Cognition, Vol. 6, No. 1

Editorial board

Hiroshi Faculty Tokyo Hongo, Tokyo,

Azuma of Education, University, Bunkyo-ku Japan

Paul Bertelson Laboratoire de Psychologie Experimentale, Universite Libre de Bruxelles I I 7, Av. Adolphe Buyl, B-l 050 Bruxelles, Belgique Ned Block Dept. of Philosophy, M.I.T., Cambridge, Mass. 02139, U.S.A. T. G. R. Bower Dept. of Psychology, University of Edinburgh, 60, Pleasance, Edinburgh EH8 9TJ, Gt. Britain

Richard Cromer Henry Hecaen MRC Developmental Directeur d%tudes, Psychology Unit, Ecole des Etudes, Unite de Drayton House, Gordon Street, London, WCIH OAN, Gt. Britain psychologiques, I.N.S.E.R.M., 2, rue d’Alt%a, Margaret Donaldson F- 75014 Paris, France Department of Psychology, University of Edinburgh, Michel Imbert 1-7 Roxburgh Street, Laboratoire de NeuroEdinburgh EH8 9TA, Gt. Britain physiologie, Peter D. Eimas Walter S. Hunter Laboratory of Psychology Brown University, Providence, RI. 02912, U.S.A. Gunnar Fant Lab. of Speech Transmission, Royal Institute of Technology, S-10044 Stockholm 70, Sweden

Francois Bresson Laboratoire de Psychologie 54, bvd. Raspail F-75006 Paris, France

Cilles Fauconnier C.N.R.S. Paris, France

Roger Brown Dept. of Psychology, Harvard University, Cambridge, Mass. 02138,

Jerry Fodor Dept. of Psychology, M.I.T. ElO-34 Cambridge, Mass. 02139,

U.S.A.

Jerome S. Bruner Dept. of Exp. Psychology, University of Oxford, South Parks Road, Oxford, OXI 3UD, Gt. Britain Peter W. Carey Laboratoire de Psychologie, 54, bvd. Raspail, F-75006 Paris, France

Kenneth Dept. of Monash Clayton,

College de France, 11, place Marcelin Berthelot, F-75005 Paris, France Barbel Inhelder Fact&k de Psychologie et des Sciences de I’Education, Universitd de GenPve, CH-121 I GenPve 14, Suisse Marc Jeannerod Laboratoire de Neuropsychologie Experimentale, Doyen L&pine, F-69500 Bron. France

U.S.A.

Forster Psychology, University, Vie. 3168, Australia

Merrill Garrett Department of Psychology, MI. T. ElO-034 Cambridge, Mass. 02139, U.S.A.

Noam Chomsky Dept. Modern Languages and Linguistics, MI. T., Cambridge, Mass. 02139, U.S.A.

Lila Gleitman Graduate School of Education, University of Pennsylvania, 3700 Walnut Street, Philadephia, Pa. 19104, U.S.A.

Eve Clark Department of Linguistics Stanford University Stanford, Calif 94305, U.S.A.

David T. Hakes Department of Psychology, University of Texas, Austin, Tex. 78712, U.S.A.

James Jenkins Center for Research and Human Learning, University of Minnesota, Minneapolis, Minn. 55455,

U.S.A.

Philip Johnson-Land Laboratory of Experimental Psychology, Centre for Research on Perception and Cognition, Sussex University, Brighton BNl 9QG, Gt. Britain Daniel Kahneman Dept. of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel Jerrold J. Katz Dept. of Philosophy, MI. T., Cambridge, Mass. 02139, U.S.A.

Mary-Louise Kean Cognitive Science Program, School of Social Sciences, University of California, Irvine, Calif. 92717, U.S.A.

Daniel Osherson Department of Psychology, University of Pennsylvania, 3813-15 Walnut Street, Philadelphia, Pa. 19174, U.S.A.

Harris B. Savin Dept. of Psychology, University of Pennsylvania, Philadephia, Pa. 19104, U.S.A.

Edward Klirna Dept. of Linguistics, La Jolla, University of California, San Diego, Calif. 92037, U.S.A.

Domenico Parisi Istitu to di Psicologia, Cons&ho Nazionale delle Rtsherche, Piozzale delle Scienze 7, Rome, Italy

Scania de Schijnen Laboratoire de Psychologie, 54, Boulevard Raspail, _ 75270 Paris Cedex 06, France

James R. Lackner Department of Psychology, Brandeis University, Waltham, Mass. 02154, U.S.A. Alexei Leontiev Faculty of Psychology, University of Moscow, 13, Frunze Street, Moscow G.19, U.S.S.R. Wilhelm Levelt Psvcholoaical Laboratory, Nt?megen- University, Erasmuslaan I6, Nijmegen, Netherlands John Lyons Dept. of Linguistics, Adam Ferguson Building, Edinburgh EH8 9LL, Gt. Britain David McNeill Department of Behavioral Sciences, Committee on Cognition and Communication, University of Chicago, 5848 South University Avenue, Chicago, RI. 60637, U.S.A. John Marshall Psychological Laboratory, Nijmegen University, Erasmuslaan 16, Nijmegen, Netherlands John Morton AppliedPsychology Unit, 15, Chaucer Road, Cambridge CB2 2EF. Gt. Britain George Noizet Laboratoire de Psychologie Experimentale, F-13 Aix en Provence, France

Michael Posner Dept. of Psychology, University of Oregon, Eugene, Ore. 97403, U.S.A.

Tim Shallice Psychology Department, The National Hospital for Nervous Diseases, Quenn Square, London WCI, Gt. Britain

David Premack Psychology Department, University of Pennsylvania, 3813-1.5 Walnut Street, Philadelphh, Pa. 19174, U.S.A.

Dan I. Slobin Department of Psychology, University of California, Berkeley, Calif 94720, U.S.A.

Zenon Pylyshyn Department of Psychology, The University of Western Ontario, London 72, Ont., Canada

Sidney Strauss Department of Educational Sciences, Tel Aviv University, Ramat Aviv, Israel

Martin Richards Unit for Research on Medical Applications of Psychology, University of Cambridge, 5, Salisbury Villas, Station Road, Cambridge CBI ZJQ, Gt. Britain Andre Roth Lecours Hotel-Dieu de Montreal 3840 rue St. Urban, Montreal, Quebec H2 W I T8, Gntada Steven Rose Biology Department, The Open University, Walton Hall, _ Milton Keynes MK 7 6AA, Gt. Britain Nicolas Ruwet Dept. de Linguistique. Centre Univ. de Vincennes, 12, Rue de Tourelle, F- 75012 Paris, France

Alina Szeminska Olesiska 513, Warsaw, Poland Virginia Valian Ph.D. Program in Psychology, C. U.N. Y. Graduate Center, 33 West 42nd Street, New York, N.Y. 10036, U.S.A.

Peter Wason Psycholinguistics University ColIege London, Research Unit, 4, Stephenson Way, London NW1 2HE, Gt. Britain

Hermina Sinclair de Zwart Centre d’Epistt?mologie Genetique, Universite de Geneve, CH-121 I Geneve, Suisse

Cognition, 6 (1978) 1-13 @Elsevier Sequoia S.A., Lausanne

1 ~ Printed

Transformations,

in the Netherlands

basic operations

JUDITH

WINZEMER

and languag’e acquisition*

MAYER,

ANNE ERREICH and

VIRGINIA

CUNY

Graduate

VALIAN Center

Abstract Errors in child speech show that some children initially formulate tensehopping and subject-auxiliary inversion as copying without deletion. Other errors suggest that some children may formulate other movement rules as deletion without copy*ing. A claim about the nature of the language acquisition device is made on the basis of our analysis of these errors: the language acquisition device formulates hypotheses about transformations in terms of basic operations. The basicoperations hypothesis predicts that for any transformation which is composed of more than one basic operation, there exists a class of errors in child speech correctly analyzed as failure to apply one (or more) of the operations specified in the adult formulation of the rule. One of the aims of linguistic theory is to enumerate the set of basic transformational operations of which any transformation is composed. For example, Akmajian and Heny (1975) list four basic operations: movement, copying, deletion and insertion. Chomsky (1965: 144, 147), however, has suggested that movement is not a basic operation but can be decomposed into two operations, copying and deletion. Foss and Fay (1975) argue that

*This research was supported by a grant from the National Institute of Child Health and Human Development (HD-00231) to the City University of New York. The order of the authors’ names is random. We would like to thank D. Terence Langendoen, Robert Fiengo, Jerrold Katz, Fred Katz and two anonymous reviewers for their valuable comments in the preparation of this paper. We would also like to thank Jean Singer for transcribing R’s data and Jacqueline Sachs for providing N’s data. Requests for reprints should be addressed to any of the authors, Developmental Psychology, CUNY Graduate Center, 33 West 42nd Street, New York, N.Y. 10036.

2

J. W. Muyer, A. Erreich and V. Valian

performance errors reflect the analysis of movement as copying and deletion. In this paper, we assume that movement is copying and deletion. The basic operations are thought to be linguistic universals and are therefore part of the child’s language acquisition device. We hypothesize that basic operations are the building blocks out of which a child constructs the transformations of a language. Acquisition data for subject-auxiliary inversion and tense-hopping* indicate that children may initially formulate some movement transformations as copying alone, later adding the deletion operation. Acquisition data for ing-hopping indicate that children may initially formulate some movement transformations as deletion without copying. The data suggest that children may, in general, learn transformations by determining which members of the set of basic operations comprise a given rule. In this paper we present data from three children and propose a transformational analysis of each child’s data. We consider and reject several arguments against a transformational analysis. Our conclusion is that a transformational analysis both provides a better account of the data and makes more specific and empirically falsifiable predictions about the course of language acquisition. R’s partial grammar The first set of data comes from R, aged 2; 4. During the period in which he was observed, R produced the following declaratives and interrogatives: A 1. Jenni did left with Daddy. 2. I did rode my bike. 3. I did broke it.

1. 2. 3. 4. 5.

B Why did you say probably? Do bananas have pits? Did you cook that? Is it upstairs? Can I have lox?

It is apparent that the main verbs of A are incorrectly marked for tense while the main verbs of B are correctly unmarked. We will argue that the errors in A are due to the application of an incorrect version of the tensehopping rule, one which mistakenly copies without deleting the abstract tense marker. *Tense-hopping is not a separate rule in the standard adult grammar but is a special case of the affut-hopping rule (Akmajian and Heny, 1975). However, Akmajian and Wasow (1975) argue that the affur-hopping rule is actually two separate rules, tense-hopping and en/ing hopping. Our analysis assumes only that tense-hopping is transformational; whether it is a syntactic or morphological rule is left open here.

Transfomations, basic operations and language acquisition

3

To explain how R produces incorrect declaratives and correct questions Bl-B3, we propose the following partial grammar. The grammar includes three transformations, ordered as follows: subject-auxiliary inversion, tensecopying and do-insertion. (1) Subject-auxiliary

inversion

SD:

Q

NP

SC:

1 1 3

2 2

Tense ( Modal ) Have I Be I

X

4 4

(2) Tense-copying SD: SC:

X 1 1

Tense ;

V 3 3#2

Y 4 4

Y 3 3

Condition:

(3) Do-insertion* SD: SC:

X 1 1

Tense 2 do#2

X # Modal or V

R’s partial grammar is similar to the adult grammar in two ways: (1) subject-auxiliary inversion and do-insertion are formulated the same way in the adult grammar (Akmajian and Heny, 1975; 377 and 223); (2) the rules are ordered in the same way in the adult grammar (Akmajian and Heny, 1975; 392). R’s grammar differs from the standard adult grammar in that R’s grammar contains a tense-copying rule, whereas the standard adult grammar contains an affix-hopping rule which copies not only tense but also the suffixes en and ing onto the right-adjacent verbs, deleting the affixes from their original positions. Using these rules, the ill-formed declarative sentences of A can be derived. For example, A3, I did broke it, has the following derivation:**

*If one assumes dodeletion instead of do-insertion the error would not be analyzed as copying without deletion but would be analyzed as double tense-copying, and deletion. **In all of the derivations, we have omitted certain details such as S and VP brackets as well as the internal structure of NP.

(a)

~p[Il

~~s[Past]

(b)

~p[ I] TNs [Past] v [v [break]

cc>

NP[Il

v[v[dol

v[break]

~p[it]

tense*opyine

r~s [Past] 1 Np[it]

do-insertion

l

TNSiPaStlI

v [v [break I TNS [Past] 1 Np [it]

(d)

’

morphophonemic ru1es ’

I did broke it.

Using the same partial grammar, the well-formed questions B l-B3 derived. For example, B3, Did you cook that? is derived as follows: (a)

Q ~p[youl

(b)

Q TNs [Past]

(c)

Q v [v [doI

TNSkStl

vicookl

up [ YOU] v [cook]

Npfthatl

Np [ that]

TNSbStl v [cookl I NPLYOUI NP,fhafl

subject-auxiliary

do-insertion

can be

inversion

,

>

morpho-phonemicrules

,

(d) Did you cook that? Note that A sentences are ungrammatical (in adult English) because tensecopying was applied without accompanying deletion. The error can not occur in Bl-B3 sentences because the operation of subject-auxiliary inversion precludes the application of tense-copying; it destroys the environment in which tense-copying can occur. Thus, questions like Bl-B3 are always well-formed because the child’s grammar contains the correct subjectauxiliary inversion rule, the operation of which precludes the application of any tense rule. The declarative sentences, on the other hand, are ungrammatical because the structural description for the tense-copying rule is met. Three features of R’s data suggest possible objections to our analysis. First, all of the main verbs in A are irregular, and these same verbs do not occur in B. Perhaps R simply does not know the unmarked form of leave, ride, and break. What argues against this interpretation is that irregular verbs also occur in B. In addition, as is discussed later, other children show examples of copying without deletion for elements other than tense. The second objection concerns the scope of R’s partial grammar. Perhaps R was producing correctly tensed declaratives as well as double-tensed ones, even though our data contain no examples of the former*. In order to *R’s mother

was asked to transcribe

only verb errors

and questions.

Transformations, basic operations and language acquisition

5

generate both correct and incorrect declaratives, the grammar would have to be expanded to contain two competing rules, tense-hopping and tensecopying. This might be considered objectionable. It is only objectionable, however, if one assumes on a priori grounds that no child grammar can have two competing rules; there are no such grounds. In fact, a grammar with competing rules would be expected if the language acquisition device is one which sometimes tests competing hypotheses about alternative syntactic expressions of the same thought. For example, the thought ‘I left it’ could have two derivations in R’s grammar. If R used tense-copying, he would utter I did left it; if R used tense-hopping, he would utter I left it. The existence of competing rules predicts systematic variability in child speech. A third objection concerns B4 and B5. These questions involve inversion of be copula or a modal and therefore do not preclude the application of tense-copying. Yet it is evident that in B4 and B5 tense-hopping, rather than tense-copying, has occurred. If tense-copying had occurred, R would have said Does is it upstairs? It is therefore necessary to add rule (4):

(4) Tense-hopping SD:

X 1

SC:

1

Tense

V 3 3#2

Y 4 4

Thus, it seems that R’s grammar does have two competing rules: tensecopying and tense-hopping, both of which may apply in producing declaratives, but only one of which (tense-hopping) applies in producing questions. The objection to our analysis would point out that tense-copying never occurs in questions but is restricted to declaratives, while tense-hopping might apply in both questions and declaratives. Why is tense-hopping, a more advanced rule, always used in questions? We use “more advanced” here to mean in closer conformity with the adult formulation of the rule. Nonquestions and questions, when spoken by adults, are not equally informative for R. R can misanalyze present tense emphatics that he hears (except thirdperson singular) like I do like it, as do+pres like+pres, as evidence for tensecopying. In questions, however, R never hears any sentences which his incorrect rule predicts. Put another way, R’s incorrect rule will account for a small portion of the nonquestions that he hears, but it will not account for any of the questions that he hears. Thus, if R has competing tense rules, he should

6

J. W.Mayer, A. Erreich and V. Valian

reiinquish the incorrect questions.*

rule in questions

before

he relinquishes

it in non-

ES partial grammar

The second set of data comes from Hurford’s (1975) observations of E, aged 1 ;lO-2;6. Samples of the questions that E produced during this period are,* * C 1. What’s that is? 2. What’s this is? 3. Whose is that is? 4. What did you bought? 5. What did you did? 6. Did you came home? From these data, Hurford argues that E’s grammar contains an auxiliarycopying rule rather than the adult subject-auxiliary inversion rule. The auxiliary-copying rule copies tense and be (if present) into pre-subject position but does not delete them from their original post-subject position. To account for E’s sentences two transformations in addition to auxiliarycopying are necessary: tense-hopping and do-insertion. They are ordered as follows: auxiliary-copying, tense-hopping and do-insertion. The ordering of the rules, as well as the formulation of do-insertion, corresponds to the adult grammar. For the formulation of do-insertion and tense-hopping see (3) and (4). (5) Auxiliary-copying SD:

Q 1

SC:

132

NP 2

Tense (Be) 3 3

X 4 4

C6, Did you came home? is derived using rules (4), (5) and (3). (To derive the other questions a rule of wh-placement must be added.)

*R also forms the progressive properly in questions but not in declaratives: Are you going to tape it?, Are you having a walk? VS. The people standing next to my house. That going to be the chimney. Since R’s progressives, as well as his tensing, are more advanced in questions than declaratives, it is possible that there is an alternate explanation which will account for the advanced status of both progressives and tensing in questions. **Hurford only supplies data on questions, so we are unable to compare E’s questions to her declarative sentences.

Transformations,

(a)

Q ~p[youl

(b)

Q TNs[Past]

(c)

QTNS[hStl

(d)

Q vIv

[doI

rNs[Past]

operations and

v[come]

Np[home]

~p[you]

rNs[Past]

v[come]

Np[you]

v[v[comelTNS[hSt]]

TNS[PaStl

auxMary-copying ’ Nplhome]

tenae-hopping +

Np[home]

1 NP~YOUI

V[V[cOmel

do-insertion

morpho-phonemic rules

TNS[PaStl

7

acquisition

1 NP[homel

3.

(e) Did you came home? The correct tense-hopping rule (4) rather than the incorrect tense-copying rule (2) is necessary to derive E’s sentences because the application of a tense-copying rule in the above derivation would result in Did you did came home?

(a)

Q ~p[youl

(b)

Q TNS[PaStl

TNS[PaStl NP[YOul

v[comel -rNS[PaSt]

Np[home] V [come] NP

(c)

Q TNSbstl

NP[Youl

V[V[comel Cd)

Q V IV [doI

TNS[Past)

1 NP[Youl

v [v [come]

r~s[Past]

tense copying

f

[homel

TNS[PaStl TNSbStll

auxiliary-cOpyinp +

do-insertion NP[homel V [V Idol

,

mS[PaStl)

] NP[home]

morpho-phonemicrules +

(e) Did you did came home? Implications

of R’s and E’s grammars

Our analysis indicates that each child’s grammar contains one (incorrectly formulated) rule which copies elements without deleting them from their original positions. To attain the correct formulation of these rules, each child must learn to delete from their original positions those elements which have been copied. Although the children’s grammars differ in terms of which movement rule is incorrectly formulated, they are similar at a more abstract level. The abstract similarity in the grammars suggests a hypothesis about the nature of the language acquisition device: the device formulates hypotheses about transformations in terms of basic operations. What would lead the child to postulate rules which are incorrect from the standpoint of the adult grammar? Any hypothesis about a rule must predict

8

J. W. Mayer, A. Erreich and V. Vahizn

some portion of the incoming data. In the case of incorrect hypotheses, the datd consist of utterances which the child has misanalyzed. As we suggested with R, all present tense emphatics, except those in the third person singular, can be accounted for by his tense-copying rule, if he misanalyzes the main verb as having the structure V + pres. Similarly, for E, present tense questions involving do-insertion, such as Do you like it?, provide evidence for an aux-copying rule, if E misanalyzes them as do+pres NP Zike+pres. Notice that R could produce correct sentences like Zdo like it and E correct questions like Do I like it?, but with the incorrect tense-copying rule in the former case and the incorrect auxiliary-copying rule in the latter case. It is only in the present tense third person singular and the past tense that the error would be apparent from the surface form of the sentence. In order to produce errors like I did broke it and Did you came home? the child must generalize from the cases that the rule predicts (i.e., the present tense cases) to cases where the evidence is inconsistent with the hypothesis (i.e., past tense emphatics like / did like it and questions like Did you like it?). Although such an overgeneralization may seem odd, children do overgeneralize rules to cases where the adult data are inconsistent with the rule (e.g., the overgeneralization of the regular past tense ending to irregular verbs). What appears to be a bizarre consequence of the theory is a familiar phenomenon in language acquisition. Our analysis can be contrasted with a similar approach put forward by Foss and Fay (1975). The difference between Foss and Fay’s analysis and ours with respect to language acquisition concerns the cause of copying without deletion errors in children. Foss and Fay argue that such errors result from a performance limitation on the number of operations a child can perform in producing an utterance. On their analysis, children’s grammars contain the correct formulation of the rules, but children fail to delete in order to reduce the number of operations they must perform; the more operations the production of a sentence requires, the more likely it is that some operations will be omitted. Our analysis, on the other hand, states that the errors result from rules in the child’s grammar that are incorrectly formulated as copying without deletion. Two conclusive arguments demonstrate that Foss and Fay’s analysis is incorrect. Foss and Fay must predict both that the total number of operations used in producing a sentence is reduced by, for example, failing to delete, and that sentences which require more operations are more likely to result in copying without deletion errors than are sentences requiring fewer operations. R’s and E’s data contradict both predictions. First, take R’s declaratives Al-A3. R copies tense after the verb and fails to delete it before the verb, thus saving an operation. However, the presence

Transformations, basic operations and language acquisition

of the stranded tense marker before the verb necessitates do-insertion, thus adding an operation.* The net result, then, is no reduction in the overall number of operations performed. Next, take E’s sentences Cl-C3. E copies tense and be into pre-subject position without deleting them from postsubject position, thus saving an operation. However, the presence of the tense marker and be before the main verb necessitates a second application of tense-hopping, thus adding two operations,- copying and deletion. Similarly, in the case of C4-C6, E copies tense into pre-subject position without deleting it, thus saving an operation. The stranded tense marker necessitates tense-hopping on the main verb, adding two operations. The net result for E’s data, then, is an increase in the overall number of operations performed. Second, Foss and Fay must predict more errors of copying without deletion for questions than for declaratives, since more operations are involved in producing questions than declaratives. Contrary to this prediction, R fails to delete in declaratives, but not in questions. Thus, Foss and Fay’s argument that copying without deletion errors result from a performance limitation on the number of operations a child can perform is not supported by R’s and E’s data. It is still possible, however, that all or some of the copying without deletion errors are performance errors. We in fact expect performance errors in child speech since children, like adults, should utter sentences which are ungrammatical from the point of view of their own grammars. Even though R’s and E’s errors could not be performance errors made in order to save the child operations, they could be the result of some other (as yet unspecified) performance limitation. The decision between a competence or a performance explanation of the errors must await the formulation of an alternative performance hypothesis. Arguments

against a transformational

analysis

There have been two criticisms of Hurford’s ( 1975) analysis of which could apply to our analysis as well. Kuczaj (1976) (1976) argue that one need not invoke underlying structures mations to account for the acquisition of language by children.

E’s questions and Prideaux and transforBoth attempt

*On an analysis in which do is present in the base and a rule of do-deletion applies to derive nonemphatic declaratives, there would still be no saving of operations. Failure to deletedo saves the child one operation, but necessitates two copying operations - copying tense onto do and onto the main verb. Deletion of do costs the child one operation but necessitates only one copying operation copying tense onto the main verb.

9

10

J. W. Mayer, A. Erreich and V. Valian

to explain the child’s speech output by postulating rules or strategies that operate on only the surface properties of utterances. We will argue that both Kuczaj’s and Prideaux’s accounts are merely descriptions of regularities in child speech; they are not explanations. Kuczaj argues that Hurford’s data need not be explained by an auxiliarycopying rule. Rather, he divides Hurford’s data into two groups and proposes a different explanation for each. For one set of data (Cl-C2), Kuczaj makes the plausible suggestion that the errors result from segmentation difficulties. For the other set of data (C3-C6), Kuczaj argues that the errors are redundancies in the child’s speech which are due to processing difficulties. He presents data from children who produced sentences such as I did felZ when I got blood, arguing that they represent redundancies that cannot be explained by the auxiliarycopying rule. Kuczaj’s declaratives are not, however, true counterexamples to the auxiliary-copying rule. These sentences are identical to R’s A sentences and can be accounted for by the tense-copying rule (2). Although the deviant declaratives result from the application of a tense-copying rule, whereas the deviant interrogatives result from the application of an auxiliary-copying rule, the errors in both types of sentences are similar because the rules which generate them consist of copying without deletion. Kuczaj’s redundancy argument can be rejected both as a description and as an explanation. As a description of the child’s errors, redundancy is inadequate because the class of errors that exists is much narrower than the class encompassed by the term redundancy. Kuczaj’s account is not an explanation because he gives no indication of what the child’s processing difficulties are, no indication of why the difficulties should result in redundancy, and no indication of why the redundancies take the particular form they do. Prideaux ( 1976) argues that children’s linguistic knowledge consists only of surface structure generalizations. For example, for E’s sentence C4, What did J’OU bought?, Prideaux offers the following analysis for the child’s double-tensing. The tensing of the auxiliary and main verb results from the fact that E has previously learned to tense main verbs and, since some main verbs are also auxiliaries, she tenses auxiliaries as well. Prideaux assumes that the child later learns that only the left-most verb is tensed. Prideaux’s analysis not only fails to account for R’s corpus, but, a more general limitation is that it is not an explanation; his account is simply a description of the child’s output at a given stage. One cannot generate predictions about language acquisition on the basis of Prideaux’s analysis. Our analysis, on the other hand, makes highly specific and empirically falsifiable predictions about classes of errors in child speech. It also has implications for the theory of the language acquisition device.

Transformations, basic operations and language acquisition

11

The transformational analysis makes possible a general claim about the principles which underlie the acquisition of transformations. We hypothesize that the language acquisition device has available to it, and utilizes, the basic operations in constructing transformations. For any transformation, then, the acquisition device hypothesizes which basic operations comprise it. It follows from this hypothesis that, for any transformation which is composed of more than one basic operation, there exists a class of errors in child speech* correctly analyzed as the result of failure to apply one (or more) of the operations specified in the adult formulation of the rule.** In the case of movement transformations, the basic-operations hypothesis predicts the existence of errors which are the result of copying without deletion. The data of R and E confirm this prediction. There are also apparent instances of auxiliary-copying without deletion errors for: the present tense marker (What does this does?, Menyuk, 1969: 90) the past tense marker (What did you doed?, Klima and Bellugi, 1966: 203, be copula (Is this is the powder?, Menyuk, 1969: 90), and modals (What shall we shall have?, Bellugi, 197 1: 100). The basic-operations hypothesis predicts copying without deletion errors for other movement rules as well. For example, it predicts copying without deletion for particle-movement (The barber cut off his hair off, Menyuk, 1969: 56), for which errors have been reported. It also predicts copying without deletion for: wh-placement (What did I see what?), ing-hopping (I being going to the store) and negative-placement (Where not can’t I go?), for which errors have not been reported. We are currently listening for errors of this type.

*Given a model of speech production for adults in which operations are performed on underlying strings of elements (Foss and Fay, 1975), the basic-operations hypothesis also predicts errors resulting from failure to apply one (or more) operation(s) in adult speech. **For any transformation, the language acquisition device must make other determinations as well. The basic-operations hypothesis considered here predicts only a subset of basic-operations errors. Other basic-operations errors would result from projection of the wrong basic operation(s) (e.g., copying instead of deletion), or the addition of extra basic operations (e.g., double tense-copying, instead of single tensecopying (see first footnote on page 3)). Furthermore, the language acquisition device must determine the correct structural description and structural change of a transformation. Mistakes in these determinations will result in characteristic errors in child speech. For example, on the &deletion analysis discussed in the first footnote on page 3, the child makes two errors: (1) a structural description error - the SD contains an extra occurrence of the category verb; (2) a basicoperations error - the rule contains an extra copying operation, copying of tense onto the second verb: SD: X Tense V (4v) y 1 2 3 SC: 1 0 3#2 4#2 : See Valian, Mayer and Erreich (unpublished) for a taxonomy of predicted transformational errors.

12

J. W. Mayer, A. Erreich and V. Valian

There is another sort of error that the basic-operations hypothesis predicts for movement rules, namely, deletion without copying. An example of deletion without copying for ing-hopping would be lam go. Examples similar to I am go were produced by another child, N: D 1. Is Georgie wake up? (1 ;l 1) 2. I’m feed the birdie meat (2 ;O) There are at least two difficulties involved in analyzing such errors as deletion without copying. First, the frequent use of the contracted form suggests that some apparent cases of deletion without copying could be segmentation errors (e.g., D2). Second, the errors could reflect lack of the element ing in the phrase structure rules used for a particular utterance. The child’s grammar may lack ing, or the grammar may contain competing phrase structure rules for expanding the auxiliary, some of which contain ing and some of which do not. Problems of the second sort are presumably general: it will often be difficult to distinguish deletion without copying errors from incomplete phrase structure rules. Dl, then, could be an example of deletion without copying, but it could also result from the application of a phrase structure rule which lacks ing. The attribution of deletion without copying errors is, thus, particularly difficult. Nevertheless, the basic-operations hypothesis predicts the existence of such errors. The basic-operations hypothesis predicts two kinds of errors for movement rules: copying without deletion and deletion without copying. Similarly, for other rules composed of two or more basic operations, it predicts errors which result from failure to apply one (or more) basic operation(s). Discontirmation of the basic-operations hypothesis would result if errors were not found for each transformation composed of two or more operations. It is possible that some of the errors predicted by the basic-operations hypothesis would be ruled out by principles of derived constituent structure or other universals. The basic-operations hypothesis is a rich source of specific predictions about errors in child speech as well as a suggestive notion for acquisition theory*.

*For

a fuller

presentation

of acquisition

theory,

see Erreich,

Valian

and Mayer

(unpublished).

Transformations, basic operations and language acquisition

13

References Akmajian, A. and Heny, F. (1975). An introduction to the principles of transformational syntax. Cambridge, MIT Press. Akmajian, A. and Wasow, T. (1975). The constituent structure of VP and AUX and the position of the verb Be. Ling. Anal., 1, 205-245. Bellugi, U. (1971). Simplification in children’s language. In R. Huxley and E. Ingram (eds.), Language acquisition: models and methods. London, Academic Press. Brown, R. (1970). Psycholinguistics. New York, The Free Press. Chomsky, N. (1965). Aspects of the theory of syntax. Cambridge, MIT Press. Erreich, A., Valian, V. and Mayer, J. W., Aspects of a theory of language acquisition. Unpublished manuscript, 1978. Foss, D. and Fay, D. (1975). Linguistic theory and performance models. In J. Wirth and D. Cohen (eds.), Testing linguistic hypotheses. New York, Hemisphere Press Inc. Hurford, J. (1975). A child and the English question formation rule. J. child Lung., 2, 299-301. Klima, E. and Bellugi, U. (1966). Syntactic regularities in the speech of children. In J. Lyons and R. Wales (eds.), Psycholinguistic papers. Edinburgh, Edinburgh University Press. Kuczaj, S. (1976). Arguments against Hurford’s ‘aux copying rule’. J. child Lung., 3, 423-427. Menyuk, P. (1969). Sentences children use. Cambridge, MIT Press. Prideaux, G. (1976). A functional analysis of English question acquisition: a response to Hurford. J. child Lang., 3, 417-422. Valian, V., Mayer, J. W. and Erreich, A. From where do speech errors come from? Unpublished manuscript, 1978.

Les erreurs rencontrees dans le discours des enfants montrent que certains enfants formulent d’abord la transformation affixe et Pinversion sujet-auxiliaire comme copie sans effacement. D’autres erreurs suggerent que certains enfants peuvent formuler d’autres regles de mouvement comme l’effacement sans copie. En se fondant sur I’analyse de ces erreurs on fait une proposition sur le mecanisme de l’acquisition du langage: ce mecanisme d’acquisition du langage formule les hypotheses sur les transformations en terme d’operations fondamentales. Cette hypothese d’operations fondamentales predit que pour chaque transformation composee de plus d’une operation fondamentale, il existe une classe d’erreur dans le langage de l’enfant. Cette classe d’erreur peut s’analyser comme un echec i appliquer i une (ou plus) des operations specifides par la formulation adulte de la Ggle.

Cognition, @Elsevier

6 (1978) 15-33 Sequoia S.A., Lausanne

Intellectual

2 - Printed

realism

in the Netherlands

in children’s

drawings

W. A. PHILLIPS, and

of cubes*

S. B. HOBBS

F. R. PRATT

StirlingUniversity,Stirling

Abstract Ninety-six children copied simple line drawings of perspective views of cubes and similar designs unlikely to be seen as representing objects. The views of cubes were copied much less accurately than the non-object patterns, and the errors made in copying the cubes involved replacement of properties specific to the single perspective view by properties more appropriate to the object itself Some copies were drawn with the child continually looking at the model and unable to see his own copy, others were drawn in the normal way. Copies made in the former way were more accurate, but even under these conditions cubes were copied less accurately than the nonobject patterns. The disadvantage of object pictures, as far as literal copying accuracy is concerned, was still present at 5% years of age, but was less than at 71/2 Two possible explanations are discussed. One is in terms of computational complexity, the other in terms of graphic motor schema. On the basis of the drawings obtained a few suggestions are made about the content and development of the data-structures for cubes. Children’s drawings often seem to represent intrinsic properties of objects rather than views of objects. Drawings that seem to be canonical displays of the properties of objects rather than views of objects are also found in the adult art of many cultures (Arnheim, 1954). A classic example from children’s drawings is that six year olds tend to draw a hatpin sticking through an apple as a single continuous line going right across the apple (Clark, 1897). The invisibility of part of the pin seems less important to children of this age *The authors wish to thank the children and staff of Menstrie Primary and Parks Primary, Alloa, for their cooperation in this research. We also wish to thank members of the Psychology Department, Stirling University, particularly R. N. Cambell and D. F. M. Christie, for helpful comments on earlier drafts of the paper. Correspondence to W. A. Phillips, Medical Research Council, Applied Psychology Unit, 15, Chaucer Road, Cambridge, CB2 2EF, Gt. Britain.

16

W. A. Phillips, S. B. Hobbs and F. R. Pratt

than the integrity of the pin as a single object. Other examples abound, and are easily collected by asking children to draw things. Some examples of the way children draw cubes are shown in Figure 1. These drawings are inadequate or incorrect as representations of views of cubes. Figure l(a) is an ambiguous and highly improbable view, and the others are impossible views. Intrinsic properties of cubes, however, such as symmetry, square faces, and right angles, seem well represented in these drawings.

Figure 1.

Examples

of the way in which children of about 7 years of age draw cubes;

a) and b) are from

Lewis (1963),

c) is from Minsky and Papert (1972),

d) is one of our own examples.

(a)

(b)

(cl

(d)

The representations of possible photographic views of objects is often described as visual realism (Luquet, 1927), and attempts to draw such pictures seem to emerge only gradually, both historically and in the development of the individual. Representation of the structural essentials of solid objects is often described as intellectual realism. When using these terms we wish to do so without implying any particular theoretical interpretation of the phenomena. The most common conclusion drawn from intellectual realism is that the child draws what he knows rather than what he sees; or, in other words, that his aim is to draw reality rather than appearance (Clark, 1897; Luquet, 1927; Piaget & Inhelder, 1969; Freeman & Janikoun, 1972). This conclusion contains implicit and apparently untested assumptions, but even if correct it provides no adequate account of why the child draws ‘reality’ rather than appearance, nor any account of how he draws the way he does. Minsky and Papert (1972) have recently used children’s drawings to support their approach to problems in artificial intelligence. On the assumption that children’s drawings are close approximations to their mental representations, Minsky and Papert claim them to be evidence that these mental representations are schematic and symbolic. We agree that drawings have great potential as a source of information, but they cannot be pure reflections of mental representations. Drawing requires expression of selected aspects of the mental representation within the constraints set by the medium, the child’s graphic skill, and by any other cognitive capacities

Intellectual realism in children ‘sdrawings of cubes

17

involved in the particular drawing task. Interpretation of the content of the drawing should, therefore, proceed together with an analysis of the drawing process. The present report is concerned with two main empirical questions. The first is whether the gross structural accuracy with which simple line drawings are copied depends upon whether they are pictures of objects or not. This is interesting for a number of reasons. The drawings described as intellectually realistic are often simpler than those described as visually realistic; a single continuous line representing a pin, or a square representing a cube, are easier to draw than perspective views. It is possible that some of the features attributed to intellectual realism reflect what the child is able to draw rather than what he knows about objects. We, therefore, included drawings to be copied that were of comparable complexity to the pictures of cubes, but which, it was hoped, the child would not see as pictures of objects. If intellectual realism occurs because of general output limits then his copies of drawings not seen as objects will be at least as inaccurate. This first empirical question is also interesting because another possible reason for intellectual realism is that the child only slowly learns that people wish him to draw perspective views. Asking the child to copy simple line drawings should reduce this difficulty of communication. Combining object and non-object drawings in one experimental series should reduce the chance that any differences between the,m are due to the child’s interpretation of instructions. Finally, it is of interest to know whether intellectual realism occurs at all when copying drawings. In most, if not all, previous studies children have had to draw real objects, either from memory or from life. Translating the representation of a solid object into a two-dimensional graphic medium is necessarily complex. It may be that intellectual realism only occurs until the child acquires a solution to this translation problem. If so, it is possible that intellectual realism will be removed by showing the child a solution in the form of a simple perspective drawing. The other main empirical question investigated concerns the relation between perception and intellectual realism. An interesting voice of dissent from the usual account is that of Amheim (1954). He denies that children draw what they know rather than what they see, and suggests instead that they draw the way they do because that is the way they perceive. Amheim argues that knowledge of the general properties of objects affects perception, and appears in drawings as a consequence. This suggestion has much in common with, and gains support from, current cognitive theories of perception as hypothesis testing. If it is correct then concentrating attention on a single perspective view of the object while drawing should not remove intellectual realism. However, Freeman and Janikoun (1972) suggest that

18

W. A. Phillips, S. B. Hobbs and F. R. Pratt

intellectual realism occurs because of “the general tendency for conceptual knowledge to be dominant over perceptual experience”. This implies that perceptual experience is not affected by the processes causing intellectual realism. Thus, if the perceptual representation of a perspective view of a cube is used as the basis for drawing then intellectual realism shoud disappear. The normal method of drawing involves looking away from the model so that memory as well as perception is involved and this may well reduce the probability that perceptual representations are used as the basis for drawing. Therefore, in addition to drawings made in the normal way, we studied drawings made while the child looked continuously at the drawing being copied, but not at all at the drawing being produced. Intellectual realism is sometimes thought to disappear rather abruptly, and this fits well with Piaget’s theory of intellectual development. Luquet (1927) suggests that intellectual realism is succeeded by visual realism at about 8 or 9 years of age, and partly because of this Piaget and Inhelder (1969) link intellectual realism with the topological phase, and visual realism with the projective and Euclidean phases of their theory of the development of spatial intelligence. On the basis of a more recent investigation Freeman and Janikoun (1972) suggest that it may occur a little earlier, but still fairly abruptly. The results of Lewis (1963), on the other hand, suggest that intellectually realistic aspects are still present until at least 12 years of age. Thus, to obtain some indication of the rate of change from intellectual to visual realism, we used two age groups, one a little younger than the age at which the change is thought to occur, the other a little older.

Method Conditions

and design

There were four experimental conditions, in each of which every child copied a particular stimulus pattern using one of two specified drawing techniques. The patterns and techniques used in the four conditions are shown in Table 1. Pattern B (i.e.; the pattern used in condition B) has the same number of lines and regions as pattern A, but has no dots and does not in any obvious way represent a solid object. Pattern C is identical to pattern A except that it has no dots. Pattern D is identical to pattern C except that it is rotated 45 degrees anticlockwise. On the basis of preliminary observations it was hoped that at least some of the children would not interpret pattern D as a solid object. Children of this age nearly always see patterns A and C as pictures of objects.

Intellectual realism in children S drawings ofcubes

Table 1.

Condition

19

Patterns, conditions, and numbers of correct copies in each condition (CLAM = continuous looking at model)

Stimulus

Drawing

Technique

Number

Correct

Primary 3 (Max 48)

Primary 5 (Max 48)

TOTAL (Max 96)

NORMAL

Practice /I Practice

CLAM /%

A

C

A cube drawn from memory

NORMAL

I

21

28

NORMAL

39

43

82

CLAM

18

29

41

CLAM

34

40

14

2

11

13

NORMAL

In the normal drawing technique children could see both the model and their own drawing, and could look back and forth as much, or as little, as they wished. The other technique required them to look continuously at the model, and they were unable to see their own drawing. This technique is referred to in Table 1 as CLAM. Previous informal observations suggested that people are quite good at controlling such things as line length and angle under these conditions. However, the present investigation was concerned with the general kind of structure drawn and not with the precision of the drawing. The order with which the four experimental conditions A, B, C and D were presented varied from child to child, such that each of the 24 possible orders occurred 4 times.

20

W. A. Phillips, S. B. Hobbs and F. R. Pratt

Subjects

Children from two primary schools in the Stirling area were used. They were from two classes in each school: Primary 3 (mean age 7 years 6 months; range 6 years 9 months to 7 years 9 months), and Primary 5 (mean age 9 years 4 months; range 8 years 10 months to 9 years 11 months). Preliminary drawings were collected from all children in the four classes about two weeks before the main experiment. These drawings were of a chair, a square building block, and a house. Twenty-four children were selected from each class such that they were matched across schools for age, sex, and, approximately, for drawing ability. The matched pairs within each class were randomly assigned to one of the 24 possible permutations of the four experimental conditions. The total number of children used was therefore 96 (24 X 2 classes X 2 schools). Apparatus

The apparatus consisted of a wooden easel, size 15” X 12” X lo”, and is shown in Figure 2. A black curtain hung from the upper ledge so that the child’s hand and drawing would be hidden when placed below. The patterns to be copied were drawn on 8” X 10” cards, and were placed individually on the upper ledge. In the normal drawing condition the easel was placed approximately 12” from the edge of the desk, and the child drew on paper put on the desk in front of him. In the other drawing technique the easel was placed directly in front of the child, who put his hand under the curtain and drew on the paper below. Short stubby felt pens were used for drawing. Procedure Before beginning the experiment the experimenter explained to the classes concerned that she was interested in children’s drawings and that it did not matter whether or not they were good at drawing, it was how they drew that was important. Children were then taken individually to a quiet room in the school. After establishing rapport, the experimenter explained the nature of the task in the following words: “While it is quite easy to copy drawings when you can see what you’re doing, I want to find out how you can manage if your hand is hidden by the curtain and you can’t see what you’re doing! ” Each child was given a practice session to become familiarized with the apparatus. The practice card consisted of an isoceles triangle with three vertical lines across it. The child first copied the stimulus drawing normally. They then copied it using the other drawing technique, and were given the

Intellectual realism in children’s drawings of cubes

Figure 2.

21

The apparatus. The copy shown was made by a child from PrimaT 5 in Condition C.

following instructions: “That’s fine! Now let’s see how you can manage when you can’t see! Just to give you a hint the easiest way to do this is to pretend that you’re tracing. Look closely at the lines and as you move your eyes down the lines try to make your hand follow them!” As the experimenter was giving the instructions she traced the lines of the triangle with a pen. When necessary the experimenter indicated to the child that even though the lines may not join up exactly they were correct and that was just what she was expecting. The child was then presented with the prescribed random arrangement of the four conditions. The first card was placed on the ledge of the easel and when the child had completed it both the card and the drawing were removed and placed face-downwards on a desk, so as not to interfere with the future conditions.

22

W. A. Phillips, S. B. Hobbs and F. R. Pratt

Before actually copying patterns A and C the children were asked what the stimulus cards represented. On the rare occasions when the child seemed uncertain the experimenter produced a wooden cube painted with pale dots so that it served for both conditions. The children were encouraged to count the number of faces and in condition A to understand what purpose a dice served in a game. During the presentation of pattern D the children were asked if it reminded them of anything and records were kept of the remarks. The main purpose of this was to elucidate any differences that might result from the recognition of the upturned cube. On completing the four conditions they were asked to draw a house on the paper in front of them. Finally, they were required to draw a square building block from memory. Where necessary additional instructions such as “like the dice only without the dots on it” were given to ensure that the nature of the task was clear. They were discouraged from drawing Necker cubes for either the memory task or condition A. Where necessary they were allowed a second attempt at the drawing. On completion the child was encouraged to comment on the drawings, e.g., as to how many faces he had drawn and why, how many faces a cube had, and how many of these were visible at any one time.

Results When analysing the drawings we attempted to assess the kind of structure drawn rather than the precision with which it was executed. We hoped to avoid some of the difficulties inherent in such a distinction by making only a very gross classification of structures. The main analysis was simply into two categories: ‘correct’ and ‘incorrect’ structures. Drawings were classified as correct if they had no more than one gross structural error. By ‘structure’ we mean the number of regions, their basic shape, and relations. Structural errors therefore involve changes in any of these. Examples of drawings classified as correct and incorrect are given in Figures 3 and 4. The drawings in the top row of Figure 3 were classified as having no structural errors (straightness of lines, and their precise length, etc., were disregarded). The drawings in the bottom row of Figure 3 were classified as having one main structural error. The child who produced the drawing shown at the bottom left, for example, has clearly squared the corner at the bottom left of the rightmost face, but has the rest correct. (No use is made of the distinction between no errors and one error; we simply mention it here to clarify the classification ‘correct’.) There was no attempt to quantify error in those cases classified as ‘incorrect’; usually they were wrong in many ways. Al-

Intellectual realism in children’s drawings of cubes

Figure 3.

23

Examples of drawings classified as correct.

CONDITION A

B

C

D

Memory

though most drawings could be classified easily, decision was difficult in a few cases, particularly in conditions C and D where the exact placings and lengths of lines have to be discounted because of the drawing procedure used. As a check on the reliability of the classifications made, three independent judges each classified 60 drawings. The correlation of their classifications with those of the experimenter was 0.82. The number of drawings classified as correct in each condition and for each age group is shown in Table 1. Drawings made from memory were classified as correct if they had no more than one gross structural error in relation to any perspective view on a cube. It did not need to be the view copied earlier. McNemars test for correlated proportions was used to examine the significance of the difference in the proportions correct for both age groups

24

W. A. Phillips, S. B. Hobbs and F. R. Pratt

combined between all possible pairs of conditions. All differences are significant. The smallest difference is that between conditions B and D. This difference is just significant at the 0.05 level. Thus pattern A was copied less accurately than pattern B. Pattern C was copied more accurately than pattern A, but less accurately than pattern D. The fact that pattern D was copied more accurately than pattern C suggests that, as hoped, some children did not see pattern D as a picture of an object. This is supported by the children’s verbal descriptions which indicate that 44 children saw pattern D as a design and not as an object. As 74 children copied correctly in condition D this suggests that 30 children saw pattern D as a cube, but, nevertheless, copied it correctly. It seems likely that most of these would be amongst those who copied correctly in condition C. Figure 4.

Examples of' drawings classified as incorrect.

CONDITION

Intellectual realism in children’s drawings ofcubes

25

Differences between the two age groups within each condition were analysed using the chi-squared test. The Primary 5 group produced significantly more correct drawings in conditions A and C, but not in condition B and D. Thus the older age group seem to be more accurate when copying pictures of objects, but not when copying non-object patterns. The Primary 5 group, however, still copy pictures of objects significantly less accurately than non-object patterns. Furthermore, only 11 of the 48 Primary 5 children drew a passable perspective representation from memory. Analysis of these results also shows that 10 of the 13 children who drew passable perspective representations from memory also drew copies classified as correct in condition A. Of the 28 children who drew correct copies in condition A, 23 drew copies classified as correct in condition C.

Table 2.

Classification of the nature of the errors in incorrect copies Condition

Intellectually Realistic errors Other

errors

D

A

C

66

44

7

19

2

5

15

4

Memory

The drawings were further analysed to investigate the nature of the structures drawn. The numbers of drawings in conditions A, C, D and Memory which seemed to contain intellectually realistic aspects are shown in Table 2. Most of the drawings made in conditions A, C, and from memory were classified as showing intellectually realistic aspects. Figure 5 may make clearer why they were so classified. This figure shows the frequencies of the most commonly drawn structures in condition A, and from memory. Most of the deviations from the perspective view seem intellectually realistic in that they involve such properties of cubes as symmetry, square faces or right-angled junctions, and flat bottoms. The structure formed from three square faces (fourth on the left in Figure 5) was more frequent in the younger age group, and most of the other drawings seem to be compromises between such a structure and the perspective view. Thus our classification of these drawings as containing intellectually realistic errors does not mean that they were totally intellectually realistic. The three-square structure itself seems to be a compromise in relation to the number of faces depicted. Those few structures classified as intellectually realistic for the purpose of Table 2 but not

26

W. A. Phillips, S. B. Hobbs and F. R. Pratt

shown in Figure 5 were usually easily so classified. The bottom left and top right drawings in Figure 4 are examples. The top right structure is the same as that observed by Minsky and Papert (1972). It was drawn by a few children but was not amongst the most frequent structures. Of the 96 children 64 drew structures from memory that seemed quite different from those drawn in condition A. A drawing consisting of three Figure 5.

Frequencies of the most common structures drawn in Condition A, and from memory. The structures are arranged such that going from left to right they increasingly approximate the perspective model copied. (Dots are omitted from the condition A structures.) The last two structures on the right correspond approximately to those classified as correct in Table I. This figure accounts for 88 of the 96 drawings in condition A, and 73 of the 96 drawings in the memory condition.

n

CONDITION

‘A’: I

MEMORY

CONDITION:

II

Iii

lAL_

Intellectual realism in children’s drawings of cubes

21

regions made as a copy of a perspective view was by no means indicative that the child would draw either three regions or a similar structure from memory.

Discussion There are two principal results of this investigation. The first is that drawings seen as objects are copied much less accurately than those not seen as objects. It is astonishing to see a child copy drawings of cubes using only squares and rectangles but copy similar designs not seen as cubes quite accurately. It is particularly astonishing when the child is looking continuously at the drawing being copied. The other main result is that although continuously looking at the drawing being copied does not remove intellectual realism it does reduce it. In the following sections we discuss the results, and suggest some possible theoretical interpretations. Intellectual

realism and copying

accuracy

Although alternative explanations are possible it seems reasonable to assume that patterns A and C are copied less accurately because they are seen as pictures of objects. Intellectual realism, therefore, is not removed simply by showing the child a solution to the problem of translating the representation of an object into a two-dimensional drawing. Their drawings are to some extent affected by what they are copying, however; few children copy pattern A by drawing exactly the same structure that they draw from memory. It has been pointed out to us (D. Christie, private communication) that patterns B and D are symmetrical about a vertical axis whereas patterns A and C are symmetrical about a diagonal axis. This could account for the differences in the accuracy with which they are copied, but it does not seem likely because, for example, the difference in the axes of symmetry is counteracted by a preponderance of diagonals in patterns B and D. Nevertheless this possibility should be tested by comparing copies of pattern C with copies of pattern B rotated 45” clockwise. Explallations

of intellectual

realism

These results weaken explanations of intellectual realism in terms of children’s understanding of what kind of picture is wanted. Children of this age seem to understand the idea of copying without difficulty, and, furthermore, the instructions, etc., applied to object and non-object patterns alike.

28

W. A. Phillips, S. B. Hobbs and F. R. Pratt

Lewis (1963) showed that children frequently prefer drawings that are more advanced towards visual realism than the drawings they produce themselves. It has been claimed that this cautions against making inferences about internal representations from children’s drawings. This claim seems mistaken, however. Both kinds of data are valid sources of evidence; they need not tell us about the same internal knowledge. One may tell us about the child’s knowledge of how to draw, the other about his knowledge of which is, in some sense, preferable. Furthermore, interpretation of preference data is not simple; drawings chosen are no more a direct route to the nature of internal representations than are drawings produced. This debate relates to our data because it is often assumed that the difference between preference and drawing is due to general graphic output limits, and that such limits could, therefore, explain intellectual realism. For the results reported above, however, explanations in terms of general graphic output limits do not seem likely. Children are able to copy drawings of this degree of complexity quite adequately ~ provided that they are not pictures of objects. Thus, in this case at least, intellectual realism seems to result from what children know about the objects depicted, rather than from general constraints set by their graphic skill. Why then do children copy perspective views of objects inaccurately, and depict instead the general properties of objects? The suggestion that it is because they are trying to draw reality rather than appearance implies that they could draw either but choose to draw reality. Why children make such a choice and how they distinguish between reality and appearance is usually not specified, but these problems may not be worth pursuing because such a choice may not be involved at all. Explanations are possible in which intellectual realism results from what the child is able to do, and not from what he chooses to do. In the following we briefly outline two such explanations. The first explanation is in terms of computational complexity. It seems likely that the computations necessary to translate an internal visual description into a drawing will be more complex when the internal description is of a solid object than when it is a description of a two-dimensional design. The necessity for such a translation may occur not only when drawing actual solid objects but also when copying pictures of objects. When copying a drawing the internal description created by seeing the drawing as a solid object will presumably describe the form of that object in three-dimensional space (or at least in ways that go beyond two-dimensional space). If so there still remains the problem of generating graphic instructions in a two-dimensional medium from a description which is not two-dimensional. There is also another way in which seeing something as a familiar object may increase computational complexity. Object data-structures are likely to contain infor-

Intellectual realism in children’s drawings of cubes

29

mation about the behavior and function of the object. This information may not be easily separated from a description of its shape. For example, information about the object’s stability when placed on various surfaces is likely to be related to a description of the shape of its base or bases; most of our children’s drawings had flat bottoms so this may be a major aspect of the data-structure for cubes. There is in general abundant evidence in children’s drawings of a concern for such behavioral and functional properties. This suggests that increasing the information in the data-structure from which a drawing is being created may increase the problems involved in selecting the aspects to draw, and in deciding how to draw them. Thus, an explanation in terms of computational complexity proposes that drawings seen as objects are copied less accurately because there are then more problems to solve. Drawings tend to display general properties of objects because they are relatively simple computations upon object datastructures. If the data-structure describes an object as having square faces this easily generates instructions to draw squares. If the data-structure emphasizes the stability of the object when placed on a flat surface this may tend to generate instructions to draw something with a flat bottom. The second possible explanation that we wish to discuss begins by noting that drawing does not necessarily involve generating graphic motor instructions by processing a visual image or description. It is possible that there exist motor programs for drawing which are self-contained in the sense that they do not refer to any visual representation, but which, when executed, produce a picture of something. In other words, knowing how to draw something may mean knowing what movements to make to produce a picture of it. Such a motor program we will call a graphic motor schema. Although graphic motor schema may at first seem unlikely, they may be much easier to represent, execute, and acquire than instructions on how to process the visual representation of something so as to produce a picture of it, For example, we can see what actions someone makes when drawing, but we cannot see how he is processing his internal representations. Thus, this explanation proposes that when copying a drawing that is seen as an object children use the graphic motor schema they have for that object. The drawing being copied serves only to select the graphic motor schema to be used, and does not guide it thereafter. Copies will be accurate, therefore, only to the extent that the childs’ graphic motor schema happens to produce the same particular view as that which he is copying. An explanation of this kind seems possible, but would have to be adjusted to account for the fact that the pictures being copied do often affect the children’s drawings to some extent. This could perhaps be achieved by an explanation combining computation upon a visual representation and

30

W. A. Phillips, S. B. Hobbs and F. R. Pratt

graphic motor schema; perhaps with the representation being processed to discover parts for which graphic motor schema are available. This suggests that it may be fruitful to study the interaction between the graphic familiarity with objects or their parts and the sequence of graphic movements with which they are drawn. A related study has already proved fruitful, for Goodnow and Levine (1973) have found a high degree of regularity in the graphic actions involved in copying geometric designs. Intellectual

realism and perception

Intellectual realism still seems to occur when children draw while looking continuously at the model being copied. This can be seen by comparing performance on patterns C and D. All children saw pattern C as a cube, but only about half saw pattern D as a cube. Fewer children copied pattern C accurately, and their errors were of the intellectually realistic kind. This result, therefore, provides support for the view that intellectual realism in part reflects intellectual realism in perception. The results, however, do not support the view (Arnheim, 1954) that intellectual realism in drawing wholly results from intellectual realism in perception. They suggest that the intellectual realism in drawing normally exceeds that in perception. The evidence for this is that pattern A was copied less accurately than pattern C. These patterns are identical except for the dots on pattern A, and these were ignored when assessing the accuracy with which the cube was drawn. The higher accuracy with which pattern C was copied implies that there is more view specific information in the accessible perceptual representation than is shown in drawings made under normal conditions. Continuous perception of the model is not the only way in which the two drawing procedures differ. For example, drawing while continuously looking at the model removes feedback from the drawing being produced. Such differences are interesting and important, but do not seem crucial to the present issue. Intellectual

realism and visual memory

The greater accuracy with which drawings of objects are copied when looking continuously at them raises the question as to why view specific information available in perception is omitted from copies made under normal conditions. An obvious possibility is that since normal drawing involves looking away from the object being drawn any information acquired during perception must be remembered while actually drawing. Evidence that some information is remembered is that copies of pattern A were more

Intellectual realism in children’s drawings of cubes

31

similar to pattern A and less intellectually realistic than were the drawings, made from memory. Although the times involved are short they are too long for iconic memory to be of any use. Recent studies of visualization and visual memory (Phillips & Christie, 1977a) suggest the existence of an easily disrupted and low capacity system for visualizing, which is in some ways analogous to verbal short-term memory. This system has the appropriate properties for use in drawing, and would enable the child to visualize information acquired from the model while looking at his own drawing. The capacity for visualization is severely limited, however (Phillips & Christie, 1977a; 1977b), and this limitation will particularly affect any view specific information that is not represented in the long-term data-structures for the object being drawn. By this process of active visualization, therefore, some, but not all, of the novel information acquired during perception could be carried over into the drawing. Age and learning

Our results show effects of intellectual realism in the drawings of 9% year old children. This conflicts with the suggestion of Freeman and Janikoun of a fairly abrupt change from intellectual to visual realism at between 7 and 8 years of age. However, they are consistent with the results of Lewis (1963), which suggest the presence of intellectually realistic aspects until at least 12 years of age. If intellectual realism changes gradually and persists this long then the attempt of Piaget and Inhelder (1969) to relate it to their theory of spatial intelligence is greatly weakened. Although intellectual realism is still present at 9% it is less than at 7% A possible process contributing to this change can be seen in the differences between the drawings made under different conditions. Copies of drawings of cubes contain more view specific information than drawings made from memory, and even more when the copy is made while looking continuously at the model. Thus, information specific to particular views may be gradually built into the child’s long-term data-structure for that object, either by being actively visualized or by being emphasized in perception. This in turn suggests that the main developmental change may be the gradual acquisition of detailed knowledge about specific and limited aspects of objects, rather than a change in the basic structure of the child’s spatial intelligence. If the developmental progression is a gradual increase in view specific knowledge the question arises as to when intellectual realism disappears. A possible answer is that it may never disappear. It is common to assume that perspective drawings, such as patterns A and C are produced as a result of visual realism. However, it could easily be argued that for anyone to see a

32

W. A. Phillips, S. B. Hobbsand

F. R. Pratt

few ink marks upon a piece of paper as a solid object requires a good deal of intellectual realism. At all stages of development, therefore, drawings and their interpretation may depend upon both a knowledge of general properties and knowledge of specific views. Ontology

Finally, we must make a brief comment on the question, “Which kind of representation is best?“. Gombrich (1972), for example, supports a particular kind of perspective view. Arnheim (1954), on the other hand, presents a spirited defense of the intellectually realistic kind of representation. Our description of the children’s drawings as accurate or inaccurate may suggest that we take the perspective view that they were copying to have a superior status. This we in no way intend. Both ‘intellectual’ and ‘visual’ aspects have a necessary role. Our aim is not to determine which is closer to reality, but to understand them better.

References Arnheim, R. (1954) Art and Visual Perception. Berkeley, University of California Press. Clark, A. B. (1897) The child’s attitude towards perspective problems. In E. Barnes (Ed.), Studies in Education. Vol. 1. Stanford, Calif., Stanford University Press. Freeman, N. H. and Janikoun, R. (1972) Intellectual realism in children’s drawings of a familiar object with distinctive features. child Devel., 43, 1116-l 121. Gombrich, E. H. (1972) The “‘What” and the “How”: Perspective representation and the phenomenal world. In R. Rudner and I. Scheffler (Eds.), Logic and Art. Indianapolis and New York, BobbsMerrill. Goodnow, J. J. and Levine, R. A. (1973) “The grammar of action”: Sequence and syntax in children’s copying. Cog. Psychoi., 4, 82-98. Lewis, H. P. (1963) Spatial representation in drawing as a correlate of development and a basis for picture preference. J. Genet. Psychok, 102, 95-107. Luquet, G. H. (1927) Le dessin enfantin. Paris, Alcan. Minsky, M. and Papert, S. (1972) Artificial intelligence progress report. Memo 252. Cambridge, Mass., M.I.T., Artificial Intelligence Lab. Phillips, W. A. and Christie, D. F. M. (1977a) Components of visual memory. Q. J. Exper. Psychol., 29, 1177133. Phillips, W. A. and Christie, D. F. M. (1977b) Interference with visualization. Q. J. Exper. PsychoZ., 29,637-650. Piaget, J. and Inhelder, B. (1969) The Psychology of the Child. London, Routledge.

96 enfants ont eu a copier un materiel compose de deux types de dessins faits de traits simples. Darts le premier cas les dessins representent des vues de cubes en perspective, dans l’autre les dessins sont similaires mais ne peuvent representer aucun objet.

Intellectual realism in children S drawings of cubes

33

Les representations de cubes sont reproduites avcc moins de precision que celles des non-objets. Les erreurs faites en copiant les cubes impliquent que les enfants remplacent des proprietes specifiques a la vue en perspective par les proprietks propres a l’objet lui-me^me. Dans une condition l’enfant copie en ayant sous les yeux le modele mais sans voir son dessin, darts I’autre la copie s’effectue normalement. Avec la premiere methode, les copies sont plus precises; cependant les cubes sont encore moins precisement copies que les patterns ne representant pas d’objets. En ce qui concerne la precision lit&ale de la copie, les copies d’objets sont encore desavantages i 9 ans et demi cependant moins nettement qtr.8 7 ans et demi. Deux interpretations sont avancees. Une en terme de complexit de calcul, l’autre en termes de schema moteur graphique. Sur la base des dessins obtenus, on presente des suggestions i propos du contenu et du developpement des structures don&es pour les cubes.

Cognition, @Elsevier

6 (1978) 35-53 Sequoia S.A., Lausanne

Planning

- Printed

in the Netherlands

units and syntax

in sentence

MARILYN

FORD*

VIRGINIA

M. HOLMES

University

production

of Melbourne

Abstract The study was conducted to determine, first, whether it is the deep or the surface clause that is more important as a speech planning unit, and second, whether syntactic decisions are made during sentence production. Subjects, while talking, heard tones to which they had to respond by pressing a button; reaction times to these tones were taken as an index of processing load during production. It was found that there were increased R Ts at the ends compared with the beginnings of deep structure clauses. No difference was found between RTs at the beginnings and ends of surface clauses not corresponding to a deep clause. The results were interpreted as showing that deep clauses are major planning units and that some planning for clauses occurs at the end of the preceding clause. Differences were found between RTs during clauses of different syntactic structure. These results were interpreted as indicating that syntax influences production and were discussed in relation to previous studies of pausing and speech disruption.

In order to produce an utterance which has coherent semantic organization and appropriate syntactic structure, a speaker must plan at least part of the utterance in advance. A central issue in the study of sentence production has been whether or not speakers plan in units that have some consistent basis. If they do, it seems likely that the unit is larger than the single word. Boomer (1965) found that hesitation pauses in spontaneous speech occurred towards the beginning of phonemic clauses. On the assumption that pauses reflect sentence planning activity, Boomer argued that speakers plan in phonemic clauses. Since phonemic clauses are usually surface structure clauses, these *Requests for reprints should be addressed Melbourne, Parkville, Victoria, Australia 3052.

to M. Ford,

Department

of Psychology,

University

of

36

Marilyn Ford and Virginia M. Holmes

results could also be interpreted as implicating the surface clause as a planning unit. This interpretation would seem to be supported by Hawkins (197 1), who found a much higher proportion of hesitation pauses at surface clause boundaries than at positions within clauses. In fact, the general opinion at the moment seems to be that the surface structure clause is probably the pri1974; Bever, mary speech planning unit (e.g., Fodor, Bever and Garrett, Carroll and Hurtig, 1976). The results of previous studies are, however, open to question. They do not preclude the possibility that speakers plan in more basic units such as simple propositions, which, in speech, correspond to deep structure clauses. It is possible that the deep structure clause is the primary speech planning unit and that the apparent importance of the surface clause has arisen because deep structure and surface structure boundaries often coincide. For example, the surface structure clause John is walking contains only one proposition or deep structure sentoid, and thus can also be considered as a deep structure clause. But the surface clause, John prefers to walk consists of two deep propositional units John prefers it and John walk which are realized in surface form by the deep structure clauses John prefers and to walk. Thus, in John prefers to walk the surface and deep structure clause boundaries do not coincide. It is impossible, from previous studies, to say whether it is the deep or the surface clause that is the more important unit. Because it is vital to the development of a model of sentence production to know the basic unit in which speech is planned, the present study aimed to see which of the two types of clauses is the major planning unit. Another important issue is whether decisions about syntax have to be made during sentence production. Goldman-Eisler (1968) has argued that general planning for content and syntactic structure takes place before utterances are produced, but that once a word is uttered, all further decisions involve lexical choice. She has proposed that selection of the syntactic structure occurs automatically, that words are merely slotted into an “existing structure” formed on the basis of well-learned routines. Her evidence for this view is not very convincing (cf., Boomer, 1970). Moreover, recent evidence has indicated that some syntactic operations do require planning. Rochester and Gill (1973) found that sentences .with different clause structure resulted in different amounts of disruption during their production. Specifically, complement sentences such as The fact that the woman was aggressive threatened the professors contained more filled pauses, corrections and other disruptions at the clause boundaries than superficially similar relative clause sentences such as The book which was written by Milleft was lauded by all. Results obtained by Goldman-Eisler (1972), showing that the amount of silent pausing differs before clauses of different syntactic types, could also be seen as suggesting that syntactic operations are involved in speaking. A second aim of

Planning Units and Syntax in Sentence Production

37

the present study was to seek further evidence for the role of syntactic decisions in sentence production. Clauses of the four major syntactic types were studied. It was not hypothesized that the more transformations needed to derive a certain structure the more difficult it would be to produce. Rather, it was simply hoped to see if clauses of different structure differ in production difficulty, thereby indicating that speakers make syntactic decisions of some sort. Most previous studies onsentence production have analyzed the occurrence of pauses or disruptions in spontaneous speech, assuming their location and frequency to be a valid index of where planning takes place and of how difficult it is. In fact, Goldman-Eisler (1968) has claimed that planning can only occur during pauses. However, it is possible that speakers can plan and talk at the same time. If this is true, then the study of pauses and disruptions alone is limited, since planning cannot be examined while words are actually being uttered. To overcome this problem, in the present study we used a modification of a technique used by Valian (197 1) which was based on the “click” reaction time task of Abrams and Bever (1969) and Holmes and Forster (1970). While they were talking, Valian’s subjects heard high- and low-pitched tones to which they had to make a motor response. The reaction times were presumed to measure the amount of spare processing capacity available at the time of the tone’s occurrence and thus to measure the difficulty of speech encoding at that point (cf., Kahneman, 1973). Valian compared reaction times at the beginnings and ends of surface and deep structure clauses in an attempt to decide which was the critical planning unit. However, her results did not allow an unequivocal interpretation to be made. Reaction times decreased significantly from the beginning to the end of clauses which were both surface and deep units, but this pattern did not hold true for surface clauses containing more than one deep structure clause, a result which would have been necessary to establish the surface clause as the more important unit. Similarly, the significance of the deep structure clause was not demonstrated either, because reaction times did not vary within deep structure clauses that did not correspond to surface structure clauses. It seems likely that the lack of any clear trends in Valian’s data results from the generally very high variance in the reaction times. Perhaps the most obvious possible cause for this was the extreme difficulty of the task, a fact which Valian herself conceded. Subjects had to discriminate between two different tones occurring very frequently, as often as once a second, and make an accurate motor response while they were telling stories to a friend. In the present experiment we felt that more reliable results would be obtained using a simple reaction time task with the tones occurring at longer intervals than those used by Valian. To further reduce error variance our subjects talked to the same

38

Marilyn Ford and Virginia M. Holmes

person rather than to a friend. It was hoped that an examination of performalice on this task would provide some insight into the nature of sentence production.

Method Design and Procedure

The subjects, who were unaware that the experiment was concerned with sentence production, were each interviewed individually by the senior author in two half-hour sessions. In one session the subjects heard and responded to tones while talking; in the other session tones were not presented, as a check for the possibility of disruptive effects of tones in the tone condition. Half of the subjects were interviewed in the tone condition first, and half were interviewed in the nontone condition first. In each session subjects spoke on five topics, the first of which was a practice topic. The eight test topics were The Role of Men and Women in Society, Attitudes to University Life, Old People, Childhood, Migrants, Schools You have Attended, Prevention and Punishment of Crime and Family Life. Eight orderings of the topics were used. At the introduction of each new topic subjects were asked three broad questions about it which were then repeated. Subjects talked for about five minutes on each topic. For the tone condition subjects were instructed to keep their right index finger on a response button and to press it as quickly as possible whenever they heard a tone. The subjects wore an earphone/microphone set through which they heard the tones, their own speech and that of the experimenter. Tones, which were 100 milliseconds in duration and 1000 Hz in frequency, were generated randomly by a PDP-1 1 computer at intervals of 2.0, 2.5, 3.5, 4.0 and 5.0 seconds. Reaction times to the tones were measured by the computer in milliseconds, and the tones and speech were tape-recorded. Data A naI_vsis

The subjects’ speech was transcribed verbatim by one of the experimenters. To locate the tones within the speech, the experimenter listened to the tapes at a reduced speed while following the speech on the transcripts. Pen recordings of the tapes were used to determine whether any tone near the beginning or end of a word actually occurred during the word or between words. The speech was then segmented into sentences, which were further segmented into surface and deep structure clauses. Each unit of speech which contained either an explicit or an implied verb was classified as a deep clause. Prenominal adjectives were not regarded as deep clauses because some discontent has been

Planning Units and Syntax in Sentence Production

39

expressed about deriving these from underlying sentences (cf., Lazarus, 1973). The speech in each clause was coded both for completeness, and for the number and position of meaningful words, filled pauses, repetitions, word choice mistakes, tongue slips, intruding incoherent sounds, and redundant words such as well and you know. The word and was considered as redundant when the speech following it was not syntactically dependent on the speech preceding the and as, for example, in the utterance There’s only room for one snob suburb and we weren’t in it. The words but, because, although, so and then were considered redundant in cases where, if they were omitted, the utterances preceding and following them were still meaningful. The word but, for example, was considered redundant in the utterance Some societal alterations could cure crime but I think the best way to cure it is to cure sick individuals. After the speech in the clauses had been coded the reaction times were marked on the transcripts and coding sheets. Reaction times in or before an incomplete clause were not included in the analyses. For each data analysis, the mean of the RTs of a given subject was calculated, and, in order to minimize the influence of any extremely long or short RTs, any score which was more than two standard deviations away from the mean was set at that cutoff value. Five per cent of the scores were adjusted in this way. For each subject, the means of the RTs from relevant speech samples were determined for the different classifications. Repeated measures analyses of variance with planned orthogonal contrasts were performed on these data (Kirk, 1968, pp. 81-82). Statistical decisions were based on a Type 1 error rate of (Y= 0.05. It should be noted that the min F’ statistic (Clark, 1973) is not relevant to the present experiment. Since each subject produced a different number and a completely different set of ‘items’, any significant result obtained could not be due to any particular ‘item’ or ‘items’. In fact, the calculation of min F’ would be impossible. For most analyses there were enough RTs to obtain reliable means for each subject. In three cases only was it necessary to estimate missing data for subjects by using Yates’ (1933) procedure. In carrying out the analyses when estimations were made, the degrees of freedom for the error sums of squares were appropriately reduced (Yates, 1933; Kirk, 1968, pp. 146-147) and corrections for bias of the treatment sums of squares were made (Yates, 1933; Anderson, 1946). Also, adjustments to the number of effective replications were made in performing the planned contrasts (Taylor, 1948). Footnotes in the tables of results show when Yates’ (1933) procedure was used. While the segmentation of speech into different clause types is relatively objective, it could be argued that segmenting spontaneous speech into sentences is difficult. Therefore, an independent judge was given transcripts of speech from four subjects, each talking on a different topic in the tone con-

40

Marilyn Ford and Virginia M. Holmes

dition, and was asked to segment the speech into sentences by applying criteria used by the experimenter. The judge and the experimenter agreed on 94% of the sentence boundaries. It might also be thought that one possible difficulty with the ‘click’ technique could be that the number of tones occurring during as opposed to between words might differ for different conditions and that significant RT differences could thus be due simply to whether or not subjects were vocalizing when a tone occurred. However, analyses were performed which ruled out this possibility. RTs during and between vocalizations were compared for each analysis of the study. The differences obtained were not consistent and in no analysis did they approach significance. Subjects

The subjects were 10 paid volunteers from the general student population at the University of Melbourne. They were all native speakers of English. The data for one subject were rejected because for over 15% of the tones he either forgot to respond or took longer than 1.4 seconds. The data for one other subject were rejected because his speech was indistinct.

Results Disruptions

It was first necessary to establish that requiring the subjects to listen for tones and respond to them did not prove disruptive to their speech. For each subject the number of meaningful words and speech disruptions was totalled as a measure of speech output, and the percentage of output consisting of different disruptions was calculated for the tone and nontone conditions. The group means are shown in Table 1. The main effect of disruption type was significant, F(6,42) = 41.68. Tukey’s HSD test for making post hoc pairwise comparisons among means (Kirk, 1968, pp. 88-90) showed that there was more speech consisting of redundant words than of any other types of disruption, and more filled pauses than tongue slips. The crucial finding was that the percentage of disrupted speech in the tone and nontone conditions did not differ significantly, F( 1,7) = 1 .lO. The interaction between speech condition and disruption type was also not significant, F(6,42) = 1.33. To see if there might have been more silent pausing in the tone than the nontone condition, the mean number of speech elements (words and speech disruptions) per minute was calculated for each subject by sampling two minutes of speech from each topic. The mean number of elements per minute in the nontone condition was 160.9, while that in the tone condition was

Planning Units and Syntax in Sentence Production

Table 1.

41

Mean percentage of speech consisting of different types of disruption for tone and nontone conditions Disruption

type

Speech

condition

Tone

Nontone

Filled pause Redundant word Repetition Word choice mistake Sentence incompletion Tongue slip Intruding sound

4.0 10.3 1.4 0.6 1.8 0.2 0.4

3.4 9.3 1.6 0.8 1.7 0.3 0.6

Total

18.7

17.7

162.1. The lack of any significant difference between these values (F < 1) provides further evidence that hearing and responding to tones had no detectable effect on the subjects’ speech. Deep

vs. Surface

Structure

Clauses as Planning

Units

By studying the production of clauses which are both deep and surface structure clauses, such as those in (A) of Table 2, it is possible to see if clauses are important planning units, though it is not possible to see whether it is the deep or the surface clause that is of primary importance. To answer this question, a different set of clauses must be examined. It is vital to study, as separate units, deep structure clauses which do not correspond to surface clauses, as shown in (B) of Table 2, and the surface clauses containing such units, as shown in (C). Thus, processing load at the beginnings and ends of these three types of clauses was studied. The beginnings and ends were the first and last half of clauses respectively, the division being made on the basis of the number of meaningful words in a clause. For clauses which were both deep and surface clauses, RTs were studied at the beginnings and ends of the first clause in a sentence and at the beginnings of the second clause. RTs at the ends of second clauses were not examined because such segments do not form a homogeneous group - some are followed by another clause while others are not. The analysis permitted RTs in three consecutive segments, each of which was relatively homogeneous, to be studied. The mean data over the eight subjects are shown in Table 3. RTs during the ends of the clauses were significantly longer than those at the beginnings, F( 1,14) = 5.64. There tended to be longer RTs at the beginning

42

Marilyn Ford and Virginia M. Holmes

Table 2.

Examples of sentences analyzed into clauses Sentences If capital punishment were brought in the murder rate would go down. I began working a lot harder when I finally decided to come to Uni. _ Clause analysis (A)

Clauses which are both cleep and surface structure If capital punishment were brought in 1. the murder rate would go down 2.

(B)

Deep structure 1. 2.

(C)

I began working

clauses which do not correspond 3. a lot harder 4.

Surface structure 1. 2.

clauses which

contain

clauses

to surface clauses when I finally decided to come to Uni

more than one deep clause

I began working a lot harder when I finally decided to come to Uni

-

Table 3.

Mean RTs (msec) as a function

of clause segment in clauses which are deep

and surface clausesa Clause segment Beginning

of first clause

Beginning

of second

aThe mean number

431 (9) 470 (10)

End of first clause clause of items per cell is shown

399 (12) in parentheses.

of the first than the second clauses, but the difference was not significant, F(1,14) = 1.36. The result showing that processing load increases towards the end of clauses which are both deep and surface clauses provides some evidence that clauses may be planning units and that planning may occur during the end of the previous clause. The two critical sets of clauses were examined next, to see which is more important: the deep or the surface clause. To analyze deep structure clauses not corresponding to surface clauses, the surface units containing these clauses were classified as being either (a) the first or only surface clause in a sentence or (b) a subsequent surface clause. Mean RTs at the beginnings and ends of the first deep clauses and the beginnings of the second deep clauses were studied. As the ends of the second clauses do not

43

Planning Units and Syntax in Sentence Production

form a homogeneous group these were not considered. For the analysis of surface clauses containing more than one deep unit, the presence of the deep clauses was ignored and RTs were examined in segments analogous to those studied in clauses that were both deep and surface clauses. Examples of subjects’ speech and the classification of tone locations in regard to the analyses are shown in Appendix A. In Table 4 the mean data for the critical sets of clauses are presented. For deep clauses, RTs were significantly longer at the ends of clauses than in the preceding and following beginnings of clauses, F (1,14) = 5.84. Neither the main effect of surface clause position nor the interaction between this factor and deep clause segment was significant, with F (1,7) = 2.95 and F (2,12) = 1.06 respectively. Thus, the same pattern of RTs during deep clauses exists regardless of the position of the surface clause in the sentence. Moreover, these results are the same as those found for clauses which are both deep and surface clauses. In contrast, no such pattern was found for the surface clauses which did not correspond to one deep unit: RTs at the ends of the clauses were not significantly different from those at the beginnings, F < 1. A further finding was that, overall, there was a tendency for RTs to be longer at the beginning of the first than the second clauses, though the result for neither the deep nor the surface clause analysis was significant, with F < 1 and F (1 ,13) = 1.11 respectively. The fact that the results obtained for clauses that were both deep and surface units were also found for the critical set of deep clauses, but not for the surface clause set, suggests that clauses which are deep units are basic units of planning. It has been assumed so far that the increase in RT at the ends of deep clauses is a function of speakers planning what to say in the next deep clause. An alternative view is that the increased processing load results from the Table 4

Mean RTs (msec) as a function of clause segment in the critical set of deep and surface claUsesa Clause segment

Beginning

Deep clauses

of first clause

End of first clause Beginning

of second

clause

Overall

Surface clauses

406 (8)

415

430c (4)

477 (6)

463

429

(5)

417 (5)

401

413

(9)

In fist or only surface clause

In subsequent surface clauses

423

(7)

448

(8)

384b (3)

%re mean number of items per cell is shown in parentheses. bin this cell the data for two subjects were estimated. ‘In this cell the datum for one subject was estimated.

44

Marilyn Ford and Virginia M. Holmes

speakers monitoring what they have just said. If this explanation is correct, RTs would still be expected to increase in deep clauses that are at the end of a sentence. However, if the increased RTs are largely due to planning for the next deep clause, then it is not so obvious that a variation in RTs would be expected in the last clause of a sentence. It is clear from the work of GoldmanEisler (1972), for example, that sentences are distinct units in speech and are, in the majority of cases, preceded by a pause. Thus, it seems unlikely that much planning of a completely new sentence would take place while the previous sentence was still being uttered. To see, then, whether increases in processing load at the end of deep clauses are due to monitoring or planning, RTs were examined for the two types of deep clause at the end of a sentence. The mean data are presented in Table 5. Neither the main effect of clause segment nor its interaction with clause type was significant, with both Fs < 1. The main effect of clause type was also not significant, F (1,7) = 1.6 1. These results lend support to the idea that the increased processing load is caused by planning for the next deep clause, rather than by monitoring earlier output. The results so far presented suggest that the deep clauses in a sentence are planned and produced successively. However, it is very possible that before each surface clause containing more than one deep unit, there is some planning and integration of all the deep clauses it contains. If the latter is true, then it might be expected that RTs would be longer before surface clauses containing more than one deep unit compared with surface clauses containing only one. RTs were considered before surface clauses at the beginning of a sentence, and during the ends of clauses preceding clauses later in the sentence. As Table 6 indicates, the mean RTs did not differ consistently as a function of the number of deep units contained by the surface clause. For both initial and subsequent surface clauses, the differences were not significant, with both Fs < 1. It appears that before a surface clause there is little, if any, planning and integration of all the deep clauses it contains, and thus that it is essentially only the first deep clause that is planned prior to the beginning of a surface clause. We have no evidence, then, to reject the hypothesis that sentence production does proceed basically by each deep clause being successively planned and uttered. Syntax and Production

Difficulty

The possibility that processing load might differ for clauses of different syntactic types was investigated to see whether speakers make decisions about syntax. Examples of the four types of deep clause considered are shown in italics in sentences (A) - (D) in Table 7. Since the results presented so far suggest that some planning occurs during the end of deep clauses, RTs

Planning Units and Syntax in Sentence Production

Table 5.

45

Mean RTs (msec) as a function of clause segment in final deep clauses of a sen tencea Clause segment

Clauses which are both deep and surface clauses

Deep structure clauses not corresponding to surface clauses

Overall

Beginning End

426 (12) 429 (16)

385 (5)

405 415

401(10)

&The mean number of items per cell is shown in parentheses.

Table 6.

Mean RTs (msec) before surface clauses as a function of number of deep unit? Segment

Before surface Before surface

initial clauses subsequent clauses

Number of deep units in surface clause One

More than one

417 (41)

435 (11)

453 (14)

429 (5)

aThe mean number of items per cell is shown in parentheses.

Table 7.

Examples of clause types (A)

Complements Her father thought that she should go to Uni. I liked swimming in rivers when I was a child.

(B)

Adverbials I went to a country school when I was in England.

(0

Right-branching relatives It had super footbrakes which you pressed on to stop it. They’ve got a wealth of experience to look back on.

(D)

Nonembedded clauses My brother came to Uni but my sister didn’t. As I was lonely I didn’t like Uni when I fist came.

46

Marilyn Ford and Virginia M. Holmes

were examined at the end of clauses preceding the four types. To see if there are differences in difficulty in the output phase when producing clauses of different structure, RTs during the beginning of the clauses were also exam ined. Allinstancesof the four types of clauses were included if they followed a completed clause. In Table 8 the mean data are shown. There was no significant clause type effect before the clauses, F < 1. However, at the beginning of the clauses the effect was significant, F (3,2 1) = 7.25. Post hoc orthogonal comparisons using Scheffes (1953) method showed that RTs during nonembedded clauses were significantly shorter than those during any other types of clauses, with F (1,2 1) = 10.0 1, and that RTs during right-branching relatives were significantly longer than those during complements and adverbials, F ( 1,2 1) = 11.3 1. The difference between complements and adverbials was not significant, F< 1. Table 8.

Mean RTs (msec) before and at the beginning of clauses as a function of clause type” Clause type ---

End of preceding

Complements Adverbials Relatives Nonembedded

447 448 432 440

aThe mean number

clause

(14) (6) (7) (9)

of items per cell is shown

Beginning 413 427 483 385

of clause -

(16) (8) (5) (6)

in parentheses.

Discussion The conclusion that the deep structure clause is the major unit of speech planning is opposed to the generally accepted view that the surface or phonemic clause is primary. The contrast between the suggestions from previous research (e.g., Boomer, 1965; Hawkins, 1971) and the present conclusion can be explained by the fact that the role of deep clauses has previously been ignored in production studies. The present findings suggest that the significant results of these earlier studies were caused by the fact that the critical speech constituents were deep clauses, and not, as has previously been assumed, by the fact that they were surface clauses. From the results of the present research it is obvious that in studies investigating planning units it is essential to distinguish the three possible classes of deep and surface clauses. While these three clause sets were considered in

Planning Units and Syntax in Sentence Production

47

Valian’s (197 1) study, her data, as already stated, could not justifiably be interpreted as showing whether deep or surface clauses are more important. It is interesting though, that Valian found RTs to be significantly longer at the beginning than the end of clauses which were deep and surface clauses. It is possible that this result was obtained because the serial position of clauses was not taken into account. Thus, for example, the first and last clauses of sentences would have been classified together. The present results indicate that such a procedure would have masked any real differences between the beginnings and ends of clauses. Also, there was a tendency in the present study for RTs to be longer at the beginning of the first than the second clause, although the differences were not significant. If there is any decrease in RTs throughout a sentence, then it is vital, in “click” studies, that only those clauses which occur in the same serial position be classed together. Fodor et al. (1974) have been the only theorists to argue that the abstract deep structure of sentences has “psychological reality” for the speaker, even though they have suggested that the surface clause is the basic speech planning unit. They hypothesize that the abstract deep structure is one processing level in the translation of ideas into sentences. The results of the present study cannot show that representations of standard abstract deep structures are constructed by speakers. However, the results do show that speakers must form representations of sentences in which propositions corresponding to deep clauses are encoded separately. The representation of the propositions within a sentence may eventually be shown to be that of a standard abstract deep structure. If this is so, however, it would appear from the present study that abstract deep sentoids would be even more important than Fodor et al. suggest. They maintain that the deep structure representation of a sentence “guides” its construction in such a way that when a surface clause contains a number of deep clauses, the sentence producer integrates the deep sentoids and translates these into a surface clause form. The results of the present study suggest that if sentence construction is “guided” by a deep structure representation, each abstract deep sentoid is independently translated into a surface form as a sentence is being produced. It is clear that the representation of a sentence is constructed with the progressive addition of new propositions corresponding to deep clauses. It is instructive to consider the present results in relation to views put forward about the perceptual segmentation of speech. Although there have been studies indicating that some kind of clause is the major unit of speech perception (for a review see Fodor et al., 1974), it has recently been suggested by Tanenhaus and Carroll (1975) that clauses may vary in the degree to which they can act as perceptual units. They have suggested that clauses that are more complete, that is, clauses where the relations between actor, action and

48

Marilyn Ford and Virginia M. Holmes

object are more clearly specified, are better perceptual units than are more degraded clauses. Thus, for example, on their view the surface structure clause that Jim refused the offer would be a better perceptual unit than the deep structure clause Jim’s refusing the offer. A number of degraded clauses may need to be processed together to form a perceptual unit. Tanenhaus and Carroll have reported that they have found some support for their views. The results of the present study, however, show that in speech production very degraded clauses are just as important as very complete clauses, the results for deep clauses being the same regardless of whether or not they corresponded to a surface clause and thus regardless of whether or not they were complete or degraded. It seems, then, that the basic units of speech production and speech perception might differ. Perception requires listeners to recover propositions that someone else has expressed. Thus, when propositions have been expressed in the form of very degraded clauses, the listener may need to process several successive clauses before being able to recover much meaning. Production, however, requires speakers to produce propositions that they themselves have created. Regardless of the form of the clause in which a speaker chooses to express a proposition, that proposition must have been planned. In production, then, a clause corresponding to a deep propositional unit may be a unit of planning no matter how completely it expresses the proposition. One important point to note is that if Tanenhaus and Carroll (1975) are correct, then the basic perceptual unit does not correspond to a specific syntactic unit. Since it corresponds to a stretch of speech where the meaning expressed can be recovered easily, it could be considered to be more like a semantic unit. In contrast, the major planning unit of sentence production seems to be a syntactically defined semantic unit. Thus, it is not easy, or perhaps even possible, to say whether the speech planning unit is basically syntactic or basically semantic. The unit we have proposed is obviously semantic, in that it corresponds to a basic proposition. However, the conventional definition of that proposition is a syntactic one, in that it is a unit of speech containing or implying a verb. What is clear is that our results indicate that the deep structure clause is a primary unit of speech planning. As well as establishing the importance of the deep structure clause as a planning unit, the present study clearly demonstrated that decisions must be made about syntax during sentence production. Results showed that the processing load during nonembedded clauses is lower than that during other clauses, and that the load is lower in complements and adverbials than in relatives. Hence, it must be concluded that the difficulty of the output phase in production differs for clauses of different syntactic types, and therefore that some decisions about syntax are made during this phase. By contrast,

Planning Units and Syntax

in Sentence Production

49

although some planning for deep clauses apparently occurs during the end of their preceding clause, no evidence was found to indicate that the processing load at the end of clauses differs before clauses of different structure. Perhaps at the end of a clause general planning for content and structure takes place for the next deep clause, but some of the syntactic details of this next clause may not be worked out fully until it is actually being uttered. It is interesting to compare the present results with those of previous studies. Rochester and Gill (1973) found that there were less disruptions at the clause boundaries of relatives than at the boundaries of complements. Goldman-Eisler (1972) also found that there was less silent pausing before relatives than before ‘other’ subordinate clauses. In addition, her results showed that there was less pausing before subordinate than coordinate clauses. Thus, the results for pausing and disruption at the beginning of clauses appear to be the reverse of the present results for processing load during clauses. The present results, however, seem meaningful in light of the correspondence between amount of processing load during clauses and the degree of linguistic integration of these clauses with main clauses. In the deep structure of relatives, which have the greatest processing load during output, there is always an element that is identical with an antecedent in the matrix sentence. Other types of clauses do not require such an antecedent (cf., Huddleston, 1971, p. 141). For example, in I agreed with the decision that he made the relative pronoun that stands for the decision which is the object of made and which has been mentioned in the matrix sentence. However, in I agreed with the decision that he should go the word that is merely a complementizer, having no referential meaning. While relatives are more closely tied to the matrix clause than are other subordinate clauses, all subordinate clauses, because they are embedded, are more integrated with preceding clauses than are nonembedded units. The results of the present study, then, show that processing load during clauses increases with increasing clause complexity as indexed by degree of linguistic integration of clauses with their preceding clause. What needs to be explained is the apparently strange fact, indicated by previous studies, that amount of pausing and disruption at clause boundaries decreases as clause complexity increases. It may be that the amount of pausing and disruption is dependent not on the difficulty of planning the next clause, but on the degree to which what has just been said is a complete linguistic unit. It is, of course, the simpler less closely integrated clauses that are preceded by more linguistically complete units. Speakers may produce more pausing and disruption after these more complete units because there is less need to produce the next clause immediately and also, perhaps, more chance to change what is to be said. A further point is that processing load during clause output may decrease with decreasing linguistic

50

Marilyn Ford and Virginia M. Holmes

integration, not only because of the decreasing complexity of the clauses, but also because the greater pausing before the simpler clauses may allow more complete planning to take place and thus a subsequent ease of production. Whatever the explanation of the relationship between prior pausing and disruption, clause complexity and output load, it is clear that syntax does affect the difficulty of encoding throughout sentence production and thus that speakers do make syntactic decisions. One important aspect of the present study is that a new technique was used to overcome the problem inherent in pause studies, that planning taking place while speech is being produced cannot be investigated. The technique showed that speakers do plan and talk at the same time. This finding shows that pause studies should be supplemented with investigations using other methods, and also demonstrates the value of the “click” technique. A further interesting conclusion emerging from the present study was that the amount of disruption and silent pausing before clauses probably does not correspond with clause complexity and processing load during clauses. It seems that the function of pauses and hesitations in speech may not merely be for planning what is to be said next - their face validity as indicators of planning may be misleading.

Appendix

A

The coding of speech

and tone locations

Four small samples of the speech of different subjects talking on different topics are presented here to show more clearly the clause analysis and the classification of tone locations in regard to the three sets of clauses. Key for clause analysis.

sentence boundaries surface clause boundaries deep clause boundaries that are not surface clause boundaries Filled pauses, redundant words, repetitions, word choice mistakes truding sounds are shown in italics. i,’

Key for tone location: * location of the tone in speech

Tone locations are coded on three variables: i. clause segment b beginning of clause e end of clause

and

in-

PlanningUnitsand Syntax in Sentence Production

51

ii.

clause type A clauses which are both deep and surface structure clauses B deep structure clauses which do not correspond to surface clauses C surface structure clauses which contain more than one deep clause iii. clause position 1 (for A and C) the first surface clause in a sentence (for B) the first deep clause in a surface clause 2 (for A and C) the second surface clause in a sentence (for B) the second deep clause in a surface clause Thus, for example, the code eB1 would stand for any tone located at the end of a deep structure clause which did not correspond to a surface clause and which was the first in a surface clause.

Speech samples: i.

FAMILY LIFE

. . . [(urn my mother intelligent these

person

pe$%)

ibhA&e less respect

for) (I’m afraid)]

[(she’s not a very

at al;)] [(she’s a bit of a chain smoker)]

[(and she’s one of

(who

are intensely

cleaning the place up)] the p&e ii.

up)]

[(my

houseproud)]

[(and she get?%her

sister is niiyvery

[(she spends all her time /

annoyed

at anyone)

(who mucks

nice person either) (I’m afraid)] . . .

OLD PEOPLE

. . . [(The people they’re

r%m bad thing is) (that / and reacting reacting

lose too)]

[(*urn I’m just tryingB/lto

knowing)

(how

think of ah the other

deaf / and tend / t(; go blind)]

and urn you know a;d generally (as $yget

understanding

[(oh ;!k:e’s the sort of physical disabilities)

[(JOU know yE;et

a bad thing)] deteriorates)

to them / around you / or or or*rather

to you)]

types of *urn* things)]

you lose the facili?;1/b8%

(that you

[(that’s that’s

bad health get [(your health

older)] . . .

iii. SCHOOLS YOU HAVE ATTENDED advantages / of knowing kids) (that haven’t gone . . . [(ah it doesn’t ha;rlhe *eBl .pF”. mversity and that / and had all the advantages riaalb)] [They were onto more or less expectz$l

to go onto University)]

[(and they’re

they’re ill very

52

Marilyn Ford and Virginia M. Holmes

urn conservative greater advantage

in this way)]

[( *urn coeducational

/ th%%ngle-sex

schools)]

have a great much

school

...

iv. THE ROLE OF MEN AND WOMEN IN SOCIETY . . . [(ah *it’s a matter changes) cated)

/ of changing

(such that the channels

(and can be tr%$d

att&?es

are availible)

so much)

(that

the system

(so that women

can be edu-

managers) ] [(because

/ to become

*eBl

bLzc;ght up by management

are

say) (right he

/ to become

managers)]

is likely / to be a manager)]

[(and

put him through

this / to become

[( ylow the system ha?&& to change) (such that

the managers woman

managers)]

*$l?b5?ck

i’they

out a woman

/ and say) (right

[(they

managers

this this this and

I *w”8 give get this

/ to do such such such and such / to train h& / to be a manager)]

...

It can be seen from the speech samples that there are nine different coding combinations. bA1, eA1, bA2 and bC1, bC2 signify tones used for the analysis of the type A and C clauses respectively. bB 1, eB 1, bB2 signify tones used for the analysis of type B clauses. These last tones, however, were further coded according to whether they occurred in a deep clause in (a) the first or only surface clause in a sentence or (b) a subsequent surface clause. Although some of the tones in the speech samples are not coded because they did not occur in one of the relevant positions, they would have been used in other analyses of the study.

References Abrams,

K. and Bever, T. G. (1969) Syntactic structure modifies attention during speech perception and recognition. Q. J. exper. PsychoZ., 21, 280-290. Anderson, R. L. (1964) Missing-plot techniques. Biomet. Bull., 2, 4147. Bever, T. G., Carroll, J. M. and Hurtig, R. (1976) Analogy or ungrammatical sequences that are utterable and comprehensible are the origins of new grammars in language acquisition and linguistic evolution. In T. G. Bever, J. J. Katz and D. T. Langendoen (Eds.),An integrated theory of ling&tic ability. Sussex, Harvester Press. Boomer, D. S. (1965) Hesitation and grammatical encoding. Lang. Sp., 8, 148-158. Boomer, D. S. (1970) Review of F. Goldman-Eisler Psycholinguistics Experiments in spontaneous speech. Lingua, 25, 152-164. Clark, H. H. (1973) The language-as-fvtedeffect fallacy: A critique of language statistics in psychological research. J. Verb. Learn. Verb. Behav., 12, 335-359.

Planning

Units and Syntax

in Sentence

Production

53

J. A., Bever, T. Gand Garrett, M. F. (1974) The psychology of language: An introduction to psycholinguistics and generative grammar. New York, McGraw-Hill. Goldman-Eisler, F. (1968) Psycholinguistics: Experiments in spontaneous speech. London, Academic Press. Goldman-Eisler, F. (1972) Pauses, clauses, sentences. Lang. Sp., 15, 103-113. Hawkins, P. R. (197 1) The syntactic location of hesitation pauses. Lang. Sp., 14, 277-288. Holmes, V. M. and Forster, K. 1. (1970) Detection of extraneous signals during sentence recognition. Percept. Psychophys., 7, 297-301. Huddleston, R. D. (1971) The sentence in written English: A syntactic study based on an analysis of scientific texts. Cambridge, Cambridge University Press. Kahneman, D. (1973) Attention and effort. Englewood Cliffs, Prentice Hall. Kirk, R. E. (1968) Experimental design: Procedures for the behavioral sciences. Belmont, California, Brooks/Cole. Lazarus, L. M. (1973) The deep structure of the prenominal adjective in English. Linguistics, 102, 41-57. Rochester, S. R. and Gill, J. (1973) Production of complex sentences in monologues and dialogues. J. Verb. Learn. Verb. Behav., 12, 203-210. Scheffe, H. A. (1953) A method for judging all possible contrasts in the analysis of variance. Biometrika, 40, 87-104. Tanenhaus, M. K. and Carroll, J. M. (1975) The clausal processing hierarchy... and nouniness. In Papers from the parasession on functionalism, Chicago Linguistic Society. Chicago, University of Chicago Press. Taylor, J. (1948) Errors of treatment and comparisons when observations are missing. Nature, 162, 262-263. Valian, V. V. (1971) Talking, listening and linguistic structure. Unpublished doctoral dissertation, Northeastern University. Yates, F. (1933) The analysis of replicated experiments when field results are incomplete. Emp. J. Exper. Agricul., I, 129-142. Fodor,

Resume Cette recherche a 6te faite pour determiner, premierement si c’est la proposition de surface ou la proposition de base qui est la plus importante comme unit6 de planification dans le discours, et deuxiemement si des decisions syntaxiques se font pendant la production de la phrase. Les sujets entendent pendant qu’ils sont en train de parler, des tons auxquels ils doivent repondre en appuyant sur un bouton. Les temps de reaction servent d’indice du poids de calcul durant la production. On trouve que les temps de reaction correspondant a des fins de proposition en structure profonde sont plus longs que ceux qui correspondent i des debuts de propositions. Pour les temps de reaction correspondant au debut et a la fin des propositions de surface lorsque celles-ci ne coincident pas a des propositions de la base on ne constate pas de difference. On interprete ces rdsultats comme indiquant que les propositions de la structure profonde sont les unites principales et qu’une partie de la planification pour les propositions se produit a la fin de la proposition precedente. On trouve des temps de reaction differents pendant des propositions de structure syntaxique differentes. Ce qui est vu comme l’indice d’une influence de la syntaxe sur la production et est discuti en relation avec les travaux anterieurs sur les pauses et les interruptions des discours.

Cognition, @ Elsevier

6 (1978)

Sequoia

55-77

S.A., Lausanne

- Printed

The interpretation

in the Netherlands

of universal

WILMA

affirmative

propositions

BUCCI”

State University Downstate

of New

Medical

York,

Center

Abstract It is proposed that All F are G is often given a ‘structure-neutral’ interpretation, as All, F, G, lacking a subject-predicate distinction. In the first experiment, children aged 6-7-8, and 11-12, and adults, acted out instructions like “‘Make a building in which all the yellow blocks are square”. The experiment demonstrated the dominance in children and decline with age of structure-neutral interpretations. In a second experiment, with the same age groups, propositions of the form All F are G, varying as to the factual inclusion relations expressed, were presented as the major premises of syllogistic items. The results indicated the presence of structure-neutral interpretations under some circumstances in adults as well as children, and also demonstrated the existence in all subjects of a ‘pragmatic processing’ mode that becomes less obligatory with age. In pragmatic interpretations, meaning is determined by previously known factual relations between the things which the words represent, rather than by grammatical relations between the words themselves.

Errors

in interpreting

universal

affirmative

propositions

of general

form:

*The author wishes to thank the principal, the faculty, and the very articulate students of Jefferson School in Maplewood, New Jersey, who participated in this study. This report is based on a Ph.D. dissertation submitted to New York University. The author is indebted to the committee members Murray Glanzer, Louise Kaplan, Annick Mansfield and Karl Schick and particularly to the chairman, Martin D. S. Braine. Requests for reprints should be sent to Wilma Bucci, Department of Psychiatry, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203.

56

W. Bucci

have been observed in many investigations of child and adult reasoning. After a brief review of several of these investigations, a new approach to accounting for such errors will be advanced. In a study by Inhelder and Piaget (1964), children were shown assortments of objects, e.g., red squares, blue circles, and blue squares, and were asked questions in which universal affirmative propositions were embedded, e.g.,: (2)

Are all the circles blue?

Five year old children were wrong on 33% of the items, (with 50% expected by chance) compared to 15% for seven year olds and 6% for nine year olds. Inhelder and Piaget attributed the young children’s errors to a type of sentence misinterpretation called ‘false quantification of the predicate’. According to this formulation, the children interpret (2) incorrectly to mean: (3)

Are all of the circlesall

whereas the correct (4)

of the blue (things)?;

interpretation

should be the following:

Are all of the circles some of the blue (things)?

Inhelder and Piaget link the young child’s error to his failure to grasp the relation of inclusion. That is, his application of the wrong quantifier to the predicate is linked to his inability to understand that one category (circles) can be part of another larger category (blue things). Studies of formal syllogistic reasoning, using subject matter such as letter names, have shown that adults also tend to make errors in interpreting universal affirmative propositions. For example, many adults erroneously accept the conclusion in the item below: (5)

All A’s are B’s. All C’s are B’s. Therefore all A’s are C’s.

Error rates on such items have averaged 50% or greater, depending on differences in procedure in the various studies (Begg and Denny, 1969; Ceraso and Provitera, 197 1; Chapman and Chapman, 1959; Woodworth and Sells, 1935). Two major theories have been proposed to account for errors on such items. According to the hypothesis of illicit conversion (Chapman and Chapman. 1959), people tend to understand quantified propositions as equivalent in meaning to their converse, even where such conversion alters truth value. Thus ‘All A’s are a’s would be misinterpreted to mean ‘All B’s are A’s’ as well. Given this misinterpretation of each proposition in (5),

Universalaffirmative propositions

57

acceptance of the conclusion follows. * The second major theory, the atmo sphere hypothesis of Woodworth and Sells (1935) holds that people may reach conclusions in such items not by reasoning, but simply by reacting to the general atmosphere created by the quantifiers (universal or particular) and valences (positive or negative) of the premises. Thus, two universal affirmative propositions as in (5) would create an atmosphere favorable to acceptance of a universal affirmative conclusion. Additional specific rules are included to account for items where different valences and quantifiers are used. All of these formulations may be questioned on either empirical or theoretical grounds. There are several reasons for doubting the adequacy of false quantification of the predicate (Inhelder and Piaget, 1964) as an account of the characteristic errors in either children or adults. On a theoretical basis, it has been pointed out by logicians that the general notion of quantifying predicates raises problems of logical formulation and may be unworkable (Kneale and Kneale, 1962). The overall approach is attributed by Inhelder and Piaget (1964) to the nineteenth century Scottish philosopher Hamilton, and has generally been rejected in other writings on logic and the logical apparatus of natural language. In general, predicative position is viewed as inaccessible to quantifiers and occupied instead by terms which complement quantifiers to yield sentences (Strawson, 1967). There is no quantification over predicates in first-order logic, and in set theory predicates are treated as classes and quantification over predicates is allowed only in the sense that idioms like ‘for some class’ and ‘for any class’ are admitted (Quine, 1960). Modern logic provides no notation that renders Piaget’s ‘All of the F are some of the G’. On an empirical level, ‘false quantification’ accounts for some of the children’s errors, e.g., responses of the following type to (2): (6)

No, because there are blue squares;

but fails to account (7)

for other errors such as the following:

No, there are red squares.

The presence of red squares would of course be irrelevant given the interpretation proposed in (3).** Another crucial empirical problem with the Piagetian formulation is the occurrence of errors in adults, who presumably *Another formulation, which holds that the copula is sometimes interpreted as incorporating the meaning ‘equal to’, is viewed here as a form of the conversion hypothesis, and will not be considered separately. **Certain of the children’s errors, as in (6), might also be generated if ‘all’ were understood to mean ‘all and only’. However this formulation would have even narrower applicability than the other approaches as a general account of errors with the universal quantifier, being unable to account for errors of the type of (5) as well as (7); and will not be further evaluated.

58

W. Bucci

have mastered inclusion. The issue raised here, of course, is not whether the young children lack mastery of class inclusion, but whether false quantification of the predicate is necessary (or sufficient) to account for the particular errors of interpretation shown in this task. Overall, the empirical adequacy of both the atmosphere and conversion hypotheses depends on their ability to account for items including particular and negative as well as universal and affirmative premises; this aspect will not be evaluated here. The atmosphere hypothesis is usually understood in terms of failure of reasoning processes, but error at the encoding stage is also implied (Revlis, 1975). The person forms a ‘global impression’ of each premise, rather than a logical representation of it (Begg and Denny, 1969). Given such a failure at the encoding stage, it is not clear that any further breakdown of reasoning processes need be postulated within this theoretical framework to account for the data. However, the specific nature of the possible encoding deficit has not been discussed by proponents of this approach. The conversion hypothesis generates the same interpretation of the proposition as false quantification of the predicate - i.e., a semantic representation in which F and G coincide. Thus, illicit conversion, like false quantification, accounts for the type of error where objects that are not-F and G are seen as falsifying the proposition, as in (6), but fails to account for errors involving objects belonging to neither F nor G, as in (7). Both illicit conversion and false quantification are essentially accounts of how a logical subject-predicate distinction may be nullified. In false quantification, the quantifier ‘all’ is extended over both terms, thus erasing the logical distinction between them. In illicit conversion, the two content terms are permitted to occupy either grammatical position interchangeably, so that the distinction between their grammatical functions is entirely eliminated. Both of these theories assume a basic linguistic structure in which a subjectpredicate distinction is assigned. Each model then provides a means by which this distinction may be nullified. It is suggested here that the assumption of an omnipresent subject-predicate dichotomy in every semantic representation reflects a confusion between the linguist’s theoretical definition of a complete sentence, and the actual output of the sentence comprehension process. A subject-predicate dichotomy may be a necessary criterion of a complete sentence; however this structure may not be achieved in every instance of processing a string of words. This paper will argue that there is a type of sentence interpretation, occurring under certain circumstances and in certain age groups, in which a subject-predicate distinction between the content words is not properly registered. The sentence is encoded as a simple string or unordered set of substantive words without hierarchical structure. i.e. :

Universalaffirmative propositions

(8)

59

All, F, G.

Given such a representation, the quantifier is not applied directly to one of the terms and excluded from application to the other, as would be the case were the subject and predicate functions properly distinguished. Therefore the correct inclusion relation - of F within G but not necessarily G within F - cannot be recovered. This ‘structure-neutral’ form is initially registered simply as a listing of semantic information including the main content may or may words, e.g., ‘all, blue, circles’. Then some further interpretation not be imposed, determined by context or by guessing strategy - not by the original sentence structure as such. For example, the sentence may be understood as indicating that the objects are all blue circles. This type of sentence processing would account for the characteristic errors in interpreting universal affirmative propositions, in a simpler and more direct manner than either of the theories discussed above. Furthermore, the structure-neutral interpretation can account for the type of error that the other theories cannot explain. For example, in the Piagetian experiment, suppose the child understands the question as dealing with application of the undifferentiated string to the set of objects, e.g., ‘Are they all blue circles?‘. This interpretation would cover all types of error responses, including those, such as (7), referring to objects that are neither F nor G. The errors in the syllogism studies are also consistent with this approach. For example, given ‘They’re all A, B’, and ‘They’re all B, C’, it follows that ‘They’re all A, B, C’ (or any subset). A corollary of the structure neutral hypothesis deals with the effect of familiar subject matter on sentence interpretation. The studies discussed so far have involved subject matter that may be described as ‘abstract’, where familiar factual relationships are not expressed. There is conflicting evidence as to the effect of familiar vs. abstract content on sentence interpretation. For example, Henle (1962) found that familiar subject matter interfered with logical responses; however, Wason and Johnson-Laird (1972) reported improvement in performance with such content. The effect of content on sentence interpretation can be accounted for on the basis of an underlying structure-neutral approach. Given an initial structure-neutral representation, the factual inclusion relations between the sets designated by the content words may replace the lost grammatical relations between the words in determining the meaning of the sentence. Where the real world contains obvious entities that are not-F and G, the interpretation reached will correspond to the one that would be generated by correct assignment of grammatical structure. In this case, familiar content will appear to aid logical processing. Where such entities do not come to mind, substitution of factual for grammatical relations will lead to a nonlogical representation. Where

60

W. Bucci

subject matter is abstract and factual knowledge is not applicable, the semantic interpretation can only be derived from the grammatical representation, whatever its nature, and is determined directly by this. This paper attempts to demonstrate the occurrence of structure-neutral interpretation of universal affirmative propositions, and to explore the relationship of this type of sentence processing to age level and subject matter. Experiment One involves subject matter where previous knowledge is not relevant to sentence interpretation. The effect of variation in subject matter is investigated in Experiment Two.

Experiment

I

This experiment included two tasks: in one, called the ‘Block building task’, subjects acted out block building instructions incorporating universal affirmative propositions; the second, called the ‘Display task’, was a verification task like the Inhelder and Piaget experiment above. Subjects Two child and one adult group were used: 37 young children ranging in age from 6 years, 6 months to 8 years, 4 months; 38 older children 11 years, 5 months to 12 years, 5 months; and 28 adults, N.Y.U. undergraduates fulfilling a psychology laboratory requirement. Children were chosen randomly in a suburban public school and were similar in socio-economic level to the college group.

1. Block Building Task Method Materials Fifty wooden

blocks, varying in shape, color, and size.

Experimental items Using the same content words (e.g., ‘yellow’ grammatical structure, a number of different generated, as in the following set:

and ‘square’), and varying instructional forms can be

(9) Make a building in which all the yellow blocks are square. (10) Make a building in which all the square blocks are yellow. (11) Make a building in which all the blocks are square and yellow.

Universalaffirmative propositions

61

(12) Make a building using all the square yellow blocks. If sentence structure were properly assigned, blocks which are not yellow (not-F) would be permissible in response to an instruction such as (9); blocks which are yellow and not square would be excluded. In response to (lo), blocks which are not square would be accepted and blocks which are square and not yellow would be rejected. In contrast, (11) leads to a building entirely of yellow square blocks; all others are rejected. Instruction (12) directs the person to use all the yellow squares available to him, and permits but does not require use of any other block. If sentence structure is not correctly assigned, but instead the structure-neutral interpretation ‘All, F, G’ is given, the person will have no basis for distinguishing between the instructional forms. That is, they will be registered as the same, in some form such as the following: (13) Make a building (in which they’re)

all F and G.

Given this form, the person would have no basis for including any particular blocks that are not F or not G, and excluding any others. Each subject was given a set of eight block building instructions. Four instructions incorporated universal affirmative propositions as in (9) and (10). Two instructions used three rather than two attributes, e.g. : ( 14) Make a building

(15) Make a building

in which all the small yellow blocks are square. in which all the small blocks are yellow

and square.

These were included to investigate the relationship of complexity to adequacy of sentence interpretation. The other two instructions were forms such as (11) and (12). These forms, which do not incorporate propositions of general form ‘All F are G’ were included for comparison purposes. They were not scored since accuracy of response to these forms per se is not relevant to the purpose of this research. In the eight instructions as given to the subjects, the attribute names were varied in balanced order, using color names ‘red ‘, ‘yellow’, ‘green’ and ‘blue’; shapes ‘rectangle’ and ‘square’; and sizes ‘large’ and ‘small’.

Probe questions

After the subject finished each building, the experimenter asked three followup questions of the following form: (16) Could you use any of these in a building in which (all the yellow blocks are square)? The particular proposition used in each instruction was embedded in the

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W. Bucci

question, and the question was asked with reference to three different blocks successively; these were held up as the questions were asked. Two of the questions referred to blocks that were acceptable given a structuredetermined but not a structure-neutral interpretation of ‘All F are G’, i.e., where the correct answer would be ‘yes’. These would be blocks with the properties ‘not-F’ and ‘G’, e.g., green rectangles, and with the properties ‘not-F’ and ‘G’, e.g., green squares. These two questions were used to probe for presence of a structure determined interpretation where for some reason this may not have been reflected in the initial block selection. For example, a subject may have decided on a strategy of using only blocks whose properties were explicitly stated (e.g., for (9) yellow squares) as the surest and most direct means of complying with the instruction. Similarly, subjects may have been biased by implicit conversational expectations, e.g., “If the experimenter had intended me to use the rectangles as well as the square yellow blocks, she would have said so”. However if they were capable of a correct interpretation of the proposition, they would accept ‘not F’, e.g., green blocks, in response to the probes, even if these had not been chosen at first. Thus the probes were intended to communicate the intent of the instructions to persons whose competence permitted the structuredetermined interpretation. This would be expected to remove the interfering biases and strategies in subsequent block selections as well as in response to the probe question itself. A third follow-up question was also used. This referred to blocks that would be unacceptable given a correct meaning of the proposition, i.e., with attributes ‘F’ and ‘not-G’, such as yellow rectangles for (16) where the correct answer would be ‘no’. This probe was intended to screen out responses where correct block selection was achieved by chance. An additional function of the probe questions was to insure that memory failure was not a factor in an error response. The proposition was fully restated in the question, and these were asked with the completed building in full view. Procedure The subject sat at a table with blocks piled on one side. The experimenter read each instruction aloud, then following with the probes as described above. The children were told that memory was not being tested and were advised to ask for repetition as often as necessary. The series of eight items was given with order randomized and counterbalanced over subjects. An item was scored as correct if the appropriate response was made either to the instruction or the probe. As noted, only the six items incorporating the general form ‘All F are G’ were scored.

Universalaffirmative propositions

63

Results and discussion

The performance of the subjects in the three age groups is shown in Table 1. In the group of 6 to 8 year old children, 5% had all items correct, one child had 4 out of 6 correct, and the remaining 92% gave responses of the type predicted by the structure-neutral hypothesis consistently for all forms. That is, they selected only blocks with both properties F and G in response to every instruction type and rejected blocks with attributes not-F and G and not-F and not-G in response to the probes. They explained their answers to the probes on the basis of absence of one or both of the stated attributes, e.g., “No, you said yellow squares”; “ No, you said it had to be yellow and it had to be square”; “No, you said a building out of yellow squares”; “No, it needs to be yellow”. They frequently expressed frustration at the small buildings to which their interpretation restricted them, e.g., “How can I make a building out of three little rectangles?“; “Why do you keep telling me to make these stupid little buildings ?“. However, they could not see their way to a different response. The 11 and 12 year olds showed some advance although less than had been expected: 16% had all items correct; 5% were correct on 5 out of 6; 5% had 3 correct; the remaining 74% gave the type of response predicted by the structure-neutral hypothesis consistently for all forms. For the latter, responses to the probe questions were essentially the same as for the 6 to 8 year olds, and they showed similar annoyance at the restrictions on their block selection. Overall, the adults showed mastery of this task, with 50% correct on all items, an additional 25% correct on 5 out of 6 items, and only 7% in error on all items. The response distribution of the adults, with 18% correct on 2, 3, or 4 items, indicates that a number of adults acquired insight into the task gradually, in the course of exposure to the items. This response spread across the middle range was not observed in the child groups. With very few excep-

Table 1. Age

6-l-8 11-12 Adult

Block building task: number of items correct (proportion of subjects) Number

31 38 28

of Subjects

Number

of Items Correct

6

5

4

3

2

1

0

0.05 0.16 0.50

0 0.05 0.25

0.03 0 0.07

0 0.05 0.07

0 0 0.04

0 0 0

0.92 0.74 0.07

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W. Bucci

tions, children were either correct on 5 or 6 out of 6, or wrong on all items. Many adults reported that the probe questions had stimulated the shift in the nature of their responses. As one said, “Oh, I see, that means I can use other ones. It was obvious but I didn’t get it at first”. Others referred to the variation in sentence type to explain their insight, e.g.: “Now I see a difference between the sentences. I can still use these because of the way it is worded”. Thus, the procedures were apparently effective in eliciting a correct response in those adults who presumably had the capacity to generate logical representations. The mention of three rather than two attributes in a proposition was not related to level of correct response at any age level. That is, if people were able to interpret the propositions logically, they did so for three as well as two attribute items, although with greater effort. For subjects who responded correctly, reaction times tended to be longer to the more complex items, and more repetitions were requested. The type of thought process involved in solving these items may be illustrated by the following adult, thinking aloud: “Let’s see, all the red blocks are small and square. That means I can’t use any red blocks that aren’t small and square. O.K., that means I can’t use any of the red rectangles, but I can use these... etc.“. In contrast, subjects whose responses were structure-neutral handled the three attribute items as easily as the two. It appeared no more difficult for them to select blocks that were ‘small and red and square’ (in their interpretation) than to select blocks that were red and square.

2. Display Task The second part of Experiment One was a replication with minor variations of the Piagetian experiment described above. This employed the same type of proposition as in the building task, but in a different context. Method Materials Six sets of 5 or 6 small plastic blocks varying in size, shape and color, glued onto cards. Test items Two sentences, one true and one false, were prepared for each card. For example, given a card containing yellow and blue squares and blue rectangles, the following sentences were used:

Universalaffirmative propositions

65

(17) On this card all the yellow blocks are square. (18) On this card all the blue blocks are rectangles. Two of the six sentence pairs involved three to test the relation of complexity to recognition the building task.

rather than two attributes, of syntactic structure, as in

Procedure

Each subject was given three true and three false items. The task was presented in the same experimental session as the block building, with balanced order. Since the primary reason for including this task was to provide some comparison with the results reported by Inhelder and Piaget (1964), it should be noted that the procedure differed slightly from the Piagetian paradigm. First, small sets consisting of 5 or 6 objects were used here, compared to sets ranging up to more than 20 in the Piagetian paradigm, in order to reduce the possibility of errors resulting simply from careless examination of the set. Second, the propositions were presented as true-false items rather than in the question form used by Inhelder and Piaget, to retain the surface declarative form of ‘All F are G’. Results and discussion

Comparable data from Inhelder and Piaget are available only for the 6 to 8 year old age group, on the two attribute types of item. The 6 to 8 year olds in the display task reported here were correct on 84% of such items compared to 85% for thirty 6 to 8 year olds tested by Inhelder and Piaget (computed from Inhelder and Piaget, 1964, Table 1a, p. 64). The 11 and 12 year olds in this study were correct on 91% of such items and the adults on 96%. These age groups were not tested by Inhelder and Piaget. In the Inhelder and Piaget study, 47% of the 6 to 8 year old children answered all such items correctly, compared to 54% of 6 to 8 year olds in this experiment, 7 1% of 11 and 12 year olds, and 72% of adults. The similarity of results for the 6 to 8 year olds suggests that the same general abilities were probably tapped by both studies, despite slight differences in procedure. These results seem to indicate considerable ability to interpret universal affirmative propositions correctly at the 6 to 8 year level, and essentially mature performance by 1 l- 12. However, this finding may be somewhat misleading. Analysis of the fundamental nature of this task reveals that only true statements are relevant to the presence of structure determined vs. structure-neutral sentence interpretation. For example, consider a statement such as (17) above, ‘All the yellow blocks are square’, where the display

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consisted of yellow and blue squares and blue rectangles. Given a correct interpretation, this statement is true. However, a structure-neutral interpretation, e.g., ‘The blocks are all yellow and square’ would be false since blue and rectangle blocks are present. Now consider a statement such as (18) above, ‘All the blue blocks are rectangles’. Given a correct interpretation, this statement is false for the display described above. Unlike ( 17), however, the structure-neutral interpretation of (18) has the same truth value as the structure determined one. That is, the sentence remains false given a structure-neutral interpretation, e.g., ‘All the blocks are blue and rectangle’, since yellow and square blocks are present. Therefore, while errors on the true items may be attributed to structure-neutral sentence interpretation, errors on the false items do not derive from this source, and probably relate to nonlinguistic factors such as failure of attention. Figure 1.

Block display task: per cent of subjects responding correctly to ‘true’ vs. ffalse.’ items. 100 90 (I) I-

F

80-

E 702 =I GOu-l I& 50g, 40530% 20 IO

t

OL$_:18--’ II-12

AGE GROUP

The proportion of subjects at-each age level answering true vs. false items correctly is shown in Figure 1. (The figure includes data for all three as well as two attribute items.) For true items, differences between adult and older children’s response levels were significant (x2 = 7.86, df = 1, p < 0.01). The data also point toward a possible difference between older and younger children on this task, although this finding is less clear (x2 = 3.07, df = 1, p < 0.10). In contrast, performance on false items was virtually unchanged over the entire age range covered here, with slightly over 80% in each group answering all false items correctly.

Universal affirmative propositions

The implications of performance differences on true vs. false items were not reported by Inhelder and Piaget. The data of the true-false study, as in the block building task, may be interpreted as indicating misinterpretation of universal affirmative propositions well beyound the age at which operational class inclusion structures have presumably been acquired. Performance of the 1 l- 12 year old children was in fact significantly different from that of the adults, and not quite significantly different from the younger age group. Adults showed little difficulty with this display task. Their performance was essentially equivalent for both truth value categories with 88% correct on all true and 82% on all false items. Thus their errors can generally be attributed to nonlinguistic factors such as inattention rather than to misinterpretation of the propositions.

Experiment II This experiment investigated the effect of variation in subject matter on the interpretation of universal affirmative propositions in a syllogistic reasoning task. In one subject-matter type, many examples of G that are not F would be likely to occur to a subject; in the second, F and G probably have the same extension for most subjects; and in the third no prior inclusion relation could be known. Method Subjects The two child groups consisted of 32 subjects each, ages 6-7-8 and 11-12, selected on a random basis from the sample in Experiment One; the adults were the same 28 subjects as in Experiment One. Item composition Three types of content were used, termed ‘broad predicate’, ‘narrow predicate’, and abstract’. Four propositions were generated to represent each content type. These were presented as the major premises of syllogistic forms. In broad predicate items, the property referred to by the predicate could apply to many entities other than referents of the subject term: Broad predicate items (19) All football players are strong. (20) Every cat has whiskers. (2 1) All bears are dangerous. (22) All haunted houses are dark and quiet.

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In narrow predicate items, the predicate term was far less general, applicable to few or in some cases no entities other than referents of the subject term:

Narrow predicate items (23) All oak trees have acorns. (24) All birds have feathers. (25) Every dog can bark. (26) All birds hatch from eggs. Occasional specific instances of G and not-F may come to mind for the narrow predicate items. For example, seals do a version of barking; fish and reptiles hatch from eggs. However, such instances are less obvious and numerous than for the broad predicate items. In the abstract items, there were no necessary or habital associations that could be previously known. (This use of ‘abstract’, as denoting absence of familiar, well-known relationships, is similar to that of Wason and JohnsonLaird, 1972.)

Abstract items (27) All the pink blocks are rectangles, (28) All the large blocks are orange. (29) All the square blocks are purple. (30) Every white block is small. Content words in the three categories were equated for familiarity by reference to the American Heritage Intermediate Corpus norms for grades three to eight (Carroll et al., 197 1). For each of the 12 major premises, four syllogistic forms were generated, yielding a total of 48 items. The minor premise either affirmed or denied membership in the subject or predicate category: Modus ponens

Affirming the Consequent

Denying the Antecedent

Modus tollens

All F are G. X is F. Is X G?

All F are G. X is G. Is X F?

All F are G. X is not F. IsXG?

All F are G. X is not G. Is X F?

Given a correct representation of the major premise, such that F must be included in G, but G is not necessarily included in F, the correct response is ‘yes’ for modus ponens, ‘no’ for tollens, and ‘not sure’ for the other two forms. However, if the internal representation assigned to the major premise were such that one category did not extend beyond the other, the answer

Universalajfirmative propositions

69

would be ‘yes’ for affirming the consequent, just as for modus ponens, and ‘no’ for denying the antecedent, as for tollens. That is, any member of one category would necessarily belong to the other; similarly, any entity excluded from one category would necessarily be excluded from the other. The predicted responses differ only for affirming the consequent and denying the antecedent. Therefore, these are the critical forms with respect to interpretation of the major premise. The predicted responses for ponens and tollens are the same given either a correct or a nonlogical representation of the major premise. Therefore, errors on these forms may be attributed to factors other than sentence intepretation, such as failures of memory, attention, or deductive processes. Procedure Subjects were told that the experimenter would read some sentences and then ask some questions. The instructions stressed the following major points: they should answer the questions on the basis of what the sentences said, not what they happened to know; in some cases, the sentences might not contain enough information to answer the question, so that the correct answer would be ‘not sure’; memory was not being tested and any item would be repeated as often as required. The following sample item was used to illustrate the task requirements, particularly the point of relying on the premises as given: All zorru birds are yellow. The animal I am thinking of is a zorru bird. Is it yellow? If a subject indicated that he was unable to answer the question because he “never saw a zorru bird”, he was then reminded to attend to what the sentences told him. The items were read aloud in all groups. In the broad and narrow predicate types, the minor premise was given in the form used in the sample for the first two items, i.e., ‘The (X) I am thinking of is a . ..‘. and in a shorter form thereafter, i.e., ‘This (X) is a . ..‘. While reading the abstract items, the experimenter showed the subject an opaque bag that had been described as containing blocks of different colors, sizes, and shapes, and reached inside it, presumably to take a particular block in her hand. The minor premise was given in the following form: ‘The block in my hand is ...‘. The special wording of the minor premise in all items, and the use of the opaque bag in the abstract items were designed to imply the existence of specific referents without presenting visible objects. Pilot work had indicated that such anchoring to specific objects avoided confusion, particularly for the younger children.

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W. Bucci

Each person was given 12 items, one of each of the four forms in each of the three content categories, with order randomized and counterbalanced over subjects. The total set of 48 items was balanced over subjects within each age group. The children were given the syllogisms in a session separated from Experiment One by several days, with order of experiments balanced. For adults, both experiments were performed in a single session with order balanced. Results

and Discussion

Complete response distributions to all forms of the syllogisms in each content type are shown in Table 2. The proportion of correct responses (‘yes’ to ponens, ‘no’ to tollens, ‘not sure’ to affirming the consequent and Table 2.

4x

Responses to syllogistic items: three content types (per cent of total) Content Type

Syllogism Forma

Broad

-

Predicate

Yes

Not sure

_ No

Narrow

Predicate

Yes

Not sure

Abstract No

Yes

Not sure

No

6-7-8

M.P. A.C. D.A. M.T.

81b 78 13 3

6 I3 31 6

13 9 56 91

91 84 6 6

3 3 9 3

6 13 84 91

81 91 22 25

9 0 9 3

9 9 69 72

11-12

M.P. A.C. D.A. M.T.

88 50 6 6

6 34 53 9

6 16 41 84

91 69 6 6

6 31 21 3

3 0 72 91

84 84 3 3

3 6 16 0

13 9 81 97

Adult

M.P. A.C. D.A. M.T.

96 4 0 0

0 96 96 27

4 0 4 73

96 22 4 4

4 78 79 8

0 0 18 88

93 48 0 0

7 48 67 22

0 4 33 78

ahl.P. Modus ponens; A.C. Affirming the consequent; bCorrect answers are shown in italics.

D.A. Denying

the antecedent;

M.T. Modus tollens.

denying the antecedent) are shown separately for each form of the syllogism in Figure 2. Level of correct response on the modus ponens and modus tollens forms did not vary significantly with either age level or content type. The ability of even the young children to answer these forms correctly indicates a general capacity to combine propositions and draw correct inferences. Therefore, errors on the other two forms cannot be attributed to absence of

Universal affirmative propositions

Figure 2.

71

Per cent of correct response to syllogistic forms as a function of age and content type. AFFIRMING THE CONSEQUENT

DENYING THE ANTECEDENT

MODUS TOLLENS

l\

‘,

.--. o--o o---o

ADULTS II-12 6- 7- 6

BROAD NAR. ABSTR. PRED. PREO.

\

?\ \\ \\ \\ \\ .

D.._ -*._ \ --0, ---._

0

BROAD NAR. ABSTR. PRED. PRED.

I

BROAD NAR. ABSTR. PRED PRED.

I

I

BROAD NAR. ABSTR PRED. PRED.

CONTENTTYPE

this capacity. Performance of the older children actually surpassed that of adults on modus tollens, particularly in the abstract content type. As noted, correct response to tollens is compatible with structure-neutral sentence interpretation. However, the ‘not sure’ response given by approximately onefourth of adults (in the broad predicate and abstract items), although an error for this form, nevertheless implies a representation of the major premise in which one category extends beyond the other. Thus the adult error on this form does not appear to reflect faulty sentence interpretation of the type characterized here as structure-neutral. The particular difficulty with the modus tollens form for adults, which is outside the scope of this paper, has been discussed by Wason and Johnson-Land, (1972). For all age groups, correct performance on the two critical forms of the syllogism (affirming the consequent and denying the antecedent) was highest in the broad predicate category and declined in the other two types, as shown in Figure 2. The difference between the broad and narrow predicate categories on the two critical forms was significant for adults (x2 = 6.6, df = 1, p < 0.02) and for 6-7-8-year-olds (x2 = 5.2, df = 1, p < 0.02),

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W. Bucci

but was only a trend for the 1 l- 12-year-olds (x2 = 3.41, df = 1, p < 0.1 O).* Performance on the two critical forms was significantly better for narrow predicate than abstract items for adults (x2 = 4.63, df = 1, p < 0.05) and 1 l-12-year olds (x * = 4 . 16, df = 1, p < 0.05). The difference was slight and insignificant for the 6-7-8-year-olds, who showed little competence in either content type.** The errors on the critical forms in all content types were predominantly to answer ‘yes’ to forms where the consequent is affirmed, as to ponens, and ‘no’ where the antecedent is denied, as to tollens, as predicted on the basis of a structure-neutral representation of the major premise. The higher performance levels for all age groups on the broad predicate items suggest that pragmatic representation aids sentence interpretation at all age levels. This fact suggests a processing mode in which pragmatic relations between things are substituted for grammatical relations between words in generating a representation for the sentence. Where the predicate is broad and general, there are many possible examples of G and not-F that may come to mind. The resulting representation of the relationship between the subject and predicate terms, in which G may extend beyond F, is equivalent to one that would be derived from the correct grammatical structure. Where the predicate is limited in application, so that such examples do not come to mind, the representation is similar to one that would be generated by failure to differentiate the subject and predicate functions. The children’s dependence on specific instances of G and not-F in generating a logical response is supported by their comments accompanying their answers. For example, given the item, ‘All haunted houses are dark and quiet; This house is dark and quiet; Is it haunted?‘, a 7-year-old said: “Might be a rented house or a beach house that nobody is using; it doesn’t have to be haunted”; and an 1 l-year-old said: “Not sure - our house used to be dark and quiet and it’s not haunted”. Similarly, given the item, ‘Every cat has whiskers: This animal is not a cat; Does it have whiskers?‘, typical answers were: “My daddy has whiskers. He has to shave every morning. And he’s not a cat”; “Maybe - because there are other animals that have whiskers - a goat “. , “Mice have whiskers, and rats”. As might be expected in this type of processing, children sometimes referred to instances of the subject not

*The data in the 11-12 year-old group were affected by a high level of logical response to one narrow predicate item, ‘All birds hatch from eggs’. For this item, entities that were G and not-F (e.g., snakes, turtles, and fish) came to mind very readily for some 1 l-l 2 year-old boys, so that the item actually functioned as a broad predicate type for them). **For all age groups performance in the more difficult categories was an almost perfect predictor to the easier ones, so that the items functioned as a scale. Only 3% of subjects who were correct on both items in a more difficult category made even a single error on an easier one.

Universal affirmative propositions

73

belonging to the predicate category, thus generating a special type of error response. For example, given the modus ponens item, ‘All football players are strong; This man is strong; Is he a football player?“, an 1 l-year-old said: “Not sure. Some football players don’t have to be real strong. Quarterbacks have to be good passers”. Errors of this type were relatively rare since the propositions were intended as true, i.e., without factual instances of F and not-G. This pragmatic approach to sentence processing can generally yield a logical representation only for items of the broad predicate type. Specific instances of G in narrow predicate items are likely to be instances of F also. Persons who were successful on the narrow as well as broad predicate items were apparently able to generate a correct representation even where specific instances did not come to mind, as reflected in the following comment by a 12-year-old : “I have to say not sure. There could be other trees that have acorns. I can’t think of any but there could be some”. In contrast to the pragmatic processing mode, here the possibility of G and not-F is derived from sentence structure rather than from specific instances, and is maintained even when it appears counter-factual. As a lZyear-old said: “Not sure, because it doesn’t say other animals don’t have feathers, it just says birds have feathers. The answer is really yes, but it doesn’t say it.” Thus performance differences between narrow and broad predicate items can be accounted for by differential use of pragmatic processing. The data suggest application of this type of processing at all age levels. Predictions as to sentence representation in this processing mode will of course vary with the sentence processor’s particular state of knowledge and interest concerning the subject matter. At least two factors may have contributed to higher performance levels on the narrow predicate over the abstract items. First, pragmatic processing may have been effective, at least to a limited extent, in the narrow predicate items. The subject matter in these items was similar to the broad predicate ones in that specific referents were likely to come to mind. Most of these were instances of F and G and thus not conducive to a correct interpretation. However, for certain items, there were in reality factual instances of G and not-F, although fewer than in the broad predicate type. For example, seals make a sound sometimes described as barking, and species other than birds hatch from eggs. In contrast, in the abstract items, the subject matter was such that specific referents were not likely to come to mind, and in fact did not do so for the subjects in this experiment. There was no case in which a subject volunteered a response based on evocation of specific instances such as were common in the other content categories, i.e., no one ever said anything like, “I have a rectangle block and it’s not pink”.

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A second reason for higher performance levels on narrow predicate over abstract items may be that subject-predicate structure is more readily assigned in sentences of the former type. The very fact that specific familiar referents of any type are evoked may affect assignment of sentence structure itself. The evocation of a specific referent may aid assignment of sentence structure by establishing the fundamental semantic distinction between reference and attribution. That is, it may be easier to distinguish the entity that the sentence is about (the subject term) from the part of the sentence that says something about it (the predicate) when one has a specific entity in mind. This very speculative notion remains to be tested in future work. The tentative conclusion may be reached that there are two basic types of processes, one pragmatic and the other based on surface grammatical structure, that contribute differently to interpretation of universal affirmative propositions in the three content types. Pragmatic processing will generally lead to correct sentence interpretation in the broad predicate items, is less likely to do so in the narrow predicate types, and does not apply in the abstract content type. Appropriate assignment of grammatical structure would of course produce consistently correct sentence interpretation independent of the nature of the subject matter. However, grammatical structure may be less readily assigned in items of the abstract content type.

General Discussion The data presented here may be accounted for by a type of sentence interpretation in which the grammatical subject-predicate distinction is not made. This investigation has dealt with universal affirmative propositions only. It is not clear to what extent or under what circumstances the subjectpredicate dichotomy might be lost in other logical forms. For example, in propositions with ‘some’, unlike the universal ones, the meaning of the quantifier itself indicates that the two categories do not necessarily coincide, i.e., G does not have to apply to all of F. This in itself may signal the need to make a logical distinction between the substantive terms. Correct grammatical structure may also be more readily assigned in sentences dealing with particular actions or events, where the functional subject-predicate distinction might be derived on the basis of semantic roles. Young children showed little capacity for assigning grammatical structure correctly in these propositions, in either experiment. The data suggest that where young children appear to respond logically to universal affirmative propositions in natural language situations, they may be relying on pragmatic rather than grammatical representations. They may appear to function well

Universalaffirmative propositions

75

because broad predicate propositions are probably the most common type in everyday discourse, and in such propositions pragmatic representation will yield a logical response. Narrow predicate propositions are relatively rare and difficult to generate, as the reader can demonstrate for himself. The performance of the older children indicates that ability to assign grammatical structure consistently to these propositions is achieved fairly late in development - perhaps in the adolescent years. The l l-12-year-old subjects showed some capacity for assigning grammatical structure in the display and building tasks where visible referents were present, and in the narrow predicate items, where subject matter was familiar, but very little competence in the abstract syllogism task. In general, their performance was below the level anticipated on the basis of previous studies in the Piagetian framework. The majority of adults was able to respond correctly to the block building and display tasks; however, their performance varied with content in the syllogistic items. Overall, the findings suggest that adults may have several modes of generating a representation for universal affirmative propositions. These may operate either as alternative processes or in a combined strategy. For example, in the first pass through a sentence an adult may register the simple unstructured list of quantifier and content words. He may then generate a representation of the sentence by imagining specific referents of the subject and predicate terms and combining these on the basis of his general knowledge of the relationships between them. This would provide an initial interpretation of the sentence. The notion that sentence processing involves imagining specific referents is compatible with a model proposed by Johnson-Laird (1975). According to this, people may represent universal affirmative propositions by imagining discrete members of the two classes F and G, in some form that may be either iconic or abstract. The two classes are then related by mapping individual representatives of one class onto representatives of the other. In Johnson-Laird’s model, the relation between the classes, and the possibility of members of one class who do not belong to the other (G and not F) are derived from sentence structure. In contrast, in pragmatic processing, the relation between the classes and the possibility of G and not F are derived from general knowledge. Under some circumstances, the adult may stop his processing at this initial interpretation, and accept the pragmatic representation as the meaning of the sentence. In this case, his interpretation, like that of the children, will usually be correct, since the majority of propositions in natural language usage tend to be of the broad predicate type. However, error will arise in some instances, e.g., in processing narrow predicate forms. At other times, the adult will generate not only a pragmatic representation but also a repre-

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W. Bucci

sentation based on formal grammatical cues. He may then test his tentative pragmatic interpretation by comparing it to the grammatical structure, and adjust his interpretation accordingly. A combined processing strategy along similar lines was proposed by Collins and Quillian (1972). In their model, the processor searches through a semantic network filled with factual information for paths connecting the words of a sentence, before syntax is considered. The combined strategy is of course applicable only where familiar content is used. Otherwise the only route to a correct interpretation is through the use of grammatical cues. In children’s processing, no such combined strategy has evolved. For them, the pragmatic interpretation is applied directly, rather than filtered through a system of structural checks. It has been assumed by some that by about four years of age a child “ .. . will have mastered nearly the entire complex and abstract structure of English” (Miller and McNeill, 1969, p. 714). Piagetian theorists frequently make this assumption, attributing advances to cognitive restructuring without investigating the possibility that linguistic changes may be occurring as well. This paper has explored a linguistic area in which mastery is incomplete at age 1 l-1 2, and in which the nature of mature competence is also unclear.

References Begg, 1. and Denny, P. (1969) Empirical reconciliation of atmosphere and conversion interpretations of syllogistic reasoning errors. J. cxp. &~chol., 81, 35 l-354. Carroll, J. B., Davies, P., and Richman, B. (1971) The American Heritage Word Frequency Book. Boston, Houghton Mifflin Co. Ceraso, J. and Provitera, A., (197 1) Sources of error in syllogistic reasoning. Cog. Psychol., 2, 4 11420. Chapman, 1. J. and Chapman, J. 1’. (1959) Atmosphere effect re-examined. J. exper. Psychol., 58, 220 -226. Collins, A. M. and Quillian, M. R. (1972) Esperiments on semantic memory and language comprehension. In L. W. Gregg (Ed.), Cognition in learning and memory. New York, Wiley. Iicnle, M. (1962) On the relation between logic and thinking. Psychol. Rev., 69, 366-378. Inheldcr, B. and Piaget, J. (1964) The carfy growrh of logic in the child. London, Routledge. Johnson-Laird, P. N. (1975) Models of deduction. In R. 1:almapne (ed.), Reasoning: Representation arzd process in children arzd adults. Hillsdale, N.J., Erlbaum. Kneale, W. and Knealc, M. (1962) The development oflopic. O?tford. Clarendon Press. Sliller. G. A. and McNeill, D. (1969) Psycholinguis&“In G. Lindzey and E. Aronson (Eds.), The handbook ofsocial ps_vchology, (2nd cd.), Vol. 3. Reading, Mass., Addison-Wesley. Quine, W. V. (1960) Word and object. Cambridge, Mass., The M.I.T. Press. Revlis, R. (1975) Two models of syllogistic reasoning: I;eature selection and conversion. J. verb. Learn. verb. Beh., 14. 180-195. Strawson, P. 1:. (1967) Singular terms and predication. In P. F. Strawson (Ed.), Philosophical logic. London, Oxford University Press. Wason, P. C. and Johnson-Laird, P. N. (1972) Psycholog_v of reasoning: Structure and content. Cambridge, Mass., liarvard University Press. Woodworth, R. S. and Sells, S. B. (1935) An atmosphere effect in formal syllogistic reasoning. J. exper. /‘swhol., 18, 45 1--460.

Universal affirmative propositions

77

On propose quc l’idee tous /es F sent G est souvent interpret& comme “neutre au point de vue structure” c’est-a-dire comme tous, b*, G sans distinction sujet-predicat. Dans une premiere experience, on demande i des enfants ages de 7-8 ans et de 11-12 ans ainsi qu’a des adultes d’agir selon dcs instructions du type “Faites un bitiment ou tous les blocs jaunes sont carres”. Les don&es montrent que l’interpretation domine chez les jeunes enfants et dkcroit “neutre au point de we structure” en fonction de l’age. Dans une seconde experience faite avec des mimes groupes d’age, on presente comme premise majeur de syllogismes, des propositions de la forme tous les Fsont G qui varient selon les relations d’inclusion des faits exprimes. Les rdsultats montrent qu’il y a, sous certaines conditions, presence d’interpretations “neutres au point de vue structure” chez les adultes aussi bien quc chcz Its enfants. Les resultats indiquent aussi l’existence chez tous les sujets d’un mode de “traitemcnt pragmatique” qui devient moins necessaire avec l’age. Dans les interpretations pragmatiques, le sens est determine plus par les relations factuelles connues entre les chases representdes par les mots que par lcs relations grammaticales entre les mots.

Cognition, 6 (1978) 79-85 @Elsevier Sequoia S.A., Lausanne

Discussion - Printed

A criticism

in the Netherlands

Unfulfilled expectations : of Neisser’s theory of imagery

P. J. HAMPSON and P. E. MORRIS” Department University

of

Psychology

of Lancaster

Abstract Neisser’s recent theory of imagery (Neisser, 1976) is critically discussed and is found to contain several weaknesses. (I) It is not clear that the theory avoids the alleged difficulties of alternative accounts in explaining the lack of subjective confusion of images and percepts and the nature of the observer of mental operations. (2) In viewing imagery as a perceptual anticipation, Neisser resembles Ryle (1949). The conclusions and derivative arguments of both authors are criticized: Anticipation may well be a necessary but is not a sufficient component of imaging. (3) Neisser’s account has severe problems in explaining how images are manipulated and used in cognition. (4) The conscious experience of having an image is seen to differentiate imaging from just knowing - a possibility not admitted by Neisser. (5) Finally, Neisser’s view of introspection is criticized on the grounds that the use of real world descriptive terms does not imply a description of real world objects. Introspection, whilst not error free, still occurs. There has been much debate recently concerning the status of mental images. There are two main approaches. The “analogue” or “representational” approach (e.g., Shepard, 1975; Kosslyn and Pomerantz, 1977) maintains that images are a qualitatively distinct form of internal representation and that the experience of having a (visual) image resembles the experience of seeing the referent of the image. The “propositional” account (e.g., Pylyshyn, 1973, 1975) replaces the analogical representation by abstract structural descriptions accessed by computationally primitive semantic interpretation

*The contributions of the authors in the production of this paper were of equal weight. We wish to thank Andrew Young for his helpful comments on an earlier version of the manuscript. Requests for reprints should be sent to: Peter E. Morris, Department of Psychology, Fylde College, University of Lancaster, Lancaster LA1 4YF. England.

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functions and argues that the conscious image has no functional role in cognition. Recently, Neisser (1976) has rejected both of these approaches. He argues that both are versions of the linear cognitive model in which information is processed through successive levels from sensory reception input to consciousness. He wishes to replace the linear model with a cyclical model of cognitive activity which has three principle elements: the first are the objects in the real world and the information that specifies them, the latter modifies the second, the schemata that the subject possesses or constructs for perceiving the world, which in turn direct the third element, exploration of the environment, which controls sampling of the first element, objects in the real world. From this cyclic model Neisser derives a new theory of the nature of imagery which will be examined below. Central to Neisser’s account of cognition and imagery are schemata. He defines a schema as “that portion of the entire perceptual cycle which is internal to the perceiver, modifiable by experience and somehow specific to what is being perceived” (p. 54). He clarifies the functions of schemata by means of two analogies. In one sense, a schema is like a format in a computer programming language in that it accepts information but only in an appropriate form, otherwise it is ignored or leads to meaningless results. However, schemata do not merely accept input, they also lead to actions, and as such they are like the plans of Miller, Galanter and Pribram (1960). Neisser’s account of imaging is that images are “the anticipafory phases” of perceiving. They involve the activation of a schema independent of the usual cycle in which the schema plays a part. Thus “when you have an image of a unicorn at your elbow . . . you are making ready to pick up the visual information that the unicorn would provide” (p. 132). What are the advantages of Neisser’s account of imaging? Apart from the obvious one of making imaging compatible with his general theory of cognition he claims that it avoids the difficulty, inherent in both the analogue and propositional accounts, of explaining why images and percepts are not systematically confused. Neisser claims that his account escapes this problem because perceiving involves the continuous pickup of new information which is absent in imaging. It also escapes the problem of the observer of the image in the analogue account. Unfortunately, there are several weaknesses in Neisser’s theory of imaging. First it does not necessarily escape his own criticisms of the alternative accounts. The clear separations of images and percepts is one of the grounds for acceptance of the new theory. However, knowing that one is experiencing information pickup implies knowledge about one’s cognitive processing. If this knowledge is allowable in the case of his own account Neisser

A criticism of

Neisser’s theory of imagery

81

must allow it for the other accounts. Once knowledge of input or non input of information into the system from external sources is accepted, then any of the models can cope with the separation of image and percept. We, incidentally, believe that the separation of image and percept is not invariably possible, (e.g., hallucinations) and a complete model of imagery must allow for the occasional error. Neisser also hopes to avoid problems concerning the nature of the observer of the image. However, similar problems arise in accounting for who it is who would be aware of the presence or absence of information input and hence the distinction between images and percepts. Troublesome as the threat of an homonculus may be, it is better to face it and attempt to develop an adequate account for its apparent occurrences rather than attempt to define it out of existence. Another example of Neisser’s attempts to escape the homonculus problem via definition is his treatment of percepts. We maintain that percepts can be examined and their appearance described. For example, short sighted people can describe their percept as blurred. Neisser’s strategy in this case is to define “the “percept” . . . as the particular object that would most nearly provide the same information if it were actually present” (p. 32). This is a misleading definition. We will return to this point later when discussing introspection. Neisser places considerable emphasis on imaging being an anticipation of perception. In doing so he resembles Ryle (1949) who attempted to account for imaging as a disposition to see the thing imagined. The methods by which both authors derive this conclusion are also remarkably similar. Neisser argues from the employment of cognitive maps as unsupported anticipations during locomotion to imagery; Ryle claims that having an imaginary tune run in one’s head is similar to following a real tune. Both subsume imaging into the wider class of imaginings. Hannay’s (1971) criticism of Rule’s derivation of imagery from perception is thus appropriate to Neisser. He maintains that the two types of anticipation, imaginal and perceptual, are totally different in kind. Unfulfilled perceptual anticipations are well described in terms of disappointment or surprise. Yet such qualifications are wholly inappropriate as descriptions of images. While attempting to form an image, one may be said to be anticipating the formation of the image, but one is not anticipating a true perceptual experience of the thing imagined. Indeed, one would be surprised if such a true perceptual experience did follow imaging. Neisser’s use of “anticipation” is extremely misleading, since, at best, only a low level schema in the hierarchical system of schemata can be said to anticipate. Neisser restricts discussion to these levels because he has no room for any internal representations in his account. Further, while an anticipation may be a necessary part of the imaging process it is clearly not a sufficient one,

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since people can anticipate seeing without experiencing a mental image. Returning home one anticipates seeing one’s wife or one’s friends, but does not constantly experience an image of them. According to Neisser, anticipatory schemata are continually being used as the very essence of perception. They must be extremely rapidly and easily activated. Why then does it take effort and time to generate a mental image? Morris and Reid (1973) reported that the latency of forming an image to the referent of a concrete noun averaged over one second, while images incorporating two referents took over two seconds. Other difficulties concerning the time taken in imaging arise when we consider the inability of Neisser’s account to cope with the manipulation of images that have been studied by Cooper and Shepard (1973) and Kosslyn (1975). During normal perception, schemata are modified through the input of information from the real world and direct further exploration by acting as plans. By definition, no such input from external sources takes place during imaging, and the plan function is not discussed by Neisser, yet the ability to manipulate images is well established. It is difficult to see how a given schema could update or modify itself without exploration and input of information. Neisser could argue, of course, that higher order schemata control the ones used in imaging. This could mean one of two things: an image scheme might accept and explore stored information from a higher order schema; this would be tantamount to reintroducing an internal representation - a strategy that Neisser hopes to avoid. Alternatively the higher order schemata might simply “activate” or “switch on” the lower order schemata without providing any image referent specifying information; in which case, the problem of modification without input remains. In fact, Neisser’s solution to the problem is to suggest that the schemata used for, say, the rotation of images are of the type used when we perceive rotating objects. No explanation is given of how these “rotation schemata” might differ from other types. If they also modify themselves by information uptake and exploration then the problem of manipulation still remains. On the other hand, if image manipulation simply involves switching through a preexisting set of expectations, then how is new knowledge derived, or better still, “realized” by means of imaging? Neisser himself recognizes the weakness in his account. Image rotation takes place at a slow and regular rate, while we can perceive all kinds of speeds of rotation. Also, Hochberg and Gellman (1977) have shown that rotation rates are faster for those stimuli which contain “landmark” or orientation features. Without some appeal to properties of an image or internal representation it is hard to see why one rotation should be harder and take longer to perform than another.

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83

The crucial aspect of imaging is the conscious experience. It is only the experience itself which makes imaging different from just knowing and from simply anticipating. For example, a person may know that the color of his front door is white, that it has a glass panel and so on. However, when he images the front door he does something more than just know these things. He has a conscious experience which at least partially resembles experiencing the door in real life, and he can give a description of the door using the terms normally used when describing the real world. Neisser does appreciate the close similarity of perceptual and imaginal experiences by claiming that imaging involves perceptual schemata. Yet, his account tends to shift our attention away from the real experience of the image to the anticipation of a percept that we do not really expect in any case ! The theory tells us nothing new about the nature of imagery. It asserts the relation to perception, but that is hardly novel. Nor is it clear that it answers the problems tackled by the propositional and analogue accounts. As soon as we go beyond accepting Neisser’s cyclical theory of cognition at a general level we will have to ask questions about how a specific schema is activated, what it is for a schema to be activated, what are schemata and so on. Further, how is one schema selected from the enormous number available for activation in imaging. Some answers will be necessary for such problems and it was to deal with such questions of image storage, construction and retrieval that the propositional account was formulated. Neisser’s elaboration of the nature of schemata would probably differ markedly from the propositional model, yet the need for elaboration remains. As, described earlier, Neisser does not cope adequately with the manipulation or use of images in cognition and, so, he is faced with the same problems that have led other researchers to prefer analogue models. The lack of specificity in Neisser’s theory leaves ample room for elaboration, but we feel that such elaboration is likely to destroy the very qualities of the theory which Neisser finds attractive. Finally, we must consider Neisser’s discussion of introspection. Like others, including Skinner and Ryle, before him, he blames dualistic metaphysics for the difficulties usually associated with introspection. “We seem to be describing something that is inside us rather than in our environment, something examinable by the mind’s eye and not by the body’s” (p. 172). “Children have not absorbed dualistic metaphysics so ‘Children do not have these hang ups’.” And “What seem to us like descriptions of images and cognitive maps are really . . . descriptions of potentially perceivable objects, of what one would see if such-and-such a thing were present. Introspection is a kind of preparation for exterospection” (p. 173). We are not sure where in the environment Neisser would locate pleasures, pains and other emotional experiences! No mention is made of these. At best,

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anu’ P. E. Morris

his account is only appropriate to some objects of introspection. The pink elephant that I claim to be imaging may be potentially perceivable as an object. However, this is irrelevant to whether or not I am consciously experiencing and describing an image of a pink elephant, or merely describing what a pink elephant might look like, without any such mental image. Only the individual giving the description knows whether he is experiencing an image or not. Nor does the fact that we use terms applicable to real world objects in any way imply that we are describing those same objects. What other words could we possibly use? It is true that there might be oblique references to the real world, in that, perhaps, any description of a visual mental experience could be translated into the description of a real thing, if such a thing existed, but, surely, this is little more than a communication device. The real intention of the introspector is to describe his conscious experiences. Also, the fact that certain terms applicable to mental experiences, such as “vivid”, “faithful” of “fuzzy”, are inapplicable ro real world objects suggests a difference between introspection and exterospection. We describe the quality of an image just as we might describe the texture of paint or the detail in a painting. Note, that we are not suggesting that introspection is error free. In common with Natsoulas (1970) we consider introspection to be the acquiring of beliefs, rather than knowledge, concerning one’s mental operations and experiences. Our conclusion is that whatever may be the merits of Neisser’s cyclical theory, its application to imagery adds nothing new to our understanding of the phenomenon, and may even prove detrimental if it distracts attention from the interesting and centrally important properties of the conscious experience itself.

References Cooper,

L. A. and Shepard, R. N. (1973) Chronometric studies of the rotation of mental images. In W. G. Chase (Ed.), Visual information processing. New York, Academic Press. Hannay, A. (1971). Mental images A defence. London, George Allen & Unwin. Hochberg, J. and Gellman, L. (1977). The effect of landmark features on “mental rotation” times. Mem. Cog., 5, 23-26. Kosslyn, S. M. (1975). Information representation in visual images. Cog. Psychol., 7, 341-370. Kosslyn, S. M. and Pomerantz, J. R. (1977). Imagery, propositions and the form of internal representations. Cog. Psychol., 9 52-76. Morris, P. E. and Reid, R. L. (1973). Recognition and recall: latency and recurrence of images. Er. J. Psychob, 64, 161-167. Natsoulas, T. (1970). Concerning introspective “knowledge”. Psychol. Bull, 73, 89-l 11. Neisser, U. (1976). Cognition and realify. San Francisco, Freeman.

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Pylyshyn, Z. W. (1973). What the mind’s eye tells the mind’s brain: a critique of mental imagery. Psychol. Bull., 80, I-24. Pylyshyn, Z. W. (1975). Do we need images and analogues. Paper presented at the Conference on Theoretical Issues in Natural Language Processing. Massachusetts Institute of Technology. Boston, Mass. Ryle, G. (1949). The concepf ofmind. London, Hutchinson. Shepard, R. N. (1975). Form, formation and transformation of internal representations. In R. Solso (Ed.), Information processing the Loyola Symposium. Hillsdale, NJ., Lawrence Erlbaum.

Cognition, 6 (1978) 87

Books

87

received

Experimental

Psychology:

Theory and Practice, Philip J. Durham, Harper & Row, Hagers-

toun, 1977; & 10.45. Semantics 2, John Lyons, Cambridge University

Press, London,

1977.

Propositional Structure and Illocutionary Force, Jerrold J. Katz, The Harvester Press Ltd.,

1977:t

13.50.

Artificial Intelligence

and Natural Man, Margaret Boden, The Harvester Press, Ltd., 1977;

& 13.50. Experimental

Phenomenology,

The Human Machine:

Don Inde, G. P. Putnam’s Sons, New York, 1977; $ 7.95.

A View of Intelligent Mechanisms,

by J. G. Taylor, Georgi Publishing, Canada), SFr. 18.90.

Switzerland,

I. Aleksander with a foreword 1977; & 3.90 (U.K.), $ 9.95 (USA and

Chomsky, John Lyons, The Harvester Press Ltd., 1977; E 5.50.