processes. The goal of such experiments is to change performance by manipulating processes; especially when process analyses are incomplete, instruction can influence process without influencing performance. In order to determine whether a failure to change performance results from a failure to change the target process, unobtrusive process measures
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should be taken during instruction. Also, when instructions designed to improve the performance of younger people also improve the performance of older people, unobtrusive process measures taken prior to instruction are needed to determine whether the older people who benefited did so because they were processing relatively youthfully before instruction. Whenever the effects of instructions are assessed with a posttest, process measures must be taken then, to assure that the subjects continued to use the instructed processes following the termination of instruction. Few intellective problems allow any, let alone unobtrusive, measurement of the processes required for their accurate performance. Cognitive scientists have invested heavily in inferential procedures and lightly in developing more direct measures of cognitive processes (Belmont & Butterfield, 1977). Until this lamentable trend (Newell, 1973) is reversed, satisfactorily complete instructional tests of developmental cognitive theory will be few indeed. Moreover, the few tests will be performed with criterion procedures that have been around for a long time, because only for well-studied problems have underlying processes been identified and the necessary range of unobtrusive measures been developed. Cognitive theorists now study criterion performances that are markedly different from what they used to be, so that any investigator who tries seriously to follow the strategy outlined in Table I may be criticized as old-fashioned and outdated with respect to his performance measures. Our best advice is to turn the other cheek and persist, because we see no way other than the strategy in Table I to produce valid developmental cognitive theory.
111. Illustration of the Strategy for Studying Intellectual Development We will use our own research to illustrate the strategy outlined in Table I. No other work seems as suitable for this purpose, although the programmatic studies of memory by Ann Brown (1975, 1978; Brown & Barclay, 1976; Brown & Campione, 1978; Campione & Brown, 1977), those of imagery by William Rohwer (1973), James Tumure (Taylor & Turnure, 1979; Turnure, Buium, & Thurlow, 1976), and John Borkowski (Kendall, Borkowski, & Cavanaugh, 1980; Kestner & Borkowski, 1980), and those of the balance beam problem by Siegler (1976; Klahr & Siegler, 1978) could be used to illustrate many of the substeps enumerated in Table I. The entire strategy outlined in Table I seems to have been satisfactorily approximated only by programmatic efforts of closely associated investigators. Having searched the literature extensively (Belmont & Butterfield, 1977), we find that no amount of research in a particular cognitive domain, when spread across many laboratories, has managed to approach a satisfactory representation of the strategy in Table 1. Two of us (Belmont and Butterfield) began to plan the research that we will
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use here for illustrative purposes in 1967, several years before we had fully formulated all aspects of the strategy outlined in Table I. Steps 1 through 3 occurred to us immediately, as we suppose they must to any investigator who contemplates a new investigative effort intended to clarify intellectual development. Table II shows that the first report of research from this program (Belmont & Butterfield, 1969) satisfied the requirements of Steps I through 3 and included instances of the sort of work called for by Steps 4A, 4B, 4C, 5A, and 6A. The next fourreports (Butterfield, Belmont, & Peltzman, 1971; Butterfield, Peltzman, & Belmont, 1971; Buttefiield & Belmont, 1971; Kellas & Butterfield, 1971) concentrated on within-age process analysis (Steps 4C and 4D).Then came six reports (see Table 11) that combined instructionalwork of the sorts called for in Steps 6 and 7 with further within-age analysis (Step 4) and correlation of age with process (Step 5 ) . Shortly before the last of these reports (Butterfield& Belmont, 1977), we finished formulating the strategy outlined in Table I. The most recent report in this series (Butterfield, 1978) described our first efforts to assess the completeness of our process account of performance in our domain of investigation (Step 4E) and of our account of performance development (Step 5C). The chronology depicted in Table I1 suggests that implementing the strategy is a back-and-forth affair, characterized by moving recursively among the strategy’s steps. The last column of Table I1 lists the pages in this article where descriptions are given of work that illustrates each step of the strategy. Some of the illustrations are drawn from the published reports listed in Table 11; others are from previously unpublished research. A. SELECI’ION OF AN INVESTIGATIVE DOMAIN
In 1967, Belmont and Butterfield began their program of research into the information-processing aspects of intelligence. They satisfied Step 1 of the strategy outlined in Table I by judging that the laboratory study of children’s memory functions would reveal intellectively important strategies for processing information. In part, memory seemed a suitable investigative domain because the science of mnemonics offered solid background data about normal adults and a wide range of methods that could be elaborated to expose the developmental character of information processing. Reviews of comparative and developmental research on both long-term memory (Belmont, 1966) and short-term memory (Belmont & Butterfield, 1969) showed that forgetting rate does not vary appreciably with either age or intelligence, so the research was focused on the relatively directly measurable processes involved in information input and retrieval. B. PROBLEM SELECTION
In order to provide separate measures of input and retrieval processes and to make input measures operationally independent of performance measures, Bel-
TABLE II. Steps of a Research Strategy to Validate an Explanation of Cognitive Development That Are Illustrated (X)by Experiments by Belmont, Buttefield, and colleagues
step I
103
step 2
103
sap3 X
X
10s 106
step 4
4A
X
X
Lo7
48
4c
X
X X
X
X
I11
X
X
X
X
X
X
X
X
114
X
X
116
4D 4E
X
117 120
steps
5A
X
X
X
X
x
120
X
x
121
x
122
5B
X
X
X
X
X
X
x step 6
6c
X
X
6A 6B
X
X
X
X
X X
X
X
X
X
X
stcp7
7A
m 7c
X
X
123
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mont and Butterfield selected variants of subject-paced list recall procedures, reported first by Ellis and Dugas (1968), as the memory problems to be analyzed. As a person paces his or her way through a list of words, letters, or pictures, the time following each successive item is recorded. When a subject presses a push-to-see button, the first stimulus in a list appears for .5 seconds. When this stimulus disappears, a timer is started, and it runs until the next time the subject pushes-to-see. This second button-push records the time since the offset of the first stimulus, presents the second stimulus for .5 seconds, resets the timer, and starts again. This process is repeated until all stimulus items have been presented, and all interstimulus pauses are recorded. We used the subject-created pause times to make inferences about input processes. We sometimes supplemented these temporal data with overt rehearsals and introspective reports. We used several recall requirements with the subject-paced input procedure, including probes for the location of particular items, free recall, serial recall, and “circular” recall (described below). With each of these requirements, we have used response latencies or interresponse times to assess retrieval processes, and we have supplemented these data with examinations of the distribution of errors across serial positions. The procedures are thus rich with process measures, all of which can be taken on every trial of an experiment, and most of which can be taken unobtrusively. C. CORRELATE PERFORMANCE WITH AGE
It took little research to satisfy Step 3 (Table I). Even in 1967, a huge number of research articles reported age differences in various memory performances. The only thing we could not determine from the literature was whether performance measures derived from subject-paced memory procedures correlate with age. We have since shown that they do, for each of the several recall requirements we have studied. For example, it can be seen in Fig. 1 that subject-paced free recall increases with age. These data were derived from the performance of four groups of 40 children, ages 8, 10, 12, and 14. Individual children paced themselves through 15 different 9-word lists, which they then recalled in whatever order they chose. Figure 1 shows that each 2-year increment in age is associated with an increment in recall, especially across the first five serial positions. Circular recall also increases with age. By circular recall, we mean recollection of the last few items from a list before recollection of the rest. For example, in 3/5 circular recall of lists eight words long, words 6 , 7 , and 8 are to be recalled in order before words 1,2,3,4, and 5, which are also to be recalled in order. We recently administered subject-paced 3/5 circular recall to 80 people who ranged in age from 10 to 20 years. The correlation between age and number of words recalled correctly was .57 ( p < .01). Correlations of this magnitude are entirely typical of studies of age and memory performance. While the age/performance
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Fig. 1 . Mean percentage correct recall at each of nine serial positions across 15 trials offree recall by 8- (open triangles), 10- (open circles), 12- (closed triangles). and 14-year-old (closed circles) children. (Afer Butterjield & Belmont, 1977, Fig. 7.4.)
relations are almost always statistically significant, they also leave enough unexplained variance in memory performance to allow within-age studies of the relations between process and performance. D. ANALYZE PROCESSES WITHIN AGES
None of the five sorts of studies listed under Step 4 (see Table I) produces by itself a process analysis of problem performance, but together they provide ample bases for inferring processes that underlie problem performance and for judging the completeness of the inferential analysis. Being comlational, Substep 4A provides no evidence for inferring that variations in a process cause variations in performance, but it can provide ample bases for causal hypotheses and for manipulative research that might justify causal inferences. Substep 4B embodies the cognitive science criterion of converging validation (Garner, Hake, & Erikson, 1956). Since no underlying process can be measured directly, process inferences must be validated by converging measurements. Substep 4C calls for experimental manipulations of identified processes. Substep 4D requires that such manipulations be shown to influence performance. Especially in the early stages of the analysis of a performance requiring the coordinated use of several processes, some of which have not yet been isolated, one can manipulate a process without influencing performance. In such early stages, successful manipulation of the process, even without consequent performance changes, is enough to justify retaining the process in one’s model. Eventually, however, it must be shown, as specified in Substep 4D, that performance changes result from manipulation of every process in one’s model. Substep 4E calls for a multiple regression analysis of the amount of performance variance explained by measured processes. It is one of the strategy’s several checks on the completeness of an ongoing analysis. Completeness checks are included in each step because it is
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unreasonable to require a complete process analysis (Step 4) before undertaking correlational (Step 5 ) and manipulative (Steps 6 and 7) developmental research, and the results of developmental research can provide important clues to guide further analysis within ages (Butterfield & Belmont, 1977; Butterfield, Wambold, & Belmont, 1973). 1 . Correlate Process with Performance To illustrate Step 4A, we will present data to show that three process measures predict short-term recall performance within narrowly constrained age groups. The process measures were derived from temporal features of input and output activity, and the performance measure was percent correct recall. Belmont and Butterfield (1969) used a position probe recall problem to establish a relation between process and performance measures. Having paced herself or himself through a list of consonant letters, the subject’s job was to expose a probe item (selected randomly from the list’s consonants) and to indicate its position by pressing one of the transparent windows covering each of the positions at which the letters were presented during list input. Ten 20-year-old college students studied 27 lists constructed by selecting nine consonants at random from a pool of 16 consonants. Ten 1 1-year-old sixth-graders studied 21 similarly constructed lists of seven consonants. On the hypothesis that the subjects’ pauses during self-paced input would reflect rehearsal, Belmont and Butterfield selected the five subjects from each age group who paused the most (High) and the five who paused the least (Low) during input. The two leftmost panels of Fig. 2 show the mean pause times following each consonant for these High and Low groups. The middle panels show the percentage correct recall at each position, and the right panels show the latency from probe onset until response, for correct responses only. The High subjects were selected because their total pause times were long, but Fig. 2 shows that pauses following the middle items in the list contributed much more to the total pause times than did pauses following the beginning and end items. From this pattern of pausing for the High subjects, Belmont and Butterfield inferred that even those people who rehearsed most do not rehearse for the final items in a list for which they will be tested by position probe. Therefore, the percent correct functions for the High and Low subjects should differ primarily at the middle and beginning positions, which is what the middle panels of Fig. 2 show. Within both age groups, pause time, which is a measure of the rehearsal process, predicts recall accuracy at the middle and early positions. Mean correct response latency (right panels of Fig. 2) also varies systematically across serial positions, in much the same way that input time does, suggesting a relation between input and output processes. The data show a relation between process and performance within both age groups, but they also indicate that the patterning of pauses as well as total pause time might reflect interesting processing.
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(COLLEGE STUDENTS) PERCENT
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Results like the foregoing led us to distinguish two aspects of input processing: effort, which we index with total pause time, and strategy, which we index with the form of pause pattern across serial positions. Since patterns with longer total times have greater variability across positions, we study pattern form only after standardizing the pause times from each trial. For each trial of every subject, we use the observed mean and standard deviation to calculated standardized pause times with mean = 4.0 and standard deviation = 1.0. To compare the shapes of these standardized pause patterns, we use an omega square statistic (Dodd & Schultz, 1973).Omega square (a2) is derived from an analysis of variance calculated on a matrix of standardized pause times. The columns of the matrix are serial positions and the rows are the standardized patterns to be compared. From an analysis of variance of such matrices, 0 2
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We used standardized pause patterns and o * in a recent and previously unreported study to correlate accuracy with strategy. We required 48 college students to recall lists of nine words in two ways designed to produce different pause patterns. For the first 14 and last 7 of 35 lists studied, the subjects were to recall the words in the order 9 5678 1234 (called 1-4-4). This recall requirement led them to pause longer following the fourth and eighth words than following any of the other words. For trials 15 through 28, the subjects were required to recall in the order 789 456 123 (called 3-3-3). This led them to pause longest following the third and sixth words. We divided the 48 subjects randomly into two groups of 24, so that we could use replication by independent groups to assess the reliability of any observed relations between strategy and recall. We then selected the eight most and eight least accurate subjects from each replication group, by averaging the number of words recalled correctly across all 35 trials. The eight High accuracy subjects from Group 1 and Group 2 recalled a mean of 5.83 words (65%) and 6.31 words (70%) per trial, respectively. The two Low groups had means of 3.23 (36%) and 3.60 (40%). Thus, the High subgroups were nearly twice as accurate as the Low subgroups. For each of the four subgroups, we averaged pause patterns from Trials 26 through 28 (last 3-3-3 trials) and 33 through 36 (last 1-4-4 trials). The mean pause times thus obtained for each output order are shown in Fig. 3. The pause patterns for both High accuracy subgroups have higher peaks at the expected points than do the pause patterns of the Low accuracy subgroups. Since the total pause times of the High accuracy subjects were greater than those of the Low accuracy subjects, we used standardized pause times to study the relation of input strategy to accuracy. Since the High group's raw pause patterns (Fig. 3) fit ow expectations for appropriate 9r
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processing on our two recall requirements, we used their standardizedpatterns as standards of appropriate processing. To keep the standards independent of the data to which they were compared, the standardized patterns from all subjects in Group 1 were fitted individually to the averaged data from Group 2 High subjects, and vice versa. Thus, every standardized pause pattern for every subject in Group 1 was fitted to the mean standardized pattern of Group 2 High subjects on Trials 33 to 35 (our 1-4-4 standard) and on Trials 26 to 28 (our 1-3-3 standard). The High and Low subjects’ o2statistics were averaged separately. If the High subjects fit the appropriate pattern more closely than the Low subjects, then their mean o2should be higher for trials on which the standard matched the recall requirement (1-4-4for Trials 1 to 14 and 29 to 35 versus 3-3-3 for Trials 15 to 28). Both Highs and Lows should have had low o2when the standards did not match the requirements. Figure 4 shows that the High subjects from both Groups 1 and 2 had greater w 2 than both Low groups when standard and requirement match. The nonmatching data were comparably low for both groups. We conclude that the process measure of strategy (standardized pause pattern) predicts performance (recall accuracy). In another previously unreported study, we examined the correlation between output processes and recall accuracy by administering 10 trials of 3/5 circular recall during which subjects were required to recall words in the order 678 12345. Total number of words recalled on Trials 6-10 served as the performance measure. We taperecorded the subjects’ recall, and selected the first two trials for which a subject recalled nothing but words from the list and recalled at least two of the last three words before recalling at least two of the first five words. These recordings were used to derive a measure for each subject of retrieval time for 1-4-4 ,3-3-3 , - -n
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rehearsed material: the time from end of last word recalled from positions 6-8 to the beginning of second word recalled from positions 1-5. Four groups of 20 subjects were studied: CA 10, 11, 12, and 20. Correlational analyses within the age groups showed negative relations between overall accuracy and retrieval time for rehearsed words. For CA 10, 11, 12, and 20, the correlations were - .29, -.57, -.20, and -.30, respectively. We infer that speed of retrieval of rehearsed information predicts recall accuracy within ages.
Summary. Step 4A of our research strategy calls for the correlation of process with performance measures. To illustrate the implementation of Step 4A, we described three experiments. The first experiment, by Belmont and Butterfield (1969), showed that greater effort, as indexed by longer total pause time, is associated with greater recall. The second, previously unreported experiment showed that rehearsal strategy, as indexed by the standardized form of pause patterns, also predicts accuracy. The third experiment, also previously unreported, showed that faster retrieval of rehearsed information is associated with greater recall. These three process measures-ffort, strategy, and retrieval speed-will figure prominently in our subsequent illustrations of the implementation of the strategy required to show that a cognitive process develops. 2. Correlate Independent Measures of Processes Step 4B calls for the calculation of correlations between independent measures of each process. Part of the logic of Step 4B is the same as the logic of convergent validation: Unless a process can be shown to be measurable in two or more ways, an investigator cannot claim confidently that the process inheres in people instead of in a single measurement procedure. However, the logic of converging operations does not require that the various measurements be taken from the same people and that they be correlated. The logic for this requirement has been developed by Underwood (1975) and illustrated with experiments by Butterfield and Dickerson (1976). By Underwood’s logic, Step 4B is an individual differences test of process validity. Individual differences tests require that one measure of a process share appreciable variance with another measure of the process. Unless differences between individuals correlate across measures, the logic asserts that no important psychological process has been demonstrated. Our illustration of how to implement Step 4B is a previously unreported study of the correlation between two independent measures of input strategy. The two measures are pause time patterns and overt verbalizations. Fifteen 11-year-olds were required to study 30 lists for free recall. Each list was nine words long, and no word was repeated. The children were instructed for free recall, and for the first 20 trials they performed their study covertly, while we measured pause time. Immediately following the twentieth list, each child was asked how he or she had gone about learning it. The child was then instructed to show how he or she had
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studied the twentieth list by working through it again, exactly as during the first time, but saying aloud what had only been thought before. This verbalization procedure was used on each of the remaining 10 trials. A child first studied a list silently, and then worked through it again, trying to say exactly what he or she had thought the f i s t time through. In this way, each child produced two pause time curves for each of the last 11 lists (20 through 30); one with overt verbalization and one without. Since there were 15 subjects, there were a total of 165 lists for which verbalizations were taperecorded. To assess the effects on pause time of having to verbalize each list during a second time through, each child's mean pause time at each position was calculated for the last five trials (16 to 20) prior to introduction of the verbalization and for the first five trials (21 to 25) thereafter. For Trials 21 to 25, two average pause time curves were obtained, one for the covert and one for the overt productions. The three group average curves are shown in Fig. 5 . The pause time functions prior to introduction of the overt procedure (trials 16 to 20) do not differ qpreciably from pause times on the covert trials after introduction of the overt procedure (trials 21 to 25). The pause times taken while verbalizing Trials 2 1 to 25 are longer, but fall very much in the same pattern. We conclude that introducing the overt procedure did not importantly influence what the children did on subsequent covert trials, even though pause times were longer during verbalization. The taperecorded verbalizations were used to divide the 165 trials into six mutually exclusive categories of input strategy: Labeling, in which the child said each word as it appeared, but never said it again; Building, in which each word was said as it appeared, and again after all subsequent words (one; one-two; one-two-three; etc.); Building with Terminal Labeling, in which the child built from the beginning of the list, but only labeled the last word or two; Grouping, in which the child used building rehearsal for two or more isolated groups of words (one; one-two; one-two-three; four; four-five; four-five-six); Grouping with
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Terminal Labeling; and Other, in which some or all of the words were said more than once, and again following the presentation of other words, but the verbalization pattern fit none of the preceding categories. Two judges independently categorized the recordings. They agreed on 94% of their categorizations. To examine the relationship between input strategy and pausing, we averaged the pauses taken during the covert (first) trial of each list in each category. That is, the categorizations were based on verbalizations during the second NII through each list, and the averaged times came from the first run through. The mean pause time curves for each category are shown in Fig. 6, where it can be seen that Labeling resulted in a low flat function, as it should have. The pause pattern for Building increased systematically from the first to the last word, again confirming expectations from the overt verbalizations. The verbalizations of most subjects who used Grouping indicated that each rehearsed group included three items. A minority of subjects grouped by twos or fours, but the majority pattern dictated the average seen in Fig. 6. Most subjects who used Terminal Labeling with Grouping grouped by threes. A minority grouped by twos, and the average pause pattern shown in Fig. 6 is consistent with this distribution of strategies. Most subjects who used Terminal Labeling with Building built either seven or eight items and labeled two or one. A minority built six or seven and labeled three or two. The mean pause pattern in Fig. 6 for Building with Terminal Labeling is consistent with this distribution of verbalizations. The Other category was a diverse mix of active rehearsal and labeling, which is reflected in
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the irregularity of the longer pauses in the Other category of Fig. 6. We conclude that the pause patterns and overt verbalizations are well-correlated independent measures of rehearsal activity. 3. Manipulate Processes According to the strategy outlined in Table I, the plausibility of a process is only incompletely established by correlating independent measures of it. The strongest evidence for the plausibility of a process comes from manipulating it, as called for by Step 4C (Table I). Depending upon how completely an investigator has analyzed the processes underlying performance on a criterion problem, these manipulations may be crude, producing gross effects, or they may be precise, producing subtle effects. The experiments used here for illustrative purposes were conducted after our understanding of the processes underlying probe recall was relatively complete. The experiments concern retrieval processes. The flow chart in Fig. 7 is a process model of probe recall as it was understood by Butterfield and Belmont (197 1). Among other things, the flow chart expresses the hypothesis that effective information processors conclude their study of a list (at Box 3, Fig. 7) with information about items from the early portion of the list in a longterm memory store and information about the terminal items of the list in an input buffer or short-term store. With information in these two stores, a probe is presented (ExperimentalEvent 2, Fig. 7). In response to this probe, the subject first transfers a representation of the terminal items to an output buffer (Box 4) and represents the probe item in the input buffer (Box 5 ) . The subject compares the contents of the input and output buffers (Box 6) and responds if there is a match between the two (Box 8). If no match occurs, the subject transfers the representation of the earlier items of the list to the output buffer (Box 7) and compares them to the probe representation in the input buffer (Box 6), responding when a match is made (Box 8). One implication of this analysis of output processes is that it should take longer to respond correctly to items retrieved from the long-term store than to those remaining in the input buffer at the end of acquisition. Thus, people who have input eight items by rehearsing the first four and merely labeling to the last four should take longer to respond to a probe from the first four than from the last four. Figure 8 shows the correct response latencies obtained from seven college students who used such a 4-4 strategy for lists of eight consonants. Every subject took longer to respond to the first four than to the last four items. Moreover, the group average of the seven subjects shows that there is a systematic increase in latency for the first four items, but not for the second four (see Fig. 8). Butterfield and Belmont ( 1971) reported six experiments that explained the pattern of response latencies in Fig. 8 by manipulating all of the output processes included in Fig. 7. For example, Box 6 implies that the number of items in the
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Experimental Event 1: A list is presented for input. The Subject:
first items to be stored
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Experimental Event 2: Presentation of t h e probe item whose position is t o be recalled. The Subject:
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input buffer when study is completed controls the time before beginning the search for items transferred to the long-term store. Butterfield and Belmont tested this implication by having college students rehearse four consonants, and then label but not rehearse zero, one, or two additional consonants. Thus, there should always have been representations of four consonants in long-term memory, but the number represented in the input buffer at the conclusion of input processing
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should have varied between zero and two. Figure 9 shows a systematic elevation in the level of correct response latency across the four rehearsed items as the number of labeled items increased from zero (4-0) to one (4-1) to two (4-2), thereby verifying one of the implications of the model in Fig. 7. 4 . Change Peflormance by Manipulating Process Step 4D is a safeguard against retaining in one’s model processes that make no difference for performance. While epiphenomena may not abound in cognitive theory (Butterfield, 1978), one must guard against the possibility that modeled processes are functionless concomitants rather than causes of performance. Step 4D is intended to insure that an investigator’s analyses have identified processes that cause performance variability.
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In the early stages of an analysis, process manipulations might not change performance, because the effectiveness of any one (or group of) process(es) can depend upon the use of other processes. The following example of how to implement Step 4D illustrates this possibility, thereby arguing for continuing an analysis until it is reasonably complete. Butterfield et al. (1973)reported process manipulations based on the model of probe recall presented in Fig. 7.Mildly retarded adolescents were given a pretest prior to instruction about how to perform a six-item probe recall problem. They recalled inaccurately from both primacy (positions 1-3) and recency (positions 4-6) portions of the pretest lists (see Fig. lo). Following the pretest, some of the retarded adolescents were instructed in input processing alone (Boxes 1-3, Fig. 7),while others were instructed in input and output (Boxes 1-8, Fig. 7). Following instruction, both groups recalled more accurately than during pretest, and the recall gains were greater for the group that received instruction in all of the processes (see Fig. 10). We conclude that both input and output processes influence performance and that more complete process analysis allows greater instructional control of performance. 5 . Multiply Correlate Processes with Pevormance
Step 4E is a check on the completeness of a process analysis. It calls for calculating a multiple correlation between every process measure and performance. The demanding aspect of this step is that it requires measures of each process. It is not enough to implement manipulations that allow process inferences; one must measure process use. To date, our analyses have identified three processes that predict recall accuracy when taken singly. Input processes are reflected by the form of the strategy
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and the amount of effort invested in it. Output processes are reflected by retrieval time for items from the long-term store. To obtain multiple correlations of these three processes’ indices with recall accuracy, we administered 10 trials of 3/5 circular recall of lists of eight unrelated words to 20 18-year-old high school students. To index Effort, we used mean pause time per word on Trials 6-10. To secure a standard with which to index Strategy form, we instructed an independent group of 10 18-year-olds to rehearse the first five words cumulatively and to say simply the last three words once each. Following 25 trials of practice using this building-with-terminal labeling strategy, in preparation for 3/5 circular recall, we collected input pause times for one trial. These times were standardized separately for each subject, and mean standardized time pattern was calculated for the group. This pattern was fitted, using 0.3, to each of the uninstructed subject’s standardized pause patterns on Trials 6 through 10, and the mean of resulting five o2scores was taken as the index of each subject’s approximation to the appropriate input strategy for 3/5 circular recall. To measure Output, we taperecorded subjects’ recall. We selected recordings of the second trial from Trials 3 through 10 for which the subject said nothing but words from the list being recalled, and for which the subject recalled at least two of the last three words before recalling at least two of the first five words. For this trial, we measured the time from the end of the subject’s verbalization of the last word recalled from the lists’ last three words to the beginning of the verbalization of the second word of the first five from the list. This Output Time is an index of the time to retrieve words that should have been rehearsed and stored in long-term memory. Our performance measure was the number of words recalled on trials
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6-10, which could have been as great as 40. The mean number of words recalled by the 20 subjects was 32.0. We entered the three process variables (Effort, Strategy, and Output) as predictors in a stepwise multiple regression. F tests showed that each process measure added significantly (p€.O5) to the prediction of accuracy, and together the three accounted for 56% of the variance in recall accuracy ( r = .75). We conclude that our process analysis has moved a fair way toward completion, but we still need to improve our measures of identified processes or to identify other processes. We wish we knew of comparable analyses for other criterion problems, so that we could assess the completeness of this particular analysis relative to others. Our impression, untestable though it is, is that the analysis is relatively complete. 6 . Summary and Conclusions None of the five approaches listed in Step 4 is sufficient by itself to validate a within-age process analysis, but taken together they provide reasonable assurance of the validity of any process. Thus, we are reasonably confident of the validity of the three processes identified in connection with our several variations of self-paced short-term memory procedures. Besides the evidence cited above, other data validate the total time measure of Effort, the standardized pause time measure of Strategy, and the interresponse time measure of Output: Effort correlates with accuracy (as required by Step 4A) and with amount of rehearsal as determined by quantification of overt verbalizations during input (4B); it is manipulable with incentives and by direct instruction (4C); lessening effort with instruction lowers performance and raising effort increases performance (4D); and the total time index of effort contributes significantly to multiple prediction of performance by process measures (4E). Strategy indices correlate with recall accuracy (4A) and with quantification of overt verbalizations during input (4B); manipulating strategy so as to match recall requirements improves accuracy, whde manipulating it to mismatch recall requirements decreases accuracy (4C and 4D); and the standardized pattern measure enters significantly into multiple predictions of performance by process measures (4E). Output measures correlate with accuracy (4A); they are manipulable in ways that affect performance (4C and 4D); and the interresponse time measure enters significantly into the multiple prediction of recall accuracy (4E).
We conclude that each of these processes can be correlated with age with little risk that any resulting correlations will be due solely to some confound with age. The purpose of within-age analyses is to validate processes fully enough to counter the possible claim that any processlage correlation results from some
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unidentified variable that is also correlated with age. Within-age analyses do this by showing that the process predicts performance independent of age. However, it should be recalled that until within-age analysis has accounted for all of the variance in performance, even processes that have gained validity in all five of the ways specified in Step 4 might appear valid only because of their correlation with some unidentified process. Our research on memory processes indicates that we can proceed to developmental studies with some cushion of validity, since each of our process measures has substantial and diverse evidence of validity within ages. Nevertheless, our process measures do not account for all variability in performance, so we must remain alert to the possibility that an entirely different set of processes provide a more valid account of short-term memory as we have measured it. E. RELATE PROCESSES TO AGE
Armed with evidence from Step 4 for the validity of one or more processes, an investigator following our strategy would ask whether the process(es) change with age. Step 3 will have shown that performance changes with age, but not all processes identified within ages need develop. Step 5 is designed to determine which processes account for the development of performance shown in Step 3. 1 . Correlate Age with Process Measures
In order to correlate our process measures with age, as called for in Step 5A, we tested 20 children of CA 10,20 of CA 11, and 20 of CA 12 using the procedures described above for 18-year-olds (see Section III,D,5). Nine of the 60 younger subjects did not recall accurately enough to meet our criteria for calculating Output Time (Section III,D,5), so we were left with 51 younger subjects, whose data we pooled with that of the 18-year-olds, giving a total of 71 people for whom we could correlate each process measure with age. For these 71 people, age accounted for 27% of the variance in recall accuracy ( r = .51, p<.0005). Our three process variables accounted in combination for 56% of the within-age variance in recall accuracy, and we expected that no single process measure would correlate as highly with age as the performance measure itself. The question was, did age correlate significantly with the process variables? The answer was that it did correlate with Total Time and Output Time (pC.005). Age accounted for 9% of the variance in Total Time ( r = -30)and 10% of the variance in Output Time ( r = .32), but it accounted for only 3% of the variance in Strategy (I-= .17). We conclude that two of our three process measures are related to age, and that increases in accuracy with age will need to be explained at least in part as a result of developmental changes in effort during input and in output processing. At least within the age range of 10-18 years, form of strategy selected seems unlikely to help account for development of circular recall performance.
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2. Show Interactions between Age and Process Manipulations Step 5B is included to acknowledge that correlations between process and age cannot be interpreted strongly. The idea is that showing an interaction between age and a manipulation that is known or can be presumed to influence a process provides a better basis than a correlation for inferring that age relates to the process. Belmont and Butterfield (1971b) reported an experiment that meets the requirements of Step 5B by comparing the performance of retarded and normal children of the same chronological age. Mental age was the index of develop mental level. Dependent measures were derived from six-letter position probe procedures. One-third of the subjects from both the normal and the retarded group were given a series of trials on which they were free to select their own method of input processing. One-third of the subjects were instructed to rehearse the fist four letters and to label the last two; this manipulation was designed to increase recall accuracy of poor performers. The remaining third of the subjects were instructed to label each letter as they exposed it and to go on immediately to the next one; this condition was designed to decrease accuracy of good performers. Figure 11 shows the effects of the three conditions (Free, Rehearse, Label) on pause time and recall accuracy. NORMAL
RETARDED 6.5
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Fig. 1 I . Meon pause times and recall accuraciesfor Free (closed circles), Reheorse (triongles), and Label (open circles) input conditions by mentally retarded and normal adolescents. (After Belmont & Butterfield. 1971b. Fig. 2 . )
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The pause time data were collected as checks on whether the manipulations influenced input processing. Predictions in experiments designed to satisfy Step 5B concern performance measures, but unless independent evidence is gathered to show that the manipulations affected their target processes, interpreting the performance data can be difficult (Butterfield & Belmont, 1972; Belmont & Butterfield, 1977). In the present case, the process measures indicate that the two manipulative conditions had their desired effects. Compared to the Free condition, subjects in the Label condition paused very little. Compared to the Free condition, subjects in the Rehearsal condition showed a distinctive distribution of pauses (see Fig. 11). Analysis of variance applied to the performance data revealed a reliable Groups X Conditions X Positions interaction [F(10,270) = 2.18, p<.025]. This interaction resulted from the facilitative effect of the Rehearse instruction on the retarded subjects’ primacy performance and the debilitative effect of the Label instruction on the normal subjects’ primacy performance. This pattern is consistent with the inference that the normal subjects were using rehearsal prior to instruction while the retarded subjects were not, which illustrates the kind of inference called for in Step 5B. 3, Partial Out Process Variancefrom AgelPerformance Relations Step 5C is another check on the completeness of a process analysis. This check is meant to determine the extent to which the analysis has accounted for the variance shared between age and criterion performance. As a rule, more complete within-age analyses should allow more complete reduction of the covariance between age and performance, but it is possible for an incomplete within-age analysis to allow a reduction of age/performance covariance to zero. This could happen when the within-age analysis has allowed the investigator to identify all processes that develop, but has missed some that do not. The data collected to satisfy Step 5A (Section 111, E, 1) was used to assess the correlation between age and recall accuracy when indices of Effort, Strategy, and Output Time were partialled out. The zero-order correlation between age and recall for 71 subjects ranging from CA 1 1 to 20 showed a covariance of 28% ( r I 2 = S2). Removing the effects of Effort reduced the age/accuracy covariance to 20% ( r 1 2 . 3= .44). Removing Output Time reduced agelaccuracy covariance to 14.5%(r12.34= .38). Removing Strategy reduced the covariance to 12%(r12.345 = .34). Removing all three process variables from the agelaccuracy correlation reduced their covariance by 57%. Removing only Output and Effort reduced their covariance by 47%.We conclude that roughly half of the developmentalvariance in circular recall can be explained by processes identified by analyses so far completed. In this study, Effort and Output Time were far the more important sources of developmental variance. It is uncertain why Strategy form did not
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contribute more to age-related variance in accuracy. Clearly, Total Time did not capture the same variance as Strategy, since the two are correlated negligibly (r = - .06). In this sample of subjects, Strategy did not relate strongly to accuracy ( r = .22), but it has related strongly in other samples. For example, in a recently completed and as yet unpublished study of 40 mildly retarded adolescents, Ralph Ferretti and John Belmont found a strong relationship between Strategy and accuracy for a 3/4 circular recall problem ( r = .54, r2 = .29). In their sample, Effort was not related to accuracy ( r = .01). Clearly, further analysis is needed to determine the conditions under which Strategy and Effort are related to accuracy. One hypothesis is that selection of an appropriate strategy develops earlier than appreciation of how much effort to invest in the strategy. On this hypothesis, Strategy should predict accuracy for younger subjects, who are not yet investing much Effort. But for older children, all of whom are selecting basically the same Strategy, Effort should be the better predictor. F. TEACH CHILDREN TO PROCESS AS ADULTS
Step 6 calls for both children and adults to receive instruction designed to leave adults’ performance uninfluenced while raising the performance of children to the level of the instructed adults. It makes provision, in the form of preinstruction process measures, for the possibility that some adults use childish processing and therefore will be improved by the instructions. To make the elimination of differences between adults and children a compelling demonstration of understanding of normal developmental differences between them, Step 6 calls for the instructions to be based upon a process analysis that accounts for all of the relationship between age and performance. This call cannot yet be answered, because no developmental analysis has been completed for any intellective performance. Therefore, no experiment of the ideal form called for in Step 6 can be offered as an illustration. G . TEACH ADULTS TO PROCESS AS CHILDREN
The lack of even one complete developmental process analysis also precludes illustration of the ideal form of research called for in Step 7. It should be noted, however, that the instructional experiment involving normal and retarded people of the same CA, described in connection with Step 5B (Section III,E,2) meets the formal requirement of giving identical instructions to both proficient and deficient people. However, that experiment was designed to influence input processing alone, and we know from analyses described earlier that output processing is also developmentally important. Therefore, the conditions of that experiment should not, as they did not, eliminate performance differences between the normal and retarded subjects. Input and output instruction were both included in
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the two experiments with retarded people described in connection with Step 4D, but those experiments included no similarly instructed normal people (Section III,D,4). The failure of anyone to have implemented the logic of developmental instructional experimentation is perhaps the starkest indication that cognitive psychology has a long way to go before it will have validated a process theory of intelligence.
IV. A Strategy for Studying the Generality of Cognitive Processes The belief that individual differences in intellectual performances are general across problems requires the addition of further steps to the research strategy required to validate process analyses of cognition. All of the illustrations in the foregoing pages came from studies of memory performances that are accounted for by basically the same underlying processes. At the level of process, all of that illustrative research concerned the same problem. The only sort of generality established by any of the steps outlined in Table I is generality across independent measures of the same processes within the same problem. This is not the sort of generality that psychometricians refer to when they speak of intelligence as a general factor. They refer to performance differences that cut across problems whose solutions are presumed to rely upon substantially different processes. Cognitive theorists distinguish between subordinate processes, which operate on environmental input or representations of it, and superordinate processes, which operate on subordinate processes. In Piaget’s theory, both concrete and logical operations are subordinate processes. In information-processing theory, subordinate processes include, among many other processes, recognition (matching a representation of incoming information to a representation from long-term memory), labeling (applying a name drawn from long-term memory to a representation of incoming information), rehearsal (repeated verbalization of a label or group of labels), and elaboration (retrieving from long-term memory the diverse sorts of information connoted by a label or a group of labels). A major goal of process analysis as described in Sections III,D and E is to identify the subordinate processes required for accurate performance on particular cognitive problems. Thus, the memory analyses used above as illustrations identified labeling and rehearsal as key processes (see Fig. 7). A premise of cognitive theory is that different performances rely on different combinations of a limited set of subordinate processes. Each subordinate process has some range of problems to which it applies. The wider that range, the more general the subordinate process. People use superordinate processes to select and coordinate the subordinate processes required to solve any particular cognitive problem. Nobody has offered
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a detailed view of the nature of superordinate processes. Rather, superordinate mechanisms have been referred to in aggregate under various rubrics, such as metaplan (Miller, Galanter, & Pribram, 1960), self-instruction (Reitman, 1970), the executive (Anderson & Bower, 1973; Green0 & Bjork, 1973; Neisser, 1967), and metamemory (Flavell & Wellman, 1977). Despite the lack of theoretical specificity about them, superordinate processes are by definition general. They can be used whenever a person needs to select subordinate processes to solve a problem. A theorist who wishes to study the generality of a process must decide whether the process is subordinate or superordinate. Different research approaches are required to test the generality of the two, because conclusions about superordinate processes require much longer chains of inference than conclusions about subordinate processes. The only method so far identified for studying superordinate processes is to examine changes in combinations of subordinate processes (Buttefield & Belmont, 1977). Since superordinates operate on subordinates, the investigator who would study superordinate processing must measure how subordinate processes are combined and recombined as information processing problems are changed or as a subject has increased experience with a novel problem. Studying superordinate processes requires a reasonably advanced understanding of the role of subordinate processes for at least one problem. Establishing the generality of superordinate processes requires a reasonably advanced understanding of the role of subordinate processes for at least two problems. Table 111 is constructed as a continuation of Table I, because Table I11 is concerned with establishing the generality of processes identified by analyses performed as outlined in Table I. Thus, Table I ended with Step 7 and Table III begins with Step 8, which calls for a decision about the process(es) whose generality might be tested. The judgment is whether each process is subordinate or superordinate, and four questions guide the decision. A. IS THE PROCESS SUBORDINATE OR SUPERORDINATE?
When studying the generality of a subordinate process, the basic approach is to analyze various problems completely enough to know which ones people solve by using the process. The mode of analysis is as outlined in Step 4 of Table I. To study the generality of a superordinate process, one must have analyzed several problems well enough to have fashioned unobtrusive measures of the subordinate processes required for their solution. The unobtrusive measures are needed to determine whether comparable changes in combinations of the subordinate processes are exhibited as people solve the several problems for the first time. The mode of analysis is as outlined in Steps 11 and 12 of Table III. It matters greatly how the question of subordinate or superordinate is answered, because the meth-
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TABLE IIl How to Continue a Rocess Validation so as to Establish Generality Step 8.
Decide whether process explanation concerns subordinate or superordinate processes, by answering these questions: A. Does the process operate between trials? B. Does the process select, coordinate, or modify other processes? C. For people who fail to select, coordinate, or modify other processes, does brief instruction induce them to do so and improve their performance? D. Do the performance gains derived from brief instruction fail to endure or generalize? If the answer to all four of these questions is NO, the process is subordinate. Go to Step 9. If the answer to all four is YES, the process is superordinate. Go to Step 11. If the answers are mixed, or if the questions are not yet answerable. it is premature to test generality, and more experiments like those outlined in Step 4 of Table I are needed.
Step 9.
Independently analyze various problems to determine whether they share subordinate process(es). For each problem, determine whether: A. Analogous process measures correlate with performance. B. Comparable manipulations change use of process. C. Comparable manipulations influence perfonnance. Compare analyses of various problems to see whether they share subordinate process(es).
step 10.
Relate subordinate process use on one problem to its process use on others, by Correlating measures of subordinate processing across problems for heterogeneous group of subjects. B. UGing one problem, insttuct defEient subjectsin the use of the subordiaate process, and test for transfer of the process to other problems requiring use of the process.
A.
step 11.
Using two or more problems that share no subordinate processes, and working within heterogeneous groups, A. Correlate, across problems, quality of subordinate process selection. B. Correlate, across problems, rates of effective subordinate process selection.
Step 12.
Using two or more problems that share no subordinate processes, and working with inaccurate subjects, A. Instruct subjectsto use all subordinate p m s s e s required for accurate performance, but do not instruct subjects in how to combine the subordinak processes. Across problems, correlate whether subjects combine the subordinate processes. B. Use graded sequences of instruction to teach use of all of the subordinate pmcesses required for good performance and how to combine the processes. Measure how many of the instructional steps are required to promote good performance on each of several problems, and correlate, across problems, indices of the completeness of the required instruction. C. Correlate, across problems, the extent to which instruction in superordinate processing reduces the completeness of subordinate instruction required to promote accurate processing.
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odological requirements for determining the generality of superordinates are considerably more demanding than those for determining the generality of subordinates. B , DETERMINING THE GENERALITY OF SUBORDINATE PROCESSES
I . Process Analyze Various Problems In principle, the generality of a subordinate process can be established simply by showing that the process contributes to performance on more than one problem. To establish the degree of generality of a subordinate process, one needs to determine the number and range of problems for which the process influences performance. For each problem tested, one should determine whether measures of the target process correlate with performance, whether manipulations that are comparable across problems with respect to their target process change use of the process, and whether the comparable manipulations influence performance. These requirements are specified in Step 9 (Table 111), and are illustrated earlier in connection with Steps 4A (Section 111, D, l), 4C (Section III, D, 3), and 4D (Section 111, D, 4). In practice, developmental cognitive psychologists have not limited themselves to the foregoing approach when trying to establish generality of subordinate processes. They have striven instead to establish generality by correlating the use of subordinate processes across problems (Butterfield & Dickerson, 1976) or, more frequently, by showing that instruction in the use of a subordinate on one problem induces its spontaneous use on another (Borkowski & Cavanaugh, 1979; Brown & Campione, 1978). The methodological demands of these approaches can seldom be satisfied, so they are not only unnecessary but risky ways to seek evidence of generality. They are listed in Table III under Step 10, but only to acknowledge that they may some day be practical ways to establish the generality of subordinate processes.
2. Correlate Process Use across Problems Step 10A calls for a demonstration of correlated differences across problems in people’s use of a process. It is Underwood’s individual differences test (described on p. l l 1) turned to testing generality. It is a risky test because there are no completely analyzed cognitive performances. Therefore, failure to obtain a correlation across problems can easily result from a failure to use some process other than the one whose generality is being tested. For example, a child might appreciate the value of rehearsal, and use it when the names to be rehearsed are supplied, as in aural presentation of words in a subject-pacedrecall problem. The same child might fail to appreciate the need to generate labels, as when pictures are presented in a subject-paced memory experiment. Such a child would rehearse only in an aural problem and would contribute error variance to a study of
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rehearsal’s generality across aural and pictorial problems. That error variance should not be attributed to a lack of generality of rehearsal, but rather to a failure to label, a process whose generality is not in question. The investigator’s chore, when seeking cross-problem correlations of process use, is to insure that his or her subjects use all necessary processes other than the one whose generality is being tested. This is the only condition under which a failure to use the target process is interpretable as a failure of generality. The lack of complete process analysis for any cognitive problem makes it impossible to verify that such a condition has been met. An investigator might nevertheless proceed, on the gamble that the test will not be destroyed by subjects’ failures to use nontarget processes. The gamble might establish cross-problem generality, but failure cannot be taken as evidence against generality. Unless an investigator has used either concurrent measurement or direct instruction to insure that pertinent nontarget processes were used, failure to observe generality across problems can be taken only as an indication that more process analysis is required to make the failure interpretable.
3. Show Transfer of Process Trainingfrom One Problem to Another The reason most often given for studying transfer of training of subordinate processes is to establish that training has changed some “real,” “true,” or “genuine” aspect of cognition (Borkowski & Wanschura, 1974; Denney, 1973; Kuhn, 1974). The idea is that any cognitive process worthy of the name is a general one. Most efforts to secure transfer have failed (Borkowski & Cavanaugh, 1979), and the reason seems to be that, before undertaking transfer studies, investigators have not analyzed the roles of processes other than the ones whose generality is being tested. It would be lovely if informed guessing or loose reasoning could provide the process analysis required for tests of transfer. Unfortunately, the necessary understandings of training and transfer problems are much too specific and detailed. The investigator who would demonstrate transfer must thoroughly understand both the problem used for training and the problem used for transfer. By definition, training and transfer problems are similar; both require processes taught during training. However, they are not identical. Performing the transfer problem must also require processes not taught during training. Otherwise, the test would be for durability rather than transfer. Because the problems are not identical, both must be analyzed to demonstrate that they require the instructed processes. However, certainknowledge that two problems require shared processes does not guarantee that failing the problem used to test transfer results from not transferring the trained processes. The child might well understand that the transfer problem requires use of his or her newly learned processes, and the child may use them but fail the transfer test for not using the added untrained processes it
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requires. Without knowing precisely where each subject’s processing breaks down, an investigator cannot interpret a failure to obtain transfer. Investigators have not known these things about their transfer tests because no performance studied in instructional tests of transfer has been well analyzed. As with correlational studies of processes across problems, an investigator might choose to perform a transfer test knowing that a failure would say nothing about generality. Failure would indicate only that more process analysis is required, even though successful promotion of transfer could be interpreted as evidence for generality. The belief that only a general instructional effect justifies the inference that intelligence has been trained has led many investigators to gamble blindly on tests of instructional transfer. C . DETERMINING THE GENERALITY OF SUPERORDINATE PROCESSES
When testing generality of subordinate processes, investigators will progress faster and will be able to interpret their data more fully if they have analysed their criterion problems completely. Still, when the focus is on subordinate processes, an investigator can choose to gamble by proceeding in the absence of welladvanced process analyses. Evidence of generality can be sought as soon as one has identified any subordinate process that accounts for significant criterion variance. This sort of flyer is not possible when seeking evidence of the generality of superordinate processes, because it is only from the changing organization of subordinates that superordinatescan be inferred. Analysis must have validated at least two subordinate processes for each of two problems. Ideally, the two problems will share no subordinate processes, so that any observed correlation in changes in combinations of subordinates across problems can be attributed unambiguously to superordinate processes rather than to shared subordinate processes. This ideal calls for process analyses to be relatively complete for all criterion problems before any attempt to determine the generality of superordinate processes. The generality tests outlined in Steps 1 1 and 12 are based on the assumptions that people use superordinate processes to fashion solution strategies for all previously unencountered problems and that solving problems is central to what we mean by intelligence. Thus, Steps 11A and 11B are variants of Underwood’s individual difference test, which reflects the psychometric notion that individual differences in intelligence are general. Steps 12A and 12B employ a responseto-instruction criterion of superordinate processing. The assumption is that people who use superordinate processes effectively should require less subordinate process instruction to perform well on novel problems than people who use superordinateprocesses less proficiently. The more proficient should fill in larger gaps in instruction than the less proficient. The more proficient should “learn” more from minimal instruction.
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1 . Correlate Quality of Subordinate Process Selection across
Problems Implementing Step 11A requires two problems that depend upon different processes for their solution, that are novel to a group of people, and that yield indices of the quality of combinations of subordinate processes selected by people after they have had some experience with the problems. The problems must have been analyzed well enough for an investigator to specify and measure both effective and ineffective combinations of subordinate mechanisms for working the problems. The test of generality is whether people who select effective combinations of subordinate processes (strategies) for one problem also select effective combinations for the other. The interpretation of the test is substantially clearer when effective solutions for the problems share no subordinate processes. When two problems’ solutions depend upon some of the same subordinates, question remains about whether people who solve problems have selected one or more strategies. Unless they have selected more than one strategy, it cannot be concluded that the superordinate process of selection is general. 2.
Correlate Rates of Effective Subordinate Process Selection across Problems Step 11B is a refinement of Step 11A. The assumption underlying 11A is that effective superordinate processors will select more appropriate strategies than ineffective superordinate processors. The assumption underlying Step 11B is that effective superordinate processors will differ among themselves in the rate of strategy selection, and that the more effective ones will select appropriate strategies more quickly than the less effective ones. Step 11A focuses on whether a person selects an appropriate or inappropriate strategy in a given number of trials, and Step 11B focuses on the number of trials required to select an appropriate strategy. The test is to administer to each subject two or more novel problems for which it is possible to measure the quality of the subordinate mechanisms selected to solve the problems. Subjects are carried to a criterion of strategy selection on each problem, and the dependent measures are the numbers of trials required to meet the criteria. The test is to correlate the number of trials required for the different problems. The presence of a significant correlation across problems is taken as evidence for the generality of differences in effectiveness of superordinate processing, which is analogous to taking differences in trials to a learning criterion as evidence of differential learning ability.
3 . Correlate Responses to Subordinate Process Instructional Routines Implementing Step 12 requires the development of instructional sequences whose components are graded according to the age at which the processes taught in each component are typically used without instruction and according to how many of their target subordinate processes are required for the solution of several different
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criterion problems. Developing such an age- and completeness-graded instructional sequence for even one problem will normally require considerable developmental research and process analysis. Step 12A calls for graded instructions for several problems, each of which depends on different subordinate processes. ButterField er al. (1973) have shown that teaching the use of all subordinates required for problem solution does not produce accurate memory performance by all initially inaccurate subjects, but that adding instruction in ordering and combining the subordinate does. Implementing Step 12A requires a group of subjects, all of whom perform poorly on all criterion problems. All subjects are instructed in all of the subordinate processes required for accurate performance on all problems, but none are instructed on how to combine the processes. The test is to determine whether those subjects who spontaneously combine the processes on one of the criterion problems will do so on the others, while those subjects who do not combine the subordinates on one problem will not on the others. The assumption is that combining subordinates is a superordinate process, and those subjects who use this superordinate at all should use it whenever the opportunity presents itself. The test in Step 12B uses graded instruction about all subordinate processes and about how to combine them. The assumption is that subjects who use superordinate processes more effectively will require less complete subordinate and combining instruction on all of the criterion problems than will subjects who use superordinate processes less effectively. The test of generality incorporated in Step 12B is to determine whether completeness of needed instruction on one novel problem correlates with the completeness of needed instruction on other novel problems. 4 . Instruct Superordinate Processes To implement Step 12C, an investigator needs a model of superordinate processes, ways of teaching them, a number of criterion problems, and a graded sequence of subordinate process instruction for each. The test begins by identifying a group of people who perform poorly on all of the criterion problems. It proceeds with superordinate training for some but not others of these people. The test of superordinate generality is whether the trained subjects require less subordinate process instruction to achieve excellent performance on all of the criterion problems.
V. A.
Illustration of the Research Strategy for Testing Process Generality DECIDE WHETHER PROCESS IS SUBORDINATE OR SUPERORDINATE
As indicated in Table 111, one begins to test the generality of a process by deciding whether it is subordinate or superordinate. This decision will be based
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primarily on evidence collected in the course of validating a process explanation of performance, as outlined in Table I, but it might also be necessary to collect data whose only purpose is to facilitate the subordinate/superordinatedecision. I . Does Process Operate between Trials? Analyses described above (Section III,D) focused on labeling and rehearsal. Since every trial in every experiment contributing to those analyses consisted of a different list of letters or words, labeling and rehearsal done between trials could not have contributed to performance. Still, interviewing subjects and inspecting changes in their patterns of pause times across trials led us to believe that accurate performers sytematically evaluate and revise their approach to the memory problems we pose for them and that they do this between experimental trials, especially between the first several trials. We came to believe that accurate performers of our memory problem, and probably of any novel experimental problem, use superordinate processes, which behavior cannot be seen directly in our subordinate process measures but might be seen in changes in the patterning of those measures across trials. The hypothesis is that people use superordinate processes to match subordinate processes to problem demands. Even though the chief source of input for that matching process must be the subjects’ experiences during experimental trials, we concluded that accurate subjects use the time between trials to revise their understanding of the requirements of the problem in view of their accumulated experience with it, to evaluate the effectiveness of the strategy they have just tried, and, when indicated, to design a new strategy and set new goals for the next trial. Therefore, one test for the presence of superordinate processes is to determine whether the deployment of subordinate processes changes sytematically across trials. We will use some previously unreported data collected by Siladi and Butterfield to illustrate the sorts of trial-by-trial changes in subordinate processing that can indicate the presence of superordinate processing. Siladi and Butterfield assumed that people require direct experience with novel problems to determine the problem’s information processing requirements. Early trials should be more informative than later ones, so subjects should change their strategies more across early trials; people should be more consistent strategically on later trials. This pattern of results should occur for all novel problems, and it should be more pronounced for accurate than for inaccurate problem solvers. To test for such trials’ effects, Siladi and Butterfield administered a memory and a series completion problem to 30 high school juniors. Each subject received a block of 15 memory trials on each of which they were to recall nine words in the order 9 5678 1234 (1-4-4), counterbalancedwith a block of 15 trials of series completion (e.g., complete the series AAXBBXCCL--). Pause times were taken during self-paced study of both the memory lists (as described on p. 105) and the series problems. Subjects paced themselvesonce through each series prob-
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lem, viewing one letter at a time in a left-to-right order. The study time arrays created for the letters of each problem were used to index underlying processes. Earlier studies had shown that distinctive pause time arrays were obtained from problems that contain both next (e.g., ABC) and backward relations (e.g,, KJI), so we chose such problems (e.g., KJAIHBGFC---). Earlier data had shown that subjects pause longest at the ends of periods in the series (at the A, B, and C in the foregoing example). A sensible interpretation of this pause pattern is that during early problems subjects discover the series’ recurring relations, the number of letters separating the recurrences, and the rules relating them. On later problems, they pause at points of recurrence to check the continuing applicability of their induced rule, and to extrapolate the answer. Kotovsky and Simon (1973) have built these inferred processes into a functioning computer simulation of people’s series problem performance. Accuracy was measured for each memory trial by the number of correctly ordered pairs of words (i.e., perfect recall in the order 9 5678 1234 gives eight correct pairs: 95 56,. . . 34). For the series problems, subjects were asked to say which three letters would complete each problem, and accuracy was measured by the number of correct letters. Siladi and Butterfield chose the 10 most accurate subjects (Highs) and the 10 least accurate subjects (Lows). Across the 15 recall trials, the Highs gave a mean of 4.8 correct pairs per list (59% correct), and across the 15 series problems they gave a mean of 2.6 correct letters per problem (87%correct). The Lows gave 1.4 correct pairs per recall list (18%correct), and .7 correct letters per series problem (24%correct). The High accuracy group was thus over three times as accurate as the Low accuracy group. Since the predictions about changes in input strategies relate to the forms of pause time arrays, the pause times were standardized trial-by-trial, and 3 was used to compare the standardized arrays (see p. 108 for procedural details). To examine changes across trials in strategic consistency, Siladi and Butterfield calculated for each High and Low accuracy subject an 02 for Trials 1-4, one for Trials 2-5,3-6, and so on for every group of four adjacent trials. They calculated the mean 02 for blocks of three adjacent groups of trials: one mean for Trials 1-4, 2-5, and 3-6; one for Trials 2-5, 3-6, and 4-7; and so on for each successive block of three groups of trials. Figure 12 shows the mean Ctrial consistencies (02)for the High and Low accuracy subjects on both the recall (R) and series (S) problems. The averages are plotted against the numbers of the last trials for each block (e.g., the points above Trials 4-6 are the overall means for the three 02 for Trials 1-4,2-5, and 3-6). The High subjects showed increases of more than .30 in their 4-trial consistencies (3) across the 15 trials of each problem, ending up with 02 near .60.The Low subjects showed only slight changes in their 4-trial consistencies across the recall trials, (OZ stayed near .28), but showed an increase across the series completion problems of about .20, ending up near 02 = .35. Thus, the High subjects’ patterns became more consistent than the Low subjects’
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TRIALS Fig. 12. Mean o2showing dixerences in strategic comisrency across trials by high- (solid line) and low-:l(dashedline) accuracy subjects on series completion (S)and recall (R) tasks.
patterns by the final trial block on both problems. These trends were confirmed by an Accuracy Group (2) X Problem (2) X Trial Blocks (4) analysis of variance, which yielded significant main effects for Accuracy [F(1,18)= 9.70,p<.OOl] and Trial Blocks [F(3,54) = 15.83, p<.OOl], and a significant interaction of these factors [F(3,54) = 5.38,p<.Ol]. No other effects attained significance. The Low subjects’ mean w” did not increase significantly across trial blocks for either problem, while the High subjects 02 increased significantly across trial blocks for both problems. This study illustrates how one can use trial-by-trial changes in the deployment of subordinate processes to decide whether superordinate processes play a role in criterion problem performance. The data from both the memory and the series completion problems are consistent with the inference that accurate subjects use superordinate processes between trials. Clearly, this inference could not have been made without measuring subordinate processes, so the first question in Step 8 (Table 111) can be answered either Yes or No, depending upon whether one’s main interest of the moment is in the superordinate processes by which problem solutions are defined or in the subordinate processes that are implemented as a problem solution. Answering Yes indicates that the process of interest is a superordinate. 2. Does Process Select, Coordinate, or Mod@ Other Processes? The second question to be answered when deciding whether a process is subordinate or superordinate is whether people use it to select, coordinate, or modify other processes (Step 8, Table III). The alternative is that the process operates on environmental information or its transformations. An equally satisfactory way to
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pose the question is to ask whether the process is used to change or define one’s method of approach to a problem type or whether it is used to yield an answer to an instance of the type.If the process is used to define or change an approach, it is superordinate. If it is used to yield an answer, it is subordinate. In either form, this question is about a theory of what is required to arrive at a solution to a criterion problem. Answering the question requires examination of a theory. Figure 13 depicts a theory of the processes a person should use to solve a novel problem such as circular recall or series completion. A person should first determine the best possible outcome allowed by the problem, by answering such Description of Process
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Fig. 13. Outline of processes a person shouM use to solve novel problems.
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questions as: “What kind of response would I make if I solved this problem,” and “How many responses would I make if I solved the problem perfectly?’’ Faced with a balance problem of the sort studied by Klahr and Siegler (1978), the answer would be “After the experimenter puts weight on both sides of the balance, but before he releases it so it can tilt, I need to tell him which side will go down. I can choose only one side, and the best I can do is to pick the side that goes down when he releases the beam. ” The child may arrive at an answer after listening to introductory instructions, questioning the experimenter to find out what is expected, or noticing the experimenter’s reactions to the child’s responses. In any event, the child should define the best possible outcome as completely as possible before designing a strategy for the problem. How completely the child’s queries of self and others define the best possible outcome will depend upon the child’s knowledge of the problem (what to ask), which means that the child might change his definition following some experience with the problem. Accordingly, the step of defining a goal should not be a one-time effort, completed only before undertaking the first try at problem solution. Rather, prior to each attempt to solve a problem, the person should define the best outcome as completely as possible. Defining the best possible outcome is not a way to produce an answer to a particular problem; its purpose is to help design an approach to a problem type, and it is therefore superordinate, as indicated in the right-hand column of Fig. 13. Figure 13 shows that Process 2 has four parts. Process 2A, Designing Strategies, calls for a person to draw on his or her knowledge of information processing mechanisms and on the results of other processes listed in Fig. 13. It is a superordinate process (see right column of Fig. 13). Having designed a first strategy, a person should estimate the probable outcome of implementing it (Process 2B). The person shouId ask, “What sort of response(s) is this approach to the problem likely to generate?” For example, the best possible outcome for a six-word free recall problem is to say all six words in a list. To reach this outcome, a person might design the strategy of saying each word once, as it is presented. If a person has had much experience with such an approach, he or she should estimate its probable outcome as about three wordsthe last three presented. Process 2B is also superordinate. Having estimated the likely outcome of applying the first designed strategy (Process 2B). a person should compare (Process 2C) the likely outcome to the best possible outcome (Process 1). If the likely outcome and the best outcome are not the same, the person should design an alternative strategy (return to Process 2A), estimate its likely outcome (Process 2B), and compare the new estimate to the estimated best outcome (Process 2C).A person should continue this process, keeping track of discrepancies between likely outcomes and best possible outcomes. Process 2C is superordinate. Process 2D calls for a decision about which of several strategies should be
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implemented. The rule is that a person should implement the strategy associated with the smallest discrepancy between its likely outcome and the best possible outcome. Thus, when facing a six-word memory problem, if a person designs no strategy that yields an estimate of more than three words recalled, he or she should use the three-word strategy. Process 2D is superordinate. Process 3 concerns strategy implementation. While implementing a strategy, Process 3A calls for monitoring how well the implementationreflects the strategy design. This comparison is necessary to allow modification of the implementation in response to local and unanticipated requirements. For example, when applying a rehearsal strategy to a list of words, acoustic similarities among the words create problems, and a subject cannot always know whether there will be such acoustic similarities until implementing a strategy, that is, rehearsing the words. Monitoring how well the implementation matches one’s strategic design is also necessary to noting (Process 3A) whether the implementation and the design are the same, which is required later in the event of an unsatisfactory outcome, to decide whether the fault lay in the strategy or in its implementation. This matters, because if it was only in implementation, then an unsatisfactory result may not call for strategy revision. Process 3A is superordinate. Process 3B is to assess periodically how accurately one would be able to respond if one stopped implementing the strategy at the time of the assessment. The purpose is to provide a basis for deciding whether one should continue preparing to respond or should stop preparing and actually respond. The assessment in Process 3B permits such decisions. It is a superordinate assessment. Process 3C calls for a comparison of the most recent estimate of probable response accuracy with previous estimates. Notice, the comparison is not between the degree of accuracy with which a person would respond now and the person’s estimate of the accuracy the strategy would permit before implementing it (Process 2B). The reason is that either a failure to implement a strategy accurately or having misestimated its likely outcome could result in never approaching the 2B estimate, in which case one might continue to implement a strategy indefinitely or unnecessarily. Asking only about whether the strategy is yielding further gains in estimated response accuracy precludes such inefficiencies, and it eliminates the need during implementation to refer further back in memory than to the last estimate of probable accuracy. Process 3C is superordinate. Comparisons of the most recent to prior response accuracy estimates are used in Process 3D to decide whether further implementation of the strategy will yield a more accurate response. When estimated accuracy ceases to increase, a response is initiated. Following the response, its outcome is assessed (Process 4A). The person asks, “HOWaccurate was my response?” There are problems for which assessing outcome accuracy is not simple, but the problems we study allow rather
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straightforward accuracy judgments. Thus, a child might count how many words he or she recalls, or, he or she might compare the direction in which the balance beam tilts with his or her prediction of which way it would tilt. In this latter case, Process 4A includes Process 4B, which is a comparison of accuracy of one’s response to one’s prior estimate of the strategy’s likely outcome (Process 2B). This comparison is not necessary to solve a current problem, but combined with Process 4C, it provides feedback about an important part of managing one’s future efforts to solve novel problems, namely, about estimating outcomes (Process 2B). Increasing the accuracy of a child’s estimates of outcome should improve his or her self-management of problem solving. All of the processes outlined in Fig. 13 are superordinate. Therefore the second question in Table I11 should be answered Yes. 3 . Do Simple Instructions Rapidly Induce Eflective Subordinate Processing? The third question in Step 8 of Table 111 is a production deficiency question (Flavell, 1970). It is answered by a subordinate-process instruction of the sort described above in connection with Step 4D of Table I (Section III,D,4). Investigators first determine the subordinate processes required for good performance on a particular problem; then they instruct children to use those processes (e.g., Brown, Campione, Bray, & Wilcox, 1973; Butterfield et al., 1973; Moely, Olson, Halwes, & Flavell, 1969). Even though the instructions are designed to influence subordinate processing, investigators have emphasized superordinate immaturities to explain why children benefit from instruction, which is to say, why they are production deficient. Thus, some investigators have undertaken to study metamemory (Brown, 1975; Flavell & Wellman, 1977), on the grounds that what the child does not yet know (e.g., about his memory system, the mnemonic requirements of different problems, the utility of particular subordinate processes) prevents him or her from producing effective combinations of subordinate processes on his or her own. Other investigators have undertaken to study executive functions presumed to be responsible for the construction of memory strategies (Butterfield & Belmont, 1977). The reason for emphasizing superordinate explanations, such as metamemory and executive functions, is that the instructions used to test for production deficiencies are simple, yet the performance gains resulting from them are swift and dramatic. Investigators have found it unreasonable to suppose that such simple and effective instructions teach children the specific processes upon which the instructions focus. It has seemed more reasonable to suppose that the investigator is selecting, through his instructions, the subordinate processes a child will use. We view children’s failures to make such selections for themselves as failures of superordinate processes. Question 3 under Step 8 is built on the assumption that whenever simple
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subordinate process instruction results in swift performance gains, the problem is one of superordinate processing. The assumption is certainly reasonable for the memory problems that we have studied (Belmont & Butterfield, 1971b; Butterfield et al., 1973). 4 . Do Instructed Performance Gains Fail to Endure or Transfer? The fourth question designed to decide whether a process is superordinate (Step 8, Table III) is based on an extension of the reasoning underlying the production deficiency question. The extension to tests of transfer of subordinate process training assumes that the training is simple and brief, as in production deficiency studies. Transfer tests are given only to people who require instruction on a training problem. The fact that training is successful, as it must be before the investigator tests for transfer, indicates that the people who are tested for transfer did not lack the appropriate subordinate processes; they simply failed to invoke them spontaneously. This conclusion follows from the fact that simple instructions cannot reasonably be represented as having imparted subordinate processes. Cognitive instructional experiments have used simple instructions, which are best represented as ways of telling people to do what they already know how to do. It follows that the trained subjects’ failure to invoke the trained processes on their own was a superordinate failure to assess the cognitive requirements of the training problem. Since training and transfer tasks come from the same class of cognitive problem, Superordinateassessment of cognitive requirements is no less important for the transfer test than it is for the pretest that indicated a need for training. In view of the child’s superordinate failure on the pretest, the best prediction is that the child will fail similarly on the transfer test. Failures of successful subordinate process instruction to transfer or even to endure are evidence of a processing failure at the superordinate level, and such failures abound in the memory domain (e.g., Butterfield et al., 1973).
5 . Conclusion Any problem for which it can be shown that superordinate processes contribute to successful solutions will be a problem for which the use of well-defined and measurable subordinate processes are required. Without good measures of the requisite subordinate processes, one cannot assess trial-by-trial changes in strategy, advance a compelling theory that might posit superordinate as well as subordinate processes, or design effective process instructions whose transfer can be tested. If the answer to all of the questions in Step 8 is No, the processes whose generality is at issue are subordinate, and the investigator should move to Step 9 of Table 111. If the answers are a mix of Yes and No, the investigator should return to Step 4 of Table I and perform enough additional within-age analysis to permit identical answers to all four questions. If the answer to all of the questions in Step 8 is Yes, the investigator has a choice of whether to focus
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on subordinate (Step 9) or superordinate processes (Step 11). We will argue below that superordinates are theoretically more interesting and practically more important, but first we will illustrate generality tests for subordinate processes. B . TESTING THE GENERALITY OF SUBORDINATE PROCESSES
I . Independently Analyze Various Problems Step 9 in Table I11 indicates that the generality of subordinate cognitive processes can be established by independent analyses of a number of criterion problems. Experiments involving more than one problem are not required. All that is required is enough within-problem analysis to determine that the target process contributes to performance on each of two or more problems. The process measures used for different problems need only be analogous to one another (Step 9A), which means that reasonable adjustments can be made in the measurement procedures to allow for the performance characteristics of the various problems. Similarly, manipulations of the target process need not be identical for various problems (Steps 9B and 9C). The manipulations need be comparable only in the sense that they can be assumed to have influenced the same process(es). Such tests of generality require process analysis, but the tests themselves are judgmental. The judgments are based on comparisons of processes used for different performances. Knowledge of those processes will come from experimental analyses of different criterion problems. The more explicit the models generated by these analyses, the more straightforward the judgments. Among the more explicit models are flow charts of the sequences of processes used to solve various problems. For example, Figs. 14, 15, and 16 are flow chart models of the processes implicated by experimental analyses of serial recall, circular recall, and position probe recall, respectively. Since these models incorporate identical processes, we judge that the memory problems themselves require use of the same subordinate processes. In Fig. 14, we use four boxes to describe subject-paced input in preparation for serial recall. Taken together, these four boxes specify a sequential chunking strategy, involving labeling and rehearsal, to create and transfer an ordered representation of an entire list to a long-term memory store (LTS). We describe output with two boxes. Box 5 stands for transfer of a stored representation of an ordered list from LTS to an output buffer. Box 6 stands for recitation of the contents of the output buffer. The legend of Fig. 14 indicates that this model can also apply to free recall: Some people solve free recall problems by recalling serially. Figure 15 shows that input processing for circular recall is identical to that for serial recall, except that the last few items in a list are not transferred (by rehearsal) to LTS. Rather, they are entered by labeling into an input buffer (Box 5 ) . Output for circular recall is accomplished much as it is for serial recall, except
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Experimental Event I: A list is presented for input. The Subject:
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Validating Theories of Intelligence Experimental Event 1: A l i s t is presented for input. The Subject:
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in output buffer t o position on console
Fig. 16. A model of position probe recall.
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probe come at output. Output processing for position probe is more complex than for circular recall. Comparing the three models shows that labeling and rehearsal are general across serial, circular, free, and position probe recall requirements. As for all generality judgments, the investigator should decide whether the range of problem models compared is broad enough to make the judgment important. Nobody should dispute the claim that labeling and rehearsal are general across four recall requirements, but somebody might argue that these problems are only trivially different and hence the identified processes are only trivially general. The argument would not be compelling for the process of labeling, since people label whenever they refer to environmental events (e.g., whenever they read). For rehearsal, the argument of triviality may seem more compelling, since the tendency these days is to attribute more importance to memories that result from efforts after comprehension or from semantic elaboration than to memories resulting from rehearsal. On the other hand, people do use rehearsal, for example, to learn new phone numbers, when preparing to go grocery shopping, when cramming for final examinations, and when learning a foreign language. The foregoing paragraph shows that judgments about subordinate process generality do not always depend upon experimental data. Strictly speaking, such judgments depend only on consensus that a process is used to solve diverse problems. Securing such consensus requires experimental analyses whenever the underpinnings of performance are unclear to any informed observer. In fact, they usually are unclear for intellective problems, and, therefore, analyses like those for serial, circular, and position recall usually are needed to establish subordinate process generality.
2 . Correlate Process Use across Problems Part of the reason for trying to establish the generality of subordinate processes is the psychometric view that individual differences in intelligence are general. Another reason is the view that no psychological process has been identified until independent measures of it have been shown to covary across people (Underwood, 1975). This latter view can be tested during process analysis of a single problem (Step 4B, Table I), but the former requires correlation of process use across problem types. In practice, developmental cognitive psychologists have acted as if correlations of subordinate process use across problems are needed to establish a process’s generality. We have included Step 10A in Table 111 to acknowledge this practice, even though we believe that the generality of subordinate processes can be established satisfactorily without such correlational evidence (see Section IV, B, 2). Establishing cross-problem correlations of process measures can be a difficult experimental chore (Butterfield & Dickerson, 1976). The difficulties arise from the need to control and insure the use of processes that might interfere with
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expression of the process whose use is being correlated across problems. Comparing process models of circular recall (Fig. 15) and probe recall (Fig. 16) illustrates how such difficulty can arise. The circular and probe recall problems call for identical input processing. Therefore, one might choose to correlate the use of rehearsal across these two problems. However, accurate performance on the two problems requires different output processes, and subjects' failure to appreciate either of the required output methods could lead to their rehearsing for only one of the problems. Butterfield and Belmont (1977) reported data that illustrate this difficulty. Independent groups of 9-, 11-, and 13-year-olds were given Free Recall or Position Probe using six- or nine-word lists. The 9-year-olds showed little rehearsal for either Position Probe or Free Recall, and the 13-year-olds showed considerable rehearsal for both requirements (see Fig. 17). The 11-year-olds rehearsed considerably when preparing for Free Recall, but little when preparing for Position Probe (see Fig. 17). The 11-year-olds showed during Free Recall that they could rehearse, yet they did not rehearse for Position Probe. Having failed to appreciate the output requirements of Position Probe, they used only
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labeling. Including data from 11-year-olds in a correlational study of rehearsal across Position Probe and Free Recall or Position Probe and Circular Recall would show a far lower correlation than would be observed with only 9- and 13-year-olds, because of the effects of age-related nontarget output processes on the target input processes. In order to minimize the risk of encountering such problems in cross-problem correlational studies, one might use only subjects whose performance is quite accurate, thereby indirectly insuring satisfactory use of all requisite processes, target and nontarget alike. A likely cost of this approach would be a restriction of variability in measures of the target process, and a consequent reduction in the magnitude of correlations observed. A more direct approach would be to do cross-problem correlational studies using only problems for which there are unobtrusive measures of target and nontarget processes. This would allow elimination of subjects who do not use pertinent nontarget processes, but it would sharply narrow the range of usable problems and, consequently, the sorts of processes one could study. Less narrowing would result from insuring by direct training that one’s cross-problem subject population can use pertinent nontarget processes. This latter approach would permit cross-problem correlational study of generality of subordinate processes among young and deficient populations, which no other approach permits. As far as we know, none of these approaches has been used to test the generality of subordinate processes. Until such a p proaches are used, we expect that investigators will have little success with cross-problem correlations as a way to establish the generality of subordinate processes. 3. Test for Transfer of Process Training Step 10B (Table 111) calls for subordinate process training of subjects who do not use a target process, followed by a test of transfer. The developmental cognitive literature contains much discussiqn of the conditions required to secure transfer of subordinate process training (Belmont & Butterfield, 1977; Borkowski & Cavanaugh, 1979; Brown & Campione, 1978; Butterfield, 1978), and the pertinent issues remain unresolved. Our guess is that subordinate process instruction will not (indeed, should not) transfer across problems whose solution depends importantly on uninstructed nontarget processes. The reason is that children who fail to use and therefore require instruction on a target process will likely fail to use nontarget processes, and unless they also receive training on the latter, transfer of the trained target process will be prevented or obscured. Since instruction on nontarget processes has never been tried, we can illustrate instructional transfer only with a study employing closely related training and transfer problems. Belmont, Butterfield, and Borkowski (1978) sought to promote the transfer of rehearsal to position probe recall by teaching mentally retarded people how to rehearse for circular recall. Using six-letter lists, different groups of subjects
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were shown how to rehearse for either 314 (567 1234) or both 314 and 413 (4567 123) Circular Recall. Transfer was tested first with a seven-item Position Probe problem and then with a 215 (67 12345) Circular Recall problem. The subjects trained for both 3/4 and 4/3 transferred their rehearsal to both transfer problems; the subjects trained for 3/4 only transferred only to the 2/5 problem. Clearly, transfer of instructed subordinate processes can be obtained between problems that do not differ importantly in their nontarget processes. Until transfer is shown to be obtainable across problems that do differ importantly in their nontarget processes, or until investigatorsbegin instructing nontarget processes required by their transfer problems, transfer studies will have little utility as tests of the generality of subordinate processes. C.
TESTING THE GENERALITY OF SUPERORDINATE PROCESSES
We have described independent analysis of various problems (Step 9) as the main way of testing the generality of subordinate processes. We have also described the correlation of process measures across tests (Step 10A) and the measurement of transfer of training (Step 10B) as potentially useful complements of Step 9. We have not included in Table III a test analogous to independent analysis of various problems as a way to establish the generality of superordinate processes. Independent analysis of various problems for superordinate processes was included in Step 8 as a way of deciding whether one’s target processes were subordinate or superordinate. We do not regard such analysis as a satisfactory test for the generality of superordinates, because superordinates exist at a very high level of inference. Therefore, our first suggested test (Step 1lA, Table 11) for the generality of superordinate processes is a cross-problem correlation. 1 . Correlate Quality of Subordinate Process Selection across
Problems Step 11A is a variant of the individual differences test advocated by Underwood (1975) and incorporated at various points in the research strategy outlined in Tables I and 111. Inclusion of Step 11A is based on the premise that psychological importance cannot be attributed to a superordinate process until somebody shows reliable covariance between two independent measures of the process. If those two measures are drawn from problems that share no subordinate processes, then showing significant covariance establishes both the psychological importance and the generality of superordinate processes. These are the two purposes of Step 11A. The conception of superordinate processes underlying the test of Step 11A is that, when used in combination, they help a person solve problems well by selecting, coordinating, and modifying combinations of subordinate processes. The end product of good use of superordinate processes, during experience with a problem, is a strategy (i.e., combination of subordinate processes) that fits well
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the requirements of the problem. Assuming that the quality of a strategy’s fit to a problem’s requirements reflects the quality of the person’s superordinate functions, seeking covariance of strategy quality across problems is a way to test the generality of superordinate functions (Step 11A). To implement the test specified in Step 11A, one must give a group of people experience with at least two different problems, assess the quality of their strategies at the end of those experiences, and correlate the assessments across problems. We met these conditions in a study described above (Section V,A,l), in which 30 young adults were given 15 trials of circular recall and 15 trials of series completion. To compare the quality of their solutions to these problems, we used the subjects’ standardized pause patterns on Trials 13-15 from both the series and recall problems. Each subject’s three patterns were compared by WZ to a standardized pattern obtained from independent groups of highly accurate subjects. The three o2values obtained for each subject on each problem were averaged and correlated. The resulting correlation was .43( p < .Ol), indicating that people who arrived at quality solutions to the recall problem tended also to arrive at quality solutions for the series completion problem. Since accuracy across the two problems was correlated .51, a value of .43 between strategy measures seems substantial. The oz index of strategy quality correlated with accuracy .52 for the recall problem and -62 for the series problem. To our knowledge, the foregoing correlations are the only report of any experimental data that meet the requirements of Step 11A. They should be taken as illustrative of the possibilities of the approach, and not as definitive evidence that superordinate processes are general.
2. Correlate Speed of Eflective Strategy Selection across Problems Step 1IB calls for an examination of individual differences in the speed with which people fashion effective strategies for different problems. To correlate speed of strategy selection, one would allow people continued experience on various problems until they reached a criterion of solution quality. Then, the number of trials required for different problems would be correlated. A crude approximation to this approach would be to carry people to some criterion of performance accuracy. We find this an unsuitable approximation, because it does not allow any inference about the character of the strategies employed to reach a solution. Most problems allow various solutions, and to determine how quickly people arrive at a particular solution requires that the subjects be separated according to the strategies they develop. For this reason, Step 11B specifies that, for each problem studied, people be carried to a criterion of fit to a strategy of known effectiveness. The test is to correlate the number of trials to such criteria, across problems. This approach has never been implemented, but we have established its feasibility. BeImont (1980) examined standardized pause patterns created by children and adults as they studied lists of words in preparation for 3/5 circular recall. Using
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he fitted a standard pattern from instructed subjects to each trial of each child and adult’s standardized patterns. He identified the trial number on which each subject began a series of three consecutive trials whose patterns matched the standard by OZ of at least .60.The adults reached this criterion of strategy quality in about half as many trials as the children, showing that for circular recall it is possible to establish a criterion of strategy quality that differentiates among people. We have reason to believe from examining data from Siladi and Butterfield (see Fig. 12) that one can as successfully set quality criteria for series completion strategies. Accordingly, we are planning a test of the sort specified in Step 11B. 02,
3 . Examine Response to Subordinate Process Instruction The test in Step 12A assumes several problems whose solution depends upon different subordinate processes. For each problem, the investigator needs a separate set of instructions that promote the use of each of the subordinate processes required for accurate performance, but the instruction must not teach how to combine the subordinates to achieve criterion performance. The combining is left to the subjects. The test is to determine whether some people combine the instructed processes for all of the criterion problems, while others combine them for none of the problems. An experiment by Butterfield and Dickerson (1976) illustrates the implementation of Step 12A. The subjects were mentally retarded people who did not use the subordinate processes whose combining was the focus of the study. A recall problem required the subjects to combine conceptual categorization and rehearsal by (1) organizing a group of 16 pictures into four groups of four conceptually related pictures and (2) rehearsing the names of the pictures in each group. A recategorizing problem required combination of (1) a covert categorized recall of a list of 12 nouns and (2) overt naming of nouns whose categories cut across the ones learned for covert recall. An inferential behavior problem required the combination of (1) discriminative lever pulling to secure a large marble and (2) a marble-inserting response to obtain gum. Butterfield and Dickerson taught each subordinate process to the subjects. To assess the generality of combining subordinate processes across problems, each subject’s criterion performance was scored padfail; each subject either combined or did not. Chi square analyses showed significant covariance across problems ( p < .001), indicating that combining subordinates is a general superordinate process. Such studies presume sufficient problem analysis to have identified pertinent subordinate processes for the problems studied. The test in Step 12B requires instructions like those used in 12A, but in addition, the graded sequences for each problem must include instruction on how to combine the subordinate processes as they will need to be combined during criterion problem performance. The purpose of the test is to establish for each of several problems how
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completely a person must be trained before he adopts an optimal strategy. The assumption is that good performance following incomplete instruction indicates that the subject has used superordinate processes to fill instructional gaps. The test in Step 12B is to correlate indices of the amount of instruction required to produce excellent performance on various problems. We know of no study that fits the requirements of 12B. The lack probably results from the extensive process analyses required to build the requisite instructional sequences. 4 . Instruct Superordinate Processes None of the three foregoing approaches to establishing the generality of superordinate processes incorporates any manipulation of superordinates. Step 12C calls for such manipulation. It presumes a theory of superordinate processes or at least some scheme, such as the one in Fig. 13, to guide one’s instructional efforts. No such scheme has yet been used by any investigator to guide instructional experimentation, but six of the seven successful studies of the transfer of subordinate process training that we have found have included instruction in some aspect of the superordinate processes listed in Fig. 13. Our discussion of these seven studies is organized around Table IV. Brown and her colleagues performed two experiments (Brown & Barclay, 1976; Brown, Campione, & Barclay, 1979), which, taken together, are perhaps the most impressive laboratory demonstration of generalized instructional effects. Their results were achieved by adding a readiness-to-recall instruction to the training of a standard rehearsal strategy. Training the rehearsal strategy itself should have had no influence on superordinate processes. Like most practitioners of the instructional approach, Brown and her colleagues designed a strategy for their subjects, rather than teaching them how to design one for themselves (Process 2A, in Fig. 13 and Table IV). The additional instruction was designed to induce retarded children to attend to the effects of rehearsing upon their readiness to recall. In the terms of the model in Fig. 13, the added instruction should have induced children to monitor their rehearsal (Process 3A), to estimate periodically how accurately they are ready to recall (Process 3B), to compare their most recent accuracy estimate to prior estimates (Process 3C), and to decide to respond when their estimates ceased to increase (Process 3D). The instructions were given for a list-learning problem, and generalization was tested 1 year later with a prose-recall problem, which seems to be a far transfer test. Retarded children whose MAS were greater than 7 years generalized the strategy; those with lower MAS did not. Like Brown and her colleagues, Kendall, Borkowski, and Cavanaugh (1980) designed a strategy for their subjects and provided them with added instructions that probably induced superordinate processing. The strategy was to use selfinterrogation to produce interactive images between items in a paired-associates problem. Superordinate processing was taught indirectly, by providing the re-
TABLE IV Self-Management Recesses Influenced (X) by Instructional Experiments That Have Promoted Transfer of Subordinate Process Training Instnrctional experiments
Self-management processes step 1
Brown and Barclay
Brown et al.
Kendall et al.
Belmont et al.
Bomstein and Quevillon
Knapczyk and Livingston
Ross and Ross
Kahn
(1976)
(1979)
(1980)
(1978)
(1976)
(1974)
( 1978)
( 1977)
X
X X
X
Define best outcome
X
Step 2A Design smtegies 2B Estimate outcomes 2c Compare estimates to goal 2D select strategy Step 3A 3B 3c 3D
Monitor strategy implementation Estimate response accuracy Compare accuracy estimates Decide when to respond
Step 4A Assess response outcome 4B Compare outcome to estimate 4c Evaluate outcome
X X X
X
X
X X
X
X
X X X X X X
X
X
X X
X X
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tarded subjects with feedback about the effectiveness of their strategic efforts. Since the instructions were at first very detailed and specific and were then gradually faded, it seems likely that control over self-interrogationand provision of feedback was transferred to the subjects themselves. In terms of our model of superordinate processing, Kendall et a!. (1980) probably instructed Processes 4A, 4B, and 4C (see Table IV). The instruction was achieved with a standard paired-associate learning problem and transfer testing with a triadic-associate test. Like Brown et al. (1979), Kendall et al. obtained substantial transfer only from retarded children with MAS greater than 7 years. Bornstein and Quevillon (1976) and Ross and Ross (1978) produced generalization by retarded people with lower MAS. Ross and Ross (1978) worked with mentally retarded children whose MAS were about 5.5 years. They instructed some to use rehearsal strategies and others to use imagery strategies. Their instructions concentrated on designing strategies and deciding when to use them (Process 2A, Table IV). Before and 5 months after training, multiple association memory tests were administered. Compared to a control group that received no strategy training, experimental groups showed great improvement from before to after training, which is to say, they showed good generalization of the instructions. Bornstein and Quevillon (1976) produced the farthest generalization of any of the seven experiments. Their subjects were 4-year-olds who exhibited difficultto-control impulsive behavior. Bomstein and Quevillon taught their subjects (in a laboratory setting) to ask questions about solving intelligence test items, thereby inducing the children to set goals (Process 1) and helping them to design strategies (Process 2A). They taught the children to instruct themselves in strategy implementation and monitoring (Processes 3A, 3B, 3C,and 3D). They also instructed the children to reinforce themselves for good performance (Processes 4A, 4B, and 4C). Transfer data were obtained by observing classroom performance. Impressive transfer was obtained. The subjects in this experiment were younger than those in any other successful study of cognitive transfer, perhaps because Bornstein and Quevillon instructed more superordinate processes than any other investigators. Belmont et al. (1978) provided detailed instructions in the use of a particular rehearsal strategy that would apply to their training and their generalization problems, thereby doing an especially detailed job of designing a strategy for their subjects. In addition, they provided full feedback on the results of applying the strategy (Process 4A) and related those results to the use of the instructed strategy (Processes 4B and 4C). Their generalization tests were rather near to their training problem. They secured substantial transfer. Knapczyk and Livingston (1974) taught junior high school retarded boys to ask questions of their teachers, thereby helping them to set performance goals (Process 1) and to design study strategies (Process 2A). This instruction in-
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creased the amount of time the boys spent doing assignments in class, and it increased their reading comprehension. In an experiment with prelinguistic, severely retarded children, Kahn (1977) first taught Piagetian sensorimotor skills and then instructed language use. Progress in language training was thereby facilitated. This looks like far generalization without instruction of any superordinate process, though we would need to see a more complete description of Kahn’s procedures before affirming that conclusion. Lacking a fuller description, we conclude that this experiment is an example of teaching prerequisite skills and knowledge, rather than an example of instructing superordinate processes. There is no doubt that some learning depends upon prior learnings, and we take Kahn’s experiment as a demonstration of this fact rather than as a contradiction of the utility of instructing superordinate processes. Six of seven experiments that have produced generalized cognition by young and mentally retarded children have instructed some aspect of superordinate processing. Belmont and Butterfield (1977) reviewed 114 other publications on the use of cognitive instruction. None of these included training of superordinate processes, nor did any of them achieve generalized results. These facts suggest that the deliberate training of superordinate processes will result in important practical gains in retarded people’s productive thinking and problem solving. This conclusion is consistent with other analyses of how to promote transfer (Borkowski & Cavanaugh, 1979; Brown & Campione, 1978). The results of studies listed in Table IV justify our belief that Step 12C is a reasonable test of the generality of superordinate processes. The test will require the creation of sequences of graded subordinate process instruction for several problem types, which we view as possible right now for subject-paced recall, series completion, paired- and multiple-associates (Kestner & Borkowski, 1979; Turnure et ul., 1976), and the balance beam problem (Klahr & Siegler, 1978; Siegler, 1976).
VI. Concluding Considerations In the first two sentences of this article, we noted the complexity of the research strategy we would describe, and we termed that complexity daunting. Others too have been daunted by the requirements of analyzing generalized aspects of cognitive development (e.g., Brown & DeLoache, 1978). A.
THE SEVERAL ROLES OF PROCESS ANALYSIS
The complexity of the research strategy described above results from its repeated recourse to process analysis. Process analysis is the hallmark of the
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strategy, and we proposed it to solve several problems. To lend validity to processes that are shown to develop, we advised within-age analyses. To assess whether processes identified by one’s analyses are basic to performance, we suggested that an investigator analyze performance until all of its variance has been explained. To guide the design of instructional routines with which to increase or decrease performance accuracy, we proposed extensive process analyses. When instruction does not raise children’s performance to the level of adults’, and when instructing adults does not lower their performance to the level of children’s, we advised further analysis. We argued that well-advanced analyses of subordinates are essential before one even begins to examine superordinate processes. Whether this much process analysis is needed should be judged by assessing the importance of the problems it solves and by seeing if there are simpler solutions. Prior to the mid-1960s, correlations of age or intelligence with performance on single problems were routinely attributed to process differences among children. Then, experimental child psychologists considered the alternative of showing interactions between experimentally manipulated variables and age (Gollin, 1965) or intelligence (Baumeister, 1967). They concluded that correlating performance with age or IQ implicates no particular process, but showing interactions with a manipulation known to influence the process does allow inferences about how different age or IQ groups differ on the process. Step 5B of Table I acknowledges this conclusion by calling for demonstrations of interactions between age and manipulations known to influence processing within narrowly defined age groups (Step 4C). Often, the narrow age group has been young adults, and the manipulations have been designed by general experimental psychologists. That is, developmentalistshave used the within-age anslyses of general experimentalistsas well as their own, when selecting their manipulations for developmental process studies. Thus, the call for within-age analyses for the purpose of clarifying development is an acknowledgment of how developmental cognitive psychology has worked and will probably continue to work. There seems to be no useful alternative for isolating interpretable correlates of age. Psychologists have disagreed for years about the level of abstraction at which to cast their explanations. Behaviorists, and especially Skinnerians, argue against all explanations cast in terms more abstract than stimuli, responses, and empirical relations among stimuli and responses. Biologically inclined psychologists call for explanations of behavior to be cast at the biochemical or newonal level. Cognitive explanations fall somewhere between Skinnerian and reductionist explanations, and cognitivists disagree among themselves about which of their competing conceptualizations are basic explanations of behavior (cf. Huttenlocker & Burke, 1976). Cognitivists cannot discover which of their explanations are basic by judging which is behavioral or biological because their explanations are neither behavioral nor biological. Cognitivists need another way to resolve disagreements about whether a process is basic.
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At issue is whether scientific understandings of cognition will cumulate or whether cognitive science will continue to go from one concept to another, regularly abandoning all but the most current and never determining whether any is basic to behavior. Newell (1973) put it well when he pointed out that psychological hypotheses and theories seem always to be cast in binary, as “either. . ., or. . .,” and that choosing neither “either” nor “or” seems to advance understanding. It was Newell who suggested that sustained effort to account completely for performance variance is a way for our science to escape its noncumulating cul de sac. Process analysis is a proven tool for capturing variance. Efforts to test theories of development by accelerating it had little success until instructions were based on process analyses of adults’ performance and comparative investigations of how children process differently (cf. Belmont & Butterfield, 1977). Process analysis permits instructional tests of developmental cognitive theory, without which developmental theory would lack its most direct experimental support. Developmental cognitive psychologists who have used instruction as a tool have concluded that instruction of subordinate processes has little if any general effects. Until instruction has general effects, cognitivists cannot claim any important insight into intellectual development. A most promising approach to creating general effects is to promote superordinateprocessing (Borkowski & Cavanaugh, 1979; Brown & Campione, 1978; Buttefiield & Belmont, 1977). Since superordinate functions can be inferred only from observations of subordinate processes, analysis of the latter is required before investigation of the former. In sum, process analysis makes age/performance correlations interpretable, it can a f f m that a theoretical understanding is basic, it permits instructional experimentation, and it creates tools for studying superordinate processes. These are the reasons for our adopting process analysis as the cornerstone of our research strategy. B. NONMETRIC COMPLETENESS CHECKS
We included checks on the completeness of process analyses in Steps 4 through 7 of the proposed research strategy. We argued that Steps 8 through 12 were unlikely to be revealing unless they were preceded by relatively complete process analyses. We suggested multiple and partial correlation as tools for the completeness checks in Steps 4E and 5C. We note here that correlation is not an appropriate tool when processes combine nonmetrically to influence performance, which is relevant to Step 4E, or when development proceeds qualitatively rather than quantitatively, which is relevant to Step 5C. In such cases, nometric completeness checks should be employed. For example, when assessing the extent to which one has accounted for the covariance of age and performance, it is sometimes possible to match younger and older people according to their
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method of processing. When all pertinent age-related processes are equated, older and younger matched subjects should perform equally accurately. If they do not, one has a nonmetric rejection of the hypothesis that a process analysis.of development is complete. Whether one uses metric or nonmetric tools to check on the completeness of a process analysis is unimportant. The important thing is to assess the completeness of one’s analyses by whatever methods are most appropriate. C. INSTRUCTING AWAY AGE-RELATED DIFFERENCES IN
PERFORMANCE
Steps 6 and 7 of the proposed research strategy embody the hypothesis that all individual differences in cognition can be eliminated by theory-guided instruction. If this were not the case, we could not advocate efforts to raise deficient thinkers to the level of proficient, similarly instructed thinkers (Step 6) and vice versa (Step 7). According to Zeaman (1973), that hypothesis must be wrong, because there are structural limits on cognitive development. His argument merits consideration. Atkinson and Shiffrin ( 1968) distinguished control processes from structural features, and that distinction remains fundamental to contemporary theories of cognition. The notion is that certain invariant aspects of the human’s cognitive apparatus cannot be changed by any amount of training. Atkinson and Shiffrin called these invariants structural features. The control processes of cognition are indefinitely flexible. Atkinson and Shiffrin did not speak of individual differences between people, nor did they speak of cognitive development. ’From what they did say about control processes, it is easy to infer that many transient differences among people result from the use of different control processes to solve the same cognitive problems. It seems less clear whether they would attribute the sort of enduring cognitive differences that separate children from adults or idiots from geniuses to differential control processing or to varying structural features. Their arguments are moot on this matter; the structural features of cognition may be identical for all people, or they may account for all cognitive differences between people. Zeaman’s (1973) arguments are not moot. He says that mental retardation must be a matter of structural features. He notes that while an individual’s IQs may not be constant, rate of mental growth is, and on this matter the data are compelling (Fisher & Zeaman, 1970). Mental growth rate does remain stable and it does distinguish normal from retarded people. From this fact, Zeaman infers that intellectual differences among people must be the result of structural features, and he views his long-standing program of research as an effort to identify the structural limits that account for mental differences. He points out that his research has, from time to time, identified differences between normal and retarded
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people that might have been structural. However, in practically every case, those differences were easily eliminated by experimental intervention. When that has happened, the conclusion has been that the identified difference was not a structural feature. According to Zeaman, a difference that can be trained away is not a structural matter, but it is inconsequential as regards intelligence. Like Piaget, Zeaman believes that genuine intellectual change cannot be achieved by instruction. How, then, should we view the research strategy outlined above? Does it trivialize cognitive research by making instructability the key test of theory? On the contrary, it is the only approach to the problem of cognitive differences that might ultimately justify the structural position. To see how it might do that, consider Brown’s (1974, p. 61) argument against Zeaman’s position: There appears to be a problem with establishing a vdid distinction between fixed-capacity restrictions and trainable control processes in that this would require that the effectiveness of a training procedure be independently evaluated. The problem is not acute if a particular training procedure is successful since it would then be possible to conclude that a trainable control process was involved and had responded to training. However, difficulty arises when training does not alter performance. Is this due to the presence of a structural capacity limitation or due to the inadequacy of the training technique itself? It would be necessary to exhaust all possible training techniques before concluding that an untrainable smctural feature had been discovered, surely a logical impossibility.
Strictly speaking, Brown is correct. Zeaman’s position is logically indefensible. A structural feature cannot be established by evidence of failure to change behavior. A better training technique may be just around the comer. However, science is a practical business that does not require logical certainty, only estimated probability. The trick is to reduce the probability that a more effective training procedure will be found. When the probability is sufficiently attenuated, reasonable people will infer structural features or some similar limit on plasticity. One purpose of Steps 4 and 5 in the foregoing syategy is to provide a theoretical basis for cognitive instruction. Completing Steps 4 and 5 produces a full theory of the behavior to be changed. Given such a theory, the number of appropriate training procedures would be finite and small, and away would go Brown’s argument, the force of whose “all possible training techniques” is the specter of an infinity of unknown teaching procedures. Her argument gives too little credit to the possibility of a theoretical basis for reducing the matter from one of all possible training techniques to one of all appropriate training techniques. In practice and for some time to come, there may be no complete process accounts of any cognitive performance. Therefore, the number of training procedures that might be tried before inferring a structural feature may remain large, which does not vindicate Brown’s argument. It means simply that the inference of structural features will be based on other considerations, such as the effort
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required to produce a complete account of the variance in particular behaviors. The strategy calls for recursive retreats from the instructional steps (6 and 7) to the analytic steps (4 and 5). When instruction does not result in identical performance by proficient and deficient groups, more process analysis is indicated. However, if further process analysis fails to account for more performance variance, there will come a time when investigators judge that there are no more processes to capture.. If the investigator has applied the strategy diligently, that judgment may suffice for inferring a structural feature. One purpose of the strategy is to guarantee that developmental cognitive psychology has no more 20-year periods during which most of its practitioners believe in mediation da ficiencies because they did not bother to observe mediational processes that might be instructed. Notice the similarity between the notions of mediational deficiency and structural feature (cf. Brown, 1974). D. ECOLOGICAL VALIDITY
The strategy described here is intended to guide laboratory research. Moreover, it is intended to promote instructional experimentation with well-analyzed laboratory procedures, including rote learning problems. Brown and DeLoache (1978), Jenkins (1971), and Neisser (1976) have argued that instructional experiments have no practical utility. These authors have implied that laboratory problems in general and rote learning problems in particular are ecologically invalid. The implication is specious because the targets of cognitive instruction are processes, not problems. Without an understanding of the processes required by both laboratory and nonlaboratory problems, the claim that either has more ecological validity than the other is empty. The fact that people spend more time doing nonlaboratory than laboratory problems should drive no scientist to abandon any well-analyzed problem. Thoroughly analyzed problems are the most analytic tools a behavioral scientist has. Newell (1973) has put an interesting wrinkle on the ecological validity argument. He claims that more scientific progress will be made by analyzing complex performances like those found in the nonlaboratory world and suggests chess playing as an example. Newell argues that such performances are more likely than those prompted by laboratory problems to encompass the entire range of interesting cognitive processes. If cognitive psychologists were making more progress on analyses of evidently simpler laboratory problems, we could take Newell’s argument more seriously. As it is, his injunction seems rather like a call to jump from the frying pan into the fire. Brown and DeLoache (1978, p. 11) argue to the same end as Newell, but their reason is economic: “Given the cost of the detailed task analyses necessary for informed instruction, it seems reasonable to suggest that instructional relevance be the guiding force in the initial choice of training tasks. We should consider
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tasks where improvement would be a desirable outcome even without generalization from the training situation. ” Detailed task analysis and instruction develop ment are expensive. The more complex the behavior to be analyzed and taught, the more expensive the analysis and instruction development. Problems with “instructional relevance” sound to us like complex ones, even though we doubt that a consensus could be reached about which problems are instructionally relevant. It seems to us that our nation’s educators have decided that different problems are relevant to different subcultures. Similarly, we doubt that any improvement in performance “would be a desirable outcome even without generalization from the training environment.” It seems to us that complex intellective skills are complex precisely because they are used in many environments, and that it would therefore be extremely difficult to select a task for which improved performance in a training environment alone would be judged a worthwhile improvement. If it were possible to agree on an instructionally relevant problem, for which transfer of training was not necessary, then the economics of task analysis and instruction development would indeed dictate that that problem should be chosen for intensive investigation. Even if these unlikely conditions did obtain, many scientific questions could still be answered more economically and definitively with laboratory problems that have already been well analyzed. For many scientific purposes, turning ecologically valid is more expensive than sticking with proven procedures, because ecologically valid problems are perforce unanalyzed problems. REFERENCES Anderson, J. R. Language, memory, and thought. Hillsdale. N.J.: Erlbaum, 1976. Anderson, J. R., & Bower, 0 . H. Human associative memory. New York: Winston, 1973. Atkinson, R. C., & Shiffrin, R. M. Human memory: A proposed system and its control processes. In K. w.Spence & J. T. Spence (Eds.), The psychology of learning and motivation (Vol. 2 ) . New York Academic Press, 1968. Baumeister. A. A. Problems in comparative studies of mental retardates and normals. American Journal of Mental Deficiency, 1967, 71, 869-875. Belmont, J. M.Long-term memory in mental retardation. In N. R. Ellis (Ed.), International review of research in mental retardation (Vol. 1). New York: Academic Press, 1966. Belmont, J. M.Individual diTerences and developmental interpretations. Paper presented at the 13th Annual Gatlinburg Conference on Research in Mental Retardation and Developmental Disabilities, Tennessee, March 1980. Belmont, J. M.,& Butterfield, E. C. The relations of short-term memory to development and intelligence. In L. P. Lipsitt & H. W. Reese (Eds.), Advances in child developmen? and behavior (Vol. 4). New York Academic Ress, 1969. Belmont, J. M.,& Butterfield, E. C. Learning strategies as determinants of memory deficiencies. Cognitive Psychology, 1971, 2,411-420. (a) Belmont, J. M.,& Butterfield, E. C. What the development of short-term memory is. Human Development, 1971. 14, 236-248. (b) Belmont, J. M., & Butterfield, E. C. The instructional approach to developmental cognitive re-
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Lachman, R., Lachman. J., & Butterfield, E. C. Cognitive psychology and information processing: An introduction. Hillsdale, N.J.: Erlbaum, 1979. Miller, G., Galanter, E.,& Pribmn, K. Plans and the structure of behavior. New Yo& Holt, 1960. Moely, B. E., Olson, F. A,, Halwes, T. G., & Flavell, J. H. Roduction deficiency in young children’s clustered recall. Developmental Psychology, 1969, 1, 26-34. Neisser, U. Cognitive psychology. New York Appleton, 1967. Newell. A. You can’t play 20 questions with nature and win: Projective comments on the papers of this symposium. In W. G. Chase (Ed.), Visual informationprocessing. New York Academic Press, 1973. Reese, H. W., & Overton, W. F. Models of development and theories of development. In L. R. Goulet & P. B. Baltes (Eds.), Life-span developmentalpsychology: Research and theory. New York: Academic Press, 1970. Rcitman, W. What does it take to remember? In D. A. Norman (Ed.), Models ofhuman memory. New York Academic Press, 1970. Rohwer, W. D. Elaboration and learning in childhood and adolescence. In H. W. Reese (Ed.), Advances in child development and behavior (Vol. 8). New York Academic Press, 1973. Ross, D. M., & Ross, S. A. Facilitative effect of mnemonic strategies on multiple associate learning in EMR children. American Journal of Menral Deficiency, 1978, 82,460-466. Schank, R. C. The role of memory in language processing. In C. N. Cofer (Ed.), The structure of human memory. San Francisco: Freeman, 1976. Siegler, R. S. Three aspects of cognitive development. Cognitive Psychology, 1976, 8,481-520. Taylor, A. M.,& Tumure, J. E. Imagery and verbal elaboration with retarded children: Effects on learning and memory. In N. R. Ellis (Ed.), Handbook of mental deficiency, psychological theory and research. Hillsdale, N.J.: Erlbaum, 1979. Townsend, J. T. Some results on the identifiability of parallel and serial processes. British Journal of Marhematical and Statistical Psychology, 1972, 25, 168-199. Townsend, J. T. Issues and models concerning the processing of a finite number of inputs. In B. H. Kantowitz (Ed.), Human information processing: Tutorials in performance and cognirion. Hillsdale, N.J.: Erlbaum, 1974. Tumure, J., Buium, N.. & Thurlow, M.L. The effectivenessof interrogatives for promoting verbal elaboration productivity in young children. Child Development, 1976, 47, 851-855. Underwood,B. J. Individual differencesas a crucible in theory construction. American Psychologist, 1975, 30, 128-134. Weizenbaum, J Computerpower and human reason: From judgment to calculation. San Francisco: Freeman, 1976. Zeaman, D. One programmatic approach to retardation. In D. K. Routh (Ed.), The experimental study of mental retardation. Chicago: Aldine, 1973.
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I1. BIASES LIMITING SCOPE OF DEVELOPMENTAL THEORY ............... A . GENERALIST BIAS ............................................... B . BEHAVIORISTBIAS .............................................. C . MENTAL TESTING BIAS ..........................................
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III. INTEGRATING THE GENERAL AND INDIVIDUAL IN DEVELOPMENTAL
THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A . COMMON UNITS OF ANALYSIS ................................... B . TYPOLOGY OF CONCEPTS AND RULES ............................ C . COGNITIVE ORGANIZATION OF TYPES AND LEVELS . . . . . . . . . . . . . . .
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IV . MECHANISMS OF COGNITIVE CHANGE AND DEVELOPMENT . . . . . . . . . . . A . BASIC MECHANISMS: COGNITIVE RULE LEARNING . . . . . . . . . . . . . . . . B. UNITY OF PROBLEM SOLVING AND LEARNING .................... C . COGNITIVE LEARNING AND DEVELOPMENT ....................... D . DEVELOPMENTAL LEARNING OF BASIC AND SECONDARY RULES . .
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V DEVELOPMENTAL PHASES OF CONCEPT LEARNING . . . . . . . . . . . . . . . . . . . A . EXPLORATORY PHASE: PROBLEM EXPLORATION . . . . . . . . . . . . . . . . . . B. ORGANIZATIONAL PHASE CONCEFT INTEGRATION ............... C . MASTERY, CONSOLIDATION. AND RITUALEATION . . . . . . . . . . . . . . . . D . HORIZONTAL EXTENSION AND VERTICAL DEVELOPMENT . . . . . . . . .
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REFERENCES
I
.
Introduction
Of the many conceptual strands in the history of psychology. two of the most resistant to integration in a unified concept of development are the apparently lResent address: Laboratory of Human Development. Graduate School of Education. Harvard University. Cambridge. Massachusetts 02138.
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opposing approaches of general laws and individual differences. Is it the task of psychology to search for general patterns of functioning universal to the human species or to study characteristics that individuals share in different degrees and combinations?The problem was well defined by Allport (1937) as the distinction between the nomothetic and idiographic in human functioning. Lewin (1935) spoke of the need for psychology to shed its historic-geographic type of concepts in the Aristotelian mode, which abstracts static universals from the time and space of circumstance. He advocated study of life systems in the Galllean mode, whose laws concern the functional relations of processes evolving in interaction with environments. Brunswik (1952) urged that psychology end its preoccupation with general, molecular laws appropriate to physics and recognize the possibilities of an individual molar psychology of objective functionalism, based on probability. He argued that psychological explanation is inevitably statistical and probabilistic because of the uncertainty of ecological cues and means-end relations. Still unanswered, however, was the question of what form relations between the universal and the particular might be expected to assume. The fields of psychology abound with generalist theories relating poorly to the individual case. Personality theory, for example, recasts life histories in terms of universal traits, coping mechanisms, and stages of development or, alternatively, employs case descriptions, Q sorts (Stephenson, 1953), personal constructs (Kelly, 1955), and similar ipsative approaches that have not been conceptually linked to general laws or developmental theory. Learning processes are studied experimentally with reference to isolated variables, or concretely by applying general principles to produce changes in individuals (e.g., behavior modification) with little regard to particularities of personal style or history, Mental tests have long been used to quantify and classify mental processes mathematically in terms of intelligence, abilities, and other general factors, with scant attention to the logic of cognitive processes. In the field of cognitive development, the alternatives to general stage theories, such as those of Werner (1957) and Piaget ( 1950), have been developmental descriptions usually anchored in Gesellian test norms (Knobloch & Pasamanick, 1974). In psycholinguistics, a universal developmental theory of structural grammar (Chomsky, 1957) together with general learning theory (Skinner, 1957; Staats, 1968), competes against traditions of empirical description and the collection of developmentalnorms (McCarthy, 1954).
11. Biases Limiting Scope of Developmental Theory A.
GENERALIST BIAS
Much psychological theorizing has long been encumbered with biases that limit its success in integrating concepts of universality and individual variation.
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First, the universalist bias itself, which is essentially the bias of generality, is the belief in an overriding set of characteristics common to all human functioning regardless of time, place, situation, or culture. Piaget's theory epitomizes this bias in the realm of cognitive development. His theory is basically about the acquisition of general intelligence: Biologically programmed forms of mental processes mature in an invariant sequence of stages through developmental interaction with self-regulatory experience. In Piaget 's system, environmental experience appears to serve mainly as the material basis for cognitively regulated activity that influences the rate and ultimate level, but not the choice or order, of basic concepts acquired. Piaget does, however, spell out intelligence in terms of a dynamic organization and developmental sequence of complex cognitive processes embedded in action-a marked improvement over the static, linear incremental approach of the mental tester (see Section II,C). The problem is that Piagetian theory leaves little room for conceptualizing individual differences, other than those concerned with rates and levels of development (Flavell, 1963; Sullivan, 1969). The concept of horizontal decalage is perhaps the closest approach Piaget makes to the problem of individual variation. However, horizontal decalage is the extension of concepts basic to stages [e.g., conservation of different domains of dimensionality (e.g., number, length, weight, volume)] that, since they are also acquired in a certain order, constitute substages of the general developmental hierarchy. Experimental and cross-cultural findings, reviewed in Section m,A, 1, indicate that there may be more variation to the order of acquisition of Piagetian formal concepts than was originally prescribed. Unfortunately, the findings have been perceived more as deviations from the general rule than as gaps suggesting the need for theoretical reconstruction to accommodate multilinearity . The key problem is the weakness of the mechanism Piagetian universalists advance to explain the role of experience as a source for mental development in any form (Sullivan, 1969). If, in the final analysis, the potential for development is a single course laid out in advance, then, except for a few minor turnings, only the speed and distance to be travelled are in question. Whether it is called self-regulatory experience (equilibration) or anything else, experience serves neither generative nor directional functions but only regulatory or releasing functions that pace and limit but cannot alter the course of development or vary competence except by level. Individual differences at any age are therefore definable only in terms of the stage and substage levels of cognitive development the child has attained. Within limits, biology and culture are presumed to permit variations in the age of acquisition of various modes of reasoning, and a child may at times regress (Flavell, 1963) instead of advancing, but he may never follow a different path. Neo-Piagetian developmental theory (Case, 1972, 1978a; Pascual-Leone, 1969, 1976) provides a considerable advance, in that it opens the way for concep-
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tualizing variations in the course as well as the rate and level of development through its inclusion (along with affective factors) of concepts of cognitive style and “M space” (the number of items of information the child can hold in primary memory in performing mental tasks). Cognitive style and M space have been shown to make independent contributions to the complexity of cognitive development (Case, 1978b). Both information load and style have been shown to change with development, the former in a more or less linear fashion and the latter in stages, from fielddependent to field-independent forms of functioning. Information load itself has been shown to vary in different domains, such as number and verbal (Case, 1978b), and there is a vast body of individual difference literature on Witkin’s cognitive style of field dependence-independence (the only style concept employed in neepiagetian theory), in which style varies with a variety of characteristics and conditions (Kagan & Kogan, 1970). The logic of relations among Piagetian concepts, styles, and information load remains to be worked out in neo-Piagetian theory. One of the key problems is to define a common unit of conceptual discourse for the separate categories. According to the theory (Case, 1972, 1978b), experience and maturation appear to play different roles in the development of different factors. Also, it is unclear why information load appears to follow a linear course in development, while Piagetian operations and cognitive styles advance in stages, nor is it easy to reconcile four Piagetian stages with two stages of style. Neo-Piagetian theory might also be considerably strengthened if its conception of cognitive styles were not confined to Witkin’s constructs, ignoring many alternative styles such as those of Kagan (e.g., Kagan, Pearson, & Welch, 1966) on tempo of processing or the various cognitive control constructs of Gardner and Klein and their associates (Gardner, Holzman, Klein, Linton, & Spence, 1959; Gardner, Jackson, & Messick, 1960). Other constructs that might broaden the scope of neo-Piagetian theory are the role of language representation (coding) and variations in cognitive development arising from differences in information concepts (the latter are defined as content-related experience). People differ in terms of complex networks and hierarchies of information concepts and specialized knowledge (both common and scientific) that is specific to experience in particular cultures, trades, professions and other institutions (Mangan, 1978). The effect of media on competence is similarly proving of great importance (Olson, 1974). B . BEHAVIORIST BIAS
A second major orientation retarding the realization of an integrated theory of cognitive development and differentiation has been the objectivist or behaviorist bias. Historically reacting against the mental encapsulationof faculty psychology
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and introspectionism (Boring, 19511, behaviorism has, until recently, resisted any system of explanation not directly mediated by environmental conditions. Explanatory concepts that are closely restricted to relations between observable behaviors offer little possibility of recognizing mental processes as a mediational system capable of transforming and not merely responding to external events. The absence of an internally regulated mental system complicates study of the organization and development of modes of processing environmental stimuli that make it easier to account for person-consistency across situations (Endler, 1977). The exclusion of constructs about mental systems also narrows our knowledge of the organism’s past history, because of the absence of a storage system or device for accumulating information. General laws of behavioral learning cast individual differences merely in terms of environmentally regulated “habitfamily hierarchies” (Hull, 1934) or the history of reinforcement contingencies (Skinner, 1957; Staats & Staats, 1963). Few such constructs can handle the differential development of complex cognitive and motivational systems of goals, strategies, and competencies. The acquisition of specific molecular motor actions over short time spans is more easily explained than the influence of experience on the development of long-range cognitive transformations and molar actions. It is difficult to explain cognitive complexity, development, differentiation, or continuity of the individual without recognizing the existence of a system of internal control. It is probably in part because of the lack of inclusion of mental connections that behaviorist theory concentrated so long on general laws of learning in short-term laboratory studies-typically with rats-to the relative exclusion of developmental and life history considerations. In recent years a number of theorists, using mediationally and cognitively oriented conceptions of learning, have attempted to deal with these limitations in various ways. The Kendlers (Kendler & Kendler, 1962), for example, have conceptualized a developmental shift from associative to mediated modes of responding in discrimination learning. Children are first trained to choose large over small, for example, in each of two stimulus pairs in which color (black versus white) is varied independently. Faced with new, alternative contingencies on the same task, older children typically become able to reverse direction on the same dimension (choose small over large), while preschool children do better when allowed to shift dimensions (e.g., choose white over black). The ability to reverse direction is assumed to be more abstract than shifting to a novel dimension, requiring some mediational system such as language to facilitate the necessary mental transformation (in cognitive terms). White (1965) has reported parallel cognitive shifts in development for the 5- to 7-year age period on many different forms of functioning measured by different investigators. Among the many types of shifts he reports are increasing ability to make far as well as near transpositions (e.g., choose the larger of two stimuli across widely differing situations), increasing resistance to classical condition-
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ing, increasing ability to make inferences, shift from relative “colordominance” to “form-dominance, ” and emergence of more abstract behavior [Hofstaetter’s (1954) Factor I11 on IQ tests]. Gruen and Doherty (1977) have recently reported additional evidence on social-cognition and memory processes in a Piagetian constructivist framework supporting White’s review. Although the finding of age consistency is impressive, this simple two-stage conception of development covers little in the way of cognitive structures, functions, and change to map potential pathways for multilinear development. The addition of the Piagetian interpretation by Gruen and Doherty (1977), though adding cognitive structure, fails to account for multilinearity . Ferguson (1954, 1956) has made the beginnings of an important contribution to the relations between learning and complex abilities. He conceptualizeshuman abilities as essentially overlearned performances on various culturally defined tasks. He sees abilities as bounded by biology but open to wide variation, generalization, and channeling determined by culturally regulated experiences and opportunities for transfer in circumscribed ways. The approach is interesting for the latitude and basic transfer mechanism it provides for the development and differentiation of individual differences in abilities and for the role assigned to culture and experience. It fails, however, to specify any typology or organization of abilities that might be characteristic of the species, other than those empirically derived from tests. Weak in its recognition of organismic systems, it is therefore also vague in concepts of developmental processes. Klausmeier and his associates (Klausmeier, Ghatala, & Frayer, 1974; Levin & Allen, 1976) have worked out a cognitively oriented conception of learning that consists of a multistage model of concept learning (concrete, identity, classificatory, and formal levels) constructed with factors that appear to contribute to the acquisition of concepts in this hypothesized, invariant sequence. GagnC (1970) has developed an even more elaborate, behavioristically oriented model of concept learning that he has applied in a general way to human development (Gagnt, 1968). He sees development as a process of acquiring complex, hierarchically organized concept systems through steps involving, successively, multiple discriminations and chains, concepts, and rules that can be identified and taught systematically in educational programs. Both the Klausmeier and the Gagnt approaches provide an excellent basis for conceptualizing individual differences and multilinear conceptions of development. They have both also defined in detail mechanisms of change (learning), though Gagnd’s system appears to offer greater potential for explaining the acquisition of complex systems and networks of concepts more characteristic of long-term developmental processes. The problem is that neither model really embraces the question of the nature of mental structures and how the assimilation of novel material is affected by already acquired mental systems. They are not embedded in a conception of human functioning as a process engaged in by a dynamic, developing system with a history and developed forms actively relating
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current stimulation to the acquired forms. Gagne adheres more to the level of skill description, but neither he nor Klausmeier postulates a model of overall cognitive organization and development. Also, neither has defined a typology of particular classes of abilities and functions characteristic of human functioning and a multilinear conception of development. All concept domains remain more or less equivalent and the number of alternative combinations is apparently endless. C. MENTAL TESTING BIAS
Bias in mental testing stems from the interest in (linear) quantification. To treat all mental acts and behaviors as equivalent in value effectively precludes conceptualizing different mechanisms for acquiring different types, areas, and levels of competence. The mental tester’s conception of development is a linear incremental curve if employed with “g” alone, as in the Binet tests, or a profile of parallel linear curves if broken down into specific competencies, as in the Wechsler scales. Every scale item is assigned a unit value and competence for each area is simply the sum of all unit values. Decisions on item inclusion are defined quantitatively on the sole basis of item intercorrelations, and development is based merely on the percentage of passes for any scale at successive ages (Meyers & Dingman, 1960). The introduction of “s” factors, or a profile of specific subscale competencies, was a great improvement on the single-index IQ scales. The latter permit individual differences to be defined only in terms of greater or lesser ability along a single scale of competence, or developmentally along a uniform course of mental age progression. The “g” approach to mental functioning and development ignores the fact that different combinations of task successes and failures can add up to identical MA and IQ scores. However, as long as unit-equivalence scoring remains the predominant criterion, specific competence scales are only partial solutions. Unless specific competencies are embedded in a logic of cognitive processes, they cannot be functionally interrelated and meaningfully integrated into developmental theory. Similarly, factor analysis, being based on the same unit system of measurement, added little to theory. It is no better than the constructs on which contributing tests are based. Because the latter have typically been empirically constructed, the factors are bound by cultural and population norms for the content of the measures selected (Ferguson, 1954, 1956). The concept of underlying ability factors, as developed by Thurstone (1944), added much to the identification of ability patterns (Guilford, 1967), as well as to Spearman’s (1927) overriding concept of general ability as a universal principle of “eduction of relations.” As long as factors were mainly conceptualized descriptively and empirically in terms of test performances, however, it was difficult for developmental theory to move beyond a concept of development as incremental age growth and to approach the problem of the antecedents and development of individual differences. Therefore, a profile of specific com-
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petencies changes the base for describing individual differences to a multilinear conception of development, but differences remain limited to those empirically defined by the measures selected, by an additive conception of development, by unknown variations within specific cultural patterns, and above all by a limited logic of cognitive processes and development. The emergence of Piagetian-type scales to assess development (e.g., Goldschmid & Bentler, 1968; Uzgiris & Hunt, 1975) is a distinct advance in the direction of measuring abilities in terms of a logical sequence of development. The units of analysis are behavioral steps that reflect cognitive advances, such as searching for partially disappearing and then fully disappearing objects. They are not simply empirically selected and scaled responses whose sequential logic may reflect cultural norms, but does so without regard to cognitive complexity or an internal logic of difficulty. The fact that various scales, despite their Piagetian parentage, are able to scale multilinear, partially independent sequences of development suggests further possibilities in Piagetian theory for exploring individual differences, as neo-Piagetians have begun to do in the theoretical realm. These advances in scaling still need considerable elaboration before a theoretical framework on multilinear development is realized. The relations among the various cognitive subscales are not clear, for example, and different investigators have developed different numbers of scales for the same periods of development (e.g., Corman & Escalona, 1969; Uzgiris & Hunt, 1975). It is evident that an overriding problem of cognitive developmental theory is the need for a comprehensive logic with which to conceptualize relations between experience, competence, cognitive processes, and development. The logic should reflect both the universality and differentiation apparent in cognitive development, define relations between internal structure and external stimulation, provide the tools to measure both transformational and incremental changes, define developmentaltypologies of grammar (Colby,1975) characteristic of particular populations and cultures, and facilitate diagnosis of the profile and organization of competencies unique to each individual. Even so grand a scheme as Guilford’s (1967) factor analytic model of the structure of intelligence however intuitively appealing in this direction, gives us little conception of functional relations cognitively and developmentally within and between the “operations” (e.g., cognition, memory), “products” (e.g., units, classes), and “contents” (e.g., figural, symbolic) he has identified. Guilford has offered no conceptualization of how abilities are organized or how learning and development take place.
111. Integrating the General and Individual in Developmental Theory The contrasting demands of generalist and individual difference theory listed in Table I appear difficult to reconcile in a common conceptual framework.
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TABLE I Alternative Requirements for General and Individual Difference Theories of Cognitive Development Condition
Generalist theories
Individual difference theories
General Characteristics of functioning
Universal: Forms common to every one in all cultures, given minimal, normative experience Typology: Levels and stages only
Development
Unilinear Variation only in rate of acquisition and final level attained
Idiosyncratic: Variety of forms according to quality, variety, and quantity of experience Typology: Culturally common combinations Logically workable combinations Levels (and stages) for each type Multilinear and differentiation (branching) Variation in rates, branches, final levels, and combinationsof types attained Order variant and invariant: Complexity and abstraction sequences: invariant order Sequences of equivalent complexity and abstraction: variant order
Invariant order of complexity and abstraction
The requirements of universality, uniformity, and invariance in developmental order seem intrinsically opposed to the multilinear and sequential variations evident between cultures and between life histories. Yet we do know that characteristics common to all cultures emerge in development, while others are unique to the experience of particular cultures or individuals. People in all cultures acquire the basic motor skills of walking and running and the language skills of comprehension and speech. From recent research we also know that many complex cognitive operations (Sigel & Hooper, 1968) and linguistic competencies (Slobin, 1973) are culturally universal and developmentally ordered. On the other hand, we also know that not everyone in every culture rides a bicycle; talks the same language; or writes poetry; develops the same color concepts (Brown, 1965; Luria, 1976; Rosch, 1975), imagery skills (Segall, Campbell, & Herskovits, 1966), or abstract modes of thinking (Cole & Bruner, 1972; Luria, 1976; Mangan, 1978); masters the same work skills; or employs the same cognitive strategies in problem solving (Bruner, Goodnow, & Austin, 1956). Such differences can hardly be exclusively a function of differences in the general level of cognitive development attained. How can we pull together these observed differences into a common framework? What appear to be called for are certain integrative constructs that could serve to establish a common field of discourse between the separate domains. Perhaps the most cogent needs are to define common cognitive units of analysis, to find a
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means of reconciling variation of concepts by type with variation by complexity levels, and to specify mechanisms of acquisition that can embrace both domains. We shall develop solutions to each of these problems in turn within a framework of cognitive developmental theory and learning. A. COMMON UNITS OF ANALYSIS
Concepts and Rules Central in importance to a unified approach are conceptual units that can define the range of mental characteristics of both domains. Among the most suitable are the twin notions of concepts and rules. These apparently mundane units, long and widely employed in discussing cognitive psychology and development, have never been regularly interrelated or uniformly applied. a. Concepts. A concept-historically known as an “idea”-may be defined as any representation of phenomena. Have11 (1970) has described concepts as “the fabric of mental life” (p. 983), observing how concepts relate to and/or are defined by other concepts in endless chains and systems embracing many levels of generality. We may therefore view concepts as basic cognitive units, ranging from the most primitive cognitive adaptations of the primary neonatal reflexes to the most abstract and general systems of logic of imaginal phenomena or symbolic codes. Even at the earliest level of development, the newborn gives evidence of forming concrete concepts of objects and events through hidher construction of flexible regulatory systems of sucking, for example, selectively adaptive to critical features of the sucking task under varying conditions of position, orientation, and object properties. For example, Peiper (1956) has identified three major forms of sucking (pressure discrepancy, biting, and lapping) that babies alternatively acquire and develop into smoothly operating control systems from an initial state of crude, reflex control (Kessen, 1963). Concepts are the basic cognitive tools in human functioning, enabling the organism to deal with the environment adaptively, as lower animals do, but more abstractly and therefore more broadly, flexibly, and planfully. They enable us to recognize and make use of the repetition of essential similarities among objects and events, and to ignore the many confusing differences in irrelevant surface properties and the changes in circumstances and procedures that do not alter significantly the characters of phenomena. Chairs are chairs, regardless of form, color, or size, as long as they have seats to sit on and backs to lean on; and pulling is distinct from pushing, regardless of the instrument used or materials involved. For the neonate, sucking is distinct from expelling, within a broad variety of tongue, lip, gum, and cheek manipulations. nipplelike structures, and substances involved.
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Concepts form the structure of the mental maps and plans we make (Piaget’s schemata and schemes) to organize our actions intelligently in general form and to solve environmental problems necessary for survival and pleasure. They are mental constructions that distill significant regularities to enable us to arrange the means and ends of our activity in meaningful, generalized, and flexible goalstriving patterns. b. Rules. The concept is an essential but not the sole basic cognitive unit. A concept pulls things together in a mental construction of a phenomenon, but more useful in many ways for describing mental functions is the concept of rule, which shifts the emphasis to the dynamic, process aspect of cognition. A rule may be seen as the operative, defining (criterial) aspect of a concept, specifying the actions required for demonstrating the characteristics of a concept. The set of rules defining the concept of object permanence, for example, includes the operations of object displacement, disappearance-reappearance, and identity of object attributes. Cognitive rules involve the internal representation of actions for recognizing characteristics and processes defining concepts, in a manner similar to Piaget’s (1950) action-based theory of cognitive development. Concepts of phenomena, which form cognitive structures, are in other words rooted in dynamic mental rules for knowing exemplars of concepts through active discrimination and manipulation. They tell us both how things work and how to work them. They actively engage functional relations between cognition and environment and therefore a f f m the dynamic nature of knowledge, as operations that must be constantly recreated through use, compared to the relatively abstract and static nature of concepts. Mental rules are the active elements of maps or plans that tell us how to recognize and manipulate the phenomena we conceptualize in reasoning and problem solving to realize goals. Rules and concepts are nonetheless interdependent parts of an integrated mental process. Concepts define the cognitive structure representing phenomena and rules define the generic operations necessary to identify and make use of the structure. The concept of rules has not been widely developed in cognitive theory, except in contemporary psycholinguistics, following Chomsky ’s theory (1957) in which language is structured in terms of a generative system of rules. Various investigators (e.g., Beilin, 1965; Goldschmid, 1971; Siegler, 1973) have focused on rule learning, generally in a Piagetian framework, without making systematic efforts to conceptualize the nature of rules in cognitive processes. GagnC (1970) is perhaps the most systematic in his use of the concept of principles (which could easily be defined as rules) as chains of concepts that make up knowledge. Kessen (1963) stresses the overriding importance of recognizing the existence of higher order rules as opposed to responses alone. He more or less equates rules to principles, schemata, and generalized stimulus-response hierarchies, but he does so without much elaboration beyond pointing out the need for conceptualizing
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different kinds of rules for all domains, such as simple relations, search procedures, and recursive maneuvers, as this writer has attempted to do. The person who appears to come formally closest to this writer’s concept of rules is Bourne (1966), who sees concepts as defined by a combination of rules and attributes. In this writer’s view, attributes are integral to the rules that define concepts. B. TYFQLOdjY OF CONCEPTS AND RULES
A second basis for reconciling universality and variability in development is the recognition that concepts vary by both level and type. Virtually all developmental theorists make extensive provisions for variation by complexity, though not always in terms of distinct stages or developmental levels as Piaget does. Developmental progression in complexity, or vertical development, allows for individual differences in rates and final levels of cognitive complexity as a result of experience, as observed in Section II,A, but not for a multilinear course of development. Horizontal development at the same level is also widely recognized, e.g., in terms of processes of differentiation (Lewin, 1935, 1951; Werner, 1957; 1975), horizontal dkalage (Flavell, 1963), or generalization and transfer of learning (Gagnb, 1968). The groundwork is thus laid for a multilinear model of development, early espoused by Werner (1957), but apparently never worked out by any theorist as to the actual variations in forms different pathways might follow. Piaget’s horizontal dkalage is (again) apparently a largely universal process of vertical progression in substage levels of difficulty in formal concepts. In contrast, theorists who define horizontal development as either differentiation or generalization allow theoretically for both different starting points and different degrees of concept extension at successive levels of vertical development. In other words, for both orientations, what is learned is not predetermined. Breadth of knowledge may begin in different concept areas (history versus geography) and move in different directions (medieval versus ancient history), as well as extend for different distances. Because the expansion in breadth can also move vertically in complexity to different levels in different areas (more depth in concepts of agriculture than those of family), the potential variety of developmental permutations and combinations is enormous. Concepts do not appear to multiply equally in all directions, however. The organization, development, and extension of concepts follows a certain logic, based on characteristics of environments and the biological nature of mental processes. The differentiation of concepts by type appears to grow out of the nature of human adaptive activity in relations with the environment. These relations are structured in terms of key dimensions: first, the environment; second, the process of representing the environment and activity; and third, the activity itself. This pattern of relations would in turn demand differentiation of mental functions, beginning with three primary types corresponding to the dimensions of the activity structure.
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The first type consists of knowledge concepts, which relate to the environment. The second is coding concepts, which represent, summarize, and communicate knowledge in general form. The third category is problem-solving concepts, which involve strategies for organizing mental and physical activity to cope and create. Each of the three types thus arises from and is intrinsic to different cognitive processes essential to human adaptation, and each differentiates into various major and minor subtypes according to experience. In fact, a number of lines of inquiry-including neo-Piagetian theory (Case, 1978a), work on language codes (Bruner & Anglin, 1973) and representation (Sigel and Cocking, 1977), cognitive styles (Fowler, 1977), and Guilford’s structure of the intellect (1967t-a~ discussed previously (Fowler, 1971b, 1977), suggest the basis for the pattern of cognitive differentiation described, as will be discussed later. It is quite likely that certain basic concepts in each of the foregoing categories are widely or even universally shared because of the way human species potentials are genetically disposed to acquire certain basic concepts in each type, given the similarity of requirements for survival in any environment. Such universal concepts might include (1) rudimentary knowledge concepts about the physical and social worlds and how they work (e.g., permanance of objects, movement, and self-other distinction); (2) elementary coding concepts to make possible selectivity, generalization, summarization, and communication (e.g., ordering, substitutability, routinization, and representation in action, pictorial, and language forms); and (3) at least elementary means-end strategies for solving problems basic to environmental adaptation (e.g., searching for and interrelating key features in concrete tasks). On this foundation, variations in the form and complexity of cultural and individual experience would lead not only to a general increase in the development of cognitive complexity, but also to different forms of complexity among the three basic concept domains and to different subtypes of knowledge, codes, and strategies. Such differentiation by type and subtype offers an enormous potential for individual differences in profiles and hierarchical organization of competence. Among different subtypes would be included hierarchies of concepts specific to different cultural histories, geographical regions, human environments (e.g., urban, rural), and trades; different languages and different visual, mathematical, and other codes; and alternative strategies for solving problems that arise from variations in culture, occupation, and natural problems of adaptation. We shall outline in detail a suggested typology of concept hierarchies, interrelated at different levels of organization, that offers a wide perspective for synthesizing uniformity and variability in cognitive development. A typology of major classes and subclasses of concepts represented in each of the three types of concept systems is presented in Fig. 1. The hierarchies and sets in each category are neither definitive nor exhaustive in that various alternative organizations and further multiple subtypes are easily anticipated. The intent is
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Fig. 1 .
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its own characteristics and functions about which we formulate and acquire bodies of concepts, varying in both type and complexity, according to the differing accumulations of cultural history and personal experience. Our worlds of ideas vary in similar ways for similar reasons. The concepts from these different realms are intertwined in many ways, but this only multiplies further the potential for alternative avenues of development; the variation between individuals and cultures in competence profiles is virtually infinite. Broadness and depth of knowledge in a field can substitute for cognitive complexity in formal concepts within a wide range, as the complex competencies of skilled craftsmen, artists, and athletes (Bennett, 1967; Fowler, 1962a, l969,1971b, 1971c, 1972; Goertzel & Goertzel, 1962; McCurdy, 1957; Pressey, 1955) and scientifically untutored tribal people testify (Cole and Bruner, 1972; Cole, Gay, Glick, & Sharp, 1971; Levi-Strauss, 1966). One of the best illustrations is the remarkable complexity of the Australian tribal kinship system, whose relations and forms of address adults typically master with ease (Radcliffe-Brown, 1930-3 l), although as we have seen, they appear to have difficulty with conservation (De Lemos, 1966). But even in the core domain of formal concepts, there is mounting evidence of greater individual variation of order and type than Piagetian theory suggests. Competence in formal concepts may vary widely according to the field of specialization, as in engineering, fashion, and wine tasting. A high degree of specialization is likely to generate refinement in concrete operational competence in such dimensional concepts as sound, light, color, and taste, far beyond the rough concepts of seriation and classification the untrained person uses. Systems theorists, ecologists, engineers, and scientists acquire combinatorial operations much different from and more complex than the cognitive manipulations reflected in the standard measures typically employed by cognitive developmental researchers (Flavell, 1963; Sigel & Hooper, 1968). Such refinements and elaborations may compound themselves along dzyerent pathways to make profound type as well as level (stage) differences between individuals in different fields, as is not uncommon with great specialists (Fowler, 1971~).Competence in grasping the object concept may vary along two independent dimensions, for example, the visibility of displacements and the number of displacements (Miller, Cohen, & Hill, 1970). In conservation, materials (Uzgiris, 1964) and number of units (Zimiles, 1966) in the task make a difference. Cross-culturally, formally unschooled children are able to perform conservation tasks under certain conditions (e.g., active manipulation, familiar materials) better than others (Bruner, Olver, & Greenfield, 1966; Cole & Bruner, 1972; Cole et al., 1971; Feldman et al., 1974; Mangan, 1978), and vary in strength between dimensions. For example, Australian aborigines advance relatively better in Conservation of space, whereas West African children advance relatively better in conservation of quantity (Dasen, 1977). Formal concepts therefore appear to involve culturally regulated experiences that vary the level at which formal concepts are attained in different
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areas and aspects. It is really much too early to chart with confidence the extent of potential developmental variability of the knowledge domain. 2 . Representational Concepts (Codes) Representational or coding concepts are the means by which we summarize concepts about phenomena and ideas and establish common currencies for communication. Codes make possible the representation, storage, retrieval, and exchange of vast bodies of knowledge that could not otherwise be collected and selectively utilized for social purposes. Bruner has formulated a general developmental scheme defining three basic types of coding systems, enactive (sensory motor), ikonic (imagery), and symbolic (verbal), that he views as playing major roles in processing knowledge (Bruner, 1973; Bruner et al., 1966). Piaget sees cognition as more independent of codes, with both imaginal and verbal processes continuing to function in parallel throughout development (Piaget & Inhelder, 1971). In this sense, Piaget’s orientation is similar to Paivio’s (1971), which is supported by at least one recent independent study (Forisha, 1975). Bruner and Paivo appear to be closer in how they tie codes to cognition, however, despite differences with respect to timing and potency of imaginal and verbal codes. Whatever the exact form of relations and developmental sequences among and within codes and other concepts, codes make up distinct classes of concepts, each one potentially further differentiating development in terms of alternative branching systems. Almost everyone agrees and the evidence seems clear on the distinction between type and order of sensory-motor and verbal concepts. Language concepts are more abstract, begin later, and serve a dominant function only some time after sensory-motor codes have been the major basis for concept processing. Evidence from the factorial work of Guilford (1967) and others also supports the separateness of sensory-motor, visual-spatial, and symbolic systems throughout development. Sensory-motor action concepts, the first basic coding system, by the nature of their intimate tie to the physical world, are closer to whatever knowledge concepts the infant acquires than are the later functioning symbolic codes. Nevertheless, sensory-motor concepts appear to be constructed of rules for summarizing knowledge about phenomena distinct from the ideas of the phenomena themselves. The infant’s mode of learning about objects, for example, is derived through such generalized coding devices or action plans (schemata or schemes) as differentiating, coordinating, and sequencing means and ends in movement, moving in a direct line, moving from any angle and body position, using various hand grasps, using either hand, varying hand function, and other selected, summary forms of action, the development of which which are richly described by Piaget (1952) and Bruner (Bruner & Anglin, 1973). Knowledge concepts about objects, in contrast, consist of formal rules, such as object movement, displacement, and disappearance-reappearance, that define the identity concept and in-
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simply to assemble a set of frequently identified major concepts in a coherent organization for heuristic purposes. All concept types and subtypes are assumed to interact in different ways according to task demands and the manner in which they are organized in the individual. Interactions between types should also vary with stages of development, but again in different ways according to experience. How competencies interact in an organized mental system in relation to task demands will be considered following a discussion of the three types of concept systems. I . Knowledge Concepts Concepts of knowledge emerge from the fact that the world has substance. The problem of human existence rests on discovering and manipulating environmental regularities-the basic structure of the environment and how it works-in the face of much perceptual confusion. Over the course of history, mankind has evolved mental constructions of underlying spatial-temporal orderliness in the form of knowledge concepts to enable us to cope more efficiently. Knowledge concepts and their operational counterparts, rules, make possible consistency and purposiveness of action, a rational selection of environmental means to ends not possible without selective abstraction and operation, as noted earlier. Knowledge concepts are not confined to the physical world, of course. They apply to the substance of all things, to the worlds of the organic and inorganic, the social and even the world of ideas itself. Concepts often pose alternatives to existing patterns and serve pleasure as much as function. In short, knowledge in its most general sense embraces the content of thought. Knowledge concepts break down into two major categories. One includes the highly generalized formal concepts of physics, concerning the general nature of things, that Piaget has systematized for developmental psychology. The other, information concepts (content), relates to the specific features and functions of plants, animals, cultural artifacts and institutions, and other domains of the real and ideal worlds. Piaget’s system and the operational rules he has so well elaborated provide us with a general sequential picture of the development of concepts embracing the basic substance and process regularities (e.g., of identity, seriation, conservation, number, transitivity, and time) that transcend the content of any particular environment. The apparent invariant order of formal cognitive development need not be considered a function of biology alone, however, as Piagetian theory is inclined to affirm. There is apparently an intrinsic order of complexity in acquiring knowledge of formal concept hierarchies that arises from the nature of things, and this order contributes to the developmental invariance typically found (e.g., Elkind, 1961; Uzgiris, 1964). For example, the concept of conservation of matter would be difficult to grasp without first realizing that substances have identity and permanence; conservation of volume is perhaps more abstract than conservation of substances. Changes in shape that affect perception
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of substance involve only the visible substance itself, while volume involves reference to an additional concept4he amount of space occupied by the substance-that must be inferred or imagined. The choice between hypotheses-biological programming or task complexity-is not readily subject to experimental test, unfortunately, but such a dichotomy is probably in many ways misleading. Assessment of innate developmental invariance requires reference to specific processes by means of task manipulation, the hallmark of the scientific method, in order to determine the conditions and tasks in which invariance may and may not occur. Development does not take place in a vacuum. Although those tasks for which sequence is invariant across all cultures may be presumed to be more heavily governed by biology than those whose sequences are more variable, the evaluation process necessarily involves consideration of task complexity, without which definitions of competence, whether more biologically or experientially based, are meaningless. The evaluation process is intrinsic to both the nature of things and the nature of people. The basis for the essential universality of formal concepts is therefore probably rooted in the uniform requirements of human adaptation to any environment. The minimal basis for survival of any culture and social system may depend on socialization of most of its members in the basic sequence of formal concepts over the course of development-at least as far as some minimum floor. Therefore, the average experience in every culture socializes the average membership through the same general sequence, following an intrinsic order of difficulty, as far as some basic survival level. Beyond this floor level, individual and cultural variations in formal concepts appear to be limited mainly to differences in final cognitive level attained. We do not yet know where in the sequence the floor level falls, but cultural norms generally reach some point in the second major stage, that of concrete operations (Dasen, 1977; Sigel & Hooper, 1968). Many members of the Australian aboriginal culture, however, apparently do not master even concrete operations (i.e., conservation) well into adolescence (De Lemos, 1966), although alternative, more culturally relevant measures might well disclose greater progress along the formal sequence (Feldman, Lee, McLean, Pillemar, & Murray, 1974). Knowledge of information concepts, in contrast, provides a rich source for developmental variation. Knowledge specific to different environmental and idea domains (e.g., of factories, transportation, housing, history, anthropology, philosophy) is composed of varying hierarchies of information concepts, each demanding different combinations of long-term experience to accumulate. Information concept hierarchies produce endless developmental variations in competence by type as well as by level. To begin with, each culture and its institutions has its own set of concepts and rules about ideal and actual forms. The natural and human-made worlds each has
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formation rules, such as the presence of criterial features and functions defining various specific object concepts (e.g., face, flower, fish). Piaget, however, makes no clear distinction between knowledge concepts and enactive codes. A variety of relatively independent codes branch out from these three basic codes according to the types and combinationsof specialized experience accumulated. Sensory-motor codes, for example, take several forms that can lead to elaborate specializations, as shown in Fig. 1, given sufficient follow-through experience. Of two basic motor divisions, fine and gross motor systems of processing, the former breaks down into alternative subtypes according to the different sensory systems (e.g., visual, auditory, tactile) utilized. Gross motor systems appear to be particularly dependent on visual and kinesthetic sensory channels. The access visual perception gives to knowledge of the world, as studies of blind infants dramatically reveal (Fraiberg & Fraiberg, 1977), makes visualmotor systems typically predominant in human development, The developmental lag of blind children in movement, exploratory, social, and representational skills, for which auditory systems failed to compensate, suggests that visualmotor concepts are likely to play a universal foundation role in human development. It seems unlikely that such a foundation would lose its importance even in individuals whose auditory-motor systems or olfactory-gustatory systems become highly developed, as in musicians and gourmets, respectively, although the foundation would not be so elaborately developed as it would be for painters. Motor skills may underlie sensory coding especially in visual modes, but sensory coding may be at least partially distinct from action coding in all sensory modalities. Therefore, although sensory codes (whether visual, auditory, or other) may initially be closely related to action systems, they appear to develop with rules of their own (Forisha, 1975), particularly in the visual mode, forming the basis of much knowledge representation, but in relatively direct, perceptual form. Pictorial representation breaks down into many different two- and three-dimensional visual-spatial codes, each based on sets of variously differing and overlapping rules for diagramming or modeling intricate reality and idea systems. These codes form the foundation of all fields of the visual arts and engineering design. Both fine and gross motor rule competencies may nevertheless be coupled with many combinations of sensory-channeled concept experiences, knowledge forms, and coding systems to generate a rich variety of types of competence, as in athletics, dance, visual art, and music (see Fig. 1). Symbolic codes are obviously more abstract than either action or most pictorial codes, permitting flexible, general application to any circumstance and magnifying the possibilities for inventing and manipulating concepts about both real and imagined phenomena. Symbolic codes are composed of arbitrary symbols, and therefore knowledge (or any other concepts) can be manipulated at will at any
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level of generality or particularity. However, this power is also a limitation in that all ties of resemblance to phenomena vanish, underlining the continuing value of sensory-motor and pictorial coding and direct experience at all levels of development. Symbolic codes are further restricted by the fact that units are generally strung together in linear, time-bound series, complicating the problem of representing phenomena that are structured spatially as well as sequentially. First among symbolic codes is the verbal language system itself, which makes use of universal concepts inherent to the logic of symbolic coding (e.g., ordering, term differentiation, arbitrariness of representation, modularity) (Slobin, 1973) and other concepts specific to the code of each linguistic community (e.g., postpositions in Japanese versus prepositions in English and other European languages) (Brown, 1973). Thus, in verbal language systems, the integration of the universal and the individual is represented through variations in structural level, perhaps oversimplified by the polarities of “deep” and “surface” structure (Chomsky, 1957). Starting with oral language, from symbolic coding have evolved textual systems, which though more formal, open the way to more complex and precise logical and literary forms of expression (Olson, 1974). Numerical and musical codes are distinctly separate symbolic types, which differentiate into several logical and/or aesthetic subtypes; both are organized in terms of precise specification of units and internal coding relations, the first applied to counting and measuring phenomena in general and the second 6 musical patterns. It would appear, on the one hand, that codes vary in complexity and level of abstraction and that an increasing use of abstract, logical codes develops with experience, though not equally or in identical forms in all societies (Luria, 1976) and social conditions (Hess, 1970). In general, knowledge is first acquired and coded in infancy through direct experience in sensory-motor activity that leads to the formation of action codes (enactive) and, perhaps more gradually, various sensory codes, notably pictorial codes (iconic), which are enhanced by experience with pictures in contemporary life. The more abstract and complicated symbolic coding follows soon after these relatively more representational codes, first in the form of oral language, which gradually comes to serve as the vehicle for much of the more complex and generalized forms of knowledge. On the other hand, each of these three major coding systems is potentially highly complex, intricate, and variously multibranching in the forms it can assume. Normal experience in most cultures typically leads to parallel development of all three types, and all continue to contribute to mental life in important proportions, though to different levels, with different degrees of dominance and varying proliferation of subtypes. Unusual experience, however, may lead to exceptional specialization in various combinations of pictorial, mathematical, musical, kinesthetic, chess, or other coding systems (Fowler, 1969, 1971b, 1971~;Fowler and Swenson, 1979).
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3. Problem Solving Strategies (Cognitive Styles) Cognitive strategies or concepts representing rules of problem solving and reasoning are again quite distinct from concepts of either knowledge or coding. Knowledge is our map of the world we must adapt to, and codes enable us to condense and transform this knowledge into manageable forms; strategies are the means by which we adapt. They represent how we go about seeking and organizing information and actions to deal with the problems of adapting to the environment. In any activity, we use various methods to explore, figure out, hypothesize, and experiment with the dimensions of the activity, the problems we encounter, and the alternative courses and solutions we attempt to devise and follow. Much investigation of strategies has led to various constructs of modes of processing information, generally identified as cognitive styles, cognitive controls, or cognitive strategies (Fowler, 1977; Goldstein & Blackman, 1978; Kagan & Kogan, 1970; Kogan, 1976). The term style has been applied generically to embrace all modes of information processing, including controls and strategies. The concept of controls stresses the adaptive (unconscious) aspects of personality (ego) control (Gardner et al., 1959, 1960; Witkin, Dyk, Faterson, Goodenough, & Karp, 1974), and the concept of strategies stresses the cognitive (conscious) aspects of problem solving (Bruner et al., 1956; Wallach & Kogan, 1965). It is apparent, however, that such control concepts as focusing and levelingsharpening (which describe, respectively, extent of attention deployment and tendencies to blur or sharpen recalled perceptions) combine both cognitive and adaptive aspects of functioning. Cognitive strategies, such as the contrast between focusing on hypotheses in a tight logical sequence or employing wideranging guessing strategies, similarly have both cognitive and adaptive implications. In this context, we are concerned with their role as modes or techniques of problem solving; we see that, whatever the differences in emphasis among style theorists, it is clear that strategies for processing information are an important third source of individual differences in cognitive functioning. In fact, the focus in research on cognitive styles has been on how individuals vary in selfconsistent ways on the various styles measured (Kagan & Kogan, 1970). Individuals have been shown to vary widely on a wide variety of style constructs; this finding adds to the potential for individual differences as much as do knowledge and coding concepts. The style field is considerably fragmented, however, containing almost as many formulations of modes of processing as investigators (Goldstein & Blackman, 1978; Kagan & Kogan, 1970; Kogan, 1976). The result is a large set of style constructs around many of which extensive but usually unrelated bodies of empirically validating literature have emerged. Witkin’s (Witkin et al., 1974; Witkin, Goodenough, & Oltman, 1977) concept of degree of articulation of figure-ground relations (field dependence-independence), Kagan’s (1965) con-
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cept of tempo of information processing (impulsive-reflective), the work of Gardner and his associates (Gardner et al., 1959, 1960) on focusing, levelingsharpening, and equivalence range, and of Bruner and his associates (Bruner et al., 1966) on identity and equivalence are good examples of this trend. This fragmentation appears to have produced considerable unresolved overlap among the various styles. For example, the focusing (attention deployment) control dimension applied to perceptual processing tasks by Gardner and his associates (Gardner et al., 1959, 1960) in some ways resembles the alternative focusingscanning cognitive strategies identified in earlier work on concept attainment tasks by Bruner el al. (1956). The difference may be largely a question of level of abstraction or degree of ingrainedness (automaticity). However, the many apparent parallels of this kind between these and other combinations of constructs, such as the similarity of analytic styles involvement in the foregoing, the earlier analytic styles of Kagan, Moss, and Sigel (1963), Kagan’s reflectiveimpulsive dimension (Kagan, 1965), the field dependent-independent dimension of Witkin et al. (1974), the identity and equivalence dimensions (or analysis and synthesis) by Bruner et al. (1966), and the analysis and synthesis dimensions by the author (Fowler, 1977) point to the need for conceptual order in the field. Kagan and Kogan, in their 1970 review, discussed the work on styles in relation to the original formulations of Lewin (1935, 1951) and Werner (1957, 1975) on differentiation and hierarchical integration in development, drawing attention to the variety and incompleteness of operational definitions and the lack of organization in the field. Santostefano (1969) and this writer (Fowler, 1977) independently have made systematic attempts to link together a selected set of style concepts in a developmental framework. Utilizing the control concepts of focusing (focusingscanning), leveling-sharpening, and equivalence range of Gardner and his associates (Gardner et al., 1959, 1960), in combination with the field articulation style concepts of Witkin’s group (Witkin et al., 1974; Witkin et al., 1977), Santostefanodefined style development as movement from perceptual to conceptual levels of processing, individuals varying at successively more abstract levels in the extent of focus they employ. In this way, development proceeds from the degree of concrete focal attention in perception, through the degree of field articulation (in which organization of a perceptual field comes into play), followed by leveling versus sharpening (in which perceptual differentiation is mediated by memory of past perceptions) and, finally, by differences in equivalence range (or the extent of exemplars included in abstract classificatory tasks). Although this conception leaves many other styles and strategies unaccounted for, Santostefano’s synthesis provides a beginning model for how individuals may vary in processing strategies at successive levels of development, thus accounting for an important source of multilinearity in development. This writer (Fowler, 1977), drawing on these, Bruner’s (Bruner et al., 1956),
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and other style concepts, has conceptualized a still broader style scheme, integrating styles and development in terms of problem-solving strategies for analyzing and interrelating problem components at increasing levels of abstraction. In this scheme, individuals vary in the degree of focus they employ at successively more abstractkomplex levels of development, fmt in exploring objects; then in dealing with elements and relations prelogically in a perceptual field; next in classifying, hypothesis testing, and theme generation in concrete logical operations; and finally in logical operations and theme activity in the realm of the propositional and creative imagination (see also Fowler, 1977). Analytic and integrative styles are conceptualized as complementary problem-solving strategies that work more efficiently when developed in balance form in the individual. Measures of degree of analytic-integrative style balance have been shown to be significantly related to IQ (Lawton, 1977). Memory is seen not as a separate stage (leveling-sharpening in Santostefano’s conception), but as a distinct process tending to expand with development in the manner described by Case (1978a). This conception utilizes the Piagetian conception of stages as well, but is broadened to encompass the content of information concepts in thematic activity as a further basis for the development of complexity and differentiation, as described above. As Fig. 1 shows, a considerable variety of style and motivational concepts collectively offer ample room for cognitive differentiation of competence. They need to be interrelated before a tightly integrated conception of styles and development is realized, however. C.
COGNITIVE ORGANIZATION OF TYPES AND LEVELS
If mental processes are differentiated by concept types in the manner described in the preceding section, they nevertheless also function as an organized system, operating with whatever concepts and rules from the different categories have been acquired through experience, according to the nature of task demands. As observed earlier, each of the three concept categories represents an essential aspect of cognitive functioning that the child must develop to some degree in order to cope at all. She or he must have a minimal body of concepts about things (knowledge), expressed in some form (a code or codes), and some conception of how to manipulate means mentally and physically to achieve ends (strategies). They are all basic requisites for survival. Therefore, the three types of concepts are in reality three different but equally essential aspects of the basic total process of human mental functioning. Mental processing consists of selective mental representation (coding) and manipulation (problem solving) of concepts of phenomena (knowledge) to prefigure and solve problems of adaptation. Cognitive processing is the organized mental acquisition, storage, and manipulation of differentially coded knowledge through various modes (strategies) intended to serve human adaptation.
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As the individual develops in complexity and differentially by types and subtypes, unified cognitive organization is maintained through relating newly acquired concepts horizontally to other concepts at the same level and through hierarchical organization. Each successively acquired knowledge, coding, and style concept appears to become embedded in a network of already acquired concepts and their accompanying rules, whose utilization in an organized manner is facilitated by integration into larger types and subtypes (or concept systems and subsystems). Even quite novel experiences, such as exposure to a strange language or direct training in novel strategies, to be learned at all must apparently be related to existing structures in some way. Strange phonologies and grammars and novel strategies are likely to be compared and integrated with exemplars of familiar types, as Piagetian and information theory (Miller, Galanter, & Pribram, 1960) and many other theorists and much evidence suggests (Abelson, Aronson, McGuire, Newcomb, Rosenberg, & Tannenbaum, 1968; Allport & Postman, 1947; Berlyne, 1960; Festinger, 1957; Havell, 1970; Hunt, 1961; Sigel & Cocking, 1977). This is not to say that all concepts fit together in close harmony. Few individuals attain the level of integration of personality discussed by Allport (1937). However, integrated functioning does not preclude inconsistency among concepts, through different concepts becoming embedded in the different types and systems of knowledge (or codes and strategies) that are seldom called into play in the same context (Berlyne, 1960). It is apparently, as already noted, the organization of concepts in hierarchical systems whose component types function in different times and places that enable humans to develop such elaborate differentiation and complexity, yet maintain considerable day-to-day consistency and organization of functioning across contexts. However, if, as it appears, cognitive processes do function as an integrated system, the mental systems of no two individuals are organized along identical lines because variations occur in the combinations and levels of type concepts developed as ability test profile comparisons regularly show (Anastasi, 1958). Individuals vary not only generally in complexity and level of abstraction following a model of general intelligence (g) and the unilinear model of development advanced by Piaget; within limits, they may vary also in complexity and abstraction differently for each of the category types. An individual can thus apparently be differentially rich in the complexity of knowledge, coding skills, or strategic concepts she or he has acquired. She or he can also vary among the three categories in the level of abstraction employed, using broad-ranging syntheses in strategies, for example, with low-level abstractions of knowledge, essentially descriptive and practical or graphic-functional (Luria, 1976, Vygotsky, 19621, and highly concrete coding skills, such as spatial-motor modes-or various other combinations of levels. Variations typical in the types and subtypes of concepts within each category further add to the potential for individual differences. Many combinations and levels of information concepts (e.g., machinery, farms, geog-
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raphy, cultures), coding concepts (e.g., fine and gross motor, varied sensory channels, language, math types, musical forms, visual and performing arts), and strategic concepts (e.g., analytic versus integrative emphasis, reflective versus impulsive emphasis) may all develop and coexist in different ways in competence networks and hierarchies.
IV. Mechanisms of Cognitive Change and Development In outlining how concepts from the three categories interweave and interact cumulatively to develop individualized mental structures, we must take account of how rules are acquired in the formation of concepts and concept systems. Defining mechanisms of concept formation is the third basis for delineating relations between the general and the individual in development. A.
BASIC MECHANISMS: COGNITIVE RULE LEARNING
The generic process for all cognitive change may be defined as the acquisition of rules that operationalizeconcepts. Humans appear to have an inherent capacity to acquire adaptations to type as well as to respond by rote to fixed conditions, a process that can be identified in earliest infancy and expands with development (White, 1965). The process begins developmentally with the adaptive elaborations of neonatal reflexes (e.g., crude sucking, grasping) in repeated encounters with appropriate phenomena (e.g., nipples and liquids, graspable objects) under changing conditions. It evolves gradually by the addition and often hierarchical organization of rules of different types, as knowledge, codes, and strategies are acquired and interrelated, through adaptive problem-solving in an expanding and working mental system. Cognitive change is thus essentially a process of mental adaptation to environmental task demands that leads to learning rules about things, rules for representing concepts about things, and rules for figuring out how to manipulate and construct things. The process is one of apprehending phenomena in the three domains as exemplars of types (concepts) through defining underlying characteristics, relations, and regularities (rules) that transcend specific circumstances. Cognitive rule learning differs from traditional conceptions of learning in a number of ways. Among the most important are an emphasis on mentally governed behavior-a conception of learning as a logical (structural-functional) apprehension of general rules for understanding phenomena and for guiding action, even as Lenneberg (1962) has demonstrated for language or as has been shown in experiments on modeling and observational learning (White, 1970). This conception varies from a conception of learning as the acquisition of a
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repertoire of externally defined responses (behavior) through arbitrary association of stimuli and responses by contiguity, repetition, and reinforcement. It resembles in some ways the cumulative learning conception of Gagnd (1968) and the concept-learning orientation of Klausmeier (Klausmeier et al., 1974), but is framed more in terms of internal regulation of cognitive processes through problem solving and broader developmental, life history, and Piagetian perspectives. This concept of learning does not rule out the well-established phenomenon of rote responding as a basis for learning and development, but it does propose that rote conditioning plays a minor role in normal development. The human organism does not ordinarily encounter in life the fixed conditions typical of the classical or operant paradigms of the laboratory. In the early sucking and grasping experiences, for example, the neonate is faced with a variety of positional, object, person, and contextual stimulus variations from occasion to occasion that indicate that the problem may typically be a case of cognitive rule learning. Each event is a varying instance of the respective general rules involved in mastering sucking and grasping. This conception of cognitive learning appears, moreover, to interrelate the worlds of biological potential, the cognitive developmental universals of Piaget and psycholinguistics, and learning. Genotypes provide the potential to acquire understanding of rules about phenomena in certain species-specific ways. However, genotypic potential is highly malleable, providing ample room for developmental variation in both complexity levels and types of concept organization (Davis, 1970). Because of this malleability to experience, the individual is capable of realizing an infinite variety of specific (phenotypic) mental structures representing endless combinations of knowledge and many alternative forms of codes and strategies at varying levels of complexity. Numerous developmental universals are also the rule, however, because of certain overriding similarities in the nature of things and because of our biology. The fact that the environment is organized in terms of characteristics such as color and shape and follows general laws appears to be the principle basis for acquiring the Piagetian-type general formal concepts, such as object permanence, causality, and conservation. The fact of our biology determines how we form, code, and solve problems with concepts. Such universals develop in every environment and culture, varying with experience mainly in complexity and abstraction levels attained and the particularized forms assumed (e.g., different languages), which effect, of course, is the basis for the proliferation and variation in types and subtypes of competencies. B. UNITY OF PROBLEM SOLVING AND LEARNING
Learning and problem solving can be viewed as two aspects of the same process. Human activity may be viewed as a cyclical process of change and ritual
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in response to an endless series of alternating novel and familiar problem situations that present tasks requiring actions to attain goals. Where change is demanded, the interpretation of psychological events (which involve the mental manipulation of rules about presenting phenomena) as learning or problem solving may be partly a matter of fact and partly a matter of definition. When differences in fact are stressed, problem solving appears to be seen as a process of manipulating rules to resolve dilemmas and learning is seen as a process of acquiring new information (rules). However, in fact, as Miller and Dollard (1941) long ago speculated, learning occurs principally as a consequence of tackling problems (“learning dilemmas”). Problem solving seems to focus on the question of finding a suitable rearrangement of elements to resolve cognitive dissonances, but often includes the introduction of new elements as well as new relations, the point of departure for leaming. The question appears to hinge less on the degree of unfamiliarity of a task or situation than it does on what aspect of a novel task is the subject of focus. In highly familiar, ritualized tasks, cognitive involvement in performance is in any case minimal, neither problem solving nor learning being involved. However, whenever a situation demanding change arises, focusing on the dilemmas needing resolution stresses the process of problem solving, whereas focusing on the novel information that must be acquired stresses learning-in either case, whether new rules, new arrangements of old rules, new instances, or new contexts are involved. C. COGNITIVE LEARNING AND DEVELOPMENT
Development has long been viewed through a lens of quite different magnification than learning. The latter focuses on the acquisition of particulars in brief periods, usually in specific, well-defined tasks; the former focuses on large-scale changes that occur over long time spans under the influence of many different circumstances. Although learning may well be studied as a function of other general variables, such as age or ability, the stimuli and behavioral events are generally well specified, making it possible to define antecedent-consequent relations with considerable precision. Development, in contrast, because of its scope, generally relies on broader, difficult-to-specify antecedents like experience (cf. Wohlwill, 1973) and maturation. Developmental processes are thus typically defined in terms of the state or developmental status of the organism at various points of time or phases of the life cycle. External causes are not always considered and often studies are limited to development as a function of a host of correlations with broad interacting classes of distal events, such as social class, maternal IQ, and years of schooling (Hess, 1970). The field of education is faced with the problem of integrating the concepts of learning and development. Gagnk (1968, 1970), as has been noted, has attempted to construct an associative learning model of intellectual development as
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a cumulative build-up of a hierarchy of competencies. Although the model has similarities to the present approach, it is highly oriented to external tasks, as Case (1975) and others have observed, taking little account of many of the cognitive developmental processes identified by Piaget (1950), Bruner and Anglin (1973), and psycholinguistic theorists (McNeil, 1970). Cognitive development may be defined as a process of developmental learning in which the focus shifts from the short-term acquisition of individual rules to the long-term acquisition of sets of complex rules, many of them involving cognitive transformations that enable the use of small-scale rules to be coordinated. The acquisition of rules for conservation is a classic case, involving as it does the necessity of cognitively integrating the operation of previously acquired separate rules about dimensional shifts in a single, reciprocally operating system (e.g., length and density vary in opposite directions in conservation of number). Learning through experience is thus a primary basis for change in all periods of development, short or long; the difference is mainly a matter of the scope, variety, number, and complexity of concepts implicated. Both unit rule learning and complex rule integration learning proceed over long developmental spans, though the former is often overlooked by the broader lens employed by developmental analysis, which sees only the major benchmarks of change. We may better understand relations between short-term and long-term learning by considering the structural interrelatedness of concepts. D. DEVELOPMENTAL LEARNING OF BASIC AND SECONDARY RULES
Concepts are rarely learned in isolation, because, as noted earlier, they become assimilated into different components of developed systems of individual knowledge, coding, and strategies, however unevenly or disjointedly. However, concept learning is also seldom an isolated phenomenon because concepts are organized in terms of interconnected patterns, defined by cultural experience and interpretation of the world. They are embedded in logical systems, originating in cultural accumulation, whether popular or scientific in form, of types and subtypes whose rules are interrelated and overlap to varying degrees. We shall elaborate on this point presently. In information concepts, for example, knowledge about mammals or transportation is constructed of culturally organized networks and hierarchies of concepts about rodents, dogs, or humans, for instance, or vehicles, planes, or boats. Each involves intricate structural-functional rules that vary and parallel one another among diverse subtypes. For example, in learning formal concepts of knowledge about dimensions, the young child is aided by the parallel character of rules about magnitude variation across media (viz. size, light intensity, pitch). Certain sets of rules constitute core or foundation rules with high overlap across tasks and domains. Others are secondary to these basic rules because they
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are more specialized, tied to specific fields, codes, strategies, or tasks, and overlap less widely. Basic notions of representation, summary, structure, and modularity tend to underlie all forms of coding, whereas spatial movement and coordination are generic only to sensory-motor coding and symbolic rules are generic only to symbolic codes. Analyzing, integrating, timing, and sequencing are basic to all cognitive strategies, which, however, assume forms specific to particular categories, as in the use of spatial scanning in pictorial codes and sequential scanning and integrating in verbal language codes. The variety of rules is not, of course, restricted to the two types, basic and secondary. Many levels and degrees of rule specialization and overlap are evident, though for convenience the basic and secondary distinction will usually be adhered to. The acquisition of single concepts must thus be considered in terms of all advances in cognitive development through the accumulation of many bodies of socially derived concepts, interrelated to varying degrees in different ways. An important basis for cognitive differentiation, in both scope and complexity, is the way in which concepts appear to serve as competence modules. Each new concept provides a basis for solving problems with a host of exemplars beyond those with which the learner has grasped the concept, the extent of generality and transfer depending on the broadness of the concept. Thus, a concept about dress style may extend no further than to local fashion for a single season, while formal concepts of seriation and classification may serve as highly generalized instruments for solving problems with an infinite range of phenomena. Almost any set of objects can be ordered in magnitude and classified into types. Modules of competence for solving problems are also organized into concept clusters, networks, and hierarchies that both channel and extend learning and transfer, and determine the way in which individual profiles of competencies are organized. The acquisition of both general, widely transferable concept modules (basic rule systems) and specialized, limited transfer modules (secondary rule systems) at many levels of development is apparently necessary to generate both complexity and type variation in cognitive development. However, complexity may, in fact, often also be integral to type, in that complexity of competence often increases as a function of increasing depth in a field of knowledge (e.g., architecture) or specialized skills (e.g., oboe playing), which involves increasing in number, variety, intricacy, and complexity of organization the specialized (secondary) rules mastered. Differentiation and complexity are thus complementary and often allied modular operations in the general process of cognitive development. Concepts are thus separate but interconnected in competence systems, making cognitive learning a cyclical process, the systems interacting and altering at many stages and levels of concept organization throughout development. From birth, the infant is engaged in a progressive mapping of a concept world, defined by the material and idea worlds of the culture in which she or he is socialized. The
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concept world includes the specific codes, strategies, mythological concept systems, and cultural grammars (Colby, 1975) each culture has developed for various purposes. The commonalities across cultures, responsible for the general and universal in cognitive development, derive from the common reality base of space and time humankind shares. This reality base, interacting with speciesspecific biological potentials, has generated broad similarities in ways of conceptualizing, coding, and processing knowledge for environmental adaptation. The stamp of both cultural and individual experience is nevertheless found in the diversity of particular modular systems each culture and individual evolves to solve general problems of adaptation and cultural and personal problems of development. The developmental concept mapping process is one of moving back and forth between learning basic and secondary rules in each concept system and subsystem, weaving through the many areas and levels in an intricate, spiraling process of developmental learning. Competence facilitation through functional modularization within and among areas and between levels is necessarily widespread, but for clarity it is convenient to discuss concept acquisition in terms of single, relatively bounded systems. To illustrate, the concepts of dimensionality and seriation are of course made up of many component competence modules consisting of various rules about variations in magnitude that the child acquires in a series of steps, however disjointedly because of discontinuity of attention and experience. (Such discontinuity merely serves to dull and vary the sharpness of mastery among subtypes and instances and prolong the developmental learning process, not change its character.) The first major concept acquired in early development might consist of recognizing rules about relational differences in magnitude by polar opposites. But as Greenfield (1967) and others (Webb, 1975) have observed, there are many precursor, minor component rule steps, such as developing awareness of “bigness” applied to size, length, height, and thickness, followed by a similar development of awareness of “littleness,” before the f i i t basic integrative concept of relational opposites (i.e., big vs little) is grasped. These small steps consist of learning rules about bigness, for example, in terms of multiple exemplars from different phenomena; the learning involved takes on the form of a unit incremental, cumulative type of learning, historically best represented by the accelerating slope of the traditional cumulative learning curve. At some point, the many applications become consolidated to form a module of competence in a broad concept of more general applicability. This consolidation involves a cognitive transformation in which various component rules are patterned into a new integration of polar opposites; the latter process is better described in terms of the classic gestalt interpretation of insight learning. Subsequent development follows a similar process, moving again through many small steps, this time of like general concepts as exemplars of a higher level organizing concept, involving rules about more refined size gradations,
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perhaps based on relating the middle point first to the big end, then to the little end in diverse dimensions (e.g., length, height). Again, the process culminates in a general concept of middleness and three-point scales applicable to many types of dimensions, Further stages of dimensional concept development, ultimately to the stage of abstract seriation of multiple scales for any dimension of magnitude, follows a corresponding cyclical pattern at higher levels. The developmental learning process is a kind of quantitative unit accumulation (though not by mechanical or contiguity association alone, but through discovering rules about concept exemplars), alternating with big leaps through cognitive integrations of unit concepts at successively higher and broader levels. The process appears to apply to all systems, from the most general forms of knowledge, such as the object concept and conservation, to each body of concepts unique to a field of knowledge (e.g., butterflies or postage stamps) or a symbolic code (e.g., language, math, music). In each field of knowledge, major concept integrations. which transform the child’s approach to processing information in an area, are preceded by unit accumtblations on various criterial rules. For example, for the object concept, rules include the many small movements, variations in orientation, and appearing-disappearing-reappearing displacements; for the concept of stamp, they include acquiring familiarity with numerous miniature squares of paper and their characteristic features; for reading, they include acquiring familiarity with the general contours of graphemes (dimensions of letter forms), before the total map (scheme of rules) of the respective concepts can be laid out in new integrations at successive levels of complexity. For each complex concept, unit accumulations for component rules proceed along parallel lines more or less independently, until cognitively synthesized, one or two at a time, into successively more complete, general concepts of object permanence, postage stamp recognition, or reading text. It will be noted that the order of cumulative unit learning and qualitative shifts can be viewed in reverse. In any area, once the foundation of component rule competencies is acquired, through the unit learning processes described, the basic integration in a complex concept, such as the object concept or postage stamp or grapheme pattern concepts, leads to consolidation in a module of competence, in which more generalized rules can be applied to many other concepts of the same type. Thus the infant-assuming adequate exposurerapidly becomes familiar with many objects and object classes, the child with many types of stamps, and the beginning reader with distinctions between many letters, words, and sentences. In each case, the newly organized competencemodule can be applied broadly to accelerate quantitative, variant concept accumulations, through recognizing different exemplars and subtypes, in a process resembling Piaget’s horizontal ddcalage. The process is particularly well exemplified in early reading, in which the author (Fowler, 1962b, 1965, 1971a) has found that the young child’s first discriminations between letters (e.g., “e” vs “t”)
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come very slowly. After she or he acquires the major pattern rules for distinguishing letters, she or he learns additional minor detailed rule criteria with increasing rapidity, enabling the child to learn the remaining letters at an increasing rate (Gibson, 1965, 1970; Gibson & Levin, 1975). The process is similar in visual word recognition learning, though word learning makes use of spelling pattern competence rules as well as letter form criteria for discrimination (Gibson, 1965).
V. Developmental Phases of Concept Learning Developmental learning is a continuing process, proceeding at different rates according to the novelty, complexity, and scope of the task, and the efficiency with which developmental stimulation is applied. However, the acquisition of competence for any task or set of novel concepts can be divided into phases, characterized by the changing role of cognitive processes. Phases overlap, of course, typically proceeding concurrently as the learner attains different stages of competence in mastering different aspects (rules) of complex tasks or concepts. There are nonetheless several distinguishable processes in concept acquisition that tend to follow in sequence, as the child progresses from exploration of new phenomena, through initial integrations and rule mastery, to consolidation, ritualization, and horizontal extension. A. EXPLORATORY PHASE:PROBLEM EXPLORATION
The exposure to novel concepts or material in a task elicits characteristic exploratory behavior of scanning, manipulation, and selective focusing, as the learner orients to the phenomena in order to establish the nature of the problem. The process is the same, whether the task is a problem of adaptation, such as learning to walk, fish, or shop, or a problem of acquiring knowledge, such as learning to seriate, conserve, or identify colors, shapes, or biological orders. The process consists of exploratory activity in which the person learns a variety of small features, task elements, or component rules (e.g., letter pattern, geometric shape, aspect of insect or walking, or other type or task variations, such as letter verticality, geometric shape angularity, insect smallness, and balancing on legs). The type of learning involved in this activity may be described as unit recognition, discrimination learning, in which a variety of elementshles of a general concept, more or less perceptually separable, are learned through this exploratory activity. This activity also usually leads to some familiarity with relations among the elements, the general “shape” of the problem. The duration of this problem identification and incremental learning phase varies with the variety, effectiveness, and relatedness of already acquired
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modules. Coding and problem-solving modules are as important as the learner’s entering competence modules in relevant categories of knowledge. When the learner is engaged in a planned, sequentiallyorganized learning program, the rate may accelerate considerably, of course. The relevant component rules and features of the problem can be drawn to the learner’s attention and presented in some order of difficulty, and sufficient repetition can be assured. The essential outcome of this phase is familiarity with diverse small elements and perhaps broad contours and relations of the area or task, that permits partial or crude recognition of patterns and performance of tasks. The rate of mastery will depend on how closely related the concepts are to familiar concept areas, that permit the use of acquired competence modules. However, novel tasks and concept systems are also always complex relative to the general cognitive developmental status of the child, composed of such broad modules as the object concept for infants and hierarchical classification for preschoolers. These relate to the general status of the child in the acquisition of formal (Piagetian) knowledge and basic language coding and problem solving processes. This initial phase, even in simple tasks,such as learning to retrieve a toy with a rake, is unlikely (except in planned programs) to be neatly distinct, however; the child merely acquires component rules and takes inventory through search and inquiry, before moving deliberately into a more systematic phase. As pointed out, exposure to concept areas is rarely a well-organized sequential experience, but is encountered in bits and pieces in many contexts, and typically with differing amounts of experience in variously related concepts for each individual. However disjointed or prolonged by discontinuity, the essence of this phase is learning to recognize parts (component rules) and to establish the shape of the problem in vague structural terms. B. ORGANIZATIONAL PHASE: CONCEPT INTEGRATION
As the problem solver learns various elements and becomes familiar with the major outlines of a task, he or she begins to make trial hypotheses about key elements and how they are interrelated. Cognitive processing becomes more systematic and organized. The essence of this phase, as repeated trial organization becomes more elaborate and refined, is a rational organization of means to ends. A gradual shift from undirected learning and analysis of rule elements and scattered relations to more systematic focus on likely elements and their interrelations takes place, until the learner at some point begins to make meaningful mental integrations of the nature of the core rule@). He or she selects key elements and relations significant to the means and end rules of the task. The type of learning involved in the basic mental integrations that characterizes this phase appears to resemble what has historically been known as insight learning, in
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which the learner gains overall insight into a task or pattern as a result of such integrations. Cognitive transformations occur that bring the person’s processing to a new plane of competence in handling the type of concept material or performing operations in the task. The integrationforms a module of competencefor an area or type of activity that serves as an instrument for generalfunctioning in the area. In learning to walk the infant must learn and integrate component rules such as placement of the body’s center of gravity, controlled forward balance, forward movement, and alternative step progression, along with other even more refined skeletal-muscular regulations (Fowler, 1976). The final overall integration of the concept system of biological orders is based on similar (though more complex) subordinate interrelations of many conceptual elements, such as different levels and types of insects and mammals, these concepts themselves composed of diverse rules about features and functions. Survey and gradual quantitative accumulation of rule elements (incremental unit learning) alternate with module formation through cognitive reorganization in ever wider integrations, until overall integrations are attempted. The more complex and hierarchical the conceptual system, of course, the more prolonged the process, which actually breaks down into a series of component cycles of exploratory-organizational phases. Within limits, the process is much the same, whether the child is more or less developed; regardless of which knowledge, styles, and codes are involved; whether the child is learning tasks on her or his own through experimentation or whether he or she is aided by the modeling and guidance of others. The acquisition process is merely more or less efficient, systematic, and accelerated. C. MASTERY, CONSOLIDATION, AND RITUALEATION
Once an overall integration is realized at any level in a concept task hierarchy, further guidance and experimentation serve mainly to refine understanding of relations among rules and to perfect the exercise of modules. Children become able to perform and coordinate the necessary rule operations more selectively and efficiently and often more rapidly. They can walk, thread a needle, sort colors, add numbers, or classify familiar insects or mammals into hierarchical orders with greater accuracy and less hesitation. Repeated rehearsal, in various combinations of physical and mental rule manipulation, leads eventually to smoothness of performance that becomes largely automatic or ritualized (cf. Case, 1978a; Meacham, 1972; Reese, 1976). The rule manipulations become sufficiently consolidated to enable the learner to walk, add, sort colors or insects, or generate sentences about familiar topics in a semiautomatic fashion with minimal conscious, cognitive analysis and integration. At this stage of mastery, the role of cognitive processes changes to a peripheral monitoring function of regulating the
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smoothness and accuracy of performance. Once cognitive competence is established, the internal guidance of mental operations in repeat performances centers on problems of adapting modules to interruptions and specialized circumstances. D. HORIZONTAL EXTENSION AND VERTICAL DEVELOPMENT
The final phase in concept acquisition is the extension or transfer of rule operations to related domains, similar to what Piaget terms horizontal dbcalage. The process is generally narrower or more focused, however, than the extension of mastery at a single, general level of development (Flavell, 1963). Usually, the process encompasses no more than the extension of concept rules in a module to an increasingly wide variety of exemplars, such as extending rules for identifying noun-object relations from the first two or three words to any other nouns (Mccarthy, 1954). In form, the extension process follows the quantitative, incremental unit curve described earlier. While in many ways equivalent to the classical process of generalization and transfer in learning theory (e.g., Staats & Staats, 1963), the process is more complex and variable than automatic generalization of responses to similar stimuli. As children learn to extend the general rules in an organized module of competence to equivalent phenomena, such as labeling more and more objects, they must continue actively to process new phenomena cognitively; that is, they must also acquire familiarity with minor specific rules of little generality that apply to each case and subset. (Again, skill depends on levels of rule processing generally acquired in the three basic skills of knowledge, codes, and strategies.) In our example above of extending noun-object rules, the learner must continually acquire new label-referent (word-object) matches, each of which has certain identifying characteristics (morphophonological and object characteristic criterial rules). However, once a few of the rules for a novel basic module are mastered at a certain level, such as the rules that sound patterns and object types can be stably interrelated, basic rules are extended through transfer with increasing rapidity to related phenomena, despite the continuing problem of mastering a host of minor specialized pattern rules. The acceleration that comes with extension of a basic rule system appears wherever learning rules about novel patterns, concepts, or tasks are in question, whether for rules about visual letter forms, conservation of number, or machinery operation. In each case, basic dimensions are grasped slowly, then applied with increasing speed to other exemplars of the type (other letters and often letter systems, other sets of numbers and larger numbers, and other features of the machine and other machines), in an accelerated learning curve. Extension is different from ritualization in that the latter occurs when familiar material is processed in familiar ways with little involvement of novel concepts,
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either of novel rule elements or of novel integrations needed to reach solution. Peripheral attention to cognitive monitoring is more characteristic of the rule manipulations asked for in well-learned rituals, while extension to novel territory demands active cognitive manipulation of rules and unit learning of particular features of novel exemplars (e.g., novel sound patterns for new words, novel shape combinations for new letters, novel properties of new substances). Ease of manipulation and rate of acquisition during the extension process will increase, however, according to the simplicity and similarity of rules involved. Thus, conservation extends more rapidly across different materials (e.g., clay, metal, cubes, wire coils, plastic wire) than it does with the same dimension across different dimensions of magnitude (e.g., substance, weight, and volume), which involve more higher order integrations (Uzgiris, 1964). It is evident that cognitive involvement varies greatly at different phases of concept attainment. The process, moreover, is not the straightforward, sequential process of laboratory concept-attainment experiments. The intricacy and irregularity of cognitive developmental.learning in the endlessly varying environments of the real world generate a constant interweaving of the different phases and forms of cognitive processing throughout development. Horizontal extension and vertical development are closely knit processes, increasing the scope and complexity of the territory cognitive mapping embraces. Extension is really a core process for differentiation in development. Extension of basic general rules, or of basic system rules of a category to specialized subtypes, such as general mathematical rules to a new branch of mathematics, occurs at many levels, making possible development of many forms of individual differences. The development of cognitive complexity is not channeled in a single unilinear form, as the traditional “g” of Spearman’s (1927) concept of intelligence (Bayley , 1955) or Piaget ’s general sequence of stages suggests. Horizontal extension creates complexity through increasing the number of modular types in many directions, developing more intricate networks, but also making possible vertical development in specialized hierarchical modules. Individuals vary intraindividually as well as interindividually among multilinear types and subtypes according to diversity of experience.
VI. Summary and Conclusions We are now in a position to review the ingredients that may be taken to generate, alternatively, development that is universal to the species, which varies by experience mainly in rate and final level of complexity, and development that follows a multilinear course. First, the basic units for cognitive processing appear to be concepts composed of operating rules defining phenomenal structures and processes. Concepts and rules establish common units for comparing and inter-
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relating all types of cognitive processes. Universal, culturally specific, and individually unique cognitive processes, varying in both complexity and type, can all be described and discussed in a common framework of concepts and rule systems. Second, concepts and rules are not totally isolated mental units but are variously interrelated in logical networks, systems, and hierarchies. This separateness but varying interrelatedness of concepts in systems of different types at many levels further establishes a basis for sorting out concepts according to their degree of universality and provides the logic of complexity that determines sequence in developmental cognition. In each basic type of concept category-that is, knowledge, representational codes, and cognitive strategies-some concepts at different levels are apparently universal to all cultures because of the problem of adaptation to the physical world common to all social groups. Every culture seems to foster minimal levels and forms of formal Ragetian and informational knowledge concept systems, of sensory-motor, pictorial, and language coding systems, and of cognitive strategies for coping. But there are also sets of rules in each of the three concept categories evidently unique to cultures, subcultures, regions, families, individuals, and clusters of such groupings. Because of this cultural and individual variation, the socialization of cognitive development can follow many forms at different levels of generality. Third, mechanisms for learning and development can be defined as cognitive learning of rules, varying principally in the size and scope of the concepts the rules define and hence the time required to learn them. Learning and problem solving may be viewed as two aspects of a general process of coping to serve human adaptation. The process is always one of solving problems, through mental and physical activity, that involve, in various combinations, manipulating familiar rules and acquiring novel ones to facilitate solutions. Cognitive learning apparently takes two basic forms, the unit accumulation of similar exemplars and, at higher levels, similar concepts, both of which precede and follow the second basic process, cognitive integration or transformation of rules into novel concepts. In this way, concept development is a developmental learning process proceeding in cyclical phases; the child appears to move alternately and concurrently among different concept areas at successively more complex and/or broader levels, according to the stages of mastery, ritualization, and extension attained. The basis for learning set, transfer, and developmental accumulation and branching may be found in the acquisition through experience of functional concepts and concept systems, whose rules and sets of rules serve as competency modules of successively more complex but differentiated rule hierarchies. These modules are like general purpose concept tools, which are fashioned for use in tasks of different types. The scope of usefulness or generalizability of any
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module depends on the level of abstraction and generality of phenomena and the variety of tasks to which they apply. For instance, object identity and feature differentiation can be utilized with virtually all types of phenomena at all levels and in endless tasks, while multiple hierarchical classification can apply to all phenomena and many tasks beyond certain levels of complexity. However, as one narrows down knowledge, codes, and strategies by type, as in the case of dance skills, athletics, musical performance, specialized codes, and fields of knowledge, unique combinations of specialized modules, together with more generalized modules, contribute to the complexity of competence in many, varied ways, Biological adaptation to environment (bioenvironmentalrelations) may be assumed to determine the potentials for concept forms that human cognitive development can assume; however, within wide limits the actual forms, pace, and levels of competence development attained can vary with the type and quality of environmental, cultural, and individual experience accumulated over the course of development. REFERENCES Abelson, R. P., Aronson, E., Mffiuire, W. J., Newcomb, T.M., Rosenberg, M. J., & Tannenbaum, P. H. (Eds.). Theories of cognitive consistency: A sourcebook. Chicago: Rand McNally, 1968.
Allport, G.W. Personality. New York Holt, 1937. Allport. G. W.. & Postman, L. J. The psychology of rumor. New York Holt. 1947. Anastasi, A. Differential psychology (3rd ed.). New York: Macmillan, 1958. Bayley, N. On the growth of intelligence. American Psychologist. 1955, 10, 805-818. Beilin, H. Learning and operational convergence in logical thought development. Journal of Experimental Child Psychology, 1965, 2, 317-339. Bennett, G . The chiMhood environments of famous artists. Toronto: Ontario Institute for Studies in Education, 1967. (Mimeographed) Berlyne, D. E. Conflict. arousal, and curiosity. New York: McGraw-Hill, 1960. Boring, E. G. A history of experimental psychology (2nd ed.). New York: Appleton, 1951. Bourne, L. E.. Jr. Human conceptual behavior. Boston: Allyn & Bacon, 1966. Brackbill, Y. Research and clinical work with children. In R. A. Bauer (Ed.), Some views on Soviet psychology. New York: American Psychological Association, 1962. Brown, R. Social psychology. New York Free Press, 1965. Brown, R. A first language. Cambridge, Mass.: Harvard University Press, 1973. Bruner, J. S.Skill in infancy. In J. S. Bruner & J. M. Anglin (Eds.), Beyond the information given. New York: Norton, 1973. Bruner, J. S., & Anglin, J. M. (Eds.). Beyond the information eiven. New York Norton, 1973. Bruner, J. S., Goodnow, J. J., & Austin, G.A. A study of thinking. New York: Wiley, 1956. Bruner, J. S., Olver, R. R., & Greenfield, P. M. Studies in cognitive growth. New York: Wiley, 1966.
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Flavell, J. H. The developmental psychology of Jean Piaget. Princeton, N.J.: Van NostrandReinhold, 1963. Flavell, J. H. Concept development. In P. H. Mussen (Ed.), Carmichael's manual of childpsychology (3rd Ed., Vol. I). New York: Wiley, 1970. Forisha, B. D. Mental imagery verbal processes: A developmental study. Developmental Psychology, 1975, 11, 259-267. Fowler, W. Cognitive learning in infancy and early childhood. Psychological Bulletin, 1962, 59, 116-152. (a) Fowler, W. Teaching a two-year-old to read: An experiment in early childhood learning. Genetic Psychology Monographs, 1962, 66, 181-282. (b) Fowler, W. A study of process and method in three-year-old twins and triplets learning to read. Genetic Psychology Monographs, 1965, 12, 2-89. Fowler, W. The effect of early stimulation in the emergence of cognitive processes. In R. D. Hess & R. M. Bear (Eds.), Early education. Chicago: Aldine, 1968. Fowler, W. The effect of early stimulation: The problem of focus in developmental stimulation. Merrill-Palmer Quarterly, 1969, 15, 157-170. Fowler, W. A developmental learning strategy for early reading in a laboratory nursery school. Interchange, 1971, 2, 106-125. (a) Fowler, W. Cognitive baselines in early childhood: Developmental learning and differentiation of competence nile systems. In J. Hellmuth (Ed.), Cognitive studies (Vol. 2): cognitive deficits. New York: Brunner/Maze.l, 1971. (b)
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Gagnt, R. M. The conditions of learning (2nd 4.).New York: Holt, 1970. Gardner, R. W., Holzman, P.S., Klein, C. S., Linton. H. B., & Spence, D. P. Cognitive control: A study of individual consistencies in cognitive behavior. Psychological Issues, 1959, 1, No. 4 (Monograph No. 4). Gardner, R. W., Jackson, D. N.. & Messick, S . J. Personality organization in cognitive controls and intellectual abilities. Psychological Issues, 1960, 2, No. 4 (Monograph No. 4). Gibson, E. J . Learning to read. Science, 1965, 148, 1066-1082. Gibson, E. J. The ontogeny of reading. American Psychologist, 1970, 25, 136-143. Gibson, E. J., & Levin, H. The psychology of reading. Cambridge, Mass.: MIT Press, 1975. Goertzel, V., & Goertzel, M. G. Cradles of eminence. Boston: Little, Brown, 1962. Goldschmid, M. L. Role of experience in the rate and sequence of cognitive development. In D. R. Green, M. P. Ford, & G. B. Flamer (Eds.), Measurement and Piaget. New York McGrawHill, 1971. Goldschmid, M. L., & Bentler, P. M. Concept assessment kit: Conservation. San Diego, Calif.: Educational & Industrial Testing Service, 1968. Goldstein, K. M., & Blackman, S . Cognitive style. New York: Wiley, 1978. Greenfield, P. M. Teaching quantitative concepts. Quarterly Report, 1967, 2-5. Gruen, G. E., & Doherty, J. A constructivist view of a major development shift in early childhood. In I. C. Uzgiris & F. Weizmann (Eds.), The srructuring of experience. New York: Plenum, 1977.
Guilford, J. P. The nature of human intelligence. New Yo& McGraw-Hill, 1967. Hem, R. D. Social class and ethnic influences on socialization. In P. H. Mussen (Ed.), Carmichnel’s manual of child psychology (3rd ed., Vol. 2). New Yo& Wiley, 1970. Hofstaetter, P. R. The changing composition of “intelligence”; A study in T-technique. Journal of Genetic Psychology, 1954, 85, 159-164. Hull, C. L. The concept of habit-family hierarchy and maze learning. Psychological Review, 1934, 41,33-52, 134-152.
Hunt, J. McV. Intelligence and experience. New York: Ronald Press, 1961. Kagan, J. Impulsive and reflective children: Significance of conceptual tempo. In J. D. Kmmboltz (Ed.), Learning and educational processes. Chicago: Rand McNally, 1965. Kagan. J., & Kogan, N. Individuality and cognitive performance. In P. H . Mussen (Ed.), Carmichael’s manual ofchildpsychology (3rd Ed., Vol. l). New York: Wiley, 1970. Kagan, J., Moss, H. A., & Sigel, I. E. Psychological significance of styles of conceptualization. In J. C. Wright and J. Kagan (Eds.), Basic cognitive processes in children. Monographs of the Society for Research in Child Development. 1963, 28 (2, Serial No. 86), 73-1 12.
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Kagan, J., Pearson, L.,& Welch, L. Conceptual impulsivity and inductive reasoning. Child Development, 1966, 37,583-594. Kelly, G. A. The psychology of personal construcrs (Vol. 1). New York Norton, 1955. Kendler, H. H., Bt Kendler, T. S. Vertical and horizontal processes in problem-solving. Psychological Review, 1962, 69, 1-16. Kessen, W. Research in the psychological development of infants: An overview. Merrill-Palmer Quarterly, 1963, 9, 83-94. Klausmeier, H. J., Ghatala, E. S., & Frayer, D. A. Conceptual learning and developmenf. New York Academic Press, 1974. Knobloch, H.,& Pasamanick, B. (Eds.). Gesell and Amatruda's developmentaldiagnosis (3rd Ed.). New York: Harper, 1974. Kogan, H. Cognitive styles in infancy and early childhood. Hillsdale, N.J.: Erlbaum, 1976. Lawton, M. S. The development of analytic-integrative cognitive styles in young children. Unpublished doctoral dissertation, University of Toronto, 1977. Lenneberg, E. H. Understanding language without ability to speak: A case study. Journal of Abnormal and Social Psychology, 1%2, 65,419-425. Levin, J . R.,& Allen, V. L. ( U s . ) . Cognitive learning in children: Theories and strategies. New York: Academic Press, 1976. Levi-Strauss, C. The savage mind. Chicago: University of Chicago Press, 1966. Lewin, K. The conflict between Aristotelian and Galilean modes of thought in contemporary psychology. In K. k w i n (Ed.),A dynamic theory ofpersonality. New York McGraw-Hill. 1935. Lewin, K. Field theory in social sciences. New York Harper, 1951. Luria, A. R. Cognitivedevelopment: Its cultural and socialfoundations. Cambridge, Mass.: Harvard University Press, 1976. Mangan, J. Piaget's theory and cultural differences. The case for value-based modes of cognition. Human Development. 1978, 21, 170-189. McCarthy, D. Language development in children. In L. Carmichael (Ed.), Manual of childpsychology (2nd 4 . ) . New York: Wiley, 1954. McCurdy, H. G. The childhood pattern of genius. Journal of Elisha Mitchell Scientific Society, 1957, 7 3 , 4 4 8 4 2 .
McGraw, M. B. Growth: A study of Johnny and Jimmy. New York Appleton, 1935. McGraw, M. B. Later development of children specially trained during infancy: Johnny and Jimmy at school age. Child Development, 1939, 10, 1-19. McNeil, D. The development of language. In P. A. Mussen (Ed.), Cannichael's manual of child psychology (3rd ed.,Vol. 1). New York Wiley, 1970. Meacham, J . A. The development of memory abilities in the individual and society. Human Development, 1972, 15, 205-228. Menshinskaya, E. A. Fifty years of Soviet instructional psychology. Soviet Pedagogy, October 1967, 126-142.
Meyers, C. E., & Dingman, H. F. The structure of abilities at the preschool age: Hypothesized domains. Psychological Bulletin, 1960, 57, 5 14-532. Miller, D. J., Cohen, L. B., t Hill, K. T. A methodological investigation of Piaget's theory of object concept development in the sensory-motor period. Journal of Experimental Child Psychology, 1970, 9, 59-85. Miller, G. A,, Galanter, E.,& Ribram, K. H. Plans and the structure of behavior. New York: Holt, 1960.
Miller, N. E., & Dollard, J. Social learning and imitation. New Haven, Conn.: Yale University Press, 1941. Olson, D. R. (Ed.). Media and symbols: The forms of expression, communication, and education. Yearbook of the National Society for the Study of Education, 1974, 23, Part I .
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Paivio. A. Imagery and verbal processes. New York Holt, 1971. Pascual-Leone. J. Cognitive development and cognitive style. Unpublished doctoral dissertation, University of Geneva, 1969. Pascual-Leone, J. On learning and development, Piagetian style: A reply to Lefibvn-Pinard. Canadian Psychological Review, 1976, 17, 270-289. Peiper, A. Die Eigenart der Kindlichen Hirntatigkeit (2nd Ed.). Leipzig: Thieme, 1956. Piaget, J. The psychology of intelligence. London: Routledge & Kegan Paul, 1950. Piaget, J. The origins of intelligence in children. New York International Universities Press, 1952. Piaget, J., & Inhelder, B. Mental imagery in the child. New York Basic Books, 1971. Pressey, S. L. Concerningthe nature and n-re of genius. ScientificMonthly, 1955,81,123-129. Radcliffe-Brown, A. R. The social organization of Australian tribes. Oceania, 1930-31,1,34-63, 206-246, 322-341, 426-456. Reese, H. W. The development of memory: Life-span perspectives. In H. W. Reese (Ed.),Advances in child development and behavior (Vol. 11). New York: Academic Press, 1976. Rosch, E. Universals and cultural specifics in human categorization. In R. W. Brislin, S. Bochner, & W. J. h n n e r (Eds.), Cross-culhrralperspectives on learning. New York: Wiley, 1975. Rotter. J. Generalized expectancies for internal vs. external control of reinforcement. Psychological Monographs, 1966, 80 (Whole No. 69). Santostefano, S. Cognitive controls versus cognitive styles: An approach to diagnosing and treating cognitive disabilities in children. Seminars in Psychiatry, 1969, 1, 291-317. Segall, M. M., Campbell, D. T., & Herskovits, M .J. The influence of culture on visualperception. New York: Bobbs-Memll, 1966. Siegler, R. S. Inducing a general conservation of liquid quantity concept in young children: Use of a basic rule and feedback, Perceptual and Motor Skills, 1973, 37, 443-452. Sigel, I. E.,& Cocking. R. R. Cognition and communication: A dialectic paradigm for development. In M. Lewis & L. A. Rosenblum (Eds.), Interaction, conversation. and the development of language: The origins of behavior (Vol. 5). New York: Wiley, 1977. Sigel, I. E., & Hooper, F. H. Logical thinking in children. New York: Holt, 1968. Skinner, B. F. Science and human behavior. New York: Macmillan, 1953. Skinner, B. F. Verbal behavior. New York: Appleton, 1957. Slobin, D. I. Cognitive prerequisites for the development of grammar. In C. A. Ferguson & D. I. Slobin (Eds.), Studies in child language development. New York Holt, 1973. Spearman, C. The abilities of man. New York Macmillan, 1927. Staats, A. W. Learning. language and cognition. New York Holt, 1968. Staats, A. W., & Staats, C. K. Complex h a n behavior. New Yo* Holt, 1%3. Stephenson, W. The study of behavior: Q-technique and its methodology. Chicago: University of Chicago Press, 1953. Sullivan, E. V. Piagetian theory in the educational milieu: A critical appraisal. Canadian Journal of Behavioral Science, 1969, 1, 129-155. Thurstone, L. L. Primary mental abilities. Psychometric Monographs, 1944 (Serial No. 1). Uzgiris, I. C. Situational generality of conservation. Child Development, 1964. 35,831-841. Uzgiris, I. C., & Hunt, J. McV. Assessment in infancy: Ordinal scales of psychological development. Urbana, Ill.: University of Illinois Press, 1975. Vygotsky, L. S. Thought and langwage. Cambridge, Mass.: MIT Press, 1962. Wale, D. A developmental measure of the analytic integrative cognitive styles. Unpublished master’s thesis, University of Toronto, 1972. Wallach, A., & Kogan, A. Modes of thinking in young children. New York: Holt, 1965. Webb, R. S. Size is big or little: An approach to the dimensionality of children‘s concepts. Paper presented at the biennial meetings of the Society for Research in Child Development. Denver, Col., April 10-13, 1975.
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Werner, H. The concept of development from a comparative and organismic point of view. In D. B. Harris (Ed.),The concept of development. Minneepolis: University of Minnesota Press, 1957. Werner, H. Comparative psychology of mental development (rev. ed.). New Yo& International Universities Press, 1975. White, B. L., Watts, J. C., Bamett, I. C., Kaban, B. T., Marmor, J. R., & Shapiro, B. B. Experience and environment (Vol. 1). New York RenticeHall, 1973. White, S. H. Evidence for a hierarchical arrangement of leaming procesaes. In L. P.Lipsitt & C. C. Spiker (Eds.), Advances in child development and behavior (Vol. 2 ) . New York: Academic Ress. 1965. White, S. H. The leaming theory tradition and child psychology. In P. H.Mussen (Ed.), Carmichael's manual of child psychology (3rd ed., Vol. 1). New York Wiley. 1970. Witkin, H.A., Dyk, R. B., Faterson, H. F., Goodenough, D. R., & Karp, S. A. Psychological d@erenriation. Hillsdale, N.J.: Erlbaum. 1974. (Originally published, 1%2.) Witkin, H. A., Goodenough, D. R.,& Oltman, P.K. Psychologicai differentiation: Current srarus (ETS RB 77-17). Princeton, N.J.:Educational Testing Service, 1977. Wohlwill, 1. F. The concept of experience: S or R? Human Development, 1973, 16, 90-107. Zimiles, H. The development of conservation and differentiation of number. Monographs of the Sociefyfor Research in Child Development, 1966, 31, ( 6 , Serial No. 108). '
CHILDREN'S CLINICAL SYNDROMES AND GENERALIZED EXPECTATIONS OF CONTROL
Fred Rothbaum T U m S UNIVERSITY
I. OVERVIEW
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III. SUPPORT FOR THE HELPLESSNESS-REACTANCE MODEL ...............
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IV. TOWARD A HELPLESSNESS-REACTANCE EXPLANATION OF SYNDROMES
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II. FACTOR ANALYTIC RESEARCH ON SYNDROMES IN CHILDREN..
A. LABORATORY STUDIES OF CLINICAL STATES ..................... B. NATURALISTIC STUDIES OF CLINICAL STAGES .................... C. CLARIFYING THE MODEL LOSS AND LACK OF CONTROL ..........
A. LOCUS OFCONTROL ............................................. B. EFFECI"FBS OF NONCONTRACTUAL METHODS ................ C. CHILDREARPJG PRACTICES: ANTWEDENTS OF GENERALIZED EXPECTATIONS ..................................................
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V. CONCLUSION.. ...................................................... A. THE ISSUE OF APPROPRIATENESS.. ............................... B. SUGGESTIONS FOR FUTURE RESEARCH ...........................
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REFERENCES
I. Overview An attempt is made here to draw connections between generalized (or situationally and temporally stable) expectations of control and clinical syndromes (i.e., situationally and temporally stable behavioral clusters) in children. In supporting these connections, it is necessary to summarize several distinct literatures. An outline of these several literatures and a brief explanation of their ties to one another are provided below. Section Il contains a summary of factor analytic research on clinical syn207 ADVANCBS IN CHlLD DEVELOPMENT AND BEHAVIOR. VOL. 15
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dromes in children. This research has repeatedly led to the identification of two clusters: outward (e.g., antisocial, hostile, aggressive) behavior and inward (e.g., passive, withdrawn, somaticizing) behavior. Unfortunately, there is little understanding of the causes and correlates of the outward and inward syndromes. In particular, there is little understanding of the relationship between these syndromes and covert phenomena. The helplessness-reactance model, which is capable of filling this conceptual void, is briefly reviewed in Section III. According to the helplessness-reactance model, helpless (inward-type) behaviors are due to perceptions of severe uncontrollability,and reactant (outwardtype) behaviors are due to perceptions of slight to moderate uncontrollability. Laboratory evidence regarding clinical states (reactions with little temporal or situational stability) and naturalistic evidence regarding clinical stages (reactions with moderate temporal and situational stability) are cited in support of the helplessness-reactance model. Section II1,B is devoted to a refinement of the helplessness-reactance model. According to the refinement, helpless behaviors are due to a perceived lack of control and reactant behaviors are due to a perceived loss of control. This clarification of the perceptionsunderlying the states of helplessness and reactance paves the way for the following section, in which generalized expectations underlying the inward and outward syndromes are identified. Section IV begins with a consideration of the connections between states (the reactions with little stability identified by helplessness-reactance theorists) and syndromes (the highly stable behaviors identified in factor analytic research). The research on stages (moderately stable reactions) helps bridge the gap between states and syndromes. However, in order to close this gap further, it is necessary to identify generalized expectations that repeatedly give rise to perceptions of loss and lack of control. It is the repeated perception of loss and lack that leads to the repeated occurrence of reactance and helplessness-that is, to the outward and inward syndromes. Two types of generalized expectations are considered here. The first is locus of control-the degree to which the individual expects outcomes to be caused by himself (internal.locus of control) as opposed to luck or outside forces (external locus of control). Previous research indicates that individuals with an external locus of control are predisposed to repeated perceptions of lack of control and thus to recurring helpless (i.e., inward) behavior. The second generalized expectation treated here is “effectiveness of contracts.” Contracts are defined as agreements and norms. Previous research indicates that individuals who expect noncontractual methods to be effective in producing outcomes are predisposed to perceptions of loss of control and thus to recurring reactant (i.e., outward) behavior. Following the section on generalized expectations is a summary of the literature on childrearing practices. It is argued that the relationships between childrearing practices and clinical syndromes are consistent with those predicted by the refined helplessness-reactance model.
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Since a major objective of most conceptual frameworks involving clinical syndromes is to determine why individuals engage in inappropriate behaviors, Section V,A is devoted to the issue of appropriateness. Viewed from the present perspective, the key issue is whether the generalized expectations (that give rise to the syndromes) are appropriate. It is suggested that the question of appropriateness is a misleading one. Rather than making global assessments of appropriateness, it is more meaningful to identify the several factors contributing to generalized expectations of control. Two factors that are highlighted are the temporal and contextual similarities between situations. The shift from characterizing syndromes as inappropriate to examining the factors giving rise to them helps liberate them from the shroud of mystery that surrounds them. Research that may contribute to the further demystification of children’s syndromes is outlined.
11. Factor Analytic Research on Syndromes in Children One of the first requirements for the successful study of a scientific domain is the establishment of a system of classification (Zigler & Phillips, 1961). In the field of children’s clinical behavior, attempts to fill this requirement have frequently taken the form of factor analytic investigations (Achenbach, 1966; Conners, 1970; Miller, 1967; Patterson, 1964; Peterson, 1961; Ross, Lacey, & Parton, 1965; Werry & Quay, 1971). The findings from this research yield a surprisingly clear picture. Two broad-band syndromes (second-orderfactors) that have been repeatedly identified are inward (e.g., passive, withdrawn, somaticizing) behavior and outward (e.g., antisocial, hostile, aggressive) behavior (cf. Achenbach & Edelbrock, 1978). (The terms inward and outward are used here rather than Achenbach’s terms-internalizing and externalizing-to distinguish between the syndromes and other internalizing and externalizing constructs used later.) The inward and outward syndromes have emerged in studies of clinic and nonclinic children ranging in age from 3 to 18 years. The data, which have been analyzed with a variety of statistical methods (e.g., principal components and principal factor analysis with varimax rotation), have been derived from mental health workers’ reports, from direct observations by mental health workers, and from parents’ and teachers’ reports. Considering the variety of subject samples, of methods of data collection, and of data analysis that have been employed, the correspondence in findings is impressive. The term “syndromes” is used here to highlight the fact that the factor analytic findings identify behavioral complexes, Identification of such complexes is a necessary step in the derivation of a classification system. Also needed is evidence that the syndromes are reliable and stable entities, since the major criticism of traditional diagnostic systems is that they have weak reliability and
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stability (Freeman, 1971;Mischel, 1968;Peterson, 1961). Short-term (1 month) test-retest reliability ratings of syndromes for parents and teachers are high ( r = 32-.93), and longer term (1 month to 5 years) test-retest reliability ratings are only slightly lower ( r = .68-.89). Interrator reliabilities are of moderate to high magnitude for both teachers and parents (r = 50-.83),with six of seven studies finding correlations greater than or equal to r = .73.Perhaps the most important finding is that there are moderate correlations between raters even when they see the subjects in different situations ( r = .45-Sl).Although correlations between different types of raters (e.g., parents vs teachers) in different situations are low, these too are significant (see Achenbach & Edelbrock, 1978,for a review of all of the preceding findings). Moreover, since individuals do not spend an equal amount of time in different situations, low cross-situation correlations do not necessarily imply low intraindividual consistency (Bowers, 1973). Thus, the inward and outward syndromes are worthy of inclusion in initial attempts at a classification system: They designate consistent individual differences in behavioral complexes, individual differences that have respectable stability over time and at least low to moderate stability across situations. The consistency across these empirical findings on clinical behavior syndromes stands in marked contrast to the lack of consistency among practitioners in their use of diagnostic categories. In a recent “Project on the classification of exceptional children” (Hobbs, 1975) there was little agreement as to the most appropriate distinctions. The general consensus among participating clinicians was that cment labels are of little use in dealing with the myriad problems faced in psychological service centers. How can we account for the reluctance to translate research into practice? In large part the reluctance arises because factor analytic investigators have not provided a conceptual framework within which to interpret the empirical findings. Factor analysis is, at bottom, an atheoretical approach. Advocates of factor analytic research maintain that in order to erect a scientific framework, we must begin by classifying the phenomena of interest. Upon this foundation, they argue, an understanding of the appropriate conceptual framework, including an understanding of etiology, can be built. The issue then is whether it is reasonable to use an empirically derived classification system as a foundation in building toward a theory of clinical behavior syndromes. The present author believes that the approach taken by factor analytic researchers has been a reasonable one-the first step should be the identification of meaningful categories. While theory will not flow spontaneously from the identification of categories, the latter plays a critical role in subsequent develop ments. Now that factor analytic work has produced a fairly broad consensus, a logical next step is a concerted attempt to relate the findings regarding clinical behavior syndromes to potentially relevant theoretical literature. The most prevalent interpretation of the inward-outward distinction is that
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provided by psychoanalysts. According to the psychoanalytic view, children with inward behaviors are distinguished by excessive self-control. Inward children are seen as suffering from extreme anxiety (either “objective” or “superego”) regarding their impulses (Freud, 1950). The internalization of societal norms and/or the fear of repercussions lead them to inhibit expression of impulses. Operation of these self-control mechanisms is manifested in the tendency toward self-blame and intrapunitiveness. Children with outward behavior, by contrast, are seen as unable to inhibit impulses. Psychoanalysts attribute manifestations of outward behavior, such as impulsivity and inability to delay, to deficiencies in internalized controls. Two important characteristics of the psychoanalytic approach should be noted. The first is that notions like impulsivity and internalized controls are difficult to operationalize and do not lend themselves easily to testable hypotheses. The second is that the traditional emphasis in analytic theory is on control over impulses. This emphasis contrasts with the more recent emphasis on control over environmental events, or mastery motives (White, 1959). While ego analysts have concerned themselves with this second notion of control, the fact remains that the major psychoanalytic contribution to clinical behavior has been to advance the first notion of control-control over impulses. In order to clarify the notion of control over environmental events, I will now turn to the helplessnessreactance model.
111. Support for the Helplessness-Reactance Model A.
LABORATORY STUDIES OF CLINICAL STATES
Seligman (1975) and his associates have amassed impressive evidence indicating that experiences with uncontrollableevents lead to helplessness in subsequent situations. In their studies, “uncontrollable” is defined as independence between the subjects’ responses and subsequent outcomes. Helplessness takes various forms but is most often expressed as passivity and withdrawal in situations in which activity and effort would lead to the desired outcome. Although Seligman dues not address himself to the inward-outward distinction, he does describe behaviors that are clearly of the inward type. Fearful, depressed, and somaticizing behaviors, all of which belong to the inward syndrome, are considered expressions of helplessness (Seligman, 1975; see also Pennebaker, Burnam, Schaeffer, & Harper, 1977). In contrast to helplessness theory, which posits a relationship between uncontrollable events and inward-type behavior, is reactance theory, which posits a relationship between uncontrollable events and outward-type behavior. Brehm (1966), a major spokesman of reactance theory, argues that if freedom to engage
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in behavior is threatened or removed, individuals will increase their attempts to engage in the behavior and/or exhibit hostile and aggressive behaviors. (Although Brehm emphasizes “freedom” rather than “control,” the two terms are substituted for one another within his theory.) The disobedient, antisocial behaviors exhibited in studies on reactance contrast with the apathetic, passive behaviors exhibited in studies on helplessness. To deal with the seeming paradox, a few authors (notably Wortman & Brehm, 1975, and Roth & Bootzin, 1974) have proposed a synthesis of the preceding models. Their synthesis, hereafter referred to as the helplessness-reactance model, maintains that slightly to moderately uncontrollable experiences lead to reactance, and that severely uncontrollable experiences lead to helplessness. Moreover, the model maintains that there are inappropriate manifestations of reactance and helplessness that arise from generalizations of the perceptions of uncontrollability to situations other than those in which they are induced. Wortman and Brehm (1975) and Roth and Bootzin ( 1974) cite several studies in both the helplessness and reactance literatures that can be interpreted as consistent with their model (e.g., Glass & Singer, 1972; Thornton & Jacobs, 1971). There have been two successful attempts to provide direct evidence for the helplessness-reactance model (Roth & Kubal, 1975; Tennen & Eller, 1977). These studies employed similar paradigms: Subjects in the slightly to moderately uncontrollable condition were administered a smaller number of unsolvable trials than subjects in the severely uncontrollable condition. Subsequently, all subjects were administered a solvable task. This new task was introduced as being unrelated to the prior task and was administered by a different experimenter. The findings supported the predictions that slightly to moderately uncontrollable events lead to reactance, as manifested by increased persistence, and that severely uncontrollable events lead to helplessness, as manifested by decreased persistence. In addition, both of these studies examined attitudinal and emotional consequences of the failure manipulations. The results suggest that slight to moderate uncontrollability leads to feelings of anger as well as to increased persistence (Tennen & Eller, 1977), and that severe uncontrollability leads to feelings of helplessness and incompetence as well as to decreased persistence (Roth & Kubal, 1975). In a third test of the model, Pittman and Pittman (1979) supported the findings for severe uncontrollability and found that partial uncontrollability led to anger but not to increased persistence. The partial inconsistency may be due to the use of subjects scoring at the extremes of the locus of control scale. There are a few laboratory-state studies involving reactance and helplessness in children. In one of the earliest demonstrations of the reactance phenomenon, Weiner (1963) found that involuntary restriction of toy choice alternatives led to efforts to overcome the restriction. A reactance interpretation can also be applied to many of the findings regarding children’s aggression (Feshbach, 1970). On the
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other hand, Dweck and Reppucci (1973) found that helplessness could be engendered in children by exposing them to continuous failure-the same manipulation that has been used in many helplessness studies with adults. In a subsequent study, Dweck (1975) found that causal attribution retraining (i.e., encouraging children to attribute outcomes to their own efforts), administered in the context of primarily successful experiences, led to diminished helplessness. A study by Aronfreed (1968), in which children were punished either before or after engaging in an activity can also be seen as consistent with the helplessness reactance model. The first group, which was never allowed to engage in the activity, subsequently manifested avoidance behavior; the second group, for whom punishment was preceded by a period of freedom,did not manifest avoidance behavior in a subsequent situation.’ Despite these studies, it is safe to say that the overwhelming majority of studies on reactance and on helplessness have employed adult subjects. Moreover, the three studies demonstrating that slightly to moderately uncontrollable events lead to reactance and that severely uncontrollable events lead to helplessness (Pittman & Pittman, 1979; Roth & Kubal, 1975; Tennen & Eller, 1977) have been conducted with adults. Before moving on, it is important to elaborate on the notion of control as it is employed in the helplessness-reactance literature. The concept that Seligman and his associates had in mind was perceived dependence vs independence between one’s actions and subsequent outcomes. This is very similar to the construct of internal vs external locus of control developed by Rotter, and, indeed, several advocates of the helplessness-reactance model have drawn this connection (Cohen, Rothbart, & Phillips, 1976; Hiroto, 1974; Tennen & Eller, 1977; Wortman & Brehm, 1975; but see also Abramson, Seligman, & Teasdale, 1978). Within this broad definition of control, several variations can be encompassed. For example, Brehm emphasizes the individual’s loss of freedom to engage in activities and to make choices, whereas Seligman emphasizes lack of con-
‘Although the psychoanalytic position has been discussed earlier. its relevance to points raised in this section deserves special mention. There are several psychoanalytically oriented thinkers (Bibring, 1953; Blos, 1963; Fraiberg, 1950; Levy, 1955) who have adopted a model of children’s clinical behavior syndromes that is very similar to the present model. These authors maintain that inward (depressed) children suffer from perceptions of extreme helplessness and hopelessness. Their analysis of outward (acting-out) children also bears a striking similarity to the current formulation: Outward children are Seen as attempting to “control (their) destiny,” and “to counteract the regressive pull to passivity” (Blos, 1%3, pp. 270-271). Borrowing from the psychoanalytic literature, Dorpat (1977) has suggested that depression arises when aversive events are certain, whereas anxiety arises when aversive events are likely but uncertain. Since Dorpat associates anxiety with arousal and activity, and depression with helplessness. there are essential similarities between his model and the helplessness-reactance model. Though psychoanalytically oriented writers couch their formulations in different terms, there is agreement regarding the underlying dynamics.
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tingency between the individual's actions and subsequent outcomes. Although there is no incompatibility between these emphases, there are differences between them that should not be ignored. Adherents of the f ~ s notion t of control are more likely to employ loss of control manipulations in which subjects are led to believe that certain options exist that they later discover do not exist, whereas adherents of the second notion of control are more likely to employ manipulations in which there is a lack of contingency on complex tasks (e.g., random reinforcement on problem-solving tasks). These differencespoint to complexities that will be elaborated upon later in this paperZ(see Section I1,C). The laboratory studies cited in this section provide the most direct and rigorous tests of the helplessness-reactance model, particularly regarding the causal role of uncontrollable events. However, two major limitations of this research are that it focuses on clinical states (i.e., simple laboratory induced behavioral reactions that are restricted in time) and it focuses on adults. To find evidence that the helplessness-reactance model applies to behavioral syndromes (behavioral complexes with temporal stability) in children, it is necessary to move away from laboratory studies of states and toward naturalistically observed studies of clinical stages. B. NATURALISTIC STUDIES OF CLINICAL STAGES
There is an impressive body of research indicating that individuals' reactions to uncontrollable events occur in predictable stages. Though the terms "helplessness" and "reactance" are not typically employed in this literature, the similarity between the phenomena examined in the laboratory studies of states and the naturalistic studies of stages, and, therefore, the relevance of the helplessnessreactance model to the latter, is easily recognized.' Perhaps the best known of the There have been valuable refinements and modifications in the notion of control that will nor be treated in this article. Weiner (1974) has shown that an individual's behavior depends on whether he attributes an event to stable or variable causal factors. Rosenbaum (1972) distinguishes between intentional and unintentional causal factors. Glass and Singer (1972) have demonstrated that different consequences follow from attributions of events to difise as opposed tofocal causal factors (see also the distinction between global and specific causes made by Abramson et al., 1978). The most valuable distinction may be the one between universal and personal attributions-the perception that self's contingency is the same as otheis vs, that self's contingency is different from that of others (Abramson et al., 1978). However, it is important to note that the various concepts and operationalizations of control that are currently used by helplessness-reactance theorists are more similar to one another (and to the notion of control over environmental events) than any of them are to the impulse-control concepts and operationalizations. Moreover, there appears to be enough consensus to speak of a single coherent helplessness-nactance model construct of control. The definition adopted here is the one mentioned earlier: perceived contingency between one's actions and subsequent outcomes. This "contingency" defmition of control is the one that has been adopted in the direct experimental tests of the helplessness-reactance model (Piaman & Pittman. 1979; Roth & Kubal, 1975; Tennen & Eller, 1977). 3Nahualistic-stage reseamhers place at least as much emphasis on loss of incentives-important
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stage research is the work of Bowlby (1973), Robertson and Bowlby (1952), Spitz and Wolff (1946), and Yarrow (1963). According to these authors, children who have been separated from their parents exhibit a typical sequence of stages of reaction. Two of the most important of these stages, protest and despair, closely parallel reactance and helplessness. Moreover, the order of the reactions is the same in both instances: Bowlby and others have noted that a stage of anger, increased activity, and general protest typically precedes a stage of withdrawal, decreased activity, and general despair. The observations of Bowlby and others regarding children’s separation from parents are relatively informal and do not involve manipulations for obvious reasons. However, similar investigations have been conducted with primates in which separation from parents was experimentally manipulated, and in a few of which adequate controls were included. This research has generally supported the findings from the naturalistic studies-that is, the research with primates indicates that relatively distinct stages of protest and despair follow the loss of parents (Hinde, Spencer-Booth, & Bruce, 1966; Kaufinan & Rosenblum, 1967; Sackett, 1970). Hence, there is at least partial experimental corroboration of the stage findings. Findings similar to those reported above have emerged in studies of reactions to news of one’s own impending death-research popularized by Kubler-Ross (1969)-and in studies of reactions to the death of loved ones (Marris, 1958; Parkes, 1972). Other situations in which naturalistic observations of the protest-despair behavioral sequence have been recorded include (a) studies on blindness (Fitzgerald, 1970) and other disabilities interfering with the pursuit of enjoyment of valued incentives (Orbach & Sutherland, 1954; Talbott, 1970); (b) studies on losses of significant objects, important roles, and reputations (Averill, 1968); (c) studies on alienation that indicate that the difference between aggression and estrangement is greater before the period of appraisal than after it (Stokols, 1975); and (d) studies on group processes that lead to the conclusion that group members typically increase their communication to deviant individuals, but, if the deviant behavior continues, this is followed by a stage of d e persons, activities and objects-as on loss of control per se (cf. Klinger, 1975). Advocates of the helplessness-reactance model, by contrast. maintain that it is not the avenive experiences per se but aversive experiences in conjunction with uncontrollability that induces clinical behavior. The laboratory-state research has generally supported this distinction: Groups receiving uncontrollable avenive outcomes subsequently manifest more clinical behavior than groups receiving the same amount and kind,of aversive outcomes but not the element of uncontrollability (cf. B r e h , 1966; Seligman, 1975). Similar Frndings have been obtained when the outcomes are nonaversive (Cohen, RothM, & Phillips, 1976). Studies employing noncontingent positive stimuli have yielded mixed results; the findings appear to depend on the dependent variables, but even then the results are contradictory (Abramson er al.. 1978; Benson & Kennelly, 1976). Throughout this article it is assumed that the consequences of the uncontrollability are most pronounced in the case of aversive outcomes. (See Abramson er al., 1978, for a more extensive review of this literature.)
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creased communication (Riecken & Homans, 1954). These stages clearly resemble the reactance-helplessness pattern described earlier. A final area of stage research is the work of Selye (1956), who demonstrated that the body typically undergoes physiological stages of “resistance” and “exhaustion” in response to a variety of stressors. While strict comparisons between these physiological findings and the preceding behavioral findings are difficult to draw, the similarity between them suggests that the phenomenon in question may be manifested at different levels of functioning. The stage findings reviewed to this point involve cases in which decreasing controllability is accompanied by a sequence of outward-type and inward-type behavior. In addition to these findings, there is evidence that the stages occur in the opposite order when there is a shift from severely uncontrollable events to slightly to moderately uncontrollable events. Brinton (1952), in The Anatomy of Revolution, observes that the lower strata of society respond to rising expectations by shifting from submissive, acquiescent behavior to rebellious behavior. Therefore, the riots of the blacks in the late 1960s, for example, could be seen as resulting in part from perceiving an increase in their personal control. Similarly, in the clinical literature on children, a shift from inward-type behavior to outward-type behavior is attributed to improvement in therapy, and more directly, to the child’s increasing sense of control (Bornstein, 1949;Freud, 1950). C. CLARIFYING THE MODEL LOSS AND LACK OF CONTROL
The expressions loss of control and lack of control are frequently employed in the helplessness-reactance literature. Loss of control typically refers to the perception of contrast between expectations of control and subsequent perceptions of uncontrollability. Lack of control typically refers to the perception of uncontrollability in the present situation. While different authors typically rely on one of these constructs more than the other, few authors employ them in a wholly consistent manner. Therefore, before considering how loss and lack relate to clinical behavior, it is important to clarify how they relate to one another. The differences between loss and lack of control can best be understood by considering how each relates to expectations of control. As defined in the last paragraph, loss of control refers to the perception of contrast between expectations of control and subsequent perceptions of uncontrollability. Two factors contributing to the salience of this contrast are (a) high expectations of control and (b) abrupt transitions from expectations of control to perceptions of uncontrollability. These factors make unlikely an exclusive focus on present perceptions. Therefore, they make unlikely perception of a lack of control. The differences between loss and lack described in the preceding paragraph help account for differences in methodology employed by investigators interested in each. Those who are particularly concerned with loss of control design studies
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in which subjects are led to adopt very high expectations of control, and in which the contingencies between responses and outcomes are very clear. For example, individuals who have been led to believe that they will be granted the behavioral option they prefer and who have selected an option are subsequently told that the option they selected is not available. Brehm (1966) and Wicklund (1974), who have designed many studies of this type, emphasize the individual’s “loss of freedom. ” It is difficult to analyze the construct of freedom without acknowledging the role of expectations. Things that we come to think of as freedoms are things over which we expect control. (These expectations may arise from implicit or explicit messages indicating that control is likely, from repeated experiences in which the individual has control, or from the fact that one’s comparison group has control.) Clearly, in the study described above, subjects are led to adopt a high expectation of control. Furthermore, because the contingencies are unambiguous, there is an abrupt transition between the expected attainability of the desired outcome and the subsequent perception of unattainability. Such abrupt shifts in perception are possible only when the individual can readily assess whether his responses lead to the desired outcome (i.e., when the contingencies are unambiguous). Very different paradigms are employed by investigators who emphasize lack of control. Typically, in studies designed by these investigators, subjects are not led to adopt high expectations of control. Moreover, the transition from expectations of control to subsequent perceptions of uncontrollability is generally gradual. This is accomplished by employing tasks in which contingencies are ambiguous. A common practice is to use complex tasks on which the degree of uncontrollability is not immediately evident because of the number of possible strategies that can be adopted in the solution of the task and because failure is random rather than absolute. Since contingencies are ambiguous, expectations of control and subsequent perceptions of uncontrollability are not temporally contiguous, and the contrast between them is not brought into focus. When expectations of control are not high and when perceptions of uncontrollability are gradually introduced, individuals are not likely to focus on their expectations or to perceive a contrast. As a consequence, they are more likely to perceive a lack of control than a loss of control. Armed with the distinction between loss and lack of control, it is possible to reconsider the relationship between uncontrollability and clinical behavior. Those investigators who tend to emphasize the role of loss of control and who have employed paradigms consistent with this emphasis (see Table I) have most frequently found reactance effects. Brehm (1966) and Wicklund (1974), leading spokesmen of this research tradition, maintain that there is a linear relationship between loss of control and reactance. Presumably, the high expectations of control accompanying severe loss provide a reminder of the way things can be and make the individual unlikely to accept his uncontrollability. Then too, the
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TABLE I Summary of Conditions Giving Rise to Loss and Lack
Rior expectation of control
Present perception of control
Transition from prior expectation to present perception
High"
LOW
Abruptb
Low
LOW
GradUal
Loss of control Focus is on contrast between prior expectation and present perception Lack of control Focus is on present perception ~
~~~~~~~
Expectation of control is high when there are implicit or explicit messages indicating that control is likely, when there are previous experiences in which the individual has control, or when the individual's comparison group has control. * Abmpt transitions are likely to occur when contingencies are unambiguous.
more severe the loss, the more effort is needed to regain control. These dynamics can account for the connection between perceptions of loss and reactance. The association hypothesized between loss and reactance builds on a venerable tradition: It is closely aligned with the Dollard, Doob, Miller, Mowrer, and Sears (1939) frustration-aggression hypothesis. While Dollard ef af. did not explicitly emphasize the role of expectations, the importance of expectations is implicit in their model. One of the earliest tests of their model was to assess the effect of removing a bottle (an event for which expectations of control are presumably high) from a child (Dollard et af., 1939). As a result of the frustrationaggression hypothesis and its derivatives, expectations of options and barriers to those options (i.e., clear violations of expectations) are nearly universal features of the research on aggression in children (cf. Feshbach, 1970). Examples include the Miller and Bugelski (1948) study of children's being deprived of a movie that they eagerly expected, the Otis and McCandless (1955) study of the occasional introduction of obstacles into children's play, and the Mallick and McCandless (1966) study of interference with completion of a task for which children were to receive a reward. In each case an unexpected frustration led to aggression. Not surprisingly, several authors have qualified the frustration-aggression hypothesis in such a manner as to make the role of expectations more explicit (Bateson, 1941; Berkowitz, 1962; Cohen, 1955; Haner & Brown, 1955; Kregerman & Worchel, 1961; Pastore, 1950, 1952; Wicklund, 1974; Zander, 1944). Those investigators who have emphasized the role of lack of control and who have employed paradigms consistent with this emphasis (see Table I) have most frequently found helplessness effects (see reviews by Abramson et al., 1978;
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Roth, 1980; Seligman, 1975; Wortman & Brehm, 1975). Also falling within this camp are those investigators who have examined both helplessness and reactance effects (Pittman & Pittman, 1979; Roth & Kubal, 1975; Tennen & Eller, 1977). Results from these studies are consistent with findings from the helplessness literature in their implication that severe uncontrollability leads to helplessness. However, an equally important finding from these studies is that slight to moderate uncontrollability leads to reactance. The relationship between the latter findings, which do not involve a lack of control (i.e., severe uncontrollability), and the findings involving helplessness will be discussed shortly. The naturalistic-stage research also points to the value of the loss-lack distinction and supports the preceding claims regarding how each relates to clinical behavior. Stage researchers investigate events like maternal separation, death of loved ones, and blindness-events with unambiguous contingencies. Moreover, in each of these cases there should be high expectations of control Individuals assume that they can approach or call for loved ones, particularly when the individuals who have their sight assume that they can see things if they focus on them. Control of each of these outcomes is removed by the events in question. The fact that stage researchers emphasize the role of loss of control and typically find an initial response of protest (prolonged reactance) is consistent with the present position. The later response observed in these stage studies, despair (prolonged helplessness), is also consistent with the present explanation: As the time from onset of the uncontrollable event increases, individuals tend to "lose sight of" their earlier expectations of control. As this happens, loss of control (which stem from a focus on the contrast between expectations of control and present perceptions) gives way to severe lack of control (which stems from a focus on expectations for uncontrollability and/or present perceptions of uncontrollability). Therefore, the loss-lack distinction facilitates understanding of both clinical states and stages. The loss-lack distinction suggests that severely uncontrollable events can (a) lead to reactance or helplessness depending on the paradigm used to induce uncontrollability (see Table I) and (b) lead to protest or despair, depending on the time that has elapsed since the onset of the uncontrollable event. In summary, findings indicate that loss and lack are not identical constructs and that they should not be used interchangeably. Loss and lack relate in different ways to clinical behavior: Loss leads to reactance and protest, whereas lack leads to helplessness and despair. The fact that slight to moderate uncontrollability has a similar effect as loss of control suggests that the underlying dynamic in reactance is the perception that control can be regained; the fact that helplessness is induced by lack of control suggests that the underlying dynamic in helplessness is the perception that control cannot be regained (cf. Carver, Blaney, & Scheier, 1979; Wortman & Bmhm, 1975). The distinction between loss and lack of control will play a significant role in the remainder of this article, particularly
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when evidence regarding the relationship between generalized expectations of control and syndromes is reviewed (Section IV,A).
IV. Toward a Helplessness-Reactance Explanation of Syndromes It is my belief that the helplessness-reactance model is capable of shedding light on the inward and outward syndromes (i.e., the temporally and situationally stable behavioral clusters in children that were reviewed in Section II). To prove the relevance of the helplessness-reactance model, it will be necessary to link the clinical states of helplessness and reactance with which the model is directly concerned, and the inward and outward syndromes. The stage research is of value because it can act as a bridge in making this connection. As already noted, the stage research relates in essential ways to the state research. The ties between the stage research and the factor analytic research on syndromes constitute the other half of the bridge. This will be the next topic for consideration. The factor analytic research cited earlier was designed to provide a classification system for children’s clinical syndromes. This research has led to the identification of behavioral complexes that have at least moderate stability over time. There are several obvious similarities between the factor analytic research and the naturalistic studies of stages described earlier. First, there is overlap in the age levels studied. Unlike the laboratory-state studies, which are almost exclusively concerned with adults, several of the naturalistic-stage studies are concerned with children (cf. Klinger, 1975). Since the ultimate goal is to understand clinical syndromes of children, it is imperative that research focus on this population. A second similarity between the factor analytic and naturalistic-stageresearch is that they both address behavioral complexes. One of the benefits of naturalistic-stagestudies is that they permit the observation of numerous manifestations of clinical behavior, (Lea, of “protest” and “despair”). Instances of protest observed in the naturalistic-stage research include disobedience, hostility, and aggression; and instances of despair include depressed affect, loss of appetite, and somaticization. The resemblance between these behavioral complexes and the outward and inward syndromes derived from factor analytic research is readily apparent. Subjects are less likely to manifest clinical complexes (i.e., multiple clinical behaviors) in laboratory-state studies than in naturalistic-stage studies because the antecedents investigated in the former are less stressful. Indirect evidence of complexes could be obtained by comparing findings from several laboratory-state studies in each of the studies examined different clinical behaviors. However, the indirect approach has been impeded by the tendency of laboratory-state researchers to focus on only a few dependent variables, such as
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persistence. Though increases and decreases in persistence relate in obvious ways to outward and inward behavior, respectively, the focus on this or any other single manifestation of clinical behavior makes it difficult to draw conclusions regarding behavior complexes. A third similarity between the factor analytic and the naturalistic-stage research is that they both address behaviors extended in time. Stage researchers have indicated that both the protest and despair phases can last weeks to months. By contrast, an implication that m a y be drawn from the laboratory studies of states is that clinical behaviors last a matter of minutes. While state researchers assume that the mechanisms they are investigating can produce enduring effects, the specific behaviors that they have examined are of brief duration. Hence, the stage research is unlike the state research in that it indicates that clinical behavior reactions are extended in time. In this important respect, the stages resemble the syndromes identified in factor analytic research. The preceding analysis indicates the critical role of the naturalistic-stage research in linking the laboratory-state research to the syndromes derived from factor analytic research. On the one hand, the stage research resembles the state research in that both demonstrate that outward-type behavior and inward-type behavior relate to differences in perceived control. On the other hand, the stage research relates in essential respects to the factor analytic research on syndromes: Both of these bodies of research involve children and they both involve behavioral complexes that are extended in time. The laboratory research on states is dissimilar to the two other bodies of research in each of these respects-it involves adults and it addresses simple behaviors that are limited in time. A summary of the ties between naturalistic-stage research and laboratory-state research, and between naturalistic-stage research and factor analystic research, is provided in Fig. 1. The summary highlights the fact that the stage research serves as a bridge between the two other bodies of research. In so doing, it indicates the potential applicability of the helplessness-reactance model for understanding syndromes. The evidence reviewed to this point suggests that states and stages function in ways consistent with the helplessness-reactance model and that there are similarities between states and stages on the one hand and syndromes on the other. This evidence provides partial support for the claim that the helplessness-reactance model is relevant to the study of syndromes. In order to gain increased confidence in the relevance of the model, it will be necessary to provide direct evidence of the model’s implications. Since the helplessnessreactance model assumes a connection between clinical behaviors and perceptions of uncontrollability, the major implication for clinical syndromes (i.e., clinical behaviors extended in time) is that they relate to recurring perceptions of loss and lack of control. The question therefore arises as to whether there are generalized expectations that predispose the individual to recurring perceptions
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I
Factor Analytic Studies of Syndromes Identification of' Outward and Inward Behavior in Children
I
investigations of Children
Behaviors Extended in Time
Behavioral Complexes
1 Naturalistic Studies of Stages Identification of Prolest and Despair Behavior in Children and Adults
I
Investigations of Adults
Outward-type behavior caused by perception of' loss of control or slight to moderate uncontrollability; inward-type behavior caused by perception of lack of control
Laboratory Studies of States Identification of Reactance and Heljltessness Behavior in Adults
Helplessness-Reactance Model Fig. 1 . Similarities between clinical behavior states, stages, and syndromes.
of loss and lack of control. Evidence regarding this matter is the next topic to be reviewed. A.
LOCUS OF CONTROL
This subsection addresses four issues: (1) the similarity between the locus of control construct and the construct of control employed by helplessnessreactance theorists, (2) the generalizability of locus of control, (3) the relationships between locus of control and loss and lack of control, and (4) the relationships between locus of control and inward and outward behavior. Consideration of each of these issues is helpful in establishing a link between locus of control and the inward syndrome.
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In moving from the helplessness-reactance model construct of control, which is operationalized through situational manipulations, to a generalized construct of control, which is operationalized through attitudinal measures, a primary concern is whether the two constructs are comparable. A strong case for comparability can be made if the generalized construct selected is locus of control. The locus of control construct consists of a bipolar dimension of internality vs externality. Individuals at the internal end attribute outcomes to factors inside the self, and individualsat the external end attribute events to external factors or to chance. Stated otherwise, internal locus of control relates to an expectation of contingency between one's own actions and subsequent outcomes, whereas external locus of control relates to an expectation of noncontingencybetween one's actions and outcomes. The nearly total overlap between this conception of control and the conception of control employed in helplessness-reactance theory is not accidental. Investigators of helplessness have openly borrowed from and contributed to the locus of control literature (Seligman, 1975) and investigators of locus of control point to the essential similarities between their work and the work on helplessness (Lefcourt, 1976).4 In addition, several studies have demonstrated a relationship between external locus of control and manipulations of uncontrollable outcomes (Cohen et al., 1976; Dweck & Reppucci, 1973; Gregory, Chartier, & Wright, 1979; &to, 1974; Pittman & Pittman, 1979). To relate locus of control to clinical syndromes, it is necessary to document the generalizability of locus of control; since the syndromes that the locus of control construct are intended to explain have only limited cross-situational generalizability, it is necessary to show only that locus of control has limited crosssituational generalizability. Mischel, Zeiss , and Zeiss (1 974) have investigated this issue by employing a scale that assesses perceptions of control in different situations. Their findings indicate that there are statistically significant but small correlations ( r C .20) across items (across situations). However, it should be noted that Mischel et al. intentionally selected descriptions of specific, heterogeneoussituations. Had they selected descriptionsof broad situations and/or situations that bore greater similarity to one another, the cross-situation correlations might have been substantially higher. Consistent with this interpretation, higher correlations between items (situations) have been found with locus of conwl questionnaires that employ less heterogeneous situations. For example, 'Recently Abramson and her collaborators (Abramson er al., 1978) have maintained that locus of control and mmntingency are independent dimensions. These authors maintain that personal noncontingency (i.e., self is the only one who lacks contingency) implies an internal locus of control and that universal noncontingency (i.e., self and others lack contingency) implies an external locus of control. This follows from Abramson's definition of internal locus of control as a discrepancy between the contingency of self and others, and from her definition of external locus of control as the absence of such a discrepancy. By contrast, in the present paper, internalityis d e f i i as contingency between actions and outcomes and externality is defined as the absence of contingency. It is believed that these definitions are more consistent with the operationalizations of locus of control that have been employed in the past.
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the split-half reliabilities for the children’s Intellectual Achievement Responsibility Scale range from .54 to .60 (Crandall, Katkovsky, & Crandall, 1965). Further evidence of cross-situational generalization comes from studies that have related locus of control questionnaire responses to contingency-based behavior in situations that were not specifically addressed in the questionnaires. Children with internal locus of control score higher on reading, math, spelling, language, and total achievement tests (Chance, 1965; Crandall et al., 1965; Crandall, Katkovsky, & Preston, 1962; McGhee & Crandall, 1968), as well as on intelligence tests (Chance, 1965; Crandall et al., 1962) and grades (Crandall et al., 1965). Naditch (1973) found correlations between internal locus of control and achievement in areas that were important to the child, be they in the realm of school, social life, or athletics. Internal locus of control also relates to children’s persistence-in activities required to obtain attractive goals and to avoid aversive outcomes (Mischel et al., 1974), in attempts to solve complex logical puzzles (James, 1965), in time spent doing homework (Franklin, 1963), and in waiting for deferred goals (Walls & Smith, 1970). The preceding findings are by no means without exceptions; they vary with the sex and age of the children, the valence of the reinforcements, and other factors. (For a more extensive review see Lefcourt, 1976.) However, there is enough consensus to conclude that perceptions of contingency between actions and outcomes are at least slightly generalizable across situations. Temporal generalizability of the locus of control dimension has also been demonstrated. Findings from several studies of locus of control in children indicate that there are respectable degrees of consistency across time (Crandall et al., 1965; Nowicki & Duke, 1974; Mischel et al., 1974; Nowicki & Strickland, 1973; Rothbaum, Wolfer, & Visintainer, 1979). In these studies, retest intervals have ranged from approximately 1.5 to 8 months, and correlations in scores have ranged from .62 to .79. Hence, it appears that children’s perceptions of intemalexternal locus of control have moderate temporal stability over a period of months. The evidence that locus of control has at least slight stability across situations and moderate stability across time adds to earlier indications that this construct is well suited to account for children’s clinical syndromes. An essential next question is whether locus of control relates to the recurring perception of loss or lack of control. There is little reason to believe that locus of control relates to loss of control. It is true that internal locus of control is likely to lead to high expectations and that high expectations predispose children to perceptions of loss. However, two factors make unlikely a connection between internal locus of control and loss. First, since children with an internal locus of control adopt the perception that actions lead to outcomes, they are more likely to take steps to obtain the desired outcome and, in so doing, to lessen the chance of loss. Second, even when they enter into objectively uncontrollable situations, they are protected
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against abrupt perceptions of loss because of their initial perceptions that these situations are controllable. Only gradually do they recognize the existence of uncontrollability. Since locus of control has a similar effect on expectations and subsequent perception, locus of control should not relate to perceptions of loss. There is, however, ample reason to believe in a relationship between locus of control and lack of control. First, external locus of control should give rise to expectations of uncontrollability . Second, these expectations are likely to translate into perceptions, since the individual is unlikely to take action that will remedy the situation (that is, the expectation of uncontrollability is likely to function as a self-fulfilling prophecy). It is probably not fortuitous that locus of control theorists depict externality as entailing a lack of control more often than they depict it as entailing a loss of control. The claim here is that external locus of control predisposes individuals to perceive a lack of control and consequently, to manifest inward-type behavior. In support of the preceding predictions, a number of studies have found a correlation between external locus of control and inward-type behavior, such as passivity, withdrawal, and anxiety (cf. Lefcourt, 1976; Phares, 1976). In his review of the locus of control literature, Lefcourt concludes that externality has been related most often to depressive kinds of behaviors-behaviors that belong to the inward syndrome. These findings emerge in both self and observer reports. Harrow and Ferrante (1969) found that, in contrast to other psychiatric groups, patients with depressive symptoms showed more significant change toward greater internality following a 6-week period at a clinical facility. Schizophrenia, another disorder commonly associated with the inward syndrome because of the predominance of helplessness (White, 1965), has been related to external locus of control in several studies (cf. Lefcourt, 1976, p. 90). Data from laboratory-state research also indicate a connection between external locus of control and inward behavior. Compared to individuals with an internal locus of control, individuals with an external locus of control are more likely to respond to uncontrollable experiences with manifestations of helplessness (Cohen et al., 1976; Hiroto, 1974). Hiroto (1974) reports that externals perform more poorly on tasks than intemals, whether their pretreatments consist of contingent or noncontingent reinforcement. Even during the pretreatment task itself, externals were slower to escape, required more trials to reach an avoidance criterion, and made fewer avoidance responses. Cohen et al. (1976) also report greater inward-type behavior among externals than internals following noncontingent pretreatments but not following contingent pretreatments. The latter findings and subsequent findings by Gregory er af. (1979) and Pittman and Pittman (1979) indicate that externals do not manifest greater inward behavior following experiences that are extremely controllable (due to increases in externals’ perceptions of control) or extremely uncontrollable (due to decreases in internals’ perceptions of control). However, the finding that externals respond with more
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inward behavior than do internals following less extreme experiences (i.e., neutral or slightly uncontrollable experiences) has been obtained in all of the preceding studies. Research by Dweck and her colleagues indicates that the preceding dynamics are applicable with children as well as adults. Dweck and Reppucci (1973) found that the greatest performance decrements following laboratory-induced failure were evident in children who were assessed as having an external locus of control. In a later study, Dweck (1975) found significantly more externality in a sample of fifth grade students with a history of extreme helplessness than in a comparable sample of persistent students. More recently, Diener and Dweck (1978) found that external children respond to failure with fewer task relevant instructions, more statements of negative affect, more Statements irrelevant to task solution, and less persistence than do internals. These findings indicate that external locus of control in children relates to longstanding patterns of helplessness as well as to susceptibility to helplessness in failure situations. In contrast to the evidence linking external locus of control and inward-type behavior, there is an absence of laboratory-state evidence that external locus of control relates to outward-type behavior (but see Cherulnik & Citrin, 1974, for a possible exception). Moreover, only a few correlational studies have indicated a relationship between longstanding patterns of outward-type behavior and external locus of control, and these have serious methodological shortcomings. Williams and Vantress ( 1969) report a small but significant Correlation ( r = .27) between externality and self-reports of “aggression,” but include in the latter measure resentment and indirect aggression. That “aggression” as meant here is a measure of outward as opposed to inward behavior is unclear. Similarly, Duke and Fenhagen (1975) conclude that there is a relationship between externality and delinquency on the basis of findings that a delinquent sample had a more external locus of control than a normal “control” sample. However, the relationship between delinquency and externality may be due to the fact that the delinquents were incarcerated at the time of the study. Finally, it should be noted that mania and alcoholism-adult disorders that in several respects resemble the outward syndromes of children-have been shown to relate in an inconsistent manner to locus of control (cf. Lefcourt, 1976). Hence, the evidence linking external locus of control with outward behavior is less substantial than the evidence linking it with inward behavior. A direct test of the relationship between locus of control and clinical behavior was recently completed (Rothbaum et al., 1979). The study employed children aged 4-12 who were hospitalized for tonsillectomies. Two locus of control instruments were administered, the Nowicki-Strickland (Nowicki & Duke, 1974; Nowicki & Strickland, 1973) and the Desirable and Undesirable EventLocus of Control (DUE-LOC) scale. The new measure was considered to have greater face validity as a measure of locus of control in that it requires the child to
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make an internal or external attribution for each item. The Nowicki-Strickland, by contrast, confounds the issue of locus of control with related but distinguishable issues such as self-confidence. Both scales have respectable degrees of criterion validity and reliability. The measure of clinical behavior employed in this study was a 24-item scale fashioned after instruments devised by Achenbach (1966) and Peterson (1961). This measure was completed by the children’s mothers. (For a fuller description of the measures and their rationale see Rothbaum et al., 1979.) Results indicated that the DUE-LOC score related to type of clinical behavior. A significant positive correlation was found between inward behavior and externality [r(24) = 38, p. < .01] but not between outward behavior and externality [r(24) = -.lo, p > .lo]. The difference between these correlations was significant (t = 2.71, p < .01). In addition, externality related to the proportion of inward behavior [the number of inward behaviors divided by the total number of clinical behaviors; r(24) = .52, p < .01]. Replication of these findings was obtained in a subsequent study (Rothbaum et af., 1979). These findings constitute support for the hypothesis that the helplessness-reactance model is relevant to the study of syndromes. Consistent with the model, the findings demonstrate that external locus of control relates in a linear manner to inward behavior 6ut not to outward behavior. B. EFFECTIVENESS OF NONCONTRACTUAL METHODS
The evidence just provided indicates that external locus of control predisposes children to repeated perceptions of luck of control, and, consequently, to manifestations of inward behavior. From this evidence the question arises as to whether there are generalized expectations of control that predispose children to repeated perceptions of loss of control, and consequently, to manifestations of outward behavior. The relative deprivation hypothesis of social psychology is relevant to this issue. According to this hypothesis, it is not success or failure in absolute terms that shapes outward-typebehavior, but success and failure relative to that which is expected (Sherif & Sherif, 1969). A particularly compelling example of the relative deprivation hypothesis is provided by Pettigrew (1964) in his analysis of the protest and action of black Americans following World War II. According to Pettigrew, exclusive attention to absolute criteria of well-being leads to the expectation that black Americans should be more content during the post-war period than during any previous period in American history. This clearly is not the case. Discontent is evident in t,heu restiveness, in their anger, and in their impatience for further gains. Pettigrew persuasively reasoned that discontent manifested itself strongly when black Americans’aspirations rose at a faster pace than their actual gains. To understand
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protest and action, one must consider the relative magnitude of aspirations and actual circumstances. A similar position is adopted by Merton (1957) in his now classic “anomie” explanation of juvenile delinquency. According to Merton, the “conflict” or “disjunction” between “culturally accepted values and the socially structured difficulties in living up to these values. . . exerts pressure toward deviant behavior and disruption of the normative system” (p. 191). Merton’s anomie theory is supported by a vast sociological literature (Aubert, 1952; Barron, 1951; Glaser, 1956; Kobrin, 1951; Mannheim, 1956; Spencer, 1955; Sprott, 1954, Turner, 1954). While Pettigrew and Merton are more concerned with aspirations and motives than with expectations per se, their claims are generally consistent with the earlier hypothesis of a connection between loss of control and outward behavior. Even clearer evidence of a link between unrealistically high expectations and outward behavior comes from other theories and research on delinquency. Borrowing from the relative deprivation hypothesis, Cloward and Ohlin (1960) maintain that gang delinquency emanates from blockages in the attainment of anticipated goals. Such discrepancies, they argue, are common in the lower classes: “Since discrepancies between aspiration and opportunity are likely to be experienced most intensely at some positions along the socioeconomic scale then along others, ” there should be a greater “sense of indignation and withdrawal of supports for established norms” at these positions (p. 108). The Cohen (1955) theory of delinquency differs from that of Cloward and Ohlin in that the former emphasizes inability to conform due to failure to master necessary skills, and the latter emphasizes unjust availability of opportunity. Nevertheless, the theories have in common an emphasis on the contrast between expectations of control and subsequent preceptions. According to Cohen’s theory, the delinquency of the lower class child can be related to the discrepancy between (a) middle class pressures and “expectations” to succeed due to contacts with teachers, playground directors, ministers, and other middle class agents and (b) the inability to conform to these expectations. Reiss and Rhodes (1963) also emphasize discrepancies between expectations and subsequent outcomes. Based on their extensive study of delinquent boys, these authors conclude that delinquency arises when children compare their lives unfavorably with those of higher classes. Miller’s theory of delinquency-that lower class norms and values are conducive to behavior that is considered antisocial in middle class context+is strikingly different from the theories described above. Therefore it is particularly interesting that Miller, too, emphasizes the role of unanticipated losses: “The lower class younster who is ‘stalled’in regard to achievement aspiration is. . . likely to become delinquent” (Kvaraceus C Miller, 1959, p. 136). The link between unrealistic expectations of options and outward behavior can
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be found in the literature on normal development as well as in the literature on delinquency. Berkowitz ( 1969) observes that “excessively indulged children probably expect to be gratified most of the time, so that inevitable occasional frustrations they encounter are actually relatively strong thwartings for them. There is little doubt that these frustrations can produce aggression” (p. 379). Similarly, Jersild (1969) notes that children of overindulgent parents “are due for some hard jolts. . . their vague notions of omnipotence and illusions concerning their own rights will clash with the realities of life” (p. 139). In the theories on delinquency and explanations for “spoiled” children there is considerable support for the present formulation regarding outward behavior. First, there is a consistent emphasis on high expectations. Second and more importantly, there is a consistent emphasis on notions of “discrepancy,” “conflict,” and “disjunction” between expectations and subsequent perceptions (the terms vary but the concept does not). One limitation of the preceding analysis is that it fails to account for the ongoing occurrence of outward behavior. Repeated perceptions of loss should lead to a lowering of expectations and an eventual decrease in perceptions of loss. Moreover, if outward children have uniformly high expectations of control, this should be reflected in higher scores on internal locus of control, a finding that has not been obtained. The question therefore arises: What are the generalized expectations that predispose the individual to repeated perceptions of loss of control? In my opinion, expectations of the “effectiveness of noncontractual methods” help explain the Occurrence and nonoccurrence of repeated perceptions of loss. Contracts are defined as either (a) agreements between individuals (or between an individual and himself) in which the duties of each party and the stipulations involving the duties (e.g., when, where, and how they are to be performed) are mutually agreed upon or (b) the adherence to norms. [The association between agreements and norms should be credited to Elkind (1979) and Lemer (1977), who also employ the superordinate construct “contracts. ”1 Delinquents, sociopaths, “spoiled” children, and other groups characterized by antisocial acts have in common the expectation that noncontractual methods are more effective than contractual methods in obtaining outcomes. It is primarily because they do not rely on contracts that these individuals repeatedly experience perceptions of loss of control. Instead of relying on contracts, they proceed along an independent course with no assurance as to when, where, and how they will encounter interference from outside forces. Closely related to the expectation that noncontractual methods are effective in producing outcomes is egocentrism4he failure to adopt perspectives other than one’s own immediate ones. Descriptions of perspective-taking skills provided in the cognitive developmental literature readily call to mind the notion of contracts. For example, mutual perspective taking, the ability of two persons to
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understand that each can take both his own and the other’s perspective, is an obvious aid in the formation of contracts. Consistent with the hypothesized connection between the expectation that noncontractual methods are effective and outward behavior, several studies have indicated a relationship between egocentrism (i.e., lack of perspective taking) and outward behavior (Blumenfeld 8c Kinghom, 1979; Chandler, 1973). A common explanation for this relationship is that empathy diminishes aggression. However, the rationale provided above suggests another possibility: that an absence of contracts and, thus, perceptions of loss, mediates the relationship between egocentrism and outward behavior. Recently the notion of contracts has found a home in social psychology, in the literature on “just world phenomena.” According to Lerner (1977), people form contracts to maximize gains and minimize losses. Lerner maintains that there are two types of contracts-those the individual forms with himself (personal) and those formed with other individuals and with social institutions (social). Individuals form personal contracts to accommodate to reality restraints and their own conflicting needs. For example, in delay of gratification, one abandons an immediate goal in favor of a more realistic or preferred goal. Individuals form social contracts to accommodate to the needs of others. Without contracts, one’s expectations of control are likely to approximate one’s desire for control. Moreover, an absence of contracts implies that there are no safeguards against potential obstacles. Since steps have not been taken to appease potentially antagonistic forces, the individual who disregards contracts is very susceptible to perceptions of loss. The preceding points suggest that individuals adopt contracts to mitigate anxiety regarding future losses of control. It is interesting to note in this connection that delinquent and sociopathic individuals are characterized by high repression and low anxiety (Kilpatrick, Cauthen, & Roitzsch, 1971; Lykken, 1957). Thus, it is possible that outward children believe that noncontractual methods are effective partly because they are not particularly susceptible to anxiety regarding the potential losses associated with such methods. The hypothesized relationship between expectations regarding contracts and outward behavior has been shown to be consistent with research on egocentrism, just world phenomena, and repression. Most importantly, the literature on contracts is consistent with the earlier literature on juvenile delinquency. The two literatures agree on the essential point that children manifest outward behavior when their expectations are higher than their subsequent perceptions. The notion of contracts is particularly valuable in that it helps explain the susceptibility to recurring perceptions of loss. In a recently completed study, partial support for the relationship between expectations of the effectiveness of noncontractual procedures and outward behavior was provided. Rothbaum and Snieska (1979) administered measures of expectations, inward and outward behavior, and delay of gratification to 32
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upper-middle-class males, aged 8-11 years. Expectations were assessed by a questionnaire in which children selected either a contractual or noncontractual strategy as the most effective one for obtaining an outcome. Contractual strategies were defined as ones in which an agreement is formed or in which norms are adhered to. An example of the first kind is: The way to get to be happy is: (Contract) do something you and others have agreed you should do? or (No contract) do somethingyou think will make you happy? An example of the second kind is:
The way to keep from getting hurt is to: (Contract) do things people usually do so they don’t get hurt? or (No contract) be careful in your own way? The measure of inward and outward behavior, Achenbach’s Child Behavior Checklist, was completed by parents. The third measure, delay of gratification, consisted of two trials on each of which the child could select either a smallimmediate or a largedelayed reward. Findings indicated a significant positive relationship between expectations that noncontractual methods are effective in obtaining outcomes and outward behavior [r(30)= .39, p < .05] and a significant negative relationship between expectations that noncontractual methods are effective and delay of gratification [r(30)= -2.20, p < .05]. The mean expectations score for children who delayed on both trials was 15.1 and the mean score for children who did not delay on one or both trials was 17.1 (since only two children did not delay on both trials, they were combined with the children who did not delay on only one trial). Whereas the contracts measure related to both measures of outward behavior, it did not relate to the parent’s reports of inward behavior [r(30) = .01]. Therefore, the findings cannot be attributed to a general relationship between the expectation that noncontractual methods are effective and all clinical behavior. These findings provide direct support for the hypothesized relationship between the expectation that noncontractual methods are effective and outward behavior. C. CHILDREARING PRACTICES: ANTECEDENTS OF GENERALIZED EXPECTATIONS
The evidence in the preceding subsection indicates that clinical syndromes relate to differences in generalized expectations of control (i.e., to locus of control and effectiveness of contracts). The evidence to be cited now suggests that childrearing practices may be particularly important antecedents of these
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generalized expectations. Moreover, the present evidence is consistent with the helplessness-reactance model in that the childrearing practices relate in the predicted manner to clinical syndromes. The clinical literature is quite consistent in portraying the inhibited child as coming from a home in which the parents exercise too much control [that is, the parents determine what the child will do, and they ensure that it is done (Kessler, 1966; Freud, 1965)l. The prefix “over” is often found in conjunction with adjectives like controlling, dominant, directive, and enmeshed in describing these parents. Research has generally supported the conventional clinical wisdom that children characterized by inhibited behavior, extreme conformity, rigidity, restricted curiosity, and feelings of worthlessness (as compared to aggressive, acting out children) have parents who exercise a high degree of control (Busse, 1969; Lewis 1954; Rosenthal, Finkelstein, & Berkwits, 1962). This holds whether control is embedded in a covertly hostile childrearing context (Becker, 1964; Kessler, 1966; Rosenthal et al., 1962) or a warm and loving one (Becker, 1964; Kagan & Moss, 1962; Sears, 1961). While inward behavior relates to extreme parental control, there is evidence that outward behavior relates to insufficient or lax control. Several indices of lax control, including indulgence (Levy, 1943), failure to exercise control (Baumrind, 1966), and lack of concern (Achenbach, 1966), have been found to relate to outward behavior in children. Research on delinquency indicates a similar pattern. Glueck and Glueck (1959) found delinquency to relate to parental indifference and lack of demands. McCord, McCord, and Howard (1961) report a correlation between delinquency and parental laxness and lack of demands. Results from a longitudinal study indicate that lack of supervision in childhood is a major predictor of criminal behavior in adult men (McCord, 1979). As with the relationship between overcontrol and inward behavior, the relationship between lax control and outward behavior emerges in both covertly hostile childrearing contexts (Becker, 1964; Craig & Glick, 1963; Tait & Hodges, 1962) and warm and loving ones (Baldwin, 1949; Becker, 1964; Elder, 1971; Kagan & Moss, 1962; Sears, 1961). Besides laxness, another childrearing practice that has been related to outward behavior is inconsistency (cf. Becker, 1964; Herbert, 1978). The most common operationalization of inconsistency is a predominatly lax environment with occasional and unpredictable directiveness. Therefore, the findings regarding laxness can be seen as related to those regarding inconsistency. Although the focus in one case is on the baseline (of laxness) and in the other case on the contrast between the baseline and instances of directiveness, there is an obvious commonality between the two. The helplessness-reactance model prediction regarding inward behavior is that it should relate to perceptions of severe uncontrollability. The childrearing evidence is consistent with this prediction: Since very directive parenting is likely to lead to a suppression of children’s self-directed activities and consequently, to
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failure to perceive contingencies between one’s own actions and subsequent outcomes, it is likely to lead to expectations of uncontrollability. Loeb (1975) provides evidence of a connection between directive parenting and external locus of control. Similarly, Crandall (1973) provides evidence that children whose parents (mothers) take too much charge of them and who do not let them learn for themselves fail to develop an internal locus of control. Independent functioning leads to “more opportunity for the child to observe the effect of his own behavior, the contingency between his own actions and ensuing events, unmediated by maternal intervention” (Crandall, 1973, p. 13). Hence, there is reason to believe that the relationship between directive parenting and inward behavior is mediated by external locus of control. The helplessness-reactance model prediction regarding outward behavior is that it should relate to the expectation that noncontractual methods are effective. This is consistent with the childrearing findings. Parents who are lax and place few demands on their children are likely to have children who seek independent (noncontractual) paths to goals; the children do not learn that the formation of agreements (e.g., compromises) and the following of norms are valuable means of accomplishing goals. Parental inconsistency is even more likely to relate to an avoidance of contracts. If the child cannot depend on adults to carry through their end of an agreement or to respond appropriately to normative behavior, he has little motivation to rely on contracts. In support of the hypothesized connection between laxness and expectations that contracts are ineffective is the finding by Byrne (1 964) that children from lax homes are characterized by greater repression and less anxiety than children from restrictive homes. As noted earlier, anxiety is a major incentive for the formation of contracts. Since laxness also inhibits perspective-taking (Hurlock, 1974; Jersild, 1969), there is yet another reason to suspect that children from lax homes do not recognize the effectiveness of contracts. A summary of the relationships between childrearing practices and clinical behaviors is shown in Table II. Two major qualifications of points raised earlier in this subsection are needed. First, the connections between directiveness and inward behavior and between laxness and outward behavior are much stronger in hostile and rejecting homes than in warm and accepting homes (Anthony, 1970; see also footnote 3). Second, it can be questioned whether evidence in this section supports the prediction that the childrearing practices cause clinical syndromes. The childrearing literature, which is correlational, does not speak to the question of causality; it merely affirms the existence of a connecti~n.~ It would appear, then, that further support 5Ssince the childrearing research is carelatid, it is possible that the findings are due to differences in preference for childrearingpractices as well as to effects of the childrearing practices (cf. Bell, 1%8). For example, children with outward behavior, who have high expectationsof control according to the helplessness-reactance model. may prefer lax to directive practices. That is, they may prefex those practices which allow for their exercise of control. By contrast, children with inward
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TABLE Il Relationship between Childrearing Practices and Behavioral Syndromes“ ~
Childrearing practice
Generalized expectancy
Redisposition to perception of
Directiveness
External locus of control (“undercontrol”) Noncontractual methods are effective (“overcontrol ”)
Lack of control
Inward
Loss of control
outward
Laxness
Behavioral syndrome
In the past, the only difference between expectations and perceptions of control has been that the former referred to future events and the latter to past or present events (Abramson ef al., 1978; Wortman & Brehm, 1975). However, in the present model, it can be seen that expectations and perceptions differ in kind as well as in temporality.
for the relationships posited in this section is needed. However, the evidence cited and the associated theoretical rationale are suggestive of these particular relationships.
V. Conclusion A. THE ISSUE OF APPROPRIATENESS
As mentioned at the outset, the purpose of this article is to demonstrate that the helplessness-reactance model provides a viable explanation for clinical syndromes in children. A number of approaches have been adopted in attempting to support the value of this model. First, the link between clinical states (which provide the clearest support for the helplessness-reactance model) and clinical syndromes was strengthened by drawing from evidence regarding clinical stages. Next, it was demonstrated that syndromes relate to generalized expectations of control in a manner consistent with the helplessness-reactance model. Finally, it oehavior, who according to the model have an external locus of control, may prefer directive to lax practices. Since they see little possibility of exercising their own control, they may look to others’ guidance and direction as a substitute. Findings from research on therapeutic outcomes in adults can be wen as consistent with these predictions. Abramowitz, Abramowitz, Roback, and Jackson (1974) found individual differences in preference for and reported benefit from directive vs nondirective group therapy leaders: External locus of control clients were more likely than internal locus of control clients to prefer and benefit from the dinctive leaders (see also Helweg & Gaines, 1977). In a similar vein. it is suggested that inward children, who expect very little control, and outward children, who anticipate very much control, will prefer and select adults who act in accordance with their expectations.
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was shown that the evidence regarding childrearing practices is consistent with
the hypothesized relationships between generalized expectations of control and syndromes. In demonstrating the applicability of the helplessness-reactance model to syndromes, the preceding findings raise the perplexing issue of “appropriateness. ” Almost all helplessness-reactance theorists mentioned in this article maintain that the truly difficult-to-explain clinical behaviors are those that are inappropriate (i.e., not warranted by the present situation). According to these theorists, it is easy to understand why someone whose expectations of control are violated (who loses control) tries harder and/or lashes out, and why someone who completely lacks control gives up. What is difficult to explain is the manifestation of reactance and helplessness in situations different from those in which the individual’s control has been manipulated. Tennen and Eller (1977) go so far as to claim that the “uniqueness” of the helplessness model is the presumption that perceptions of uncontrollability generalize to situations in which they are inappropriate. However, the definition of ‘‘inappropriate” adopted by helplessnessreactance theorists is somewhat ambiguous. Two important criteria of inappropriateness are the maladaptiveness of the behavior and the unjustifiability of the reasons for the behavior. Helplessness-reactance theorists seem to rely more on the latter criterion than the former; they would not label as inappropriate a lack of persistence if the subject had a justifiable reason to believe that persistence would not lead to the desired outcome, even if persistence would in actuality have led to the desired outcome. The question thus shifts to what constitutes an unjustifiable reason. According to most helplessness-reactance theorists, a justifiable reason for the generalization of perceptions across situations is the similarity (or overlap) between the situations with respect to the experimenters, tasks, and rooms involved. In one of the best designed laboratory studies, Tennen and Eller (1977) found reactant and helpless clinical behaviors in a test session, even though the test session differed from the manipulation session with respect to each of the preceding factors. Tennen and Eller criticize other helplessness-reactance theorists’ use of the term “inappropriate” because they do not consider all of these factors. For example, they reprove Roth and Kubal (1975) for employing similar tasks in their manipulation and test sessions, even though these tasks were administered by different experimenters in different rooms. Presumably they would also reprove Dweck and Reppucci (1973), who employed different tasks but the same experimenter in the manipulation and test sessions. This repoval would fail to take into consideration a critical feature of Dweck and Reppucci’s findings: The children manifest helpIess behaviors on problems that were almost identical to problems that they had shortly before solved with another expenmenter. Although the designs in these studies do not meet Tennen and Eller’s strict criteria of inappropriateness, it is difficult to conceive of the behaviors manifested or the perceptions underlying them as wholly approMate.
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In the opinion of the present author, the attempt to distinguish between “appropriate” and “inappropriate” behaviors is misguided. It would be preferable to specify those criteria with respect to which a given behavior is inappropriate or appropriate. Tennen and Eller have identified essential dimensions of cross-situation similarity-experimenter, task, and room, but this list is by no means exhaustive. Wortman and Brehm (1975) suggest that generalization may arise from similarity in the reinforcements received. To this might be added similarity in the type of behavior required; even on different tasks, similar behaviors (e.g., reading, using a pencil, gross motor activity) may be required. The question then becomes whether similarity along these dimensions provides us justifiable a reason for generalization of behavior as does similarity along the dimensions emphasized by Tennen and Eller. One dimension contributing to cross-situation generalization that has been all but ignored by helplessness-reactance theorists is the “psychological distance” between the manipulation and test sessions. In their laboratory state studies, the opportunity for “inappropriate” reactions occurs soon if not immediately after the manipulation period, and there are no salient intervening events. It would seem that this temporal contiguity of manipulation and test sessions is at least partially responsible for inappropriategeneralizationsin that it facilitates a “spillover” of perceptions. Indeed, if it takes time for individuals to alter their existing perceptions, it would be difficult to understand how “inappropriate” perceptions could fail to occur in the new situation. The claim that temporal contiguity contributes to the appropriatenessof crosssituation generalization is consistent with the two criteria of appropriateness mentioned earlier: It seems both adaptive and justifmble that subjects should attribute uncontrollability to handicaps that will extend into the short-term future (e.g., “I’m not too alert right now. ”; “This isn’t my day. ”). These attributions can account for both reactant and helpless clinical behaviors on subsequent controllable tasks. If the prior event is seen to involve a loss of control or slight to moderate uncontrollability, subjects may become reactant “to make sure” that they overcome this short-term handicap. If the prior uncontrollable event is seen to involve a lack of control, subjects may become helpless, as they may feel that the short-term handicap is too difficult or not worth the bother to overcome. A major difference between inappropriate perceptions in state studies and inappropriate perceptions in studies of syndromes is that time, or rather Iack of time, is not a reasonable explanation of the latter. To the extent that the time from the induction of perceptions of uncontrollability to subsequent inappropriate perceptions increases, a temporal contiguity/“spillover” explanation becomes decreasingly viable. The most viable alternative appears to be a situationsimilarity explanation, the very explanation that the better designed laboratorystate studies were intended to exclude. There are several lines of evidence that help to substantiate as well as clarify this view.
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Theorists and researchers interested in the locus of control construct are very much concerned with the issue of long-term “inappropriate” generalizations. In a sense, the thrust of this literature is to use the construct of control to account for the tenacity of behaviors that are maladaptive and that are not based on wholly justifiable reamns. Therefore, it is significant that locus of control theorists maintain that similarity between situations in which uncontrollable events occur and subsequent situations is a primary determinant of the generalizationof expectations. Much effort is devoted to the attempt to identify dimensions along which situations can be compared. According to Crandall et al. (1965), the homeschool distinction is crucial: Generalization of children’s Iocus of control across situations is likely to be greatest when the situations are embedded in the same context. Mischel et al. (1974) maintain that generalization of children’s locus of control is greatest across situations whose outcomes have the same evaluative connotation (positive or negative). Locus of control theorists seem to agree that a variety of dimensions are relevant in determining similarity, and hence generalization, across Situations. Just as there is reason to believe that expectations involving locus of control are appropriate, there is reason to believe that expectations involving the effectiveness of contracts are appropriate. Outward behavior is most common among delinquents-children who have repeatedly experienced violations of contracts. Delinquents are led to accept mass media messages regarding equality of opportunity and the availability of options, only to find subsequently that these messages are inaccurate. Similarly, delinquents are frequently subjected to inconsistent and capricious childrearing practices that further destroy their confidence in contracts. That these children should in later life expect contracts to be ineffective is hardly inappropriate. Testimony to the appropriateness of their expectations is provided by the oft cited finding that when they are not interacting with teachers, police, or other authority figures (e.g., when they are among fellow gang members), contracts are sometimes rigidly adhered to and are expected to be very effective. Again, the findings indicate that the greater the dissimilarity between situations, the less the generalization of expectations. One example of the influence of long-term inappropriate expectations is provided in the now classic study of “Albert” (Watson & Rayner, 1920). Watson and Rayner conditioned an 11-month-old child to fear a white rat that previously the child had spontaneously approached, by associating the appearance of and reaching for the rat with loud bursts of noise. Though these authors systematically excluded any mention of constructs such as expectations of control, their findings could easily be incorporated within the present model. The loud noise is similar to the severely uncontrollable events used in several helplessness studies, and the fear response is part of the inward behavior syndrome. Watson and Rayner found that the conditioned fear lasted weeks and it may well have continued longer (there were no follow-ups). For present purposes, the most impor-
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tant feature of this study is the demonstration that the effect generalized to new objects: Albert feared a white rabbit, a dog, a fur coat, a ball of cotton, and a Santa Claus mask. No fear was shown to blocks or objects that did not share the apparently controlling stimulus dimension of “furriness. ” As in the case with the childrearing literature, the evidence indicates that situational similarity is a key factor in long-term generalizations of clinical behaviors. Another study in which long-term inappropriate generalizations have been demonstrated, and that had not previously been approached from a helplessness-reactance model perspective, is the study by Hetherington (1972) on the effects of father absence on adolescent girls. Hetherington’s findings indicate that loss of the father influences relatedness to other males even when the loss occurs years before the relatedness to males is assessed. Moreover, the findings indicate that the type of clinical behavior relates to the uncontrollability (or regainability) of the loss: Girls who lost their fathers through death were more likely to exhibit avoidance and withdrawal from other males (behaviors associated with the inward syndrome) as compared to girls from intact families; girls who lost their fathers through divorce were more likely to exhibit aggressiveness and approach toward other males (behaviors associated with the outward syndrome) as compared to girls from intact families. Because death is a severely uncontrollable event, it may give rise to a generalized expectation of lack of control-that is, to an external locus of control. As noted earlier, external locus of control predisposes children to inward behavior. A salient characteristic of divorce is the violation of a contract. Since the divorced fathers in the Hetherington study maintained little contact with their daughters, the contract binding father and daughter as well as the contract binding husband and wife were likely to be seen as ineffective. This could give rise to a generalized expectation that noncontractual methods are more effective than contractual methods, an expectation that, as noted earlier, predisposes children to outward behavior. Hetherington’s findings and the helplessness-reactance model are complementary. On the one hand, the helplessness-reactance model provides an explanation of Hetherington’s very intriguing but otherwise difficult-to-explain results. (Hetherington candidly referred to her own interpretations as highly speculative.) On the other hand, the findings provide perhaps the clearest example of the induction of generalized expectations of control and clinical syndromes. The temporal stability of these effects is testified to by the differences in clinical behavior ye& after the occurrence of the precipitating events. Finally, the Hetherington study is noteworthy here because it indicates that the expectations generalize to situations bearing an essential similarity to the situation in which the uncontrollable event occurred: There was more deviation in the daughters’ relationships with males than in their relationships with females. Consequently, these findings illustrate the point, repeatedly emphasized throughout this section,
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that situational similarity is critical in the formation of generalized expectations. The locus of control and delinquency literatures as well as the Watson and Rayner and the Hetherington studies suggest that, when expectations of uncontrollability occur long after the uncontrollable event(@ that induce them, it is likely that the situations to which the expectations have generalized resemble the earlier uncontrollable situation(s) . These findings raise serious questions regarding the notion of inappropriateness. The mechanism giving rise to long lusting efects (i.e., the organism’s tendency to respond to situational similarity) is essential to the organism’s capacity to adapt, even ifspecific applications of this mechanism are not. Similarly, the state studies am not providing evidence of inappropriate behaviors. As has been argued, the lack of a time delay between the manipulation and test sessions makes it difficult to label subsequent clinical behaviors “inappropriate.” For these reasons, the present author recommends against continued assessments of appropriateness and inappropriateness. A more fruitful approach would be first to identify the temporal and/or contextual factors contributing to generalization, and second to determine why subjects rely on these factors. It is only through an awareness of these factors and their origins that we will contribute to the demystification of clinical syndromes. B. SUGGESTIONS FOR FUTURE RESEARCH
There are several ways in which the empirical gaps in the model developed here might be filled. It might be recommended that future research pay particular attention to the instruments with which generalized perceptions of control are assessed. Steps should be taken to refine further the internal-external locus of control scales. Previous research has shown that those locus of control questionnaires that focus on expectations pertaining to a particular realm of functioning (e.g., intellectual achievement) yield the most clearcut findings (Lefcourt, 1976). Therefore, future research should employ scales of this type. Another improvement would be to devise scales that distinguish between different types of internal attributions of causality (e.g., effort vs ability). If refined in these respects, greater clarity regarding the relationship between external locus of control and inward behavior may be obtained. Finally, attempts should be made to devise additional measures of the expected effectiveness of contracts. It would be particularly helpful if parallel measures of locus of control and effectiveness of contracts could be developed to test the differing predictions regarding them. Developmental considerations should be kept in mind in devising future questionnaires. Expectations involving locus of control and the effectiveness of contracts are probably heavily influenced by the child’s level of cognitive functioning. For example, since preoperational children do not understand the nature of chance, they are more likely to believe that they control chance outcomes (i.e.,
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they are more likely to attribute chance events to internal factors). Similarly, younger children who are not capable of mutual perspective taking are less likely to appreciate the significance of contracts. Developmental studies of children’s understanding of contingency and contracts should shed considerable light on the development of the two measures considered here (locus of control and effectiveness of contracts). Accompanying attempts to develop measures of generalized expectations of control should be a closer examination of behavioral syndromes. Achenbach and Edelbmck (1978) have presented substantial evidence regarding the existence of subsyndromes. They have shown also that these subsyndromes depend on the age and sex of the children. It may be helpful at this juncture to examine the relationship between subsyndromesand generalized expectations of control and to compare findings for children who differ in age and sex. In so doing, it should become clearer how specific expectations become linked with specific behaviors. The value of the factor analytic research in building toward a conceptual model has been substantiated. Therefore, in attempting to refine the model, it seems appropriate to return temporarily to that body of research. Another type of research worth pursuing is that which employs manipulations of perceptions of control. In light of the evidence that childrearing practices relate to clinical behaviors and that this relationship may be mediated by perceptions of control, it seems reasonable to focus on manipulations of childrearing practices. The childrearing research should center on two predictions: (1) that laxness (which gives rise to high anticipations of control), followed by directiveness leads to perceptions of loss of control and consequently to outward behavior; and (2) that constant directiveness leads to perceptions of lack of control and consequently to inward behavior. Studies involving short-term manipulations of these variables should be preceded by studies involving long-term manipulations. With regard to the latter, it may be necessary to rely on studies employing quasi-naturalistic designs. One possibility is to assess the effects of prolonged exposure to lax vs directive teachers on clinical behaviors in subsequent test situations. By manipulating the temporal proximity and contextual (task, situation, and person) similarity between the classroom and test situations, it should be possible to obtain a fuller understanding of the dynamics of generalization. To investigate the existence of behavioral “complexes, ” studies must be compared in which different types of clinical behaviors are assessed. These studies should lead to a more robust understanding of the essence of the inward and outward syndromes. ACKNOWLEDGMENTS The author wishes to thank John Weisz, Vickie Babbin, Helen Graham, Rick McCauley, Sam Synder. and Tom Achenbach for their valuable assistance.
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AUTHOR INDEX Numbers in italics refer to the pages on which the complete references are listed.
A Abelson, R. P., 187, 201 Abramowitz, C. V., 234, 241 Abmowitz, S. F., 234, 241 Abramson, L., 213, 214, 215, 218, 223, 234, 24 I
Achenbach, T. M., 209, 210, 227, 232, 240. 241
Ackroyd, C.. 14, 15. 42 Aiu, P., 25, 29, 44 Albus, K.,19, 42 Allen, V. L., 168, 204 Allport, G. W., 164, 187, 201 Amatruda, C. S., 74, 92 Amblard, B., 26. 45 Ames. E. W.,25, 42 Anastasi, A., 187, 201 Anderson, J. R., 100, 125, 159 Anglin, J. M., 175, 181, 191, 201 Annis, R. C., 42 Anthony, E. J., 233, 241 Antoinetti, D. N., 43 Apelle, S., 10, 42 Appel, M. A.. 30, 42. 76, 90 Armstrong, E. L.,66.67, 94 Aronfreed, I., 213, 241 Aronson, E., 187, 201 A s h , R.N., 29,30,32,42, 66,71,72,77,78, 80, 83, 84, 85, 86, 87, 88, 90,92 Atkinson, J., 9, 12,30, 31, 42, 46, 62,64,77, 90, 91 Atkinson, R. C., 156, 159 Aukrt, V., 228, 241 Austin, G.A,, 171, 184, 185, 201 Averill, J. R.,215, 241 B Backmund, H., 15, 49 Baldwin, A. L., 232, 241 Ball, W. A., 26, 42, 69, 90 Barnborough, P., 26,46
Banks, M. S.. 8.9,32,42, 62,64,65,83,84, 86, 87, 90,92 Barclay, C. R., 102, 150, 151, 152, 160 Barlow, H. B., 20, 21, 23, 35, 42, 82, 90 Barnett, I. C., 206 Barron, M. L., 228, 241 Barten, S., 42 Bateson, G., 218, 241 Baumeister, A. A.. 154. 159 Baumrind, D., 232, 241 Bayley, N., 199, 201 Bechtold, A. G., 7, 8, 9, 50, 65, 69, 93, 94 Bechtoldt, H. P., 74, 90 Beck, E. C., 39, 44 Becker, W. C., 232, 241 Beilin, H.,173, 201 Belkii, M., 50 Bell, R. Q.,233, 241 Belmont, J. M., 102, 103, 104, 106, 107, 108, 111, 114, 116, 117, 118, 121, 122, 125, 131, 138, 139, 145, 146, 148, 151, 152, 153, 155, 159, 160 Bennett, G., 180, 201 Benson, J. S.,215. 241 Bentler, P. M., 170, 203 Berkowitz, J.. 218, 241 Berkowitz, L., 229, 241 Berkwits, G. K.,232, 245 Berlyne, D. E.,11, 42, 187, 201 Berman, N.,23, 26, 27, 42, 44 Berry, R. N., 60, 90 Beyerstein, B. L., 17, 42 Bibring, E.,213. 241 Bilderman-Thorson, M., 51 Bims, B., 42 Bishop, P. O., 35, 42, 49 Bisti, S., 38, 48 Bjork, R. A., 125, 161 Blackman, S., 184, 203 Blake, R., 10, 38, 43, 45, 83, 91 Blakemore, C.. 19,20,22,23,24,31,35.36. 37,38,39,42,43,48,49,51, 58,81,82, 83, 90,91. 93 247
248
Author Index
Blaney, P. H., 219, 242 Blos, P., 213, 241 Blumenfeld, P. C., 230, 241 Bodis-Wollner, I., 15, 43 Bootzin, R. R., 212, 245 Boring, E. G.,54, 91, 167,201 Borkowski, J. G.,102. 127, 128, 146, 150. 151, 152, 153, 155. 160, 161 Bornstein, B.,216, 241 Bornstein, M. H., 40, 43 Bornstein, P. H., 151, 152, 160 Borton, R., 78, 94 Bough, E., 43 Bourne, L. E., Jr., 174, 201 Bower, G.H., 125, 159 Bower, T. G.R.,2,26.30,43.69,74,75,76. 77, 91 Bowers, K. S.,210, 241 Bowlby, J., 215, 241, 245 Brackbill, Y.,201 Braddick, F., 9, 42 Braddick, O., 9, 12,30,31,42,46, 62,64,77, 90. 91 Bray, N. W., 138, 160 Brehm, J. W.,211, 212, 213,215, 217, 219, 234, 236, 242, 246 Brill, S., 9, 10, 48 Brinton, C. C., 216, 242 Brodersen, A. J., 77, 94 Bronson, G.,71, 91 Bross, M., 52 Broughton, J. M., 26, 30, 43. 69, 74, 91 Brown, A. L., 102. 127, 138. 146, 150, 151, 152, 153, 155. 157, 158, 160 Brown, P., 47, 218, 243 Brown, R., 171, 183, 201 Bruce, M., 215, 243 Bruner, J. S., 171, 175, 180, 181, 184, 185, 191, 201, 202 Bmswilc, E., 164.201 Bugelski, R., 218, 244 Buisse.ret. P.. 22, 43. 47 Buium, N.,102, 153, 162 Burian, H. M., 86, 88, 91 Burke, D., 154, 161 Burnam, M. A,, 211, 245 Bush, R. C., 77, 83, 92 Bushnell, E. W., 7, 8, 9, 50, 65, 93 B u m , T. V., 232. 242 Butterfiild, E. C.. 100. 102, 103, 104, 106. 107, 108, 111, 114, 116, 117, 118, 121,
122, 125, 127, 131, 138, 139, 144, 145, 146, 149, 151, 152, 153, 155, 159, 160, 161 Byme, D., 233, 242
C Campbell, D.T., 171.205 Campbell, F. W., 8,10, 15,18,43,44, 63,64, 92 Campione, J. C., 102, 127, 138, 146, 150, 151, 152, 153, 155, 160 Camps, J. J., 2, 30, 42, 46, 69, 76, 90,91 Carhn, V. R., 10, 11. 44, 69, 91 Caron, A. J., 69, 91 Caron. R. F., 69, 91 Carver, C. S.,219, 242 Casagrande, V. A., 39, 46 Case, R., 165, 166, 175, 186, 191, 197, 201, 202 Cassel, T. L., 26, 46 Castle, R., 74, 94 Cauthen, N. R., 230, 243 Cavanaugh, J. C., 102. 127, 128, 146, 150, 151, 152, 153, 155. 160, 161 Chambers, B. E. I., 31, 49, 83, 93 Chance, J. E., 224, 242 Chandler, M. J., 230, 242 Chavtier, G. M., 223, 225, 243 Cherulnik, P. D., 226, 242 Chi, M.T. H., 100, 161 Chomsky, N., 164, 173. 183. 202 Chow, K.L., 21,22.24.45,46,48,49,79,92 Citrin, M. M., 226, 242 Cloward, R. A,, 228, 242 Cocking, R. R., 175, 187, 205 Cohen, A. K.,218, 228, 242 Cohen, L. B., 2, 5 , 6, 44, 180, 204 Cohen. R. W., 10, 11, 44 Cohen. S., 213, 215,223, 225, 242 Colby, B. N., 170, 193, 202 Cole, M.,171, 180, 202 Comers, C. K.,209, 242 Cool, S. J., 10, 43 Cooper, G.F., 10, 19, 20, 22, 23, 24, 43 Coren. S., 33, 44, 49 Corman, H. H., 170, 202 Craig, M. M., 232, 242 Crandall, V. C., 224, 237. 242, 244 Crandall, V. J., 224, 233, 237, 247 Crawford, M. L. J., 10. 38. 43
249
Author Ina!ex Creel, D. J., 39, 44 Creutzfeldt, 0. D., 19, 32, 44, 46, 83, 86, 92 CNikshank, R. M.,69, 91 Cynader. M., 23, 26, 27, 44, 51
Escalona, S. K., 170, 202
F
D D a m , P. R., 179, 180, 202 Davis, B. D., 189, 202 Daw, N. W., 27, 42, 44 Dayton, G.O., 25, 29, 44, 85, 91 De Lemos, M. M., 179, 180, 202 Debache, J. S., 153, 158, 160 Denisova, M. P., 5, 25, 45 Denney, D. R., 128, 161 Dews, P. B., 36, 45 Dickerson, D. J., 100, 111, 127, 144, 149, 160 Diener, C. I., 226, 242 DiFranco, D., 69, 74, 91 Dingman, H. F., 169, 204 DiStefano, M.,48 Dobson, M. V., 25, 51,62, 85, 91 Dodd, D. D., 108. 161 Dodwell. P. C.,2, 45, 69, 74, 91 Doherty, J.. 168, 203 Dollard. J.. 190, 204, 218. 242 Daob. L. W., 218, 242 Dorpat, T. L., 213, 242 Duckman, R. H., 33, 44 Dugas, J., 105, 161 Duke, M. P.,224, 226, 242, 244 Duke-Elder, S., 63, 65, 86, 88, 91 Dumais, S. T., 77, 78, 83, 84, 87, 88, 92 Dunkeld, J., 74, 91 Dustman, R. E., 39, 44 Dweck, C. S., 213,223, 226, 235, 242 Dyk, R. B., 184, 185, 206
E
Fantz, R. L., 4, 45, 69, 92 Faterson, H.F., 184, 185, 206 Fegy, M. I., 12, 47 Feldman, C. F., 179, 180, 202 Fenhagen, E., 226, 242 Ferguson, G. A., 168, 169, 202 Ferrante, A., 225, 243 Feshbach, S., 212, 218, 243 Festinger, L., 187, 202 Figurin, N. L., 5, 25, 45 Findlay, J. M., 7, 28, 29, 50, 70, 71, 94 Finkelstein, M., 232, 245 Fiorentini, A., 14, 19, 23, 38, 45, 48, 49 Fisher, M. A., 156, 161 Fitzgerald, R. C., 215, 243 Flandrin, I. M.,26, 27, 45 Flavell, J. H.,125, 138,162, 165, 172, 174, 180, 187, 198. 202 Forisha, B. D., 181, 182, 202 Fowler, W.,175,180,183,184,185,186,194, 197, 202. 203 Fox, R., 45. 77, 78, 83, 84, 87, 88, 92, 94 Fraiberg, L., 182, 203 Fraiberg, S., 182, 203, 213, 243 Frankel, D., 69, 94 Franklin, R. D., 224, 243 Frayer, D. A., 168, 189, 204 Freeman, D. N., 62, 93 Freeman, M., 210, 243 Freeman, R. D., 8, 16, 17, 19, 20,36,42,45, 48, 49, 81, 93 French, J., 64,91 Freud, A., 211, 216, 232, 243 Frost, B., 42 Frost. D., 15, 49 Fry, G. A,, 56, 93
Edelbrock, C., 209, 210,240, 241 Elder, G. H..Jr., 232, 242 Elkind, D., 178, 202, 229, 242 E l k , S., 212,213, 214, 219, 235, 246 Ellis. N. R., 105. 161 Endler, N. S., 167, 202 Enroth-Cugell, C., 10, 43 Erikson, C. W.,106, 161
G GagnC, R. M., 168, 173, 174, 189, 190, 203 Gaines, L. S., 234, 243 Galanter, E., 125,162, 185, 204 Ganz, L., 23, 45
250
Author Index
Gardner, R. W., 166, 184, 185, 203 Garey, L. J., 22, 45 Gamer, W. R., 106, 161 Gay, J., 180, 202 Gelber, E., 5, 44 Gesell, A., 74, 92 Ghatala, E. S.. 168, 189, 204 Gibson, E. J., 69, 94. 195, 203 Giffm, F., 20, 48 Glaser, D., 228, 243 Glass, D. C., 212, 214, 243 Glick, J. A,, 180, 202 Glick, S. J., 232, 242 Glueck, E. T., 232, 243 Glueck, S.,232, 243 Goertzel, M. G., 180, 203 Goertzel, V., 180, 203 Goldschmid, M. L., 170, 173, 203 Goldstein, K. M., 184, 203 Goldstein, P. J., 62, 93 Gollin, E. S., 154, 161 Goodenough, D. R., 184, 185.206 Goodnow, J. J., 171, 184, 185, 201 Gordon, B.,49, 83, 93 Gordon, F. R., 30, 45, 69,14, 92, 94 Goren, C. C., 25, 44 Gorog, I., 10, 11, 44 Gottlieb, G., 6, 24, 45, 80, 92 Green, D. G., 8, 43, 63,64, 87, 92 GreenfEld, P. M., 180, 181, 185, 193, 201, 203
Greeno, J. G.,125, 161 Gregory, R. L., 14, 45 Gregory, W. L., 223, 225, 243 Grobstein, P., 21, 22, 24, 45, 46, 48, 79, 92 Gmen, G. E., 168, 203 Guilford, J. P., 169, 170, 175, 181, 203 Guillery, R. W.,37. 39. 46, 50
H Haegerstrom, G., 16, 48 Haffner, M. E., 23, 45 Haith, M. M., 2, 10, 28, 46, 47, 70, 92 Hake, H. W., 106, 161 Halwes, T. G.,138,162 Haner, C. F., 218.243 Harding, T.H., 46 Harper, D. C., 211, 245 Harris, L., 12, 46 Harris, P.,29, 46
Harris, P. L., 26, 46 Harrow. M., 225, 243 Haynes, H., 7, 46, 64,92 Heggelund, P., 19, 44 Hein, A., 23,26,27.38, 43,44, 46 Held, R.,I, 9. 10, 15,46.48,49, 63,64,74, 92, 94 Helweg, G. C., 234, 243 Hendrickson, A,, 63, 92 Herbert, M., 232, 243 Hering, E., 56, 92 Herman, J. H., 34, 35, 46 Hershenson, M., 29, 46 Herskovits, M. J., 171. 205 Hem, R. D., 183, 190. 203 Hetherington, E. M., 238, 243 Hickey, T. L., 37, 46 Hill, K. T., 180, 204 Hinde, R. A., 215, 243 Hiroto, D. S., 213, 223, 225, 243 Hirsch, H. V. B., 19, 20, 24, 38, 43, 46, 48, 83, 91
Hobbs, N.,210, 243 Hochberg, J., 54, 92 Hodges, E. F., 232, 246 Hoffmann, K. P., 37, 50 Hoffmann, M. J., 47 Hoffmann, R. F., 12, 47 Hofstaetter, P. R., 168, 203 Hohmann, A., 32,46, 83, 86, 92 Holzman, P. S.. 166, 184, 185, 203 Homms, G. C., 216, 245 Hooper, P. H.,171, 179, 180, 205 Hopkins, H. H., 8, 46 Howard, A., 232, 244 Howland, H. C., 64,91 Hubel, D. H., 18, 19, 21, 35,36, 46, 47, 52, 81, 92
Hull, C. L.. 167, 203 Hulton, A.. 74, 93 Humphrey, N. K., 14, 15, 42, 47 Hunt, J. McV., 170, 187, 203, 205 Hurlock, E., 233, 243 Huttenlocker, J., 154, 161 Hutz, C. S., 74, 90
I Imbert, M., 22, 43, 47 Inhelder, B., 181, 205
25 1
Author Index
J Jackson, C., 234, 241 Jackson, D. N., 166, 184, 185, 203 Jackson, R. W., 66, 86, 90 Jacobs, P. D., 212, 246 Jacobson, M., 24, 47 James, W.H., 224, 243 Jampolsky, A., 72, 92 Jeannerod, M., 15, 27, 45. 47, 49, 51 Jenkins, J. J., 158, 161 Jersild, A. T., 229, 233, 243 Jones, M. H.,25, 29, 44, 85, 91 Jones, R.,34, 47 Julesz, B., 31, 47, 60, 76, 92
K Kaas, I. H., 37, 50 Kaban, B. T., 206 Kagan, J.,4,47, 166,184,185,203,204,232, 243 Kahn. J. V., 151, 153, 161 Kaplan, C. P., 33, 44 Karlson, J. L., 47 Karmel, B. Z., 11, 12, 13, 14, 47, 48 Karp, S. A., 184, 185, 206 Katkovsky, W., 224, 237, 242 Kaufman, I. C., 215, 243 Kaufman, L., 54, 92 Kay, D.,71, 92 Kellas, G.,103, 104, 161 Kelly, D. H., 9, 11, 12, 13, 47 Kelly, G. A., 164, 204 Kendall, C. R., 102, 150, 151, 152, 161 Kendler, H. H., 167, 204 Kendler, T. S., 167, 204 Kennedy, H., 26, 45 Kennelly, K. J.. 215. 241 Kessen, W., 10,40, 43, 47, 172, 173, 204 Kessler, J., 232, 243 Kestner, J., 102, 153, 161 Kilpatrick, D. G., 230, 243 King, R. A,, 39, 44 Kinghorn, S. N., 230, 241 Kinney, D.K.,4.47 Klahr. D.. 102, 136. 153, I61 Klausmeier, H.I., 168, 189. 204 Klein, C. S., 166, 184, 185, 203 Klinger, E., 215, 220, 243
Knapczyk. D.R.. 151. 152, 161 Knobloch, H., 164, 204 Kobrin, S., 228, 244 Koenderink, J. J., 26, 47 Koffler, S., 25, 51 Kogan, A. I., 33, 47, 184, 205 Kogan, H., 184, 204 Kogan, N., 166, 184, 185, 203 Kotovsky, K., 133, 161 Kregerman, J. J., 218,244 Krieg, K., 66, 92 Krowitz, A,, 69, 91 Krueger, H., 8, 48 Kubal, L., 212, 213, 214, 219, 235, 245 Kubler-Ross, E., 215, 244 Kuhn, D., 128, I61 Kulikowski. J. J., 15, 18, 43, 44 Kupfer, C.. 63, 92 Kvaraceus, W. C., 228, 244
L Lacey, H. M., 209, 245 Lachman, J., 100, I62 Lachman, R., 100, 262 Lange, G. D., 51 Langer, A,, 69, 91 Lawton, M. S., 186, 204 Lee, B., 179, 180, 202 Leehey, S. C., 9, 10, 48 Lefcourt, H.M., 223,224,225,226,239,244 Leghdy, C. R., 48 Lehmkuhle, S. W., 77, 83, 92 Lenneberg, E. H., 188, 204 Lerner, M. J., 229, 230, 244 Lester, M. L., 47 Letson, R. D., 32, 42. 83, 84, 86, 90 LeVay, S., 47 Leventhal, A. G.. 20, 48 Levin, H., 195. 203 Levin, 3. R., 168, 204 Levinson, J., 18, 44 Levi-Strauss, C., 180, 204 Levy, D., 213, 244 Levy, D. M., 232, 244 Lewin, K., 164, 174, 185, 204 Lewis,H., 232, 244 Lewis, T. L., 71, 92 Ling, B. C., 28, 48, 71, 85, 93 Linton, H. B., 166, 184, 185, 203
252
Author Index
Livingston, G.,151, 152, 161 Loeb, R. C., 233, 244 Luria, A. R., 171, 183, 187, 204 Lykken. D.T.,230, 244
M MacFarlane, A., 29, 46 Macleod, I.D.G., 48 Maffei, L., 10, 14, 19, 23, 38, 44, 45, 48, 49 Magnuski, H.S.,11, 12, 47 Maisel, E. B., 11, 12, 13, 14, 47 Makarova, 0. N.,21, 22, 48 Mallick, S. K., 218, 244 Mangan, J., 166, 171, 180, 204 Mann, I., 63, 93 Mannheim, H., 228, 244 Mansfield, R. J . W., 48 Marg, E., 62, 93 Marmor. J. R., 206 Manis, P.,215, 244 Marzi, C . A., 48 Mathers. L. H.,21, 22, 46.48. 49 Matsubayashi, A., 63, 93 Maunamee,'A. E.,72, 94 Maurer, D., 7., 8, 28, 48, 70, 71, 92, 93 McCall, R. B.,5 , 48 McCandless, B. R.,218, 244 McCarthy, D., 164, 198, 204 McCarvill, S. L., 14, 47, 48 McCord, J . , 232, 244 McCord, W., 232, 244 McCurdy, H. G., 180, 204 McGhee, P. E., 224, 244 McGraw, M. B., 204 McGuire, W. J., 187. 201 McLean. J. D.,179, 180, 202 McNeil, D., 191, 204 McRoberts. G., 69, 94 Meacham, J. A., 197, 204 Memhinskaya, E. A., 204 Merton, R. K.,228,244 Messick, S. J., 166, 184, 185, 203 Meyers, C . E., 169, 204 Middleditch, P. R., 33, 51 Miller, D. J., 180, 204 Miller, G. A., 125, 162, 187, 204 Miller, J . C., 209, 244 Miller, J. F., 33, 34, 50 Miller, N. E., 190, 204, 218, 242, 244
Miller, W. B., 228, 244 Millodot, M., 16, 45, 48 Mischel, W., 210,223,224,237,244 Mitchell, D.E., 16,20,32,33,40,41.43,45, 48, 49. 51, 83, 93 Mitchell, 0.R., 11,49 Mize, R. R.. 20, 49 Mom,K.,62, 90 Moely, B. E., 138,162 Mohindra, I., 63, W Moore, M. K., 26, 30, 43, 69, 74, 91 Morgan, M. W., 65, 93 Morse, R.. 78, 94 Moser, E. A., 8, 48 Moskowitz-Cook, A,, 9, 10, 48 Moss, H.A., 185, 203 Moss, M. A,, 232, 243 Mostafavi, H.,11, 49 Movshon, J. A., 31,36,37,38,43,49, 81,83, 93 Mowrer, 0. H.. 218, 242 Muir, D.W.,18, 20, 48, 49, 51. 69, 74, 91 Muller, J.. 65, 93 Murphy, E. H.,20, 36,49, 50 Murray, J . R.. 179, 180, 202
N Nachmias, J., 57, 93 Naditch, M., 224, 244 Neisser, U., 125, 158, 162 Newcomb, T. M., 187, 201 Newell, A,, 99, 102, 155, 158, 162 Nikara, T., 35, 49 Norcia, A., 69, 74, 94 Nowicki, S.,224, 226, 244 0 Oberdorfer, M. D., 39.46 oberg. c., 74, 94 Ogle, K.N., 55, 59, 93 Ohlin, L. E., 228, 242 Olson, C. R., 26, 36, 49, 81, 93 Olson, D. R., 166, 183, 204 Olson, F. A., 138, 162 Oltman, P. K., 184, 185, 206 Olver, R. R., 180, 181, 185, 20f Orbach, C. E., 215, 244 Ordy, J. M., 45
Author Index
N.,218, 244 Ovenon, W.F., 100,162 Otis,
P Packwood, I., 49, 83, 93 Paivio, A,, 181, 205 Parkes, C. M., 215, 244 Parton. P. A.. 209.245 Pasamanick, B., 164, 204 Pascual-Leone, J., 165, 205 Pastore, N. A., 54, Ys 218, 245 Patterson, G. R.. 209,245 Pearson, L., 166, 204 Peck, C. K.,36, 38, 43, 49 Peiper, A., 85, 93, 172, 205 Peltunan, D. I.. 103, 104. 160 Peltunan, P., 62, 93 Pennebaker, J. W.,21 1, 245 Perenin, M. T., 15, 49 Peterson, D. R., 209,210,227, 245 Pettigrew,J. D., 19,21,22,26,35,42,45,49, 82, 90,93 Pettigrew. T. F., 227, 245 Phares, E. I.. 225, 245 Phillips, L., 209, 246 Phillips, S.,213, 215, 223, 225, 242 Piaget, J., 4, 49, 164, 173, 181, 191, 205 Pimlino, M., 10, 44 Pigareve, Z. D., 22, 49, 51 Pdlemar, D. B., 179, 180, 202 Pmhio, M.,14.49 Pisoni, D.B., 80, 90 Pittman, N. L., 212, 213, 214, 219, 223, 225, 245 Pittman, T. S., 212, 213, 214. 219. 223, 225, 245 Poppel, E., 15, 49 Porac, c., 33.49 Postman, L. J., 187, 201 Powers, M. K.,87, 92 Pressey, S. L., 180, 205 Preston, A., 224, 242 Ribram, K. H., 125,'162, 187, 204 Win, 1. E., 73, 93
Q Quay, H.C., 209.246 Quevillon, R. P., 151, 152, I60
253
R Radcliffe-Brown, A. R., 180, 205 Rapisardi, S. C., 22, 49 Rawlings, S. C., 56, 94 Rawson. R., 25, 29. 44 Rayner, R., 237, 246 Reese, H. W.,100, 162 197, 205 Regal, D., 78, 94 Reinecke, R. D., 73, 93 Reiss, H., Jr., 228, 245 Reitman, W.,125, I62 Reppucci, N. D., 213, 223, 226, 235, 242 Rhodes, A.. 228, 245 Richards, W.,15, 31, 33, 34, 49, 50 Riecken, H. W., 216, 245 Riggs, L. A., 57, 93 Roback, H..234, 241 Robertson, J., 215, 245 Rodieck, R. W., 50 Roffwarg, H. P., 34,35. 46 Rohwer, W. D., 102. 162 Roitzsch, J., 230, 243 Romano, J. A., 73, 93 Romano, P. E., 73. 93 Ronch, I., 42 Rosch, E., 171, 205 Rose, L., 50 Rose, M.,25, 29, 44 Rosenbaum. R. M., 214, 245 Rosenberg, M. J., 187, 201 Rosenblum, L. A,, 215, 243 Rosenfeld, A.. 11, 48, 50 Rosenthal, M.I., 232, 245 Ross, A. 0.. 209, 245 Ross, D. M.,151, 152, I62 Ross, S. A., 151, 152, 162 Roth, S., 212, 213, 214, 219, 235, 245 Rothbart, M., 213, 215, 223, 225, 242 Rothbaum, F., 224, 226, 227, 230, 245 Rotter, J., 205 Ruff, H.A., 74, 93 Ruzskaja, A. G.,5 , 25, 52 Rytoff, S. M., 13, 50
S Sackett, G. P., 215, 245 Salapatek. P.. 2,7.8,9,10,29,42,44,47,50, 62, 65, 69,85, 90, 93 Sanderson, K. I., 37, 50
254
Author Index
Santostefano, S., 185, 205 Sarlcison, D. J.. 11, 49 Sarty. M.,25, 44 Savoie, R. E.,9, 47 Scammon, R. E., 66, 67, 94 Scan, S., 69, 93 Schaeffer, M.A., 211, 245 Schank, R. C.. 100, 162 Schezhter, P. B., 36, 50 Scheier, M.F., 219, 242 Schultz, R. F., 108, 161 Sears, R. R.,218,232,242, 245 %gall, M.M.. 171,205 sekulex, R., 50 Seligman, M.E. P., 211, 213, 214, 215. 218, 219, 223, 235, 241, 245 Selye, H., 216, 245 Shapiro, B. B., 206 Sharp, D. W., 180,202 Shatz, C., 39, 50 Shea, S. L., 77, 78, 83, 84, 87, 88, 92 Sheedy, J. E., 56, 93 Sherif, C. W.. 227, 245 Sherif, M.,227,245 Sherk, H., 20, 21, 22, 23, 50 Sherman, S. M., 37, 50 Shetty, S. S., 77, 94 Shevelyevil. A.. 22, 50 S h i m , R. M.,156, 159 Shilagina, N. N., 22, 50 Shipley, T., 56, 94 Shlaer, R., 82, 94 Sigler, R. S., 102. 136. 153, 161, 162, 173, 205 Sigel, I. E., 171,175, 179, 180, 185,187,203, 205 Silfen, C. K.,25, 42 Simon, H. A.. 133, 161 Simoni, A., 48 Simons, K.,73, 93 Singer, J. E., 212, 214, 243 Singer, W.,22, 27, 50, 51 Skinner, B. F.. 164, 167, 205 Slater, A. M.,7. 13.28.29, 50, 70,71, 94 Slobin, D. I., 171, 183, 205 Smith, T. S., 224, 246 Snieska, E., 230; 245 Spear, P. D., 21, 22, 46, 48 SpeZUlllM, c., 169. 199, 205 Spence, D. P., 166, 184, 185, 203 Spencer-Booth, Y.,215, 243
Spencer, J. C., 228, 246 Spinelli, D. N., 14, 19, 24, 46, 49 Spitz, R. A.. 215, 246 Sprott, W.A. H., 228, 246 Staats, A. W., 164, 167, 198, 205 Staats, C. K.,167, 198, 205 Stark, L., 30, 52 Steele, B.. 25, 29, 44 Stephenson, W., 164, 205 Sternfels, S., 69, 94 Stigmar, G., 87, 94 Stokols, D., 215, 246 Stone, J., 37, 50 Strickland, B. R., 224,226, 244 Shyker, M.P., 20, 21, 22, 23, 50 Sullivan, E. V., 165, 205 Sutherland, A. M.,215, 244 Swenson. A., 183,203 Sykes, M..13, 50 T Tait, C. D., Jr., 232, 246 Talbott, J. A.. 215, 246 Tannenbaum, P. H., 187, 201 Tauber, E. S.,25, 34, 35, 46, 51 Taylor, A. M.,102, 162 Taylor, D. M.,86, 94 Teasdale,J., 213,214,215,218,223,234.241 Teller, D. Y.,62, 78, 85, 91. 94 Tennen, H., 212, 213, 214, 219, 235, 246 Thibos, L. N., 8, 16, 17, 20, 45 Thomas, I. P.,7, 51 Thomas, J., 63, 94 Thompson, H., 74, 92 Thornton, J. W., 212, 246 Thorson, J., 51 Thwlow, M. L., 102. 153, 162 Thmtone. L. L., 169. 205 Timney,B. N., 18, 20, 48, 51 Toni, S., 14, 15, 51 Townsend, J. T., 100, 162 Tretter, F., 22, 27, 50, 51 Tronick. E.,26, 42, 69. 90 Tumer, R. H., 228, 246 Turnure, J. E., 102, 153, 162
U Udelf, M.S., 45 Uemura, Y., 14, 15, 51
Author Index
Umezu, H., 14, 15, 51 Underwood, B. J., 111, 144, 145, 162 Uzbekov, M. G., 22, 51 Uzgiris, I. C., 170, 178, 180, 199, 205
V Van Doom, A. J., 26, 47 Van Hof-Van Duin. J., 51 Van Meteren, A., 51 Van Sluyters, R. C., 19,36,37,38,43,48,51, 81, 91 Vantress, F. E., 226, 246 Venger, V. P., 5, 25, 52 Visintainer, M.,224, 226, 227, 245 Vital-Durand, F., 51 Vollunann, F. C., 25, 51 vololchov, A. A., 22. 51 Von Cramon, D., 15, 49 von Hofsten, C., 30, 51, 75, 94 von Noorden, G.K.,32.33,51.72,86,88,91, 94 Von Senden, M., 51 Vos, I. I., 51 Vurpillot, E., 26, 42 Vygotsky. L. S., 187, 205
W Wale. D., 205 Walk, R. D., 69, 94 Wallace, J. G., 14, 45 Wallach, A.. 184, 205 Walls, R. T., 224, 246 Walraven, J., 73, 94 Walters, C., 69, 94 Wambold, C., 104, 107, 117, 118, 131, 138, 139, 160 Wanschwa. P., 128, I60 Ware, C., 32, 49, 83, 93 Warrington, E., 14, 15, 42 Watson, J. B., 237, 246 Watts, J. C., 206 Webb, R. S., 193, 205 Weiner, B., 214, 246 Weiner, J. A., 212, 246 Weiskopf, S.,40, 43 Weizcnbaum, J., 162 Welch, L., 166, 204
255
Wellman, H. M.,125. 138. 161 Werner, H., 164, 174, 185, 206 Werry, 1. S., 209, 246 Westheimer, G.. 7, 8, 33, 51 Wheatstone, C., 58, 94 White, B. L., 7, 46, 51, 64,74, 92, 94,206 White, R., 211,225, 246 White, S. H., 167, 188, 206 Wickelgren, L. W., 28, 51, 70, 94 Wicldund, R. A., 217. 218. 246 Wiesel, T. N., 18, 19, 21, 35, 36, 45, 46, 47, 52, 81, 92 Wilcox, B. L.,138, 160 Williams, C. B., 226, 246 Wishart. J. G., 74, 91 Witkin, H. A., 184, 185, 206 Witrop, C. J., 39, 44 WoNwill, J. F., 190, 206 Wolfer, J., 224, 226, 227, 245 Wolff, K. M., 215, 246 Worchel, P., 218, 244 Worth, C., 54, 94 Wortrnan, C. B.,212, 213,219,234,236,246 Wright, M.H.. 223. 225. 243 Wu, P. Y. K.,25, 44 Wyatt, H. J., 27, 44 Wybar. K.,63, 65, 86, 88, 91
Y Yarrow, L. J.. 215, 246 Yates, J. T., 46 Yinon, U.,38, 50, 52 Yonas, A., 30, 45, 69. 74, 92, 94 Z
Zander, A,, 218, 246 Zaporozhets, A. V., 5,25, 52 Zeaman, D., 156, 161, 162 Zeiss, A., 223, 224, 237, 244 Zeiss. R.,223,224,237,244 Zigler, E.,209, 246 Zimiles, H.,180, 206 Zimmerman, A. A., 66.67, 94 Zintchenko, V. P.,5, 25, 52 Zrenner, E., 8, 48 Zubek. J. P., 52 Zuber, B. L., 30, 52
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SUBJECT INDEX
A Accommodation, binocular vision and, 63-66 Acuity binocular vision and, 62-63 spatial modulation transfer function and deficiency of visual resolution and, 14-18 experimental visual deprivation and, 18-23 factors affecting visual resolution and, 7-9 perception of one-dimensionalpatterns and, 9-1 1
in infants, 28-30 levels of, 54-55, 60-62 bifoveal fixation, 55 fusion, 55-57 stereopsis, 58-60 monocular deprivation and, 35-39
C
Cognitive development cognitive learning and, 190-191 cognitive rule leaming and, 188-189 learning of basic and secondary rules and, 191- 195 unity of problem solving and learning and,
perception of two-dimensional patterns and, 11-14 Age, intellectual development and, see Intellectual development
189-190
B
Cognitive processes, generality of, 124-125 determining whether process is subordinate or superordinate and, 125-127, 131-140 of subordinate processes, 127-129 of superordinate processes, 129-131 testing, 140-153 Concept integration, 1%-197 Concept learning developmental phases of, 195 concept integration, 196-197 horizontal extension and vertical development, 198-199 mastery, consolidation, and ritualization and,
Bifoveal fixation, 55 empirical findings on, 70-72 Binocular vision, 54 abnormalities of, 31-34 developmental constraints on, 62, 67-68 accommodation and, 63-66 acuity and contrast sensitivity and, 62-63 facial dimensions and, 66-67 development in animals, 34-35 disparity and, 30-31 early experience and, 79 model of human development and, 84-89 neural mechanisms in cat and, 81-83 roles of, 79-81 sensitive period in humans, 83-84 empirical findings on, 68-69 bifoveal fixation studies, 70-72 fusion studies, 72-73 multiple-cue depth discrimination studies,
197- 198
problem exploration and, 195-196 Consolidation, 197-198 Contrast sensitivity, binocular vision and, 62-63
D
69
Depth discrimination, multiple-cue studies of,
stereopsis studies, 73-79
69 257
Subject Index
258
Developmental theory biases limiting scope of behaviorist, 166- 169 generalist, 164-166 mental testing, 169-170 integrating general and individual in, 170-172 cognitive organization of types and levels and, 186-188 common units of analysis and, 172-174 typology of concepts and rules and, 174186 Discrepancy hypothesis, visual preference in infants and. 4-6
E Environment, influence on visual development, 23-24
F Facial dimensions, binocular vision and, 66-67 Fixation, bifoveal, 55 empirical findings on, 70-72 Flicker, perception of in infants, 25-26 stroboscopically illuminated and unidirectionally moving environments and, 26-28 Fusion, 5 5 4 7 empirical fmdings on, 72-73
H Helplessness-reactance model syndromes and, 220-222 childrearing practices and, 231-234 effectiveness of noncontractual methods and, 227-231 laboratory studies of clinical states and, 211-214 locus of control and, 222-227 loss and lack of control and, 216-220 naturalistic studies of clinical stages and, 214-216 Horizontal extension, 198-199
I Intellectual development, study of, 96-97, 102-103
analysis of processes withii age groups, 97-9!2,106-1m correlation of performance with age, 105-106 correlation of process measures with age, 99-100 eliminationof age differenceswith process instruction, 100-102 problem selection, 103-105 relation of processes to age, 120-123 selection of investigative domain, 103 teaching adults to process as children, 123124 teaching children to process as adults, 123 Intelligence age-related differences in performance and, 156-1 58 ecological validity and, 158-159 generality of cognitive processes and, 124125 determining whether process is subordinate 01 and, 125-127.131-140 subordinate processes, 127- 129 superordinate processes, 129-131 testing, 140-153 nonmetric completeness checks and, 155-156
L Learning cognitive development and, 190-191 of rules, 188-195 unity of problem solving and. 189-190 of concepts, 195 concept integration and, 196-197 horizontal extension and vertical development and, 198-199 mastery, consolidation, and ritualition and, 197-198 problem exploration and, 195-196
M Mastery, 197- 198 Movement, perception of infant response, 25-26 stroboscopically illuminated and unidmctionally moving environments and, 26-28
Subject Index
0
Organismic influences, on visual development, 23-24
P Perception of flicker and movement infant response, 25-26 stroboscopically illuminated and unidirectionally moving environments and, 26-28 of one-dimensional patterns, 9- 11 of two-dimensional patterns, 11-14 Problems, exploration of, 195-196 Process analysis, in study of intelligence, 97-99, 106-120 roles of, 153-155
R Ritualization, 197- 198
S Spatial modulation transfer function deficiency of visual resolution and, 14-18 experimental visual deprivation and, 18-23 factors affecting visual resolution and, 7-9 perception of one-dimensional patterns and, 9-1 1 perception of two-dimensional patterns and, 11-14 Stereopsis, 58-60 empirical findings on, 73-79
259
Syndromes, 207-209 appropriateness issue and, 234-239 factor analytic research on, 209-211 future research in, 239-240 helplessness-reactance model and, 220-222 childrearing practices and, 23 1-234 effectiveness of noncontractual methods and, 227-231 laboratory studies of clinical states and, 211-214 locus of control and, 222-227 loss and lack of control and, 216-220 naturalistic studies of clinical stages and, 2 14-216
V Validity, ecological, in study of intelligence, 158-159 Vertical development, concept learning and, 198-199 Vision binocular, see Binocular vision in neonates, 39-40 Visual deprivation monocular, binocular vision and, 35-39 spatial modulation transfer function and, 18-23 Visual development, 2-4 course of, 40-41 environmental and organismic influences on, 23-24 Visual preference, in infants, discrepancy hypothesis and, 4-6 Visual resolution, deficiency of, factors affecting, 7-9
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Contents of Previous Volumes Volume 1
Responses of Infants and Children to Complex and Novel Stimulation
Selected Anatomic Variables Analyzed for Interage Relationships of the Size-Size. Size-Gain. and Gain-Gain Vaiieties Howard V. Meredirh
Gordon N. Canror Word Associations and Children's Verbal Behavior David S. Palenno Change in the Stature and Body Weight of North
AUTHOR INDEX-SUBJECT INDEX
American Boys during the Lsst 80 Years
Volume 3
Howard
V. Meredith
Discrimination Learning Set in Children Hayne W. Reese
Learning in the First Year of Life h i s P. Lipsin
Some Methodological Contributions from a Functional Analysis of Child Development Sidney W. Bijou and Donald M . Boer
The Hypothesisof Stimulus Interactionand an Explanation of Stimulus Compounding Charles C . Spiker
The Development of "Overconstancy" in Space Perception Joachim F . Wohlwill
Miniature Experiments in the Discrimination Learning of Retardates Betty J. House and David Zeaman AUTHOR INDEX-SUBJECT
INDEX
Infant Sucking Behavior and Its Modification Herbert Kaye Thc Study of Brain Electrical Activity in Infants Robert J. EUingson Selective Auditory Attention in Children Eleanor E . Marroby Stimulus Definition and Choice MichaeI D. Zeiler Experimental Analysis of Inferential Behavior in Children Tracy S.Kendler and Howard H . Kendler Perceptual Integration in Children Herbert L. Pick. Jr.. Anne D . Pick. and Robert E. KIein Component Rocess Latencies in Reaction Times of Children and Adults Raymond H . Hohle
AUTHOR INDEX-SUBJECT
INDEX
Volume 2 Volume 4 The Paired-AssociatesMethod in the Study of Conflict
Alfred Casraneda
Developmental Studies of Figurative Perception
Transfer of Stimulus Retraining to Motor PairedAssociate and Discrimination Learning Tasks
David Elkind
The Relations of Short-Term Memory to Development and Intelligence
Joan H. Cantor
The Role of the Distance Receptors in the Development of Social Responsiveness
John M. Belmonr and Earl C . Burrerfield
Learning, Developmental Research. and Individual Differences
Richard H. Walter8 and Ross D. P a r k
Social Reinforcement of Children's Behavior
Frances Degen Horowitz
Harold W.Stevenson
PsychophysiologicalStudies in Newborn Infants S. J. Hutt. H . G . Lunard, and H . F . R. Prechtl Development of the Sensory A n a l y ~ nduring Infancy
Delayed Reinforcement Effects Glenn Terrell
A Lkvelopmentd Apjnuach to Learning and Cognition
Yvonne B m k b i l l and Hiram E. Fitzgerdd
Eugene S.Gollin Evidence for a Hierarchical h n g e m e n t of Learning ROCeSW Sheldon H. White
The RoMcm of Imitation Justin Aronfreed
AUTHOR INDEX-SUBJECT INDEX
26 I
262
Contents of Previous Volumes
volume 5
Volume 8
The Developmentof Human Fetal Activity and Its Rela-
Elaboration and Learning in Childhood and Adolescence William D.Rohwer, Jr. ExpEorptory Behavior and Humsn Development Jum C . Nunnally and L. Charles tcmond Operant Conditioning of Infant Behavior: A Review Robert C. Hulsebus Birth Order and Pamtd Experience in Monkeys and MUl G . Mitchell and L. Schroers Fear of the Stranger: A Critical Exmination Harriet L. Rheingdd and Carol 0.Ecketman Applications of Hull-Spence Theory to the Transfer of Discrimination Learning in Children Charles C. Spiker and Jaan H.Cantor
tion to Postnatal Behavior Tryphena Humphrey Arousal Systems and Infant Hun Rate Responses Frances K. Graham and Jan C. Jackson Specific and Diversive Exploration Corinne Hurt Developmental Studies of Mediited Memory John H . Flavell Development and Choice Behavior in Robabilistic and Roblem-Solving Tasks L. R. Goukt and K a t h y S. Gwhvin AUTHOR INDEX-SUBJECT INDEX
Volume 6 Incentives and l m i n g in Children Sam L. Witryol Habituation in the Human Infant Wendell E. Jefiey and Leslie B. Cohen Application of HuU-Speme.Theoryto the Discrimination Learning of Children Charles C. Spiker Growth in Body Size: A Compendium of Findings on Contemporary Children Living in Different Pans of the world Howard V. Meredith Imitation and Language Development James A . Sherman Conditional Responding as a Paradigm for Observat i d , Imitative Learning and VicarioueReinforcement Jacob L. Gewirrz AUTHOR INDEX-SUBJECT INDEX
Volume 7 Superstitious Behavior in Children: An Experimental Analysis Michael D. Zeiler Learning Saotegies in Children from Different Socioeconomic Levels Jean L. Bresnahan and Martin M . Shapiro Time and Change in the Development of the Individual and Society Klaus F. Riegel The Nature and Development of Early Number Con=Pa R m k l Gelman Laming and Adaptation in Infancy: A Comparison of Models Arnold 1. Sameroff AUTHOR INDEX-SUBJECT INDEX
AUTHOR INDEX-SUBJECT INDEX
Volume 9 Children’s Discrimination Learning Based on Identity or Difference Betty J . House. Ann L, Brown. and Marcia S. Scott Two Aspects of Experience in Ontogeny: Development and Learning Hans G. Furth The Effects of Contextual Changes and Degree of Component Mastery on Transfer of Training Joseph C. Campione and Ann L. Brown Psychophysiological Functioning, Arousal, Attention, and Laming during the First Year of Life Richard Hirschman and Edward S. Katkin Self-ReinforcementProcesses in Children John C.Masters and Janice R. Mokros AUTHOR INDEX-SUBJECT INDEX
Volume 10 Cumnt Trends in Developmental Psychology Boyd R. McCandless and Mary Fulcher Geis The Development of Spatial Reprerntations of LargeScale Environments Alexander W.Siege1 and Sheldon H. While Cognitive Pmpectives on the Development of Memory John W. Hagen, Robert H. Jongeward. Jr., and R&n V. Kail, Jr. The Development of Memory: Knowing, Knowing About Knowing, and Knowing How to Know Ann L.Brown DeverOpmenpl Trends in Visual Scanning Mary Carol Day
Contents of Previous Volumes
The Development of Selective Attention: From PercepNal Exploration to Logical Search John C. Wright and Alice G. Vlietma
AUTHOR INDEX-SUBJECT INDEX Volumo 11
263
Developmental Memory Theories: Baldwin and Piaget Bruce M. Ross and Stephen M. Kerst Child Discipline and the h u i t of Self: An Historical Interpretrtion Howard Gadlin Development of Time Concepts in Children Willim 1. Friedman AUTHOR INDEX-SUBJECT INDEX
The Hyperactive Child Characteristics, Treatment, and Evaluuion of Research Design Gkrdys E . Eaxley and Judith M. &Elanc Peripheral and Neumchemical Pprallels of Psychopathology: A Psychophysiological Model Relating Autonomic Imbalance to Hypenctivity, Psychopathy, and Autism Stephen W . Porges Constructing Cognitive Operations Linguistically Harry Beilin Operant Acquisition of Social Behaviors in Infancy: Basic Problems and Constraints W. Stuarf Millar Mother-Infant Interaction and Its Study Jacob L. Gewirtz and Elizabeth F . Boyd Symposium on Implicationsof Life-Span Developmental Psychology for Child Development: Introductory Remarks Paul B. Ealtes . Theory and Method in Life-Span Developmental Psychology: Implications for Child Development Aletha HustonStein and Paul 8. Ealtes The Development of Memory: Life-Span Perspectives Hayne W. Reese Cognitive Changes during the Adult Years: Implications for Developmental Theory and Research Nancy W. Denney and John C. Wright Social Cognition a d Life-Span Approaches to the SNdy of Child Developrnenl Michael J . Chandler Life-Span Development of the Theory of Oneself Implications for Child Development Orville G. Brim, Jr. Implications of Life-Span Developmental Psychology for Childhood Education Leo Montada and Sigrun-Heide Filipp AUTHOR MDEX-SUBJECT INDEX Volume 12
Research between 1960 and 1970 on thc Standing Height of Young Children in Different PMS of the World Howard V. Meredith The Repnsentation of Children's Knowledge h i d Klahr and Raber~S. Siegler chromrtie Vision in Infancy Marc H. Bornstein
Volume 13 Coding of Spatial and Temporal Information in Episodic Memory Daniel B. Bereh A Developmental Model of Human Learning Barry Gholson and Harry Beilin The Development of Discrimination Learning: A Levels-of-FunctioningExplanation Tracy S.Kendler T!E Kendler Levels-of-Functioning Theory: Comments and an Alternative Schema Charles C. Spiker and Joan H. Cantor Commentary on Kendlu's Paper: An Alternative Pempective Barry Gholson and Therese Schuepfer Reply to Commentaries Tracy S.Kendler On the Development of Speech Perception: Mechanisms and Analogies Peter D. Eimaa and Vivien C. Tamer The Economics of Infancy: A Review of Conjugate Reinforcement Carolyn Kent Rovee-Collier and Marry J . Gekoski Human Facial Expressions in Response to Taste and Smell Stimulation Jacob E . Steiner AUTHOR INDEX-SUBJECT INDEX
Volume I4 Development of Visual Memory in Infants John S. Werner and Marion Perlmutter Sibship-Constellation Effects on Psychosocial Development, Creativity, and H d t h Mazie Earle Wagner, Herman J. P. Schuben. and Daniel S.P. Schubert The Development of Understanding of the Spatial Terms Front and Back Lauren Julius Harris and Ellen A. Stronuncn The Organizationand Control of Infant Sucking C.K. Crook Neurological Plasticity, Recovery from Brain Insult, and Child Development Ian St. James-Roberts AUTHOR INDEX-SUBJEm INDEX
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