Advances in Child Development and Behavior Volume 7

ADVANCES I N CHILD DEVELOPMENT

AND BEHAVIOR

VOLUME 7

Contributors to This Volume Jean L. Bresnahan Rochel Gelman Klaus F. Riegel Arnold J. Sameroff Martin M. Shapiro Michael D. Zeiler

ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR edited by Hayne W. Reese Department of Psychology West Virginia University Morgantown, West Virginia

VOLUME 7

@)

1972

ACADEMIC PRESS

New York

London

COPYRIGHT 0 1972, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. N O PART O F THIS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER.

ACADEMIC PRESS, INC. 1 1 1 Fifth Avenue, N e w

York. N e w York 10003

Uniled Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road, London N W l

LIBRARY OF

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PRINTED IN TH E UNITED STATES

NUMBER: 6 3 - 2 3 2 3 1

OF AMERICA

Contents LIST OF CONTRIBUTORS ..............................................

vii

PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ix

CONTENTSOF PREVIOUS VOLUMES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xi

Superstitious Behavior in Children: An Experimental Analysis MICHAEL D. ZEILER I. Superstition and the Reinforcement Process . . . . . . . . . . . . . . . . . . . . . . . 11. Deliberate and Adventitious Reinforcement . . . . . . . . . . . . . . . . . . . . . . . .

111. Control of Multiple Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Other Effects of Response-Independent Reinforcement . . . . . . . . . . . . . . V. Concluding Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 6 19 23 27 28

Learning Strategies in Children from Different Socioeconomic Levels JEAN L. BRESNAHAN AND MARTIN M. SHAPIRO

I. Introduction

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

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

11. Concept Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. Reward Preferences . . . . . . . . . . . . . . . . . . . . . ...........

32 34 57

IV. Instructions and Training . . . .................... V. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . References .......................

Time and Change in the Development of the Individual and Society KLAUS F. RIEGEL

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. The Concept of Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. Developmental Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

82 83 96 111 V

vi

Contents

The Nature and Development of Early Number Concepts ROCHEL GELMAN I. 11. 111. IV. V.

...................................... 116 Introduction . . . . . . . Estimators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Estimator Confidence . . . . . ............................ 143 Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Summary and Discussion ..................... . 162 References ..................................... 165

Learning and Adaptation in Infancy: A Comparison of Models ARNOLD J. SAMEROFF Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Infant Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Parameters of Conditionability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Models of Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

170 171 191 202 211

AUTHOR INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

215

SUBJECTINDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

219

I. 11. 111. IV.

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

JEAN L. BRESNAHAN Emory University, Atlanta, Georgia (31)

ROCHEL GELMAN Psychology Department, University of Pennsylvania, Philadelphia, Pennsylvania (115)

KLAUS F. RIEGEL Department of Psychology, University of Michigan, Ann Arbor, Michigan (81)

ARNOLD J. SAMEROFF University of Rochester, Rochester, New York (169)

MARTIN M. SHAPIRO Emory University, Atlanta, Georgia (31)

MICHAEL D. ZEILER Emory University, Atlanta, Georgia (1)

1 Present address: Department of Psychology, Lehman College, City University of New York, New York, New York.

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The amount of research and theoretical discussion in the field of child development and behavior is so vast that researchers, instructors, and students are confronted with a formidable task in keeping abreast of new developments within their areas of specialization through the use of primary sources, as well as being knowledgeable in areas peripheral to their primary focus of interest. Moreover, there is often simply not enough journal space to permit publication of more speculative kinds of analyses which might spark expanded interest in a problem area or stimulate new modes of attack on the problem. The serial publication Advances in Child Development and Behavior is intended to ease the burden by providing scholarly technical articles serving as reference material and by providing a place for publication of scholarly speculation. In these documented, critical reviews, recent advances in the field are summarized and integrated, complexities are exposed, and fresh viewpoints are offered. They should be useful not only to the expert in the area but also to the general reader. No attempt is made to organize each volume around a particular theme or topic, nor is the series intended to reflect the development of new fads. Manuscripts are solicited from investigators conducting programmatic work on problems of current and significant interest. The editor often encourages the preparation of critical syntheses dealing intensively with topics of relatively narrow scope but of considerable potential interest to the scientific community. Contributors are encouraged to criticize, integrate, and stimulate, but always within a framework of high scholarship. Although appearance in the volumes is ordinarily by invitation, unsolicited manuscripts will be accepted for review if submitted first in outline form to the editor. All papers-whether invited or submitted-receive careful editorial scrutiny. Invited papers are automatically accepted for publication in principle, but may require revision before final acceptance. Submitted papers receive the same treatment except that they are not automatically accepted for publication even in principle, and may be rejected. I wish to acknowledge with gratitude the aid of my home institution, West Virginia University, which generously provided time and facilities for the preparation of this volume. HAYNEW. REESE ix

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Contents of Previous Volumes Volume 1 Responses of Infants and Children to Complex and Novel Stimulation Gordon N . Cantor Word Associations and Children’s Verbal Behavior David S . Palermo Change in the Stature and Body Weight of North American Boys during the Last 80 Years Howard V . Meredith Discrimination Learning Set in Children Hayne W . Reese Learning in the First Year of Life Lewis P. Lipsitt Some Methodological Contributions from a Functional Analysis of Child Development Sidney W . Bijou and Donald M . Baer The Hypothesis of Stimulus Interaction and an Explanation of Stimulus Compounding Charles C . Spiker The Development of “Overconstancy ” in Space Perception Joachim F. Wohlwill Miniature Experiments in the Discrimination Learning of Retardates Betty J . House and David Zeaman AUTHOR INDEX-SUB

JECT INDEX

Volume 2 The Paired-Associates Method in the Study of Conflict A l f red Castaneda Transfer of Stimulus Pretraining in Motor Paired-Associate and Discrimination Learning Tasks Joan H. Cantor xi

xii

Contents of Previous Volitmes

The Role of the Distance Receptors in the Development of Social Responsiveness Richard H . Walters and Ross D. Parke Social Reinforcement of Children’s Behavior Harold W . Stevenson Delayed Reinforcement Effects Glenn Terrell A Developmental Approach to Learning and Cognition Eugene S. Gollin Evidence for a Hierarchical Arrangement of Learning Processes Sheldon H . White Selected Anatomic Variables Analyzed fdr Interage Relationships of the Size-Size, Size-Gain, and Gain-Gain Varieties Howard V . Meredith AUTHOR INDEX-SUB

JECT INDEX

Volume 3 Infant Sucking Behavior and Its Modification Herbert Kaye The Study of Brain Electrical Activity in Infants Robert J . Ellingson Selective Auditory Attention in Children Eleanor E. Maccoby Stimulus Definition and Choice Michael D . Zeiler Experimental Analysis of Inferential Behavior in Children Tracy S . Kendler and Howard H. Kendler Perceptual Integration in Children Herbert L. Pick, Jr., Anne D . Pick, and Robert E . Klein Component Process Latencies in Reaction Times of Children and Adults Raymond H . Hohle AUTHOR INDEX-SUBJECT

INDEX

Volume 4 Developmental Studies of Figurative Perception David Elkind

Corrterits of Previous Volumes

xiii

The Relations of Short-Term Memory to Development and Intelligence John M . Belmont and Earl C . Butterfield Learning, Developmental Research, and Individual Differences Frances Degen Horowitz Psychophysiological Studies in Newborn Infants S . J . Hutt, H . G . Lenard, and H . F. R. Prechtl Development of the Sensory Analyzers during Infancy Yvonne Brackbill and Hiram E . Fitzgprald The Problem of Imitation Justin Aronfreed AUTHOR INDEX-SUBJECT

INDEX

Volume 5 The Development of Human Fetal Activity and Its Relation to Postnatal Behavior Tryphena Humphrey Arousal Systems and Infant Heart Rate Responses Frances K . Graham and Jan C. Jackson Specific and Diversive Exploration Corinne Hutt Developmental Studies of Mediated Memory John H. Flavell Development and Choice Behavior in Probabilistic and Problem-Solving Tasks L . R . Goulet and Kathryn S . Goodwin AUTHOR INDEX-SUBJECT

INDEX

Volume 6 Incentives and Learning in Children Sam L. Witryol Habituation in the Human Infant Wendell E. Jeffrey and Leslie B. Cohen Application of Hull-Spence Theory to the Discrimination Learning of Children Charles C. Spiker Growth in Body Size: A Compendium of Findings on Contemporary

xiv

Contents of Previous Volumes

Children Living in Different Parts of the World Howard V . Meredith Imitation and Language Development James A . Sherman Conditional Responding as a Paradigm for Observational, Imitative Learning and Vicarious-Reinforcement Jacob L. Gewirtz AUTHOR INDEX-SUB

JECT INDEX

SUPERSTITIOUS BEHAVIOR IN CHILDREN: AN EXPERIMENTAL ANALYSIS Michael D. Zeiler EMORY UNIVERSITY

I. SUPERSTITION AND THE REINFORCEMENT PROCESS . . . . . . A. THE IMPLICATIONS O F SUPERSTITIOUS BEHAVIOR . . . . B. REINFORCEMENT DEPENDENCIES AND CONTINGENCIES

2 2 4

11. DELIBERATE AND ADVENTITIOUS REINFORCEMENT . . . . . . A. PROBABILITY O F RESPONSE . . . . . . . . . . . . . . . . . . . . . . . . . . . B. TEMPORAL PATTERNS OF RESPONDING . . . . . . . . . . . . . . . C. STIMULUS CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. REINFORCEMENT AND TEMPORAL CONTIGUITY . . . . . .

6 6 10 13 18

CONTROL O F MULTIPLE RESPONSES . . . . . . . . . . . . . . . . . . . . . . A. CONCURRENT RESPONSE-INDEPENDENT AND RESPONSE-DEPENDENT REINFORCEMENT . . . . . . . . . . . . . . . . B. SOME COMMENTS ON MEDIATION AND INDIVIDUAL DIFFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. A NOTE ON REINFORCING NOT RESPONDING . . . . . . . . .

21 22

IV. OTHER EFFECTS O F RESPONSE-INDEPENDENT REINFORCEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. ELICITATION O F PREVIOUSLY PROBABLE RESPONSES . . B. ELICITATION O F A NEW RESPONSE: AUTO-SHAPING . .

23 23 25

CONCLUDING COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27

111.

V.

REFERENCES

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

19

19

28

1 Preparation of this paper was facilitated by Research Grants HD-04652 and GB-25959 from the National Institute of Child Health and Human Development and the National Science Foundation respectively. The three previously unpublished experiments described in Sections IIB, IIC, and IVD were conducted at the Institute of Child Behavior and Development of the University of Iowa with support by Research Grant HD-02845 from the National Institute of Child Health and Human Development.

1

2

Michael D.Zeiler

I. Superstition and the Reinforcement Process A. THE IMPLICATIONS

OF SUPERSTITIOUS

BEHAVIOR

In 1948, Skinner brought the study of superstition into the realm of science. In so doing, Skinner’s work initiated fruitful analyses into how behavior is controlled by its consequences and generated concepts which may explain much complex behavior. Skinner’s experiment was simple: He presented food to pigeons every 15 seconds independently of their behavior. After a number of these food presentations, Skinner observed the behavior and found that each bird displayed consistent responses. One turned in a counterclockwise direction several times between each food delivery, another repeatedly tossed its head, a third hopped from one foot to the other, and others showed still different behavior. Since these responses were not prevalent prior to the first food presentation and stopped when it was discontinued, the delivery of food was the responsible agent. Yet the responses did not influence food presentations. The parallel to the kinds of behaviors classified as superstitious outside the laboratory led Skinner to describe his experiment as involving superstition in the pigeon. In either the natural or the experimental setting, the term “superstition” refers to behaviors which are emitted as if they have environmental consequences, but in fact do not. Herrnstein ( 1966) has pursued the relation between experimental analogues of superstition and folklore critically and in detail, and points out some provocative similarities and differences. The present discussion concentrates on laboratory situations and the relevance of experiments on superstition to an understanding of how reinforcing stimuli control behavior. Skinner’s experiment has important theoretical implications. Apparently a particular behavior predominated because it happened to occur in close temporal contiguity with the presentation of food. Food was a reinforcing stimulus even though the correlation with behavior was adventitious. Once the frequency of some behavior increased, it became even more likely that the same behavior would be contiguous with the next food presentation so that its frequency would increase still further. This circular relation eventually made the behavior so probable that it became apparent during the intervals separating food presentations. Is there a difference between this phenomenon and the typical operant conditioning situation in which a response increases in frequency when it produces a reinforcing stimulus? Perhaps not, except that in the superstitious situation the response that will be contiguous with the stimulus is unspecified by the experimenter, whereas in the typical operant conditioning

Superstitious Behavior in Children

3

situation this response is preselected by the experimenter. In either case, the behavior immediately prior to the delivery of the reinforcing stimulus increases in frequency of occurrence, is thereby even more likely to precede the stimulus in the future, and eventually becomes predominant over all other behaviors. Superstitious behavior serves as the clearest example that the temporal relation between responses and reinforcing stimuli is the critical one. Setting aside philosophical considerations about the nature of causality, superstition indicates that the cause and effect relationship maintained when reinforcing stimuli depend on a response is not essential. Although it is plausible to assume that reinforcing stimuli affect the frequency of responses via the temporal relations, a position maintained by most if not all reinforcement theorists, it is an unproven hypothesis that the essential relation is in fact temporal. The reason for the hypothetical status is that experiments involving a causal relationship between a response and a reinforcing stimulus have revealed other effects besides that of increasing the probability of the response. Until these other effects can also be observed in the absence of a causal relationship, the inference that the essential relationship is temporal rather than causal remains plausible but hypothetical. Therefore, in order to maintain that the temporal correlation is the necessary and sufficient one, it is essential to demonstrate more than that a stimulus delivered without reference to behavior increases the frequency of the temporally contiguous response. For example, response-dependent presentations of reinforcing stimuli influence the way in which responses are distributed in time depending on the schedule according to which the reinforcing stimulus is presented. That is, the pattern of responses varies depending upon whether reinforcing stimuli follow the first response occurring at regular time intervals (fixed-interval schedules), or the first response occurring at irregular time intervals (variable-interval schedules), or whether they depend on the execution of a constant or varied number of responses (fixed-ratio and variable-ratio schedules). Also, the responsedependent presentation brings behavior under the control of exteroceptive stimuli if the availability of the reinforcing stimulus is correlated with the presence or the absence of certain discriminative stimuli. To the extent that the temporal relation of behavior to reinforcing stimulus presentation is the only essential condition, superstitious behavior should mimic all of the effects observed when reinforcing stimuli occur dependent on a response. As seen in Section 11, superstitious behavior in children does reveal effects on probability of response, patterns of responding, and stimulus control when temporal rather than inevitable causal relations are scheduled by the experimenter.

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Michael D.Zeiler

B. REINFORCEMENT DEPENDENCIES AND CONTINGENCIES Several critical words, phrases, and procedures must be defined at the outset, because historically they have had multiple meanings and consequently are subject to confusion. A prime candidate is reinforcement and its derivatives. Catania (1969, p. 845) pointed out that “the vocabulary of reinforcement includes at least three nouns: reinforcer as a stimulus, reinforcement as an operation, and reinforcement as a process or as a relationship between an operation and a process.’’ The definitions used in the present paper follow from his discussion and thereby correspond with those used in the major discussions of operant behavior and reinforcement schedules (Ferster & Skinner, 1957; Morse, 1966; Skinner, 1938). By process o f reinforcement is meant an observed increase in responding, and a reinforcing stimulus or reinforcer is a stimulus which increases the frequency of the response that it follows. Reinforcement is confined to its operational sense; it refers to the presentation of a reinforcing stimulus. A schedule of reinforcement refers to the arrangement according to which reinforcing stimuli are presented. None of the definitions involves inferred events or states of the organism; all have reference to stimulus presentations and changes in response frequency. Contingency is another word that has had multiple meanings in psychology. In addition to explaining present usage, a discussion of the meaning of contingency helps to clarify the significant relationships treated in this paper. Webster’s New World Dictionary ( 1968) defines contingent as: “1. that may or may not happen; possible. 2. happening by chance; accidental; fortuitous. 3. dependent (on or upon something uncertain) ; conditional. 4. [Archaic], touching, tangential. 5. in logic, true only with certain conditions or contexts; not always or necessarily true. n. 1. an accidental or chance happening.” Other noun uses are given, but these refer to another class of meanings. Contingencies, then, properly refer to events which are not specified as necessities but which may occur. In the study of behavior, contingencies often refer to the relation between responses and reinforcement. In one use, contingency describes an independent variable, the conditions of reinforcement: The reinforcer will be presented if certain conditions are met and will not be presented otherwise. Thus, reinforcement is not a certainty but is contingent upon the occurrence of other events. In this usage, contingency is synonymous with schedule, that is, it states the conditions under which reinforcement will occur. There are two general types of condition. On the one hand, there are those requiring a specified response; these include ratio schedules which prescribe the number of responses required for reinforcement, interval schedules which specify the time that must elapse since the last reinforcement before the

Superstitious Behavior in Children

5

next response is reinforced, and schedules in which reinforcement depends on the time that has elapsed between successive responses. On the other hand, the second condition involves no response requirement; these are time schedules in which reinforcement occurs after a specified period of time elapses. Schedules involving response requirements can be referred to as involving contingent reinforcement without doing violence to the dictionary definition of contingent, since the reinforcement may or may not occur depending on whether the criterion response does or does not occur. However, although noncontingent reinforcement has been used to describe time schedules, this does not accord with the dictionary definition and, in fact, is confusing or even contradictory if taken literally. Since reinforcement is scheduled in relation to time, it is contingent on something (time), although it may be noncontingent with respect to responses. It is important to distinguish between schedules requiring responses and those that do not, but contingent and noncontingent are not the best way of doing so. The distinction is unambiguous if the classes of schedules are referred to as response dependent and response independent. A different usage of contingency refers to a dependent variable by expressing the relation between responses and reinforcement with the emphasis on the response. In this vocabulary, contingent is not synonymous with schedule but refers to the behavior that happens to occur prior to reinforcement. Although every response-dependent schedule at least requires that the specified response occur and may make it likely that other responses occur as well, none prescribes all of the behavior that may precede reinforcement. Response-independent schedules leave all of the behavior free to vary. Contingencies refer to the complex behavior that happens to occur prior to reinforcement whether the behavior is required or not. Reinforcement cannot be noncontingent because some form of behavior must occur and thus has a contingent relationship to reinforcement. Contingency in this sense is shorthand for scheduled and adventitious effects of reinforcement on behavior. The distinction between dependency and contingency derives from the efforts of Catania (1968) and Reynolds (1968) who use dependency to refer to events which must occur if reinforcement is to occur and contingency to refer to events which do not have a perfect probability of occurring prior to reinforcement. Their definitions (which a survey of recent volumes of the Journal of the Experimental Analysis of Behavior shows as being adopted with increased frequency) coincide with the present suggestion that dependencies relate to schedules and contingencies to the responses which may precede reinforcement. In summary, schedule and dependency describe how the experimenter arranges his apparatus to dispense reinforcement in relation to (or independent of) responses, and con-

6

Michael D . Zeiler

tingencies describe the behavior that is affected by reinforcement. A schedule may or may not involve a response dependency, but all involve contingencies. Students of superstitious behavior deal with contingencies in that they study behavior that need not occur. Sometimes the contingencies refer to responses, sometimes they refer to antecedent discriminative stimuli which may or may not precede reinforcement as well. Contingencies also arise in response-dependent reinforcement because behavior other than that required may also occur in relation to reinforcement. Basically, the concern is with experiments using response-independent, response-dependent, stimulusindependent, and stimulus-dependent reinforcement schedules to explore contingencies.

11. Deliberate and Adventitious Reinforcement A. PROBABILITY OF RESPONSE Although Skinner’s (1948) paradigm is the most straightforward one for revealing how response-independent reinforcement affects the probability of responses, it places severe demands on the experimenter. The experimenter has no way of knowing what response to observe, instead he must wait to see if some behavior emerges and then find some way to measure and record it objectively. A solution has been to circumvent the problem by first generating the response via response-dependent schedules and then to observe how the behavior is maintained when the response is no longer required. It must be noted though that this solution places the emphasis on the maintenance rather than on the acquisition of behavior, and thus is not the strongest test of the hypothesis that response-independent and response-dependent reinforcement are equivalent with respect to response probability. It seems fortunate, therefore, that there have been several instances in which experimenters have observed that a response-independent schedule did establish a new response as well as maintain an old one. Both initial establishment and maintenance of a response have been observed with children. Zeiler (1970) first exposed four- and five-year-old children to a fixedratio schedule. The child received candy whenever a total of 30 responses had occurred to two response keys; these responses could be distributed in any proportion to the two keys. One key was blue and the other red. Stable behavior consisted of equal responding to each key. The children either executed an entire ratio on one key and then switched to the other, or alternated keys with successive responses. Following the development of

Superstitious Behavior in Children

I

stable behavior, the schedule was changed so that responses to the red key had no effect (extinction), while not responding to the blue key for periods which were increased up to 60 seconds produced candy ( D R O 60-second schedule). This combined schedule was a concurrent extinction DRO 60second schedule. The change from the fixed-ratio to the concurrent schedule had rapid and striking effects. Responses to the blue key slowed and then stopped in accordance with the dependency between candy presentations and the absence of responses. Simultaneously, though, most of the children maintained a high rate of responding to the red key even though these responses actually were irrelevant to candy deliveries. That the responses to the red key depended on the candy deliveries was apparent in that these responses stopped when the DRO schedule was changed to extinction so that candy deliveries ceased. The behavior on the red key was similar to that observed when children received reinforcing stimuli for some response according to a fixed-interval schedule (e.g., Long, Hammack, May, & Campbell, 1958). Even though the candy was independent of responses to the red key, it maintained or increased the probability of responding. It was not necessary that the particular form of behavior emitted prior to reinforcement be pressing the red key; whatever behavior happened to occur at that time could increase in frequency. The behavior of two other children in fact did reveal different forms. Their behavior was reminiscent of Skinner’s ( 1948) pigeons. Neither of these children maintained presses of the red key during the concurrent schedule phase. One of the children instead sat quietly and watched the tray. picking up a piece of candy when it appeared. This subject had alternated successive responses between the keys during the fixed-ratio schedule phase, and early in the concurrent schedule phase had received all of the candy during rest periods following periods of sustained responding. The other child explored the room and floor between candy presentations during the concurrent schedule rather than press the keys. Early in the concurrent schedule phase, he received several pieces of candy via the DRO schedule while searching on the floor for a dropped piece. Subsequently, hc spent the time crawling around the floor, reaching up to get each piece of candy when it was discharged into the tray. These characteristic behaviors of each child also stopped when the DRO schedule was changed to extinction. It appears, therefore, that the particular forms of behavior that a child emitted prior to reinforcement became predominant whether that behavior was key-pressing or something else. Some of these data, then, indicated that a response was established that had no scheduled relation to reinforcement, and the rest indicated that the rate of a previously established response could be maintained or increased.

8

Michael D . Zeiler

Another experiment also showed the ability of response-independent reinforcement to maintain responding in children. In two experiments, Weisberg and Kennedy (1969) first trained two- to five-year-old children to press a lever by delivering snacks according to either a variable-interval or a variable-ratio schedule (Phase 1) . They then changed to a schedule which delivered the snacks independent of responses at either variable or fixed time periods (Phase 2). The remaining children were shifted from the response-dependent schedules (Phase 1 ) to extinction (Phase 2 ) . The behavior of the groups in Phase 2 provided between-group comparisons of the ability of response-independent and extinction schedules to maintain responding. Additional manipulations provided a within-subject comparison. The children who had been given the response-dependent schedule in Phase 1 and the response-independent schedule in Phase 2 were returned to the response-dependent schedule (Phase 3 ) and then were changed to extinction (Phase 4). Those who had the response-dependent schedule of Phase 1 followed by extinction in Phase 2 were returned to the responsedependent schedule (Phase 3 ) and were then changed to a responseindependent schedule (Phase 4). A comparison of Phases 2 and 4 revealed the effects of response-independent reinforcement and extinction on the behavior of each child. Weisberg and Kennedy therefore provided both within- and between-subject comparisons of the ability of response-independent and extinction schedules to maintain a previously established high probability response. The results were unequivocal. Under extinction conditions the rate of lever pressing quickly dropped to a low level. With response-independent food presentations, however, responding persisted for a much longer time before dropping to a low level. In fact, three of the four children who were shifted from the response-dependent variable-ratio schedule of Phase 1 to the response-independent fixed-time schedule of Phase 2 pressed the lever throughout the ten experimental sessions. One child showed no decrease, a second dropped to a low stable level, and the third responded at a higher rate in the response-independent schedule phase. All three subjects subsequently stopped responding after being shifted from the Phase 3 variableratio schedule to extinction. The data suggested that the durability of responding during the responseindependent phase might depend on the rate of the response when that phase began. Subjects differed in their response rates in the variable-timc schedule were ordered just as they were under variable-interval: The higher the rates during variable-interval, the higher the rates and the more persistent the behavior under variable-time. The variable-ratio schedule established still higher response rates than did the variable-interval, and responding seemed even better maintained with the shift from the ratio than

Superstitious Behavior in Children

9

from the interval to the response-independent schedules. Prevailing higher response rates imply the greater probability of a given response occurring in close temporal contiguity to reinforcement under a response-independent schedule, so that it is consistent that behavior should be better maintained if it is occurring at a high rate. These data show that stimuli which reinforce behavior when presented according to response-dependent schedules also reinforce behavior when presented independently of responses. Thus, the data support the hypothesis tkat response-independent and response-dependent presentations have similar effects with respect to developing and maintaining behavior. The only difference seems to be that the response-dependent case guarantees that a specified response will be contiguous with reinforcement, while the response-independent case leaves the particular response free to vary. Why did the rate of responding decline in the response-independent schedule phase with many of the children in the Weisberg and Kennedy (1969) study? Similar rate decreases also occur when nonhuman subjects are shifted from response-dependent to response-independent reinforcement (Appel & Hiss, 1962; Herrnstein, 1966; Zeiler, 1968). The explanation is straightforward. Skinner ( 1948) noted that when reinforcements occur independently of responses, it is likely that although a certain form of behavior is most probable that precise behavior will not always immediately precede reinforcement. Although a reinforcing stimulus does strengthen behavior that is not exactly contiguous with it, the strongest effects are on the immediately preceding events (Dews, 1960). If a behavior incompatible with the response being measured should have the closest contiguity with reinforcement (e.g., withdrawing the hand from the key after pressing is incompatible with pressing in that both cannot occur simultaneously), the measured response eventually should be replaced by the other. Thc new behavior could be of any form based on exactly what did occur at the moment of reinforcement. Skinner observed that the nature of superstitious rituals emitted by pigeons changed over time. This drift in behavior probably is due to the sort of events just described, and illustrates an important difference between response-independent and response-dependent schedules. In the response-dependent case the response requirement precludes drifting by maintaining the close temporal relation between reinforcement and the prescribed response. The recognition of drift raises the question: Why should a certain form of behavior ever persist indefinitely with response-independent reinforcement? Weisberg and Kennedy's results showed that for some children the response did persist, and Herrnstein and Morse (Herrnstein, 1966) reported similar results. Informal observations by several experimenters have suggested that a previously required behavior can continue indefinitely

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Michael D.Zeiler

under a response-independent reinforcement schedule. Why this should occur is a puzzling and unsolved question. All that can be said at this time is that apparently behavior which has been established strongly can be maintained, perhaps permanently, under certain as yet unspecified conditions.

B. TEMPORAL PATTERNS OF RESPONDING

In nonhuman subjects, response-dependent reinforcement schedules have effects on behavior other than affecting its overall probability. According to the particular schedule in force, the distribution of responses in time (the pattern of responding) varies. Thus, with fixed-ratio schedules of moderate or large size, a pigeon pauses after reinforcement and then quickly changes to responding at a high rate which continues until the next reinforcement. Fixed-interval schedules also produce a postreinforcement pause, but then responding gradually accelerates to a high rate. Variable-interval and variable-ratio schedules generate stable rates without long pauses throughout the periods between successive reinforcements. To the extent that response-dependent and response-independent reinforcement are the same, response-independent schedules should also produce characteristic patterns. Schedules involving temporal specifications are of necessity the meeting point of response-dependent and response-independent schedules. Fixedand variable-ratio schedules specify only response number as the requirement for reinforcement; by definition, there can be no response-independent analogues of ratio schedules. Fixed- and variable-interval schedules, in contrast, involve both time and response requirements: either reinforcements follow the first response occurring after fixed periods or after variable time periods. Response-independent schedules can mimic the temporal aspect of interval schedules. I n this respect, fixed-time schedules correspond to fixed-intervals and variable-time schedules correspond to variableintervals. Research with nonhuman subjects indicates that fixed- and variable-time schedules do indeed generate distinctive patterns, and, in fact, produce patterns like those occurring with fixed- and variable-interval scHedules (Appel & Hiss, 1962; Herrnstein & Morse, 1957; Zeiler, 1968). There is no published work with children on this problem; however, one might anticipate difficulty in obtaining differences between fixed- and variable-time schedules because children respond similarly on fixed- and variable-interval schedules. Both produce fairly steady response rates with occasional pauses in responding (e.g., Long et al., 1958). In a previously unpublished study, Zeiler and Orr investigated the pat-

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terns of responding established in four- and five-year-old children by candy presented according to either fixed- or variable-time schedules. For some children the initial schedule was a fixed interval in which the first response occurring after 30 seconds produced candy; for others, it was a variable interval having a mean interreinforcement interval of 30 seconds. The purpose of these schedules was to generate substantial rates of pressing the response key. After there were at least three sessions and responding had stabilized, the schedules were changed to provide candy independent of responses. The children who had been on the fixed-interval schedule now received candy on a variable-time schedule : Candy appeared at irregular intervals averaging 30 seconds. The children who had been on the variableinterval schedule now obtained candy on a fixed-time schedule providing candy every 30 seconds without reference to behavior. For one child the change from variable interval to fixed time occurred in the middle of a session, but for the others changes were made at the beginning of a session. Although there were substantial differences among the five children in the average response rate in the first phase, these differences were unrelated to whether the schedule was fixed or variable interval. Cumulative records revealed similar patterns of responding with the two schedules: All of the children responded at a fairly steady rate although pauses did occur during some interreinforcement periods. Pauses did not often occur immediately after candy deliveries but were distributed throughout the intervals. This sort of behavior is typical of children under fixed- and variable-interval schedules. The record shown in segment A of Fig. 1 is for a child given a variabletime schedule. The behavior continued much as it had been under fixed interval, with responses emitted at a fairly stable and high rate. The change from the fixed-interval to the variable-time schedule had little effect on behavior. The change t o the fixed-time schedule had rapid effects. Segment B of Fig. 1 shows the behavior on the first day of the fixed-time schedule for one of the children. The behavior up to the first two candy presentations was like that observed previously under the variable-interval schedule. Subsequently, responding became more erratic, and then was marked by periods of pauses followed either by a n abrupt shift to responding at a high rate or by positive acceleration. Pauses after candy presentations were evident. Still later in the session responding was often first positively, and then negatively, accelerated in each period so that the records were S-shaped. The next session showed similar behavior. Segment C of Fig. 1 shows the behavior of the child changed from the variable-interval to the fixed-time schedule midway through a session. Although the prevailing rate was low under both schedules, the patterns of

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Michael D . Zeiler

I

8 Minutes

-I

Fig. 1. Cumulative records obtained by Zeiler and Orr. ( A ) A full session o f the variable-time schedule, ( B ) a frill session of the fixed-time schediile, and ( C ) a sessioii in uBhich the schedule n'as changed from variable interval to fixed time. The record is broken at the point of transition. Deflections of the response pen indicate candy preserr tafiorrs.

responding were like those of the other children. The variable-interval schedule generated a rather erratic pattern : In some intervals responding was steady and in others it was positively accelerated. With the switch to the fixed-time schedule, responding was positively accelerated in nearly every interval. Two other children were first trained with a variable-interval schedule and were then shifted to fixed interval to determine whether the change in temporal patterning of reinforcement from variable to fixed was responsible for the change in the pattern of responding observed for children switched from the variable-interval to the fixed-time schedule. However, the change from variable- to fixed-interval produced no noticeable changes in behavior. These data revealed that the response-independent schedules did control distinctive patterns of response. In fact, the difference in the behavior under fixed-time and variable-time schedules was much greater than that between fixed-interval and variable-interval schedules. It remains unclear as to why the two types of interval schedule usually have generated similar behavior in children but not in nonhuman subjects. What is particularly puzzling is why both forms of variable schedule as well as the fixed-time schedule generate behavior in children like that observed with other species, while fixed-interval schedules differ. One possibility is that there is no research

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with children involving fixed intervals with substantial temporal requirements: Positive acceleration in pigeons does not always occur with short intervals (Ferster & Skinner, 1957). Perhaps fixed-time schedules will show positively accelerated responding at temporal parameter values too low to reveal such behavior under fixed intervals in human subjects. Weisberg and Kennedy ( 1969) studied transitions from variable-interval and variable-ratio schedules to variable-time and fixed-time schedules. The only data provided on patterning was on fixed-time following variable-ratio training. These data confirmed Zeiler and Orr's finding that fixedtime schedules engender positively accelerated rates of responding. Two of the children displayed positively accelerated patterns during the variableratio schedules but the pattern was enhanced by the fixed-time schedule. The third subject had a fairly stable rate under variable-ratio reinforcement and then displayed positive acceleration with the fixed-time schedule. These limited data on patterns of responding under response-independent schedules indicate that variations in the response-independent conditions do produce different patterns of response. The data confirm those of nonhuman subjects given fixed- and variable-time schedules. It may be, however, that children differ from nonhumans in that fixed response-independent and response-dependent schedules (fixed-time and fixed-interval) produce different effects. Since the data are scanty, all that can be said now is that the results are equivocal with respect to the similarity of the two forms of fixed schedule; obviously, final conclusions await further research.

C. STIMULUS CONTROL One important property of response-dependent reinforcement is that when the availability of reinforcement is differentially related to environmental stimuli, organisms usually come to respond differentially with respect to the stimuli. Stimulus control, therefore, is observed under experimental paradigms in which a response ( R ) is followed by a reinforcing stimulus (SR) in the presence of a certain antecedent stimulus (S). In one familiar instance of the S-R-S" paradigm, responding is reinforced in the presence of one stimulus and not reinforced in the presence of another; other common cases involve reinforcement in the presence of two or more stimuli with a distinctive schedule correlated with each. In any event, stimulus control is evidenced when subjects' responses differ in some respect (e.g., rate or pattern) depending on the prevailing stimulus. These typical situations involve a two-way dependency : Reinforcement requires the presence both of a certain stimulus and of a certain response. Discriminative behavior should also occur with response-independent reinforcement if the response-dependent and independent cases involve the

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Micliuel D . Zeiler

same essential processes. However, the general problems encountered in studying response-independent reinforcement in nondiscriminative situations also arise, and, in fact, seem evcn more burdensome in the discrimination situation. What response should be observed? Will the experimenter notice it if and when it occurs? In addition, how can the experimenter rigorously evaluate whether the observed superstitious behavior is differentially related to the prevailing stimuli? One possible solution is the one already described, namely, generate a high probability response by prior training and then shift to a response-independent schedule while manipulating stimuli. Although such a procedure would be of interest and might well prove effective, it apparently has not been used. Instead, a different procedure, one first reported by Morse and Skinner (1957), has proven valuable and provides related information. It consists of a maintained response-dependent schedule with changes in stimuli that have no scheduled relation to the availability of reinforcement. The procedure consists of having reinforcement be stimulus-independent while continuing to be response-dependent. Differential responding under these conditions indicates that the three-term S-R-SR dependency is not necessary for obtaining stimulus control, but is perhaps effective only because it guarantees certain temporal relationships between discriminative stimuli, responses, and reinforcement. Thus, the procedure provides a way of breaking up part of the three-term dependency to determine if in fact it is essential for stimulus control to occur. Morse and Skinner found that pigeons pecking a key which produced food according to a variable-interval schedule had a different response rate in the presence of each of two colors, although the colors were only adventitiously related to the reinforcement schedule. Thus, in pigeons, different scheduled consequences for responding to two stimuli are not necessary to establish discriminations; pigeons responded differently to two stimuli when each provided the same outcome. Tt is appropriate to refer to this phenomenon as a “superstitious discrimination” since differential responding occurred in the absence of differential requirements. The experiment reported here investigated further the occurrence of discriminations in the absence of experimenter-scheduled differential reinforcement. The research had two main purposes: ( 1 ) to investigate the generality of the Morse and Skinner effect with children and ( 2 ) to determine whether discriminations would develop with a reinforcement schedule other than variable interval. The first purpose, assessment of generality, stemmed from the absence of any data bearing on this problem with children. The second arose because previous research used only variable-interval schedules. Both variable-interval and fixed-ratio schedules were used to determine

Supersiiiioiis Behavior in Children

15

if the superstitious discriminations occur only with irregular temporally determined reinforcement presentations. The subjects were 12 children ranging in age from four to five years. During the 10 experimental sessions, they received candy for pressing a key according to either a variable-interval schedule having a mean interval of 30 seconds or a fixed-ratio schedule maintained at 15 responses per candy presentation. Six children were exposed to each schedule. The significant aspect of the experiment was that key pressing produced candy according to the schedule in force independent of the color of the key. The color alternated between red and blue, staying red for 30 seconds and changing to blue for 6 seconds. The occasional interruptions of one color by another was the same general procedure used by Morse and Skinner, although their intervals involved the presentation of the second stimulus for 4 minutes once per hour and a baseline schedule of variable interval averaging 30 minutes between reinforcements. In the first session most of the children responded at nearly equal rates in the presence of the two stimuli. Differences in rate began to develop by the end of the session. With additional sessions, 9 of the 12 children had a substantially higher rate in the presence of one stimulus than the other, and several had more than a 10-fold rate difference. Figure 2 shows the largest differences obtained in any session for children exhibiting a higher rate in red, for those having a higher rate in blue, and for those with n o clear rate difference. Figure 3 presents cumulative records showing a higher response rate when the key was red under both the variable-interval and the fixedratio schedules. The rates during each stimulus can be analyzed by com-

A

B

C

D

E

F G SUBJECT

H

I

J

K

L

Fig. 2. The largest rate differences nttained to the two Jtinirtli b y each child. The figure is segmented io show higher rates in red, higher rates irz hlite, and equal rates to boih stimuli. Thc solid bars show the rate during the blue stitnrrlus, and the striped bars show the rate during the red stimulus.

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Michael D. Zeiler

I

I

1 0 Minutes

Fig. 3. Citmrtlafive records indicating a higher response rate in red than in blue. T h e key was red f o r 30 seconds and changed fo blue during the 6-second periods ihai the response pen W ~ deflected. S Cirrve A shows an FR 15 schedule; curve B shows a VI 30-second schedule. T h e o c c ~ t r r e ~ ~ofc ecandv deliveries is riot shown.

paring the slopes in the records when the pen was in its normal position (during red) and when it was deflected (during blue). The children responded at a substantial rate (as fast as 2.00 responses per second) when the key was red, but virtually stopped pressing during the 6-second periods when it was blue. Counters and observations by the experimenter indicated that all candy was obtained either during the red periods or immediately after the color changed to blue. The overall rate of responding did not differ consistently with the two types of schedule, except that there was some pausing after candy deliveries with the fixed ratio. Figure 4 presents records showing a higher response rate in blue than in red. Again there were no marked schedule effects. With the fixed-ratio schedule children began responding during the 6-second blue periods and continued to respond until the delivery of candy. Then they paused until the next blue period. Candy

k

10 Minutes

I

Fig. 4. Cirmirlative records indicating a highrr response ratr in bliir than in red. Recording was described for Fig. 3. Cirrve A shows an F R 15 schedrrle; cirrvr B shows a V l 30-second schedule.

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presentations usually occurred in red following a burst of responses initiated by the change from red to blue. With the variable-interval schedule, they either did not respond at all in red or responded at a low rate. Almost all candy presentations occurred in blue. Different children exhibited various time courses of the discrimination. F o r some, the stimuli maintained different rates of responding over the 10 experimental sessions. Others showed a discrimination in the first four o r five sessions, but then came to respond equally during both stimuli. For others, stimulus control developed after several days of training. This sort of variability and changes in differential responding typically occurs in experiments on discriminations appearing in the absence of scheduled differential reinforcement in subjects other than children (Lander, 1968; Morse & Skinner, 1957). Also, the failure of a superstitious discrimination to occur for some subjects is not unusual in experiments of this type. Morse and Skinner pointed out that, although the stimulus which is present at the time of reinforcement is accidental, the reinforcement may increase the future rate of responding during that stimulus. If reinforcement now should happen not to occur when the second stimulus is present for any of a number of possible reasons, responding to that stimulus is likely to decrease. Now, given a greater likelihood of responding in the presence of one of the stimuli, the subject is more likely to meet the schedule requirements and to obtain additional reinforcements during the first stimulus. This sort of circularity would eventually result in a substantial degree of differential responding with respect to the two stimuli. The only difference between the superstitious discrimination and discriminations occurring when differential reinforcement is scheduled explicitly is that the superstitious case allows the stimulus which is correlated with reinforcement to vary. Because of that, either stimulus could control the higher response rate, and, because reinforcements may occur during the stimulus correlated with the higher rate (unless the subject completely stops responding), the discrimination either could disappear or even reverse its direction over a number of sessions. (Reversals in the stimulus which controlled the higher rate were not observed in the children.) These hypotheses would seem to be reasonable accounts of the nature of superstitious discriminations; as such, they demonstrate the similarity in process for the events responsible both for superstitious and experimenter-determined discriminations. Apparently, the prevailing reinforcement schedule is not critical since similar behavior occurred with both fixed-ratio and variable-interval schedules, perhaps because both schedules produced similar rates and patterns of responding in children. It seems likely, however, that supmtitious discriminations probably require at least a moderate degree of intermittency in

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the response-reinforcement relation. Continuous reinforcement or schedules having little intermittency probably would establish such a high probability of reinforcement in the presence of both stimuli that rate differences and the ensuing circular relationship between ongoing behavior, reinforcement, and consequent behavior would not develop. One new observation was that children did not require a strict correlation between reinforcements and stimuli to establish the superstitious discriminations. Some subjects had a higher rate during the blue stimulus even though the candy presentations occurred during red. Since the run of responses always did begin in blue, it seems as if the stimulus present when responding began was more important than the one present at the moment of reinforcement. This may be a difference between children and nonhuman subjects; however there are insufficient data to evaluate this possibility.

D. REINFORCEMENT AND TEMPORAL CONTIGUITY The preceding review demonstrated the close similarity between adventitious reinforcement, be it response-independent or stimulus-independent, and the effects of reinforcements scheduled to occur only under specified and experimenter-controlled stimulus and response conditions. Although there are differences which limit final conclusions, they may be more apparent than real because of the absence of sufficient data concerning the behavior of children. At the present time, the similarity in the effects of adventitious and deliberate reinforcement appears compelling. A reinforcing stimulus seems to strengthen ongoing responding even though the reinforcing stimulus and the responses and the prevailing discriminative stimuli are only temporally related. Furthermore, the behavior is essentially the same as when reinforcements require the presence of certain responses and discriminative stimuli. The temporal relation describes both the necessary and the sufficient conditions for modulating behavior. The critical events, therefore, are the same in both the adventitious case and the case in which reinforcement is delivered dependent upon the occurrence of a response and/or the presence of a specified discriminative stimulus. The only difference between superstitious behavior and the ordinary operant behavior observed with response- and stimulus-dependent reinforcement is that the dependent cases specify the behavior contiguous with reinforcement while the adventitious cases leave the behavior free to vary. Thus, behavioral control is identical for reinforcements given for specific responses and reinforcements having an accidental relation to responses and discriminative stimuli; reinforcement has the same temporal relation to behavior and stimuli in either case.

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111. Control of Multiple Responses A. CONCURRENT RESPONSE-INDEPENDENT A N D RESPONSE-DEPENDENT REINFORCEMENT A number of experiments (e.g., Antonitis, 195 I ; Skinner, 1938) have shown that reinforcement affects several forms of behavior simultaneously. For example, when a rat obtains food dependent on a bar press, the probability of bar pressing increases. In addition, other aspects of behavior, e.g., the duration o r the topography of the bar press, become stereotyped even though the reinforcement occurs independently of these aspects of behavior. (Except, of course, that the duration must exceed the minimum value specified as a n acceptable response by the programming equipment, and that the lever must be pressed in some fashion.) These data suggest that the response-dependent presentation of a reinforcing stimulus not only influences the behavior scheduled to precede it but concurrently operates on the behavior which accidentally precedes it. Some data with children also support this conclusion. Bruner and Revusky (196 I ) studied the behavior of adolescent boys when a response to one telegraph key earned five cents whenever at least 8.2 seconds but less than 10.25 seconds elapsed since the preceding response to that key. This is a differential-reinforccment-of-low-rateschedule ( D R L 8.2-seconds) with a limited hold of 2.05 seconds. In addition to the telegraph key correlated with this schedule, there were three other keys. Responses to these other keys had no consequence with respect to the delivery of nickels. The complete schedule, involving all of the keys, was a concurrent [ ( D R L 8.2 seconds limited hold 2.05 seconds) extinction extinction extinction] schedule. Subjects were instructed to press one key at a time and were permitted to use only one hand. T h e four boys all had a higher rate of pressing the irrelevant keys than the one correlated with the delivery of nickels: Three of the four confined the high rate responses to one of the extinction keys, while the fourth boy responded about equally to two of the three keys. Responses to the DRL key were spaced sufficiently in time so that nearly every such response was followed by the presentation of a nickel. When the schedule on the D R L key was then changed to extinction so that nickels were no longer available, responding became more erratic. Apparently, the responses to various keys in the D R L phase were being maintained by the nickels even though presses of all but the one key were irrelevant with respect to the reinforcing event. Bruner and Revusky interpreted their data as indicating a chain of behavior which served to bridge

Michael D.Zeiler

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the time gap between successive presses of the DRL key. What is more important is that the response-dependent delivery of reinforcement according to one schedule also generated stable behavior which had a responseindependent relation to deliveries of the reinforcing stimulus. Such effects are not peculiar to DRL schedules. In Zeiler’s (1970) study referred to in Section IIA, four- and five-year-old children began with candy presented according to a fixed-ratio schedule. There were two keys, one red and one blue, and the ratio requirement could be met by a total of 30 responses distributed in any proportion between the two keys. Every child established a systematic pattern of responding. Some alternated keys with every response, and others alternated keys after each candy presentation, Thus, the fixed-ratio schedule: ( a ) increased the probability of keypressing, the behavior on which candy presentation depended, and ( b ) fixed the way in which the responses were emitted even though such stereotypy was superstitious in that it was irrelevant to reinforcement deliveries. Tritschler’ has found similar stereotyped and often even more complex patterns of response in college students required to execute a fixed ratio on any of five telegraph keys. In the next phase of Zeiler’s (1970) study, responding to one of the two keys had no scheduled consequence and not responding to the other key for a specified period of time resulted in candy (concurrent DRO Extinction schedule). Two forms of behavior resulted. The children stopped pressing the DRO key. In addition, the DRO schedule maintained behavior which did not influence the delivery of candy. Either the children pressed the extinction key at a high rate or they consistently performed other behavior such as crawling on the floor or sitting and staring at the candy tray. Again, a reinforcing stimulus influenced both required behavior and behavior which had only an adventitious relation to the stimulus presentations. Catania and Cutts (1963), studying college students, demonstrated that the close temporal contiguity of the superstitious behavior to reinforcement maintains the behavior. Their subjects had two push buttons with responses to one reinforced on a variable-interval schedule and responses to the other having no scheduled consequences (concurrent variable-interval extinction schedule). The subjects maintained a high rate of responding to both buttons, and one subject actually responded at a much higher rate to the extinction button than to the variable-interval button. Catania and Cutts then added a new requirement: A press on the variable-interval button could not be reinforced if it followed a press on the extinction button within a certain time. The imposition of this change-over delay greatly reduced the superstitious responses to the extinction button; without the change-over 2

J. Tritschler, personal communication, 1970.

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delay, superstitious responses were maintained because they could occur in close temporal contiguity to the response deliberately reinforced on the variable-interval schedule. I t seems reasonable to hypothesize that the superstitious behavior in Bruner and Revusky’s and Zeiler’s experiments was maintained in the same way. The obvious conclusion is that reinforcing stimuli influence several forms of behavior simultaneously even when they have a response-dependent relation to one and a response-independent relation to the other.

B. SOMECOMMENTS O N MEDIATION AND INDIVIDUAL DIFFERENCES When superstitious behavior occurs during DRL or DRO schedules which require periods of not performing the criterion response if reinforcement is to occur, it may be tempting to attribute a mediating function to the superstition. The implication would be that the behavior serves to facilitate the acquisition of reinforcement by filling the time interval. The possible advantages of such behavior, though, should not obscure the fact that the particular behavior that occurs could only be strengthened because it accidentally preceded reinforcement delivery and is maintained because it continues to have this temporal relation. To pose an extreme position, perhaps mediation refers to nothing more than collateral adventitiously reinforced behavior. Although superstitious behavior would seem to have no beneficial function with schedules such as fixed ratio or variable interval where the subject can respond continuously, similar collateral behavior does occur with those schedules. Hence, the collateral behavior need not be useful for it to occur and be maintained; it occurs and is maintained because it continues to bz reinforced. Tt is possible that the same kind of independence characterizes human verbal and motor behavior. namely, that these are separate response systems which may be simultaneously affected by reinforcement. This is a different notion than the common one that verbal mediation is instrumental in producing certain kinds of motor behavior (e.g., choices in discrimination learning) ; perhaps the motor and correlated verbal responses d o not always serve a functional role with respect to each other and are related only in the sense that both can be established by the same reinforcing event. T h e concurrent establishment and maintenance of deliberately and adventitiously reinforced responses may provide some insight into the basis of individual differences. Herrnstein ( 1966) pointed out that when reinforcements depend on a certain response the specification usually involves only some of the dimensions of the response. For example, the experimenter specifies the location and minimum force of an acceptable response but does not also specify its precise topography, rate. maximum force, or dura-

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tion. Yet if these aspects of behavior are conditionable, whatever values they assume will be correlated with reinforcement and will thereby become more probable. Since the values are unspecified, they are likely to differ among individual subjects. That the laboratory situation may be analogous to the natural environment in this respect does not seem farfetched. In the natural environment children generally receive reinforcements for similar behaviors, for learning to care for themselves, for doing well in school, for obeying adults, etc. Despite this general homogeneity, many other aspects of behavior can vary. A child may answer a question in a low or a loud voice, and the reinforcement given for answering correctly may also increase the probability of speaking softly or loudly in the future. Could similar accidents play a role in creating different behavioral styles? Although speculative, it is an alternative to usual explanations of individual differences.

c. A NOTEON REINFORCING NOTRESPONDING In a DRO schedule, a reinforcement occurs whenever a specified response has not occurred for a specified period of time because reinforcements depend on the subject’s not emitting a certain response. These schedules have proven useful in rapidly eliminating behavior and as controls in a number of contexts. The delivery of a reinforcing stimulus following not responding, though, has led to some curious interpretive problems. These apparently stem from reluctance to treat the nonemission of a specified response as a functional response. Instead, starting with Reynolds ( 1961 ), DRO schedules have been defined as “differential-reinforcementof-other-responses,’’ the implication being that the reinforced behavior is not the absence of a response but rather is the occurrence of some other, although unobserved, behavior. Unfortunately, this definition of the schedule involves a theoretical account of its method of action instead of an objective description of the dependency. It may also obscure the possible fact that not emitting a particular response may actually have functional response properties. In any case in which a given behavior is occurring with some frequency, if its probability decreases following consequences for its nonoccurrence, the absence of the response meets the requirements of a functional response. To attribute the behavior to the strengthening of some other behavior is an unsupported inference even if other behavior should be observed to occur, and certainly should not be involved in the name of the schedule. It is interesting that Lane (1961 ) also used the initials DRO to describe the schedule almost simultaneously with Reynolds but translated the initials as “differential-reinforcement-of-no-responding.” Thus, the two earliest uses of

Siiperstitious Behavior in Children

23

the initials defined them differently. [At almost the same time, Kelleher ( 1961 ) used the schedule and called it DRP: “differential-reinforcementof-pausing.’’ Kelleher’s provides an objective description, but his terminology was not adopted subsequently.] It does turn out that DRO schedules can strengthen some behavior other than that prescribed as prerequisite for reinforcement (not emitting a certain response). However, the strengthening of behavior in addition to that required is true of every other reinforcement schedule as well; there is nothing unique about DRO in this respect because adventitious strengthening of responses appears to be a general property of reinforcement. Therefore, it would be appropriate to describe any schedule as involving reinforcement of “other” behavior. The concurrent reinforcement of several aspects of behavior has played an important part in theoretical explanations of how reinforcement schedules establish their distinctive effects on behavior. Thus, first Skinner (1938) then Ferster and Skinner (1957), and then Morse (1966) hypothesized that the combination of response-reinforcement dependencies and response-reinforcement contingencies operate on different schedules of reinforcement. Although we do not yet have an adequate theory of reinforcement schedules, it seems likely that a comprehensive theory will be unable to ignore the relation of reinforcement to required and unrequired behavior in all schedules.

IV.

Other Effects of Response-Independent Reinforcement

Reinforcing stimuli are defined by their ability to affect the probability of responses that precede them; however, such stimuli also have other effects on behavior. These effects do not involve a dependency between the behavior and the reinforcer and thereby qualify as response-independent effects. Staddon and Simmelhag (1971) consider such behavior to be of such fundamental importance thJt it justifies (in fact requires) revised thinking about the nature of reinforcement. Commentary on their provocative arguments go beyond the scope of the present paper, however, a number of the effects they consider important have been observed in children. A. ELICITATION OF PREVIOUSLY PROBABLE RESPONSES

One property of a reinforcing stimulus presented independently of behavior is that it may elicit a response which previously had a high probability but presently is not occurring. Reid (1957) reported such an effect. He found that when pigeons, rats, or humans had been trained to make a

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Michael D . Zeiler

response by following it with the presentation of a reinforcing stimulus, subsequent discontinuation of reinforcement deliveries eliminated the behavior. After several days of the extinction procedure, Reid delivered the previous reinforcing stimulus once without reference to behavior. The subjects immediately resumed their previously trained response. Instead of the response-independent stimulus delivery having its major effect on the behavior which immediately preceded it, the effect was on the behavior which had occurred the last time the reinforcement had appeared. Skinner ( 1938) had described somewhat similar results. Reid suggested that the stimuli provided by reinforcement delivery or by consummatory responses may have been the first part of a behavioral chain and that the free food delivery may have reinstated responding by providing the early components of the chain which had never been affected by the extinction procedure. Although this hypothesis has not received further study, the basic finding has been replicated and extended. Spradlin, Girardeau, and Horn (1966) delivered tokens to retarded adolescents after every fiftieth pull of a plunger. All of the subjects attained a high rate of responding under this fixed-ratio schedule and emitted more than 1500 responses in the last four 20-minute sessions. The schedule was then changed to a variable DRO averaging 2 minutes: A token was delivered when the subjects did not pull the plunger for periods ranging from one to four minutes. An additional degree of intermittency was added by requiring that the no-response criterion be met twice for each token delivery. This complex schedule is a second-order schedule in which the behavior under the DRO schedule is treated as a unitary response and is reinforced according to a fixed-ratio schedule: In second-order schedule notation, the schedule is F R 2 (variable DRO 2-minutes). This schedule insured that the subjects were not operating the plunger in close temporal contiguity with token deliveries. All of the subjects pulled the plunger in the period following prescntation of a token. Five of the six subjects did decrease these responses with maintained exposure to the complex DRO schedule. Even after 25 scssions, however, the remaining subject continued to pause after receiving a token, then operated the plunger at a high rate, and then paused until receipt of the next token. These data indicated that the plunger pulls were elicited by the tokens evcn though they could never precede token delivery by less than one minute. This last subject was changcd to a schedule providing tokens every 30 seconds independently of behavior (fixed-time 30-second schedule ’) . The behavior became distinctly fixed-ratio-like in that most interreinforcemcnt periods showed a pause after token presentation followed by a high response rate which usually continued until the next token appeared. This last behavior is most parsimoniously considered as maintained by adventitious

Siiperstitiorrs Behavior in Cliildren

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correlations with token deliveries rather than as elicited by a reinforcing stimulus. Other data (e.g., Zeiler, 1970) suggest that responding maintained for long periods with D R O schedules is unusual. Typically, as with the majority of the children in the Spradlin et a[. experiment, responding stops. This suggests that the ability of a reinforcing stimulus to elicit a response which once preceded it may disappear. There is no obvious explanation for the extremely persistent responding of the one child in the Spradlin et al. study. The only obvious difference between her and the other subjects was that she was the only subject with a history of response-dependent reinforcement under a differential-reinforcement-of-low-rate ( D R L ) schedule, although it is unclear as to why or whether this history should be important. O F A N E W RESPONSE:AUTO-SHAPING B. ELICITATION

In 1968 Brown and Jenkins reported the novel finding that responseindependent but stimulus-dependent presentations of food resulted in key pecking in pigeons that had not previously been shaped to peck the key. Just presenting stimuli in certain ways elicited the key-peck, a response which previous investigators developed with the explicit differential reinforcement involved in response shaping. Their procedure was as follows. A trial consisted of an 8-second period with a white key and terminated with the response-independent delivery of food. In the intertrial interval, which varied from 30 to 9 0 seconds, the key was dark. Within 160 trials all of the pigeons pecked the key during the white period. Control procedures revealed that what was essential was that the key have some distinctive stimulus during each trial and that food presentation occur after the trial stimulus came on. Brown and Jenkins ( 1 9 6 8 ) called this phenomenon “auto-shaping.” Rachlin ( 1969) observed auto-shaping when the trial stimulus was followed by the termination of electric shock; it seems, therefore, that the emergence of pecking directed at the key is the outcome of the correlation between antecedent stimuli and the occurrence of reinforcement. N o response rcquirement is involved. Some previously unpublished data show that auto-shaping also occurs with children. Four- and five-year-old experimentally naive children were given no instructions other than to stay in a small room and d o whatever they pleascd. Experimental events were programmed and recorded automatically; however, the experimcnter also observed the children through a onc-way vision window. The front wall of the booth contained a response key and a tray into which pieces of candy could be dispensed. The key was transilluminated with either red or green light; the lights alternated from

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Michael D . Zeiler

red to green, staying red for 30 seconds and changing to green for 6 seconds. The green light terminated simultaneously with the delivery of a piece of candy into the tray. Pressing the key at any time resulted in the immediate presentation of a piece of candy. Each child pressed the key during either the first or the second session of training, with the first press occurring somewhere in the middle of the session. One girl never pressed the key with sufficient force for the apparatus to record a response but instead touched the key on each trial. The key-manipulating behavior emerged much as it did in Brown and Jenkins’ study. In the early trials the children did not appear to be looking at the key. With additional trials they seemed to orient more toward the key and began to approach it when it became green. Finally, they touched or pressed it during the green periods. All of the pressing and touching began during green, but later occurred during the red periods as well. The essential finding, though, was that the pressing emerged from the responseindependent but stimulus-dependent presentation of candy. Of course, once the child began to press the key the dependency between pressing and candy deliveries undoubtedly was responsible for the increase in response rate. Research with infants has shown a similar finding, namely, that responses initially established to a stimuli via stimulus pairings become even more probable if they are followed by reinforcement. PapouSek (Reese & Lipsitt. 1970) rang a bell and then elicited head-turning either by tactile stimulation of the cheek or by manually turning the infant’s head. Each head turn was followed by reinforcement (milk). This combination of stimulus pairings which elicited the response and reinforcement following the response produced a substantial frequency of head turns. Williams and Williams ( 1969) demonstrated the noninstrumental nature of the auto-shaped key-peck by finding that auto-shaping occurred in pigeons even when key-pecking was negatively correlated with the presentation of food. They used the Brown and Jenkins paradigm with the added consideration that a peck during the stimulus that was correlated with food presentation cancelled the food delivery and reinstated the intertrial interval ( a DRO schedule). Here, where pecks eliminated reinforcement, the pecks occurred anyway. The peck was elicited and maintained by the stimulus dependencies when the consequences of the peck precluded food presentation. These results imply that auto-shaping may not involve operant behavior but rather an eliciting property of certain stimulus arrangements correlated with the response-independent presentations of food. The auto-shaping procedure involves the straightforward use of the Pavlovian conditioning paradigm : Two stimuli are paired without reference to behavior. The second stimulus (food) depends on the presence of a

Supersfirioics Behavior in Children

27

certain antecedent stimulus ( a red key) but is independent of any response. Auto-shaping does, however, differ from what is commonly considered as Pavlovian conditioning (and PapouSek’s procedure) in that the response which comes to occur during the first stimulus has no necessary counterpart in an unconditioned response to the reinforcing stimulus (cf. Rachlin’s experiment) and in that the response is directed toward the antecedent stimulus. Thus, auto-shaping is an effect of the Pavlovian conditioning paradigm that differs from the classical effects observed by Pavlov and later investigators. Auto-shaping is not the only behavior of this type (cf. Rescorla & Solomon, 1967).

V. Concluding Comments The preceding review of response-independent reinforcing effects showed that reinforcement has multiple influences on the behavior of children. Some types of behavior are elicited by response-independent reinforcing stimuli, other forms of behavior are strengthened because a responseindependent reinforcing stimulus follows them. It is this latter behavior that is referred to as superstition since the term “superstition” usually refers to behavior that occurs as if it influences environmental consequences but in fact does not. The emphasis on superstition, though, should not obscure the fact that reinforcement has multiple effects on behavior; it controls behavior scheduled to precede it, it controls behavior that is not scheduled but happens to precede it, it produces stimulus control over behavior both when discriminations are deliberately arranged and when they occur adventitiously, and it elicits various types of behavior. The complexity of the reinforcing event becomes even more evident when it is recognized that all of these different effects may occur simultaneously. The operant conditioning paradigm describes a dependency between a specified response and a consequent stimulus, and operant discrimination describes a dependency between an antecedent stimulus, a specified response, and a consequent stimulus. But superstitious responses occur when a reinforcing stimulus is presented without reference to either an antecedent stimulus or a response, and superstitious discriminations occur when a reinforcing stimulus occurs independently of antecedent stimuli. What superstitious behavior illustrates is that in the absence of a response specification, responses which happen to precede reinforcement increase in probability, and that in the absence of stimulus specification, the stimulus present when reinforcement occurs develops control over responding. Superstition shows that the essential process involved in operant behavior is the temporal contiguity among response and stimulus events.

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REFERENCES Antonitis, J. J. Response variability in the white rat during conditioning, extinction, and reconditioning. Journal of Experimental Psychology, 195 1, 42, 273-28 1. Appel, J. B., & Hiss, R. H. The discrimination of contingent from noncontingent reinforcement. Journal of Comparative and Physiological Psychology, 1962, 55, 37-39. Brown, P. L., & Jenkins, H. M. Auto-shaping of the pigeon’s key peck. Jorrrnal of the Experimentai Analysis of Behavior, 1968, 11, 1-8. Bruner, A., & Revusky, S. H. Collateral behavior in humans. Journal of the Experimental Analysis of Behavior, 1961, 4, 349-350. Catania, A. C. Glossary. In A. C. Catania (Ed.), Contemporary research in operant behavior. Glenview, Ill.: Scott-Foresman, 1968. Pp. 330-33 1. Catania, A. C. On the vocabulary and the grammar of behavior. Journal o f the Experimental Analysis of Behavior, 1969, 12, 845-846. Catania, A. C., & Cutts, D. Experimental control of superstitious responding in humans. Journal of the Experimental Analysis of Behavior, 1963, 6, 203-208. Dews, P. B. Free-operant behavior under conditions of delayed reinforcement. I. CRF-type schedules. Joirrnal of the E.uperimenta1 Analysis of Behavior, 1960, 3, 221-234. Ferster, C. B., & Skinner, B. F. Schedules of reinforcement. New York: Appleton, 1957. Herrnstein, R. J. Superstition: a corollary of the principles of operant conditioning. In W. K. Honig (Ed.), Operant behavior: Areas of research and application. New York: Appleton, 1966. Pp. 33-51. Herrnstein, R. J., & Morse, W. H. Some effects of response independent positive reinforcement on maintained operant behavior. Journal of Comparative and Physiological Psychology, 1957, 50, 461-467. Kelleher, R. T. Schedules of conditioned reinforcement during experimental extinction. Journal of the Experimental Analysis of Behavior, 1961, 4, 1-5. Lander, D. G. Stimulus bias in the absence of food reinforcement. Journal of the Experimental Analysis of Behavior, 1968, 11, 71 1-714. Lane, H. Operant control of vocalizing in the chicken. Journal of the Experimental Analysis of Behavior, 1961, 4, 171-177. Long, E. R., Hammack, J. T., May, F., & Campbell, B. J. Intermittent reinforcement of operant behavior in children. Journal of the Experimental Analysis o f Behavior, 1958, 1, 315-339. Morse, W. H. Intermittent reinforcement. In W. K. Honig (Ed.), Operant behavior: Areas of research and application. New York: Appleton, 1966. Pp. 52-108. Morse, W. H., & Skinner, B. F. A second type of “superstition” in the pigeon. American Journal of Psychology, 1957, 70, 308-3 1 1 . Rachlin, H. Autoshaping of key-pecking in pigeons with negative reinforcement. Jorrrnal of the Experimental Analysis of Behavior, 1969, 12, 521-531. Reese, H. W., & Lipsitt, L. P. Experimental child psychology. New York: Academic Press, 1970. Reid, R. L. The role of the reinforcer as a stimulus. British Journal of Psychology, 1957, 49, 202-209. Rescorla, R. A., & Solomon, R. L. Two-process learning theory: relationships between Pavlovian conditioning and instrumental learning. Psychological Review, 1967, 74, 151-182.

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Reynolds, G. S. Behavioral contrast. Journal of the Experimental Analysis of Behavior, 1961, 4, 57-71. Reynolds, G. S. A primer of operant conditioning. Glenview, Ill.: Scott-Foresman, 1968. Skinner, B. F. The behavior of organisms. New York: Appleton, 1938. Skinner, B. F. “Superstition” in the pigeon. Joitrnal of Experimental Psychology, 1948, 38, 168-172. Spradlin, J. E., Girardeau, F. L., & Hom, G. L. Stimulus properties of reinforcement during extinction of a free operant response. Journal of Experimental Child Psychology, 1966, 4, 369-380. Staddon, J. E. R., & Simmelhag, V. L. The superstition experiment: A reexamination of its implications for the principles of adaptive behavior. Psychological Review, 1971, 78, 3-43. Webster’s new world dictionary. (College ed.) Cleveland: World, 1968. Weisberg, P., & Kennedy, D. B. Maintenance of children’s behavior by accidental schedules of reinforcement. Journal of Experimental Child Psychology, 1969, 8, 222-233. Williams, D. R., & Williams, H. Auto-maintenance in the pigeon: sustained pecking despite contingent non-reinforcement. Joitrnal of the Experimental Analysis of Behavior, 1969, 12, 5 1 1-520. Zeiler, M. D. Fixed and variable schedules of response-independent reinforcement. Journal of the Experimental Analysis of Behavior, 1968, 11, 405-414. Zeiler, M. D. Other behavior: consequences of reinforcing not responding. Joirrnal of P s y ~ h o l ~ g 1970, y, 74, 149-155.

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LEARNING STRATEGIES IN CHILDREN FROM DIFFERENT SOCIOECONOMIC LEVELS'

Jean L . Bresnahad and Martin M . Shapiro EMORY UNIVERSITY

I. INTRODUCTION ........................................... A. VARIABLES ........................................... B. OUTLINE OF EXPERIMENTS ........................... 11. CONCEPT FORMATION .................................... A. EXPERIMENT I-CONCEPT ACQUISITION IN HIGHERAND LOWER-CLASS CHILDREN ........................ B. EXPERIMENT 11-PARTIAL REINFORCEMENT OF AN OBVIOUS DIMENSION .................................. C. EXPERIMENT 111-CHAOTIC REINFORCEMENT . . . . . . . . . D. EXPERIMENT IV-PRETRAINING TO CRITERION . . . . . . E. EXPERIMENT V-PRETRAINING WITH A FIXED NUMBER OF TRIALS ............................................ F. DISCUSSION OF CONCEPT FORMATION . . . . . . . . . . . . . . . .

111. REWARD PREFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. EXPERIMENT VI-AMOUNT AND PROBABILITY OF REINFORCEMENT ....................................... B. EXPERIMENT VII-REINFORCEMENT WITH AND WITHOUT SIGNALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. DISCUSSION OF REWARD PREFERENCES . . . . . . . . . . . . . . IV. INSTRUCTIONS AND TRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1This research was supported in part by Contract B89-4613 from the Office of Economic Opportunity to M. M. Shapiro, J. L. Bresnahan, and I. J. Knopf. The authors express their appreciation to I. J. Knopf for his contributions to the program of research. 2 Present address: Department of Psychology, Lehman College, City University of New York, New York, New York. 31

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V.

A. EXPERIMENT VIII-EXTINCTION AFTER INSTRUCTIONS AND TRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. DISCUSSION OF INSTRUCTIONS AND TRAINING . . . . . . .

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I. Introduction There has been much interest in the characteristics of children from different socioeconomic backgrounds. Many writers have described in detail the differences in the environments of children who come from the extremes of the socioeconomic dimensions in the United States, referred to here as high and low socioeconomic status (SES) . Comprehensive reviews of the topic can be found in the Review of Educational Research (1965) and in Education in Depressed Areas (Passow, 1963). The lower-class homes are typically depicted as overcrowded, noisy, disorderly, and lacking in many of the items associated with the development of learning skills, such as books, magazines, records, and educational toys (e.g., Gordon, 1965). Many of the authors emphasize the nature of the children’s interactions with their parents, and consider this variable to be even more crucial than the material aspects of the homes. In particular, much attention has been devoted to the differences in the verbal communication in homes of high and low socioeconomic levels, and the consequent language development of the children (Bernstein, 1961; Hess Rr Shipman, 1965; McCarthy, 1954; Raph, 1965). The general findings have been that lower-class parents speak to their children in short simple sentences, usually commands, and rarely use language to elaborate or explain concepts. The differences in the behavior of higher- and lower-class children have likewise been observed and reported. It is well documented that lower-class children perform less successfully than higher-class children in many diverse kinds of experimental, academic, and vocational situations (e.g., Karp & Sigel, 1965). Children from lower socioeconomic levels are considered deficient in reading, number concepts, time concepts, auditory discrimination, visual discrimination, and symbolic representation (e.g., Deutsch, 1963; Montague, 1964; Riessman, 1964). Their intellectual functioning has been described as more concrete and inflexible than that of more privileged children (McCandless, 1952). They are depicted as being restless and prone to physical activity, and having a short attention span. They are said to be motivated only by short-term goals, incapable of postponing imme-

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diate gratifications, nonresponsive to symbolic or verbal incentive, and lacking in aspirations consistent with middle-class values (e.g., Gordon, 1965). These descriptions of environmental and behavioral differences among socioeconomic levels have been voluminous and encyclopedic. Attempts have been made to quantify the observations and obtain correlations among several categories of variables. Unfortunately such work suffers from the limitations of all similar endeavors; it is exceedingly difficult if not impossible to separate phenomena from epiphenomena, relationships from artifacts. The question still remains, “What are the necessary or sufficient environmental conditions for the establishment of identifiable patterns of behavior?” Fortunately, the available correlational data do provide the bases for intuitions and guesses. At the start of this research socioeconomic level was the principal independent variable. However, the ultimate goal was to replace this vague and confounded construct by a set of scientifically more manageable variables. A. VARIABLES

Socioeconomic level was defined in terms of the occupation, income, and education of the parents. This gross and impure subject variable of socioeconomic level was combined with manipulations of the more clearly definable independent variables of reinforcement schedule and reinforcement contingency. From the information obtained in the first few studies multiphase experimental procedures were designed in which pretraining conditions were manipulated. In the process, socioeconomic level became less and less interesting and the pretraining became more and more interesting. Instead of assuming that social class was correlated with childhood training, the pretraining was manipulated. A similar evolution occurred in the choice of dependent variables. At first two stimuli were presented to the subject and he was asked to choose one of them in a concept acquisition task; later subjects were asked to choose between two reinforcement schedules. Subsequently, rates of responding to several different stimuli were measured. Additionally, the sequence of choices bctween two stimuli or between two responses was analyzed.

B . OUTLINE O F EXPERIMENTS In the first set of cxperirnents to be presented, concept formation procedures were used. Higher- and lower-class children were trained to select one of two stimuli either on the basis of size or on the basis of number.

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I . L. Bresriahari urid M. M.Shapiro

The discrepancy between the results on the size and number tasks was subsequently interpreted and investigated as a difference between obviousness of stimulus dimensions. A pretraining procedure was then introduced into the design to determine the conditions under which the performance of higher- and lower-class subjects would be equalized. Following this study, subjects from middle range schools were studied to test the hypotheses generated with respect to the acquisition of strategies during concept formation. In the second set of experiments reward preferences of children from high and low socioeconomic levels were investigated. The subjects were allowed to choose between two keys, one of which resulted in a fixed reinforcement schedule and one of which resulted in a variable reinforcement schedule. To investigate further the differences found in the behavior of the two groups, an experiment was designed to study the effect of the magnitude of the previous reinforcement and the effect of a signal predicting the magnitude of the next reinforcement. In the final experiment the rate of responding was considered, first as a function of social class and second as an interaction between social class and training.

11.

Concept Formation

A. EXPERIMENT T - C O N C E P T ACQUISITION IN HIGHERAND LOWER-CLASS CHILDREN

The Board of Education of Cobb County, Georgia, provided the names of schools which had children from either the highest or the lowest socioeconomic levels in the county. The following information was obtained from the school records: name, address, date of birth, occupation of parents, education of parents. Children who had repeated the first grade were excluded from the study. In Experiment I, a previously unpublished study, the following indices were used to determine socioeconomic level: location and quality of residence, occupation of parents, education of parents, grooming of the child. For the residence requirement only houses in very good condition and not too small in size qualified for the high level. The houses in the low level were quite deteriorated and in need of repair, and were often very small in size. The houses for the high and low levels corresponded to Warner, Meeker, and Eells’ (1949) house types 1 and 2, and 6 and 7, respectively. Similarly the occupations of the high and low levels corresponded roughly to Warner, Meeker, and Eells’ classes 1 and 2, and

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6 and 7, respectively. In the former were professionals, semiprofessionals, and proprietors of large businesses; in the latter were craftsmen, semiskilled workers, and unskilled workers. In the high level most fathers were college graduates. In the low level most parents had a seventh to tenth grade education. [In this paper the label “high” is used to describe a socioeconomic level which is typically called “upper-middle’’ in the United States. “High” is therefore broader than the category “upper,” which in some classifications refers to a very small percentage of the population; for instance, the upper class includes only 3% of the population in the Warner et al. (1949) system.] The schools chosen were either predominantly higher or lower class, and any one school was used as a source of only one of the groups, not both. That is, deviant children in these schools were not considered for the opposite group, e.g., a physician’s daughter in a lower-class school would not have been included in the higher group. Since socioeconomic level was of interest as a possible index of early training, the groomed appearance of the child was rated on a five-point scale. A rating of 1-3 was required for inclusion in the lower group and a rating of 3-5 was required for inclusion in the higher group. The measure of grooming proved to be cumbersome and of dubious value. In subsequent studies the criteria of grooming and quality of residence were nct used. It was anticipated that the discrepancy in the performance of the two groups would be reduced if reinforcers and tasks appropriate to the lower group were utilized. An even stronger prediction was that under some conditions there would be no difference in performance or that the lowerclass children might surpass the higher-class children. To investigate the kinds of situations which produce equal or differential success between higher and lower groups, therefore, an experiment was designed to manipulate tasks and incentives. All other factors such as the stimuli and apparatus were chosen or designed with the intent of maximizing performance for the lower group. The experimental task was one of concept acquisition (used interchangeably in this context with concept formation, concept attainment, concept utilization, concept identification). Because “concept” is a word psychology has borrowed from the vernacular, there is no consistent use of the term in the research literature. In this experiment the number of stimuli exceeded the number of possible responses, and concept formation was meant to imply simply the acquisition of common responses to dissimilar stimuli. It was necessary to choose stimuli with which children are familiar. Items that are assumed to be familiar include the common varieties of food, household objects, and clothing. Buttons were chosen for several

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J . L. Bresriahan and M . M . Shapiro

reasons. It was possible to use actual ones as stimuli; for large objects it would have been necessary to resort to either small facsimiles or pictorial representations, either of which would probably have placed higherstatus children at an advantage. Similarly, the fact that the subjects would be able actually to touch and handle the stimuli was considered to be a desirable feature. Buttons were also convenient as stimuli because they vary along many dimensions. For the experimental task itself, the use of buttons allowed the testing of a concept which all children learn by themselves at a very early age. Moreover, the buttons were also appropriate for a concept which is more dependent on specific teaching by others, or at least more related to previous training. These concepts are, respectively, size and number. The size and number tasks differed in difficulty in another important aspect which is related to the functional-conceptual classification. From infancy, size is a relevant and pervasive dimension for all children. It is a variable which they encounter in countless ways. Even more specifically, the attribute of “bigness” itself comes to have positive value for them. In the case of buttons, size can be considered the most obvious and most functional dimension. It was expected, therefore, that the task of choosing the larger of two different sizes of buttons would be extremely easy. Choosing the button with the greater number of holes, however, has very little relevance to experience in an ordinary environment. The utility of number of holes with respect to the usual function of buttons is trivial. When contrasted with the dimensions of size and color, the number of holes is a rather obscure dimension. It seemed desirable to include incentive conditions which were expected to result in different levels of performance. These conditions were knowledge of results only, knowledge of results plus social reinforcement, knowledge of results plus social reinforcement plus a tangible reward. All testing was done in the school. Ninety-eight first-grade girls were used in this first study. Each subject was brought by the experimenter from her classroom into the experimental room. She was seated directly in front of a table on which rested two plywood panels. One of the panels was used for all three reinforcement conditions. For the mechanical reinforcement condition, a large second panel was attached to the first. For the social and tangible reinforcement conditions, a much smaller second panel was attached to the first. Figure 1 shows the experimental apparatus for the mechanical reinforcement condition (knowledge of results only). All panels were painted with diagonal red and white stripes. Two cartoon faces were inserted in the first panel; the top face was a smiling one, the bottom face a sad one with tears. A royal blue plywood tray rested on the table within the opening at the bottom of the first panel. A lid

Learning Strategies in Children

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Fig. I . Apparatus panels f o r mechanical reinforcement condition in Experiment I . T h e subject has taken a hiitton f r o m the blrte tray and is putting it into the green chute. I f the biittorr is the correct one, the happy face will light rip and a bell will sound. I f the button is the incorrect one, the sad face will light rip and a buzzer will sound; the subject will then pick rip ihe other button in the blue tray and place it in the green chute, resrilting in the happy face and bell.

on the tray allowed it to be completely covered or opened, with the subject not being able to see the experimenter when the lid was in either position. Each of the second panels had a dark green chute. The buttons were presented in the royal blue tray and the subject responded by picking up one of them and dropping it into the dark green chute. All events were programmed electronically. For the mechanical reinforcement condition the experimenter merely served as the transducer, translating the subject’s response to an electrical impulse by pressing a push button switch. An easily discriminable 6 V bell and buzzer were mounted on the rear of the apparatus panel. The Peabody Picture Vocabulary Test was administered when the subject was brought from her classroom into the experimental room. Following the completion of the intelligence test, the subject was told that she was going to play a game. She was told that two things would be dropped into the blue tray and that one of them was right and the other was wrong. She was asked to pick up the one she thought was right and put it into the green chute. The procedure was demonstrated to the subject as well as the consequences for right and wrong responses. If the right response was made, the happy face lit up and the bell sounded. If the wrong response was made, the sad face lit up and the buzzer sounded. To make certain that there was no ambiguity for the subject as to which

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J . L. Bresnahan and M . M . Shapiro

stimulus was correct on any trial, a correction procedure was used. The subject was instructed to make the correct response on those trials in which the original response was incorrect. All demonstrations were done with practice stimuli distinct from those used in the actual experiment. Within each socioeconomic group there were three reinforcement conditions (mechanical, social, tangible) and two tasks (size, number) for a total of twelve independent groups. In the mechanical reinforcement condition the larger second panel was used and the experimenter sat behind the panel completely concealed from the subject. After each trial the only feedback the subject received for the response was the lighted face and bell (or buzzer). In the social reinforcement condition the smaller second panel was used. The subject could see the experimenter and after a correct response, the happy face and bell were accompanied by generous verbal support, such as “Good,” “Very good,” “Fine,” “You’ve been getting them all right.” After a wrong response, in addition to the sad face and the buzzer, the experimenter commented, “That one was wrong,” “You picked the wrong one,” etc. On a correction response, the experimenter said, “Okay,” “All right,” “Yes, that was the right one,” etc. In the tangible reinforcement condition the small second panel was used again, and in addition to the verbal support, the subject was given n penny for every correct response (pennies were not given for correction responses). Whenever the subject’s original response was correct, the experimenter put a shiny new penny into a glass dish in front of the subject. Extraneous conversation between the experimenter and the subject was minimized in all conditions. All trials were paced by the subject; as soon as she responded, the experimenter pressed the “right” or “wrong” push button, and if it was the former, the experimenter then immediately presented the next two stimuli. All subjects received 60 acquisition trials on each of which two buttons were presented in the tray. The experimenter tossed the buttons into the tray to make it apparent to the subject that location of the stimuli in the tray was not a variable. Before each trial began, the lid on the tray was closed, but it was raised as soon as the buttons were tossed into the tray. Immediately after the correct button was placed in the chute, the lid was again closed. One-half of the subjects from each reinforcement condition had the size task; the other one-half of the subjects had the number task. On both tasks, the buttons differed in color, size, and number of holes. There were four colors, four sizes, and four “numbers of holes.” For both the size and number tasks, color was an irrelevant dimension. For the size task, the correct button was always the larger of the two. There were twelve pairs of buttons presented five times each. In six pairs size and number were positively correlated, i.e., the larger button was also the button with more holes. In the other six pairs, the larger and

Learning Sirategies in Children

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smaller buttons had the same number of holes. Size and number of holes were not negatively correlated in any pairs. For the number task, the correct button was always the one with the greater number of holes. In six pairs the number of holes was positively correlated with size, and in the other six pairs the buttons were the same size. After trial 60, each subject was asked to guess which button was right without the face, bell, or buzzer (or pennies) being presented. Two buttons were then presented in the usual manner and after the subject had dropped one in the chute, the experimenter removed the remaining button from the tray and in its place immediately presented the next pair, without giving any feedback to the subject. For this transfer task, there were ten trials. Five pairs of buttons were presented twice in the same order. These buttons differed in color, size, and number of holes, but the colors were different from those of the acquisition trials. For the transfer trials after the size problem, both buttons of the pair were the same color and equal in size but differed in number of holes. For the transfer trials after the number problem, both buttons of a pair were the same color and had an equal number of holes, but differed in size. This transfer task could be viewed as an incidental learning problem. The transfer test was designed to determine whether there was differentiai attending or selective responding to the stimuli by the two socioeconomic levels. A control group of seven subjects from each socioeconomic level was run under the mechanical reinforcement condition on the size task. The procedure was identical to that used for the experimental group with the exception of changes in stimuli on three correlated trials. The set of buttons for the control group contained three pairs of buttons with size and number of holes positively correlated. six pairs in which these variables were uncorrelated, and three pairs in which these variables were negatively correlated. The transfer trials for the control group were the same as for the experimental groups. The results from this first experiment were most encouraging. The first useful finding was that IQ could be ignored as a variable. The mean IQ for the higher class was 103.52 with a standard deviation of 11.93, and the mean IQ for the lower class was 88.84 with a standard deviation of 14.51, This difference was significant.3 Correlations and partial correlations between I Q and the dependent variable yielded insignificant results in all cases. Therefore, it was concluded that although the two groups differed significantly in IQ, I Q was not related to the performance of the subjects on the concept formation task. The 60 acquisition trials were divided into 10 blocks of 6 trials each. :I Throughout this paper statistical significance implies a probability less than or equal to .05.

J . L. Bresnahan and M . M . Shapiro

40

The acquisition curves for each of the 12 experimental groups are plotted in Fig. 2. Size was significantly easier than number as a task; the acquisition curves for the two tasks are plotted in Fig. 3. There was no significant effect of socioeconomic level. On the number task the higher-class group made fewer errors, and on the size task the lower-class group made fewer errors; this reversal was reflected in a .06 probability for the interaction between SES and Task. There was a significant Trials effect and a significant interaction between SES and Trials. This interaction is shown in

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Fig. 4; in the first two blocks of trials the errors for the higher class exceeded those for the lower class, but the curves reversed and diverged in later blocks of trials. The curve for the lower class reached asymptote quite early and remained elevated. Since the results of an analysis of variance are relatively unspecific, attention was directed to a more detailed analysis of errors on trials with and without size and number correlated. It was considered possible that both the interaction between SES and Trials and the reversal between SES and Task resulted from different strategies used by the two socioeconomic groups. Since the lower group performed better on the size problem, the question arose as to whether the lower group was using size differences in their attempt to solve the

1. L. Bresrtahart atid M . M . Shapiro

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Fig. 4. Curves f o r rirrmber of errors by higher- arid lower-class groups plotted iri blocks of six acqrrisitiori trials irz Experimerit I . The higher- arid lower-class ciirves are iridicated by solid arid broker1 lines, respectively.

number problem. In view of the fact that size was positively correlated with number on one-half of the pairs and uncorrelated with number on the other one-half, responding according to size would have produced approximately 75 % correct, whereas guessing would have produced approximately 50% correct. As seen in Fig. 2, the size curves for the lowerclass subjects showed fast acquisition while the number curves for the lower-class subjects showed very little acquisition. The latter never exceeded a level superior to that which would have been attained had the

Leurning Strategies in Children

43

stimuli been chosen on the basis of size (correlated chance). They remained at a level between correlated chance and random selection of the stimuli (uncorrelated chance). The errors for the correlated and uncorrelated trials for the first two blocks of trials are shown in Fig. 5. On the abscissa the numbers 1, 4, 5, 7, 9, and 11 represent correlated trials and the numbers 2, 3, 6, 8, 10, 12, uncorrelated trials. As expected, only the number problem for the lower group (Fig. 5D) showed the uncorrelated trials to be more difficult. There is no overlap whatsoever in the number of errors on correlated and uncorrelated trials for the three subgroups of lower-class subjects trained on the number task. This relationship holds even when the group is further subdivided by reinforcement condition and the group size is thereby reduced to one-third. As seen in Fig. 5A and B, the hypothesis was supported that the higher-class subjects did not select the stimulus on the basis of the partially reinforced dimension. For the size problem the lower-class subjects selected the larger stimulus, which was the correct stimulus, thus yielding no difference between the curves in Fig. 5C. To determine whether there was any natural bias in the selection of the buttons, the number of errors prior to each subject’s first correct response was calculated. If no bias was present, the expectation was a geometric distribution ( p 1S ) for the number of errors to the first correct response. Neither the observed frequencies of the total group nor the subgroups differed significantly from the expected frequencies. The fit was good. The analysis of number of errors to the first correct response did not contradict the interpretation expressed in the previous paragraph on the correlated and uncorrelated trials. There are several possible explanations for the fact that the preference of the lower-class subjects to select the larger of the two stimuli did not operate prior to the first correct response. One is that the subjects did not form hypotheses on the first few trials, which would not be surprising since on the practice trials buttons were not even used and size was not a dimension. Another possibility is that the preference of the lower-class subjects for selecting the larger buttons did not operate until it had been reinforced. The data from the control groups were inconclusive because of the small number of subjects. The next experiment is devoted to contrasts with an adequately large control group. An analysis of the transfer task showed a significant effect of Task and an interaction between socioeconomic level and Task. For both socioeconomic groups the transfer test for size was easier than the transfer test for number, i.e., the test trials after the number problem were easier than the test trials after the size problem. The interaction between socioeconomic level and Task was in the same direction as the means for

J . L. Bresnahan and M . M . Shapiro

44 15. 14-

13. 12. (A)

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.

.

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2 3 4 5 6 7

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TRIALS L O W SES

Fig. 5 . Number of errors on correlated (solid curves) and itncorrelated (broken curves) trials in the first two blocks of trials for ( A ) high socioeconomic subjects on size task, ( B ) high socioeconomic subjects on number task, ( C ) low socioeconomic subjects on size task, ( D ) low socioeconomic subjects on number task in Experiment 1. Trials 1, 4, 5, 7, 9 , 1 1 are correlated trials; Trials 2, 3, 6 , 8, 10, 12 are uncorrelated trials.

Learriirrg Strategies in Children

45

the acquisition trials, and in the case of the transfer task, the interaction was significant. The striking result of the experiment, therefore, was that the lowerclass children maintained a partially successful size hypothesis on thc number problem. It is generally considered that on a concept formation problem the subject selects an hypothesis and retains it until he makes an incorrect response, at which time he rejects the hypothesis and samples a new one. If the hypothesis produces the correct response he stays with it. If the hypothesis produces an incorrect response, he shifts to a new hypothesis. This strategy is known as “win-stay, lose-shift’’ (Goodnow & Pettigrew, 1955). The lower-class subjects did not display this win-stay, lose-shift behavior, but continued to perseverate on a partially reinforced hypothesis. On the number task the size hypothesis produced approximately 75 % reinforcement and the subject persisted with the size hypothesis.

B. EXPERIMENT 11-PARTIAL REINFORCEMENT OF AN OBVIOUS DIMENSION The purpose of the next experiment was to replicate Experiment I, using an adequate control group. Since the interesting result of Experiment I was the behavior of the lower-class subjects on the size and number tasks, only lower-class children were sampled for this study. The apparatus and instructions given to the subject were identical to the mechanical reinforcement condition of Experiment I. The failure to obtain a significant result for reinforcement conditions in the previous study was sufficient justification for the discontinuation of that variable. The subjects in Experiment I1 were 64 children, 54 to 65 years of age, sampled from a Head Start program. All children had met the program’s economic criteria for eligibility. The subjects were sampled such that one-fourth were white boys, one-fourth black boys, one-fourth white girls, and one-fourth black girls. The experiment was conducted by Sandra Ivey (Bresnahan, h e y , & Shapiro, 1969). All subjects received 60 acquisition trials, on each of which the stimuli were two plastic clothing buttons presented in the tray. One-half of the subjects had the size task, and one-half had the number task. For both tasks, the buttons differed in color, size, and number of holes. For each of the two tasks, there were twelve different pairs of buttons which were repeated in the same order five times. For both tasks, color was a random dimension. For one-half of the subjects run on the size task, a correlated size procedure was used, and for the other one-half of the subjects, a control size procedure was uscd. Likewise, one-half of the number task subjects had correlated number, and one-half control number.

46

1. L. Bresirohuii uiid

M. M. Shupiro

For either size task, the correct button was always the larger of the two. In six of the twelve pairs for the correlated-size task, size was related positively to number of holes; that is, the larger button was also the button with more holes. In the remaining six pairs the larger and smaller buttons had the same number of holes. In no pairs, therefore, were size and number of holes negatively related. A trial on which size and number were positively related is a “correlated trial.” A trial on which the numbers were equal is an “equated trial.” In three of the twelve pairs of buttons for the control-size task, size was related positively to number of holes; that is, the larger button was also the button with more holes. In three of the pairs size was negatively related to number of holes; that is, the larger button was the button with fewer holes. In the remaining six pairs, the larger and smaller buttons had the same number of holes. The overall correlation between size and number was zero. The presentation order of correlated trials and equated trials was the same for both the correlated task and the control task. For the number tasks the correct button was always the one with the greater number of holes. In six pairs for the correlated-number task, the number of holes was positively related to size, and in the remaining six pairs, the buttons were the same size. In three pairs for the control-number task, number and size were positively related; in three pairs, number and size were negatively related; and in the remaining six pairs, the buttons were the same size. The subject in all conditions paced himself; as soon as he responded the experimenter pressed the “right” or “wrong” push button, and if it was the former, the experimenter then immediately presented the next two stimuli. If the response was “wrong,” the subject was required to make a correction response. The duration of the session was recorded and varied little among subjects. The dependent variable was the number of errors on the two types of trials within each block of six trials. For the correlated-size task and the correlated-number task, there were, within each block of six trials, three on which the two variables were positively related and three on which the irrelevant dimension was equated in value for the two stimuli. Therefore, two points were obtained for each block of six trials, one for the correlated trials and one for the equated trials. For the control size and number tasks, the identical trial separation was considered. For the control groups half of the correlated trials had size and number positively related and half had them negatively related; the equated trials were the same as in the other tasks. Figure 6 shows the total number of errors in each subset of three trials for the correlated-number task and the controlnumber task. An inspection of Fig. 6 shows that the two sets of trials

Learning Strategies in Children C O R R E L A T E D NUMBER

CONTROL

1

41 NUMBER

5L L CORRELATED T R I A L S

0

0

2

4

6

8

1

0

0

2

4

6

8

1

0

BLOCKS OF SIX TRIALS

Fig. 6 . Total number of errors f o r correlated-nrrmber and control-nrrmber tasks showing correlated and eqrrated trials in blocks of six trials in Experiment 11. (Each point represents the sirin of rhree trials. Size is a cite on the correlated trials of the correlated-nrrmber task.) From Bresnahan et al. (1969).

were undifferentiated on the control-number task, but on the correlatednumber task there were more errors on the equated trials than on the correlated trials. Figure 7 shows the results for the correlated-size task and the control-size task. It is evident that there was very little difference between the two groups in total number of errors, and very little differ-

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TRIALS

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k3 15

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2

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2

4

6

8

1

0

0

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4

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Fig. 7 . Total nrimber of errors f o r correlated-size and control-size tasks showing correlated and equated trials in blocks of six trials in Experimerit 11. (Each point represents the sum of three trials. Nrrrnber is a cue on the correlated trials of the correlated-size task.) From Bresnahan et al. (1969).

48

J . L. Bresriahan arid M . M . Shapiro

ence in either group between the equated trials and the correlated trials. The analysis of variance of the data in these two figures showed a significant difference between size and number Tasks and between correlated and equated Trials. There was also a significant interaction between size-number task and correlated-equated trial. Equally of interest, the interaction between correlated-control task and correlated-equated trial was significant. The last meaningful significant effect was the triple interaction among sizenumber task, correlated-control task, and correlated-equated trial. Therefore, all hypotheses were confirmed. There were no significant effects or interactions due to the race or sex of the subjects except the quadruple interaction with size-number task and correlated-control task, which had no readily apparent interpretation. The results of the experiment indicated that use of appropriate size and number tasks produces the same effects as an experimental manipulation of stimulus discriminability (Archer, 1962). The selection of size and number tasks for this population of subjects produced the interaction of obviousness X partial reinforcement that can be obtained in studies which manipulate the stimulus variables (Abraham, Gormezano, & Wiehe, 1964). Therefore, one has an experimental confirmation and elaboration of the fact that size comes earlier in development than number, and that the effects of this difference extend to more complex phenomena of learning. The results of Experiment I1 served as a replication of Experiment I. Young lower-class children did not adopt a win-stay, lose-shift strategy in concept formation tasks. They tended to perseverate on a dimension high in their hierarchy when the hypothesis relevant to that dimension was partially reinforced. Young higher-class children adopted a win-stay, loseshift strategy which ultimately resulted in nearly perfect performance even when the 100% reinforced hypothesis corresponded to a dimension low in their hierarchy. The results of the present study showed that partial reinforcement of size led to the adoption of a size hypothesis by the lower-class subjects when a number hypothesis would have been reinforced 100% of the time. There was n o effect of unequal number during a size task, but unequal size during a number task resulted in poorer performance. The subjects in a size task did not respond differentially to stimuli equated or unequated on the number dimension; the subjects on the number task did respond differentially to stimuli equated or unequated on the size dimension. To paraphrase, the subjects were more responsive to size than number. When number was relevant there was no effect of correlated trials on the control task, but on the correlated task there were fewer errors on correlated trials than on equated trials. This interaction did not occur when size was relevant.

Learuing Strategies in Children

49

C. EXPERIMENT 111-CHAOTIC REINFORCEMENT The previous two experiments showed that lower-class children did not adopt a win-stay, lose-shift strategy in a concept acquisition task. It was hypothesized from these data that lower-class children performed less successfully in concept attainment problems because of their inconsistent reinforcement histories. William Blum conducted Experiment I11 to investigate whether the introduction of chaotic reinforcement into the histories of higher-class children would lead to a comparable decrement in their performance (Bresnahan & Blum, 197 1 ) . The subjects were 60 first graders, with a mean age of 7 years. One-half of the subjects were from a high socioeconomic level and one-half from a low level. In each group one-half were boys and one-half were girls. The selection of subjects and the indices used to determine socioeconomic level were the same as those cmployed in Experiment I, with the previously noted exceptions of grooming and quality of residence. In this third experiment the first n trials were randomly reinforced. After the y1 random trials with no clues given to the subjects, the actual concept acquisition trials began and consistent reinforcement continued thereafter. The apparatus was a Lehigh Valley Electronics human intelligence panel. Mounted on the panel were a dual, multistimulus response key apparatus and a 1-cent reinforcement delivery system. The experimental procedure was automated. The subjects were individually seated in front of the Lehigh Valley console on which two different figures on two different color backgrounds were presented on each trial. A finger press against the stimulus activated a microswitch. Each correct response was rewarded with a penny. The use of a correction procedure required the subject to press the correct key if his initial response did not result in a reward. No penny was given for a response correction. The subject was told that he was going to play a little game with lights in each of the two openings. It was demonstrated to him that if he selected the correct light he would get a penny, and that if he selected the incorrect light he would then have to press thc correct one, although he would not get a penny. In any case, he was asked to leave the pennies in the dispenser until the completion of the game, at which time he would be allowed to keep them. The subject was requested to wait until the lights changed before beginning to play the game. He was allow to use only one hand. The first trial consisted of two stimuli that were never again used. This served as a check on the subject’s ability to follow directions. The actual experimental stimuli consisted of a triangle and a circle, one on a red background and the other on a green background. The four permutations of form and color, GT-RC, RC-GT, GC-RT, RT-GC, appeared with equal frequency in an unsystematic order. The 30

1. L. Bresnahan and M . M . Shapiro

50

subjects in each socioeconomic group were divided into three subgroups of ten subjects each. One-third of the subjects began immediately on the concept acquisition task in which the triangle was always reinforced; one-third had 6 trials in which the triangle and circle were randomly reinforced prior to the beginning of concept formation; and one-third had 12 trials in which triangle and circle were randomly reinforced prior to the beginning of concept formation. The red or green color and the positions of the circle and the triangle were never relevant stimuli. All subjects were given at least 42 trials. If the criterion of 12 correct responses in succession was not reached within the first 42 trials, the run was continued until the criterion was reached, up to a maximum of 120 trials. The number of errors in the first 42 trials, divided into 7 blocks of 6 trials each, can be seen in Table I. An analysis of variance yielded three significant main effects: SES, number of Random Reinforcements, and Trials. The higher-class children made fewer errors than the lower-class children on all tasks combined. Errors increased with an increase in the number of random reinforcements. Errors decreased over the seven blocks of trials. The interaction between SES and Number of Random Reinforcements was partitioned into two orthogonal comparisons, 12 and 6 vs. 0, and 12 vs. 6; only the former was significant. This significant result can be seen in Fig. 8; with 6 or 12 random reinforcements the subjects from a high socioeconomic level became progressively more similar in performance to the subjects from a low socioeconomic level. There were almost identical results from the TABLE I NUMBER OF ERRORS IN FIRST42 TRIALS OF CONSISTENT REINFORCEMENT

High SES

Low SES

Total:

No. of Random Reinforcements

1

2

3

4

5

6

7

Total

12 6 0

33 29 18

31 26 13

20 26 13

19 18 6

24 17 2

24 23 3 50

28 12 1 41

179 151 56 386

22 25 20

69

24 16 16 56

67

180 172 145 497

112

106

108

883

12 6 0

Blocks of six trials

-

-

-

-

-

80

70

59

43

43

31 25 24

27 28 16

24 25 25

22 25 22

-

-

-

80

71

77

30 25 22 77

160

141

136

120

From Bresnahan and Blum (1971).

-

-

Learning Strategies iri Children

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Fig. 8. Mean number of errors f o r each group of I0 subjects f o r 42 iriuls in Experitnetit 111. The high arid low socioecotiorriic lei~pls(ire iridicuted b y solid uiid opeti circles, respeciively. (The broketi litre deriote.r cliuticr level of perforr~inrice.)Fro171 Brestialiari arid B l i ~ t i i (1971).

higher- and lower-class subjccts given 12 prior random rcinforccments. It can be seen in Table I that a significant interaction between SES and Trials resulted from the fact that the higher-levcl children improved more than the lower-level children over trials. [Nonparametric statistical tests (Wilcoxon, 1947) of the numbers of trials to criterion yielded the same general results.] T h e number of errors for each of the 6 groups shown in Fig. 8 was significantly less than the chance level of 21 errors per subject; the smallest z value obtained was 2.93. T h e experiment demonstrated that the introduction of random reinforcement produced typically lower-class behavior in higher-class subjects. It was shown that this result was not a simple conscquence of all concept acquisition degenerating to a chance level. Both number of errors and trials to criterion revealed that the performance of the higher-class childrcn progressively approached and ultimately equaled the ineffectual lower-class performance. T h e data add credibility to the hypothesis that the inferior performance of lower-class children is a function of their chaotic or inconsistent reinforcement histories. Experiments IV and V were designed to investigate the conditions under which subjects will change their hypotheses during concept acquisition. I n both experiments there was pretraining on a concept and subsequent shifting to partial confirmation of that concept. In Experiment 1V the

52

J . L. Bresriahan arid M .M . Shapiro

degree of overlearning was manipulated prior to the shift to partial confirmation. In Experiments I and I1 lower-class subjects did not shift from a partially reinforced hypothesis which was high on their hierarchy. In Experiment I11 higher-class subjects, after random reinforcement, demonstrated similarly inferior concept acquisition behavior. Experiment IV was designed to invesitgate the conditions under which subjects would or would not shift from a nonconfirmed hypothesis as a function of the degree of original learning and the frequency of nonconfirmation.

D. EXPERIMENT IV-PRETRAINING

TO

CRITERION

The subjects in Experiment IV, a previously unpublished study, were 90 first-grade children, one-half boys and one-half girls. The subjects were randomly sampled from schools which had been identified as being located in areas which were neither predominantly high nor predominantly low socioeconomically. The experiment was conducted in a mobile laboratory parked outside each school. The Lehigh Valley human intelligence panel of the previous experiment was used. The previously employed task was simplified. On each trial a red and a green light were presented and the position of the two lights was an irrelevant dimension. The subject was shown the two lights and instructed to press one of the keys. If he made the correct response, a trinket was presented by a Universal feeder. The tray, into which the assortment of trinkets was delivered, had a closed clear plastic top. The subject was told that he would be allowed to keep the trinkets after the experiment. The intertrial intervals and stimuli were automatically controlled. Each subject was individually brought into the laboratory and told that he was going to play a game with the two push buttons. He was shown that pressing the correct button would turn off both lights and cause a toy to fall into the tray. When the lights came back on again, he was instructed to press one of the buttons. If the lights blinked and no toy was obtained, the response had been incorrect and the subject was instructed to press the correct button in order to turn out the lights and get another turn. The red key was always the correct key. If the subject chose the red key first, a toy was received and the lights went off for 3 seconds. If he pressed the green key the lights blinked for 30 msec and a nonreinforced correction response was required to turn the lights out for 3 seconds before the next trial began. In this first phase of the experiment, the subjects received trinkets on a 100% schedule until a criterion run was completed. For onethird of the subjects, the criterion run was defined as 6 correct responses in succession; for one-third, criterion was 12 responses; and for one-third, cri-

53

Learning Strategies in Children

terion was 18 responses. Following completion of the criterion run, partial reinforcement of the response to the red key was introduced without any indication to the subject. The partial reinforcement was 90% for one-third of the subjects, 80% for one-third, and 70% for one-third. The partial reinforcement schedules were run for 60 trials. During partial reinforcement a response to the red key was unreinforced on some trials. Since a correction procedure was employed, the subject was required to terminate these trials with a response to the green key. Following the introduction of partial reinforcement for the red key press, the subjects were expected to shift from the red key to the green key. An initial choice of the green key on any trial was categorized as an error. The dependent variable was the number of errors (initial green key responses) during the 60 trials of partial reinforcement. The results are shown in Fig. 9. An analysis of variance demonstrated that the number of trials required to reach criterion before the shift to partial reinforcement had a significant effect upon the number of errors during partial reinforcement.

I-

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90

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1 6

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I I 12 18 CRITERION

Fig. 9. Mean number of errors per subject during the partial reinforcement test as a function of the training criterion and the testing percentage of confirmation in Experiment I V . T h e number of errors is the number of response shifts during the last 60 trials on which the original response confirmation was 70%, 80%, or 90%. The right-hand figure shows the result as a function of the percentage of reinforcement to which the subjects were shifted. T h e left-hand figure shows the result as a function of the original number of trials to criterion, 6, 12, or 18.

54

1. L. Brestiuhari orrd M. M. Shapiro

The percentage of partial reinforcement also had a significant effect upon the number of errors. This difference was attributable to the discrepancy between the 70% condition and the 80% and 90% conditions combined. No other components of the analysis were significant. The results clearly demonstrated that although concept formation is considered an all-or-none process, there was a cumulative effect. The longer the criterion run in the first phase, the less likely the subject was to shift after a nonconfhnation during the second phase. The results also demonstrated that, if the proportion of nonconfirmations became sufficiently high (30% ) in the second phase, there was an increased tendency for the subjects to shift from their previously reinforced hypothesis. E. EXPERIMENT V-PRETRAINING

WITH A

FIXED NUMBER OF TRIALS

Experiments IV and V differed only in the pretraining of the first phase. In Experiment IV, the groups were defined by the number of criterion trials, irrespective of total number of trials; in Experiment V, another previously unpublished study, the groups were defined by a fixed number of trials, independent of the subject’s performance. The subjects for Experiment V were 90 first-grade children. The schools from which the subjects were sampled, the apparatus, and the instructions were the same as used in Experiment IV. One-third of the subjects received 12 trials before the shift to partial reinforcement, one-third received 24 trials, and one-third received 36 trials. After the 12, 24, or 36 trials, the subjects were shifted to 70%, 80%, or 90% partial reinforcement. Each of the nine groups were composed of one-half boys and one-half girls. The values 12, 24, and 36 in Experiment V were selected because they represented the number of trials required to reach the criteria by approximately 50%, 7 0 % , and 90% of the subjects in Experiment IV. The dependent variable was the number of errors during the 60 trials of partial reinforcement. An error was defined as any initial choice of the green key. The results are shown in Fig. 10. An analysis of variance yielded no significant effects. With partitioning, however, the discrepancy between the 80% and 90% conditions combined and the 70% condition was significant; but the 12-trial condition compared to the combination of the 24- and 36-trial conditions was not significant. In Experiments IV and V the percentage of nonconfirmations was a significant variable when that percentage was sufficiently high. In Experiment IV the number of trials to criterion was a significant variable. Once the subject had learned the correct hypothesis, the number of subsequent trials affected the probability of shifting after a nonconfirmation of the correct hypothesis in the second phase. In Experiment V the procedure did

Learning Strategies in Children 18 17 k 16

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24 36 TRANINO

Fig. 10. Mean number of errors per subject during the partial reinforcement test as a function of the number of training trials and the testing percentage of confirmation in Experiment V . T h e rirmber of errors is the number of response shifts during the last 60 trials on which the original response confirmation was 70%, 80%, or 90%. T h e right-hand figure shows the resiilt as a function of the percentage of reinforcement t o which the subjects were shifted. T h e left-hand figitre shows the resiilt as a function of the original number of training trials, 12, 24, or 36.

not guarantee that the subjects had learned the correct hypothesis and the number of trials was not a significant variable.

F. DISCUSSION OF CONCEPT FORMATION Theoretical accounts of concept formation have turned from response strengthening to hypothesis testing (Krechevsky, 1932; Lashley, 1929, p. 135). The subject has been viewed as formulating an hypothesis and retaining the hypothesis if his response is called “right” and rejecting his hypothesis and formulating a new one if his response is called “wrong.” This strategy has been referred to as “win-stay, lose-shift” (Goodnow and Pettigrew, 1955). Various models have been constructed to account for the method of shifting. All have involved the random selection of a new hypothesis from some subset of the population of all possible hypotheses. [See Levine, Yoder, Kleinberg, and Rosenberg (1968), or Gregg and

56

J . L. Brestiahari arid M . M . Shapiro

Simon (1967). for a description of the specific models.] Elaborate mathematical models have been constructed to formalize and quantity predictions generated by win-stay, lose-shift. Variables such as the numbers of errors prior to the first correct response and the stationary probability of the correct response have been investigated (e.g., Suppes & Ginsburg, 1963). In spite of occasional failures (e.g., Erickson, 1968), the basic notion of hypothesis sampling has been retained. The results of Experiments I and I1 clearly demonstrate that lower-class subjects do not display the expected behavior. They form an hypothesis which governs their selection of the larger stimulus; nonconfirmation of this hypothesis does not result in their shifting to a new hypothesis. Instead of displaying the win-stay, lose-shift behavior, they display a win-stay, losestay behavior. The results of Experiments 111, IV, and V provide some insights into this tendency to perseverate on a partially reinforced hypothesis. A procedure previously employed by Levine (1962) was used in Experiment 111. Random reinforcements at the beginning of training produced a devastating effect upon the performance of the higher-class subjects. This effect raises the possibility that inconsistent, if not random, reinforcement contingencies in the experiential history of lower-class subjects is at least partially responsible for their performance on concept acquisition tasks. When higher-class subjects received as few as six random reinforcements, they performed almost as poorly as lower-class subjects on a subsequent concept task. When higher-class subjects received as many as 12 random reinforcements, they performed as poorly as lower-class subjects on a subsequent concept task. There is no question that relatively little chaos can produce a large degradation of concept acquisition. Experiment IV yielded results which implicate another possible factor in the performance of lower-class children. Experiment IV was conducted with children from the middle socioeconomic range. The results demonstrate that overlearning can result in resistance to changing of behavior. Subjects were trained on a concept until they satisfied the requirement of 6, 12, or 18 correct responses in succession. Since all the subjects learned the correct hypothesis at the beginning of the criterion run, the procedure may be viewed as a manipulation of the number of overlearning trials, 6, 12, or 18. The subjects were then shifted to a partial reinforcement (confirmation) schedule of 70%, SO%, or 9 0 % . The results show that the greater the number of overlearning trials the fewer the number of shifts during partial reinforcement. Although concept acquisition is normally thought of as all-or-none, it is clear that, the greater the number of confirmations after learning has occurred, the less readily the subject shifts from the learned hypothesis. To paraphrase, the greater the number of win-stay occurrences, the less apt the subject is to shift after a loss. In Experiments I and I1

Learliing Strategies

iri

Children

57

lower-class subjects did not adopt a win-stay, lose-shift strategy of concept formation. The results of Experiment 111 raised the possibility that this failure to display the win-stay, lose-shift strategy could result from a chaotic reinforcement history. The results of Experimcnt 1V raised the possibility that this failure to display the win-stay lose-shift strategy could result from overlearning. In Experiment V the number of training trials was manipulated independently of the subjects’ behavior; the number of training trials had no effect upon response shifting during the subsequent partial reinforcement. In Experiment V it was demonstrated that the effect is attributable to the number of confirmations after learning has occurred and not to the total number of opportunities for confirmation, that is, the result of Experiment IV is produced by overlearning. A third possible factor may account for the failure of the lower-class subjects to display win-stay, lose-shift behavior in Experiments I and 11. Perseverating on an incorrect hypothesis enabled the subjects to obtain 75% reinforcement, a percentage which may be higher than the level to which they are accustomed. A direct test of this hypothesis would be very difficult, but the results of Experiments IV and V both demonstrate that the tendency to shift after a nonconfirmation is a function of the relative frequency of nonconfirmations. Shifting is more frequent with 70% confirmation than with 80% or 90% confirmation. The following picture emerges: lower-class subjects do not adopt a winstay, lose-shift strategy displayed by higher-class children and by adults. They perseverate on a hypothesis high in their hierarchy possibly because ( 1 ) they have had a great deal of overlearning on that hypothesis and ( 2 ) the rate of partial reinforcement is sufficiently high. The net result is that lower-class subjects are not only slow in learning new solutions but are conversely slow in giving up old solutions. This general theme will be repeated with respect to both reward preferences and observing responses.

111.

Reward Preferences

A. EXPERIMENT VI-AMOUNT

AND

PROBABILITY OF REINFORCEMENT

Experiment VI was concerned with children’s preferences for different reinforcement schedules which were equated for average quantity of reinforcement. The procedure for investigating reward preferences has been employed extensively with lower animals. There have been studies of children’s preferences with equalized mean reward for the choices but they have incorporated the additional factor of risk (e.g., Cohen, 1960; Kass, 1964).

58

1. L. Bresriahari and M . M . Shapiro

The subjects were 60 white, male, preschool children. Their ages ranged from 43 years to 53 years. One-half of the subjects constituted the lowerclass subgroups and one-half constituted the higher-class subgroups. The experiment was conducted by Stephan Silverman (Silverman & Shapiro, 1970). The experimental apparatus was a specially constructed peanut vending machine. It was a two-choice key-press device with a blue light and a “Mr. Peanut” bank. Doors in front of the keys allowed the experimenter to make either or both of the keys available to the subject on any particular trial. The experimenter sat behind the apparatus panel, operating the doors and delivering peanuts to the subject. The subject was told that he was going to play with a peanut machine. He was instructed to watch for the blue light and to press an available key when the light came on. He was shown how the key presses would turn off the lights and how peanuts would sometimes be delivered. The peanuts came down a transparent delivery tube and into a transparent covered dish. The subject was told that he could have the peanuts at the end of the experiment. Within each socioeconomic level there were three experimental groups. For one of the groups, one key was programmed to deliver one unshelled peanut 100% of the time, and one of the keys was programmed to deliver two unshelled peanuts 50% of the time. For the second group, one key produced one peanut 100% of the time, and the other key produced four peanuts 25% of the time. For the third group, the choices were between four peanuts 25% of the time and two peanuts 50% of the time. Within each group, the key assignments were counterbalanced for the right- and left-hand sides. All subjects were given 80 trials. At the beginning of each block of eight trials, the subject was free to choose between the two keys. Forced trials were instituted after the subject had chosen one of the buttons four times. Trials were forced by dropping the guillotine door over the key that first accumulated four responses. Therefore, the subject had four to seven free-choice trials and one to four forced trials within each block of eight. The probabilities were preprogrammed by using all possible permutations. On a reinforced trial, a bell was sounded and “Mr. Peanut” flashed with the delivery of each peanut. The intertrial interval was 4.5 seconds. It is clear from the experimental design that there was no right or wrong strategy. Any pattern of responses by the subjects yielded the same expected value, 80 peanuts in 80 trials. The intrusion of forced trials, within each block of eight trials, prevented any consistent perseveration of response choice by the subject. There is much discussion in the observational literature of the discrepancy between the reinforcing characteristics of the higher- and lower-class environments. This experiment represents our first

59

Learning Strategies in Children

objective attempt to determine the reinforcement schedule preferences of the two socioeconomic levels and to determine their strategies following reinforcement and nonreinforcement. As shall be seen, the sequence of choices proved most interesting. The proportion of choices to each key was computed for the free trials. Both the high- and low-socioeconomic-level subjects showed a significant preference for the higher probability alternative. They chose 100% over 5 0 % , or 100% over 2 5 % , or 50% over 25%. In the 100% vs. 50% and 100% vs. 25% conditions, the lower-class subjects exhibited a steady acquisition of preference. The mean choice proportions within each set of 16 trials are shown in Figs. 11 and 12. An analysis of the choice proportions showed that Trials was significant. It was clear that the only meaningful trends occurred in the two previously mentioned lower-class curves. The data for the four subgroups which had 100% as an alternative were analyzed to determine the frequency with which the subject remained on the 100% side from Trial n to Trial n 1. Each of these subjects’ free-choice data were submitted to a 1 x 2 chi-square test for goodness of fit. The expected proportion of n 1 trials on which the subject remained on the 100% key was .5. Since the square root of a chi-square with one degree of freedom is equal to z, a standard score frequency distribution was constructed for each subgroup. Positive or negative signs were attached to the

+

+

.9

r

L *

23

r nc L .=a,

o w

C

.a

L

2%

0

1

2

B L O C K S OF

3 SIXTEEN

4

5

TRIALS

Fig. 1 1 . Mean proportion o f free-choice trials to higher probability alternative f o r the three subgroups of higher-class subjects in Experiment VI (Silverman & Shapiro, 2970).

60

I . L. Bresnahan and M . M . Shapiro

100% vs. 25%

I 0

1 BLOCKS

2

I 3

1 4

I 5

OF S I X T E E N T R I A L S

Fig. 1 2 . Mean proportion of free-choice trials to higher probability alrernarive f o r the three srcbgroups of lower-class subjects in Experiment V l (Silverman & Shapiro, 1970).

z’s to denote greater than expected frequencies of staying or switching, respectively. Both socioeconomic levels displayed a larger proportion of responses to the 100% alternative. The z values were summed over subjects and divided by the square root of 10 (the number of subjects) to give an overall z for each s ~ b g r o u p Lower-class .~ subjects yielded z values of 11.97 for the 100% vs. 25% choice and 11.48 for the 100% vs. 50% choice. The z values for the higher-class subjects were 5.30 and 6.27, respectively. Each of the four z’s was significant in the direction of staying with the 1. The response to the 100% reinforced side from Trial n to Trial n difference between two z’s divided by the square root of 2 is also equal to z . ~The lower-class subgroups revealed a significantly greater tendency to 1 after reinforcement on Trial n than did the higher-class stay on Trial n subjects, z = 4.72 for the 100% vs. 25% subgroups, and z = 3.68 for the 100% vs. 50% subgroups. There were 112 possible response patterns that a subject could produce

+

+

4The sum of k independent normal distributions has a normal distribution with a mean equal to the sum of the k means, and a variance equal to the sum of the k variances. 5 The difference between two independent normal distributions has a normal distribution with a mean equal to the difference between the means and a variance equal to the sum of the variances.

61

Learning Strategies in Children

TABLE I1 OBSERVED AND EX~ECTED FREQUENCIES OF RESPONSE SEQUENCES~ Stereotype Group

High ( % )

Low ( % )

Low SES

141 (122) 103 (122) 244

75 (57) 39 (57) 114

High SES Total

Single alternation 0 (13)

26 (13) 26

Other

Total

84 (108) 132 (108)

300 300

-

-

216

600

Figures in parentheses are expected frequencies. From Silverman and Shapiro (1970). a

in the four to seven free trials within each block of eight. The frequencies of occurrence of each pattern for each subject were recorded. Table I1 shows the frequencies for the two stereotypic patterns (four consecutive responses to either one of the alternatives) and the single alternation pattern (ABABABA). The frequencies of all other patterns were pooled into a fourth category. It was clear that the higher-class subjects used the single alternation pattern more often than did the lower-class subjects. The use of a statistical test on these data would not be valid because of the lack of independence between entries pooled over subjects and trials; however, these data provided a rough demonstration of socioeconomic differences. The greater variability of the higher-class patterns was also indicated by the more frequent occurrence of the miscellaneous pattern category. In summary, Experiment VI explored the effects of allowing preschool children to choose between two alternatives that yielded the same mean reinforcement but differed in the amount and probability of reinforcements. For each of the socioeconomic groups, it was found that higher probabilities and lower magnitudes were preferred to lower probabilities and higher magnitudes. The finding of preference for continuous reward was in agreement with the results from studies using rats. The results were also in accord with the finding that young children prefer predictable to nonpredictable reinforcement (Lewis, Wall, & Aronfreed, 1963). When the data were analyzed for differences between the socioeconomic levels, clearly there were different approaches to the task. The two lowerclass subgroups receiving 100% as an alternative showed a significantly stronger tendency to perseverate on that response than did the higherclass subgroups. This finding is logically consistent with the data for response sequences, which revealed a tendency of the lower-class subjects to use stereotyped patterns to both the generally preferred 100% alternative and the generally nonpreferred 25% and 50% alternatives. The higher-class subjects used a greater variety of response patterns.

62

J . L. Brestiuhati arid M . M . Shapiro

Several inferential explanations may be applied to the differences in response modes used by the two socioeconomic groups. It can be speculated that the responses of the lower-class subjects generally reflected the effect of the just previous trial. They responded, perhaps, in a simple instrumental manner, for the most part, seeing success as consistent reinforcement (Wycoff & Sidowski, 1955). In a related study using a threechoice discrimination problem, Gruen and Zigler ( 1968) showed that lower-class subjects used fewer sequences of responses than did higher-class subjects. Many of the higher-class subjects’ response sequences, especially single alternation responses, may be considered as strategies. They may have 1 committed the “gambler’s fallacy” assuming that a payoff on Trial n is less likely on the same alternative that paid off on Trial n. Other investigators have found that their subjects preferred to predict correctly the less likely event than the more likely one (Brackbill & Bravos, 1962; Siegel, 1959). This preference may have been operative in the present study. It was clear that the higher-class subjects more frequently employed “cognitive” strategies than did the lower-class subjects. The lower-class subjects were bound by the outcome of the just previous trial, while the higher-class subjects were more able to discriminate between the overall contingencies. The behavior of the higher-class subjects was, therefore, less stereotyped.

+

B. EXPERIMENT VII-REINFORCEMENTWITH WITHOUT SIGNALS

AND

To pursue further the findings of Experiment VI, Experiment VII was designed to investigate the behavior of 48 third-grade children from higher and lower classes under three percentages of reinforcement. The reinforced trials were either signaled or unsignaled. A simple manual task was chosen to minimize the effcts of intelligence or previous learning. Other investigators (Espenschadi, 1946; Moore, 1941, 1942; Rhodes, 1937) have not found significant differences in children from high and low socioeconomic levels or between black and white children on manual dexterity and eye-hand coordination tasks. In Experiment VII the rate of performance on a simple motor task was measured as a function of the reinforcement on Trial n and the presentation of a signal for reinforcement on Trial n 1. The experiment was conducted by Jomary Hilliard (1970) as part of an undergraduate Honors Thesis. Twenty-four subjects were selected from the third grade of a school in a higher-class neighborhood, of whom one-half were white girls and

+

Learning Strategies in Childreti

63

one-half were white boys. Twenty-four subjects were also sampled from the third grade of a school in a lower-class area of the city. One-fourth of the children were white girls, one-fourth black girls, one-fourth white boys, and one-fourth black boys. The mean age of the higher-class subjects was 8.91 years and the mean age of the lower-class subjects was 8.95 years. The apparatus consisted of a plywood cabinet with an upright rear panel. When placed on a desk top at a comfortable height for the seated subject it formed a flat work area with the panel screening the activities of the experimenter from the subject’s view. On the right-hand side of the work area there was an opening under which was mounted a 400hole, square plexiglass pegboard. Ten individual pegboards were made of masonite with metal handles. These were fitted into the opening in the cabinet over the 20 X 20 pegboard matrix. Each individual board had 20 holes, arranged randomly with one corresponding to each row and column of the matrix. When the individual test board was in place, brightly colored banana plugs or pegs could be inserted through the holes in both boards to make electrical contact with 40 brass rods mounted beneath the rows of the matrix. These rods were wired so that insertion of the first peg, anywhere in any row, activated a timer located behind the panel facing the experimenter. With the insertion of the twentieth peg all the rows were filled and the timer was shut off automatically, giving an accurate measure of the time taken to fill the board. Above the pegboard area on the panel were a slot for dispensing and receiving pegboards and a tray for dispensing pegs. Pegs were fed into this tray manually at regular intervals by the experimenter. A coin dispenser was mounted on the right-hand side of the p a n d Two red signal lights of different diameters were mounted above the coin dispenser. The area of the cabinet directly beneath the coin slot was left clear for the child to place his rewards out of his way but in plain view. There were six groups of four subjects within each socioeconomic level. One-third of the children received a nickel on 80% of the trials, onethird received a nickel on 50% of the trials, and one-third received a nickel on 20% of the trials. For one-half of the subjects during each trial there was a signal which indicated the subsequent reinforcement or nonreinforcement; for one-half of the subjects there was no signal. The three reinforcement percentages (80, 50, 20) and the two signal conditions (signal and no signal) resulted in six independent groups. The subjects were tested in a small, quiet, well-lighted room within the school building. Each child was familiar with both the room and the experimenter. The experimenter was visible to the subject and could pass a board through the slot. The subject was told that it was a pegboard

64

J . L . Bresrrohort niid M . M . Sliapiro

game and to take the board and fit it into the hole. The subject was instructed to fill the board with pegs from the tray. I t was explained that after he finished he should pull the board out and pass it back through the slot. He was told that something would happen, sometimes a loud noise (coin dispenser) and sometimes the same loud noise and a prize (dispensed coin). He was asked to take the nickel prize and to put it down on the table. He was told that every time he was given a new board he should start again. For the signal group an addition was made to these instructions. The child was informed that if the little signal light was on there would only be a loud noise when he finished; if the big signal light was on there would be the same loud noise and a nickel prize would be given when he finished. Work with pilot subjects showed that it was necessary to insure that the subjects actually looked at the signal lights. Subjects were instructed to start the next trial only after they saw the signal light. In practice the subjects were not paced by the light; it was turned on simultaneously with the dispensing of the board. Subjects worked steadily, completing 20 trials. Between each trial the experimenter recorded the time, reset the timer, dispensed reinforcement. changed the signal light when appropriate, and provided a new board. After Trial 20, the child was allowed to keep his nickels. Only trials involving a change in reinforcement were analyzed. The signal and no-signal groups were compared for the pairs of successive trials for which Trial n was reinforced (or not reinforced) and Trial n 1 was not reinforced (or reinforced). The signal and no-signal groups were compared for the pairs of trials for which the groups had the same change in reinforcement and for which the groups had the opposite change in reinforcement. An analysis of variance for each of the four possible combinations was computed using the time taken to complete each trial as the dependent variable. For the 20% reinforcement groups, there were four trials on which a nickel was given, and, for the 80% groups, there were four trials on which no nickel was given; for these two sets of groups, the trials to be analyzed were predetermined. Within each block of five trials, the position of the one reinforced trial or the one nonreinforced trial was randomized, all subjects receiving a different order. For the 50% reinforcement groups there were ten reinforced and ten nonreinforced trials in random order; the successive pairs of reinforced and nonreinforced trials used in the analyses were randomly sampled from the first, second, third, and fourth sets of five-trial blocks. Each of the analyses, therefore, considered high vs. low socioeconomic level, signal vs. no signal, percentage of reinforcement, Blocks 1, 2, 3, 4, and Trials n VS. n 1. It should be noted that these four analyses were not completely independent but they were chosen because of our interest in the trials

+

+

65

Learning Strategies in Children

on which reinforcement changed. The no-signal groups were expected to show an effect of the reinforcement or nonreinforcement of Trial n upon performance on Trial n + 1 . The signal groups were expected to show an effect of the signal during the same trial on which the signal appeared. One question of interest was the relative effectiveness of a previous reinforcement or nonreinforcement upon the higher- and lower-class subjects. Another question was the effectiveness of a signaled expectation of a subsequent reinforcement or nonreinforcement upon the two socioeconomic groups. Figure 13 shows the mean time for completing the task for the higher and lower-class children on the pairs of trials for each of the four blocks of trials. The results are graphed for the three reinforcement percentages. Figure 14 depicts the difference in time for completing the task between 1 for the signal and no-signal groups as a function Trial n and Trial n

+

50

05 LOW

HIGH

LOW

HIGH

50

\

49 48 47 46 45 44 43 42 41 40 39

38

4

37

36

~

351 I

2

3

4

I

2

3

4

I

_ 2

3

4

% _

1

2

3

4

BLOCKS

Fig. 13. Mean time to complete task during a pair of trials (one reinforced and one notireinforced) taken from each of the four blocks. The curves denote the performance of higher- arid lower-class subjects with 80, 50, and 20% reinforcement in Experiment VII.

1. L. Bresnahan and M . M . Shapiro

66

05

50

HIGH

z

9 Z

LOW

LOW

HIGH

s.

-5 -6

-7

er CI

SIGNAL NO SIGNAL

-a 1

2

3

4

1

2

3

4

1

2

3

4

I

2

3

4

BLOCKS

+

Fig. 14. Mean difference in time to complete task during Trial n and Trial n 1 of a pair of trials (one reinforced and one nonreinforced) taken f r o m each of the four blocks. The curves denote the performance of higher- and lower-class subjects with and without signals f o r reinforcement in Experiment V l l .

of socioeconomic level, reinforcement change from Trial n to Trial n f 1, and blocks of trials. In each of the four analyses the mean time to complete the task de1). creased significantly over the four blocks of two trials ( n and n In general, the decrease in task time over blocks was relatively homogeneous for both socioeconomic groups, both signal and no signal, both sexes, and all three reinforcement schedules. Furthermore, there were no significant main effects or interactions among these variables. The difference between task time on Trials n and n 1 proved interesting. When there was no reinforcement on Trial n and reinforcement on Trial n 1 for both the signal and no-signal groups, there was no significant difference between n and n 1. There was a significant interaction between signal vs. no signal and n vs. n 1. With a signal, the task time decreased from a nonreinforcement on Trial n to a reinforce1 (Fig. 14); in the signal condition, the response time ment on Trial n

+

+

+

+

+

+

67

Learning Strategies in Children

was a function of the signaled (expected) reinforcement. With no signal, the task time increased from a nonreinforcement on Trial n to a reinforce1; in the no-signal condition, the response time was ment on Trial n a function of the previous reinforcement. These results were replicated in the comparison of signal and no-signal groups when there was reinforcement on Trial n and no reinforcement on Trial n 1. Task time increased from the signaled reinforcement on Trial n to the signaled non1. Task time decreased from the unsignaled reinforcement on Trial n reinforcement on Trial n to the unsignaled nonreinforcement on Trial n 1. The interaction between signal vs. no-signal 2nd Trial n vs. n 1 was again significant. These results were supported by statistically significant results in the other two analyses. The important and expected finding of Experiment VII was that the subjects were controlled by the anticipated reinforcement when reinforcements were signaled and by the previous reinforcement when reinforcements were unsignaled. There were no meaningful or consistent effects of socioeconomic level or sex. The particular schedules of reinforcement, 80, 50, and 20%, had occasional but weak effects.

+

+

+

+

+

c. DISCUSSION OF REWARDPREFERENCES Experiment VI was designed to investigate choice responding for two reinforcement schedules which produced equal mean reward. Both higherand lower-class subjects chose the schedule with the higher reinforcement probability and lower reinforcement magnitude significantly more often; the proportion of such choices was significantly greater for the lowerclass subjects than for the higher-class subjects. Furthermore, the lowerclass subjects showed a greater tendency to retain a choice which had just previously been rewarded. Experiment VII was designed to investigate further the effects of a previous reinforcement or nonreinforcement. In Experiment VI the subject was confronted with a choice between two simultaneously presented response keys; in Experiment VII a single response was measured during successive trials. The results of Experiment VII showed that, without a signal, response time was a function of the previous reinforcement or nonreinforcement but there was no interaction between the effects of the previous trial and socioeconomic level. Subjects from both high and low socioeconomic levels took more time to complete the task on a trial following a nonreinforcement than on a trial following a reinforcement. Some groups in Experiment VII were given discriminative stimuli (signals) which changed the paradigm from a mixed reinforcement schedule to a multiple reinforcement schedule. One signal was presented during trials in which responses were to be reinforced and

68

J . L. Brestiahaii arid M . M . Shapiro

another signal was presented during trials on which responses were not to be reinforced. For these groups, the time taken to complete the task was controlled by the signal (excepted reward) rather than the previous reinforcement. The time taken to complete the task was shorter when a reinforcement was signaled than when a nonreinforcement was signaled. Again there was no interaction with socioeconomic level. A general conclusion is that higher- and lower-class children differ in their choice behavior when simultaneously confronted with two reinforcement schedules, However, the response rates of higher- and lower-class children are not differentially affected by successive reinforcements and nonreinforcements. Particularly interesting is the finding that lower-class subjects can use the discriminative stimuli of the multiple schedule as effectively as the higher-class subjects.

IV.

Instructions and Training

A. EXPERIMENT VIII-EXTINCTION AFTER INSTRUCTIONS AND TRAINING Experiment VIII was designed and conducted by Anthony Epworth ( 1969) to determine whether different conditions of reinforcement main-

tained responding in children from high and low socioeconomic levels. There were three related procedures. Two variables were of specific interest: expectations of reinforcement produced by instructions and expectations of reinforcement produced by prior training. The purpose of the initial procedure was to compare the response rates of the two socioeconomic groups without either prior experimental training or instructionally produced expectations. In another sense, the procedure can be viewed as a determination of activity rates confounded with the ability to follow instructions. This procedure constituted the control condition for the ensuing experiments. The subjects in the first procedure were four-year-old white children, 13 boys and 11 girls enrolled in preschool programs. The higher-class subjects attended private nursery schools in Fulton County, Georgia, and the lower-class subjects were enrolled in Head Start programs in Decatur, Georgia. The Head Start program was limited to children from families with less than a $3,000 annual income. All children were tested within their school setting. The apparatus was set at a 30" angle within a three-sided acoustically shielded screen. A square panel was located in the center of the apparatus.

Learning Straiegies in Children

69

Behind the plexiglass panel was a box with milk glass on top and a twoway mirror inside. A 15 W bulb was located above the mirror and a 60 W bulb was located below the mirror. A line drawing of a smiling face was placed in the bottom portion of the box. One bulb illuminated the empty box above the two-way mirror. The other bulb illuminated, with equal intensity, the smiling face below the mirror. The 24 subjects were tested individually for 15 minutes. Four subjects from each socioeconomic level were assigned to the three conditions: (1 ) Panel press produced a counter noise, ( 2 ) panel press produced the top light and counter noise, and ( 3 ) panel press produced the lighted smiling face and counter noise. All feedback was presented for approximately 0.25 second immediately following each press. Verbal instructions and demonstrations were given preceding testing. Each subject was told to press the plexiglass panel as quickly and as often as he could. The experimenter told him to continue until he was asked to stop. Each press was counted as a response. Cumulative totals were recorded at one-minute intervals. There was no significant difference between the two socioeconomic groups, nor among the three Conditions, nor an interaction between SES and Conditions. The six mean cumulative response curves for the two socioeconomic groups in each of the three procedures were all linear. This procedure constituted a control condition. I n the ensuing experiments, any differences in responding between the two socioeconomic groups will not be attributable to base rate differences or the ability to follow directions. The purpose of the second procedure was to measure response rates for the two socioeconomic groups with instructionally produced expectations of reinforcement. Nine boys and seven girls were drawn from the same populations used in the first procedure. The apparatus was also the same and the 16 subjects were again tested individually for 15 minutes. Four subjects from each socioeconomic level were assigned to the two conditions: (1) the smiling face never appeared, and ( 2 ) the smiling face appeared for approximately 0.25 second after each press. The instructions and demonstrations of the first procedure were repeated with one modification. Each subject was told that a light would come on every time he pressed the panel and that sometimes he would be able to see a smiling face. The instructions were designed to produce an expectation of partial reinforcement. The mean cumulative response curves are shown in Fig. 15. If the subjects were told that they might see a smiling face and the face was presented after each press, both higher- and lower-class subjects responded

70

J . L. Bresnahan and M . M . Shapiro

0

10 MINUTES

20

Fig. 15. Mean number of cumulative responses f o r both higher- and lower-class groups with the instrrrctionally produced expectation of partial reinforcement and either with continuous reinforcement (squares) or without reinforcement (circles), in the first and second procedures of Experiment VIII. The solid lines indicate higherclass groups and the broken lines indicate lower-class groups.

at high steady rates. If the smiling face was never presented, the higherclass response rate was high but the lower-class rate declined during the test period. An analysis of variance demonstrated significant effects of Socioeconomic Status, Reinforcement Contingency, and an interaction between SES and Reinforcement Contingency. The main effect of Time (minutes) was statistically significant, as well as the interaction between SES and Time, the interaction between Reinforcement Contingency and Time, and the triple interaction among Time, SES, and Reinforcement Contingency. All differences were due to the group of lower-class subjects who received no reinforcement. The purpose of the third procedure was to create different expectations of reinforcement by training. The dependent measure was the number of responses during subsequent nonreinforcement. Eleven boys and 13 girls were drawn from the same populations used previously. The apparatus was also the same and the children were tested individually. The instructions and demonstrations were identical to those used in the second procedure. Four subjects from each socioeconomic level were assigned to the three experimental conditions: ( 1 ) smiling face available for 5 minutes, ( 2 ) smiling face available for 10 minutes, and ( 3 ) smiling face available for 15 minutes. Extinction immediately followed the training. Subjects were run in extinction until they reached a criterion of 2 minutes without a response. The mean total number of nonreinforced responses for each group is plotted in Fig. 16. The number of nonreinforced responses was a mono-

Learning Strategies in Childrerz

71

l5OOr

7 50

.

c

150

5

10

15

MINUTES OF PRIOR CONTINUOUS REINFORCEMENT

Fig. 16. Mean nrcmber of resporises to extinction f o r both higher- (solid line) and lower-class (broken line) grorips follou'ing 5-, lo-, and 15-minrrte periods of coiitinriorrs reinforcement in the third procedrrre of Experiment VIII.

tonic function of the length of the preceding continuous reinforcement sequence. For the lower-class subjects the function was a positive monotone. For the higher-class subjects the function was a negative monotone. The analysis of variance indicated a significant effect of Socioeconomic Status, Prior Reinforcement, and an interaction between SES and Prior Reinforcement. The results of the third procedure were of sufficient interest to warrant a replication with a larger sample. The subjects were 48 junior first-grade and kindergarten white boys between 53 and 63 years of age. The 24 lower-class subjects were enrolled in the Decatur, Georgia, Junior First Grade, a program with standards similar to those of Head Start. The 24 higher-class subjects were enrolled in private nursery schools. Eight subjects from each socioeconomic level were assigned to each of the three procedures. Only boys were tested to control for sex. The apparatus was functionally similar to that used previously, but it was placed inside a square metal box. The procedure was identical to that used previously with the exception that four subjects were tested at a time. Instructions were given individually and immediately preceding testing. Figure 17 shows the mean total number of responses during extinction. The results of the third procedure were replicated. The number of nonreinforced responses was a negative monotonic function of the length of the preceding period of continuous reinforcement for the higher-class group and a positive monotonic function for the lower-class group. All lower-class subjects who had received 5 minutes of continuous reinforcement stopped responding by the sixth minute of nonreinforcement. Figure 18 shows a minute-by-minute graphic analysis of the number of nonreinforced responses made within each of the first 6 minutes. The temporal development of the phenomenon can be seen. The analysis of variance demonstrated an effect of Socioeconomic Status, Prior Reinforce-

J . L. Bresnahan and M . M . Shapiro

12

0 z

s

1500

wl

Y

U

‘’ z z

4,

450 5

10

x z z z

15

5

10

15

zwl

MINUTES OF PRIOR CONTINUOUS REINFORCEMENT

4

MINUTES OF PRIOR CONTINUOUS REINFORCEMENT

Y

(Bl

(A)

Fig. 17(A). Mean number of responses to extinction f o r both higher- (solid line) and lower-class (broken line) groups following 5-, lo-, and 15-minute periods of continuous reinforcement in the replication of the third procedure of Experiment VIII. ( B ) Mean number of responses made during the first six minutes f o r both higher(solid line) and lower-class (broken line) groups following 5-, lo-, and 15-minute periods of continuous reinforcement in the replication of the third procedure of Experiment VIM.

ment, and Time in 1-minute blocks. There were significant interactions between SES and Prior Reinforcement, SES and Time, and Time and Prior Reinforcement. The triple interaction was also significant.

B.

DISCUSSIONOF

INSTRUCTIONS AND

TRAINING

Holland (1958) demonstrated that the schedule of signal detections controls the rate of observing an instrument. His procedure required a report of all detections. Frankmann and Adams (1962) suggested that a procedure without detection reports would limit the stimulus control found by Holland. They hypothesized that two responses occurred. The first response made a detection possible by making the display visible and the rate of this response was controlled by subject variables. The second response was a sense receptor orientation and its rate was controlled by the schedule of signals. The instructions in the first procedure of Experiment VIII emphasized the first response of making the display visible without any mention of the importance of the feedback. The task and instructions were simple and both socioeconomic groups were able to perform equally well. No reinforcement contingencies were mentioned and, presumably, there were no explicit expectancies of a specific reinforcement. The second procedure was the “zero” condition for the third procedure. The same instructions were used in these experiments. They differed primarily in that the second procedure employed zero minutes of experimental

73

Learning Strategies in Childreri Minute

1

Minute 2

/--*

45 15

Minute 3

150

r

Minute 4

Minute 5

r

15

L

5

5

10

I5

Minute 6

,

d’

10

I5

M I N U J E S OF P R I O R A € I N F O R C f h l f N l

Fig. 18. Meari tiurnher o f responses made dirring each of the first six minutes for hotli hrgher- (solid lines) und lower-cluss (hroken linesj groiips following 5 - , lo-, and 15-minrrte periodr of coritinuoirs reirijorcement in the replication of the third procedirre of Experimerit V l l I .

training and the third procedure employed 5. 10, and 1.5 minutes of training. There was a discontinuity in the results from the zero training to the 5-, lo-, and 15-minute training conditions. The lower-class group made fewer responses in the second procedure than did the higher-class group. With this procedure the lower-class group behaved more pragmatically. The subjects had been told that they would sometimes see a face. When no faces appeared the lower-class subjects soon stopped responding. This situation was most likely a very familiar one for them. However, the lowerclass behavior became relatively less pragmatic as the length of training increased. The performance of the two socioeconomic groups differed in the third procedure when a discrimination between initial reinforcement and subsequent extinction was possible. The lower-class responding was apparently based on the number of times the response had been reinforced. The higher-

J . L. Bresnahan and M . M . Shapiro

74

class group appeared to discriminate between reinforcing and nonreinforcing situations. In the second procedure, the ability to distinguish between different situations was not relevant since for any one subject there was only continuous reinforcement or continuous nonreinforcement. The two socioeconomic groups did not differ in the first procedure or under continuous reinforcement in the second procedure. The reinforcement was consistent and unchanging. There was a significant difference between the two socioeconomic groups under nonreinforcement in the second procedure. The lower-class response, which had never been followed by reinforcement in the test situation, extinguished. The higher-class response did not extinguish within the test period. Reinforcement had been described as forthcoming within the test situation but there was no reinforcement shift (contrast) in the procedure. The results of the third procedure suggested that higher-class subjects were affected by the shift in reinforcement while lower-class subjects were affected by the previous number of reinforcements. If it is assumed that higher-class children reacted to the change from reinforcement to extinction, then it follows that the longer acquisition periods made this change more obvious and the extinction more rapid. If it is assumed that the lower-class children responded on the basis of the number of reinforcements, then it follows that they stopped responding more quickly following the shorter acquisition periods.

V.

Summary and Conclusions

In this section the results reported in this paper will be reviewed first, and then some of the authors’ subsequent research and thinking on the problem will be discussed. In concept acquisition, lower-class children do not adopt the win-stay, lose-shift strategy employed by adults and higher-class children but perseverate on an incorrect hypothesis. The failure to adopt this strategy can also be established in other subject populations by experimental manipulations. In Experiments I and I1 it was hypothesized that the perseveration of the lower-class subjects occurred because the rate of partial reinforcement was sufficiently high and the incorrect hypothesis had been greatly overlearned (high in their hierarchy). Accordingly, in Experiment TIT the effects of prior partial reinforcement were examined, and in Experiments IV and V the effects of prior overlearning and partial reinforcement were examined. After a relatively small number of random reinforcements, higher-class subjects learned as poorly as lower-class subjects. When sub-

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jects were shifted to partial reinforcement after overlearning, they also did not adopt the win-stay, lose-shift strategy. In the experiments in which the subjects did not employ the win-stay, lose-shift strategy, they perseverated on a behavior which was partially reinforced. Since they retained the partially reinforced behavior, it can be said that they utilized the win-stay aspect of the strategy but not the loseshift component. In a situation in which reinforcement is continuously available f o r some alternative behavior, this perserveration is clearly disadvantageous. Conversely, in a situation in which no reinforcement is available for an alternative behavior, this perseveration maximizes reinforcement (Gruen & Zigler, 1968). The success of a subject in an experiment is not unlike the role of a person in real life. His task is to discriminate among the possible contingencies. H e must determine whether he is faced with a concept acquisition task, a simple discrimination problem, a probability learning task, extinction, an unsolvable (random) problem, etc. Certainly no one suggests that a person typically makes this decision in an orderly verbalized manner but, nevertheless, his task is to match his behavior to the contingency. A person is most able to conform to those contingencies with which he has had the most recent experience or the most extensive experience. People who have overlearned one contingency d o not readily shift their behavior when the contingency or the nature of the task is shifted. I n the reward preference studies there is also a difference in the behavior of higher- and lower-class subjects. In Experiment VI lower-class subjects more often chose consistency than did higher-class subjects; the former perseverated more than the latter. More specifically, the lower-class children showed a tendency to retain a just previously reinforced choice whereas higher-class children were more likely to shift away from a choice following reinforcement. The task is one on which only the pattern of reinforcements, but not the expected number of reinforcements, is contingent on the choice behavior. There is no “correct” or “better” strategy and yet the lower-class children exhibit highly stereotyped response patterns. T h e data from the mixed and multiple schedules of reinforcement in Experiment VII show no difference in performance between the two socioeconomic levels. Thus, when successive reinforcements are externally signaled, higher-and lower-class subjects use the information with comparable efficiency. O n the mixed schedule in which no discriminative stimuli are available, response times are a function of the previous reinforcement. 0 1 1 the multiple schedule in which discriminative stimuli are available, response times are a function of the expected reinforcement. Children from both socioeconomic levels appear equally capable of determining the nature of these particular contingencies. With these schedules there are no choices

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to be made; the dependent variable is the time required to complete the task on each trial. These schedules are probably less sensitive to differences between socioeconomic levels. In the last study there was an interaction between socioeconomic level and the experimental conditions: Lower-class children perseverated more than higher-class children under one procedure but less than higher-class children under another procedure. In Experiment VIII response rates were measured during extinction. It was found that when reinforcement is not promised and not delivered, higher- and lower-class children respond equally. When reinforcement is promised and not delivered, lower-class children exhibit much faster extinction than higher-class children; lowerclass children do not perseverate as much as higher-class children in this situation. However, when reinforcement is promised and actually delivered, lower-class children exhibit much slower extinction than higher-class children, provided there is sufficiently long prior reinforcement training. The longer continuous reinforcement is maintained prior to withdrawal, the faster the higher-class subjects exhibit extinction of the response and the slower the low SES subjects exhibit extinction. Again, it is important to note that these differences between the behavior of higher- and lower-class subjects are not always instances of the higher-class children doing “better” than the lower-class children. Some of the differences are favorable to the lower-class children, such as when these children stop responding when promised reinforcements are not forthcoming. Several training procedures were designed to encourage response shifting. None of these procedures has proven to be completely satisfactory. In one of these procedures conducted by William Blum the subjects were given a series of discrimination problems before being tested on a concept acquisition task. Each group received a different sequence of four problems, of which one to three were solvable and the rest insolvable. The results of the experiment were somewhat encouraging but not readily interpretable because of the apparently complex sequence effects. In another one of the procedures which Joan Tritschler has already employed, subjects were allowed to choose between five equally reinforced alternatives. After the choice behavior had become stereotyped, reinforcement was made contingent upon the subject’s shifting responses. The equipment was programmed so that only more complex patterns of choice behavior were reinforced. All subjects adopted the more complex patterns which had been used by the higher-class subjects in our previous experiment on reward preferences. The question of how this training would transfer to new situations requires extensive further investigation. The possibility was also considered that differences in response strategies might best be investigated as a function of personality variables rather than

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as a function of socioeconomic level. This approach was prompted by the concepts of internal and external control which had been proposed by Rotter (1966). External control was defined by Rotter in the following manner: “When a reinforcement is perceived by the subject as following some action of his own, but not being entirely contingent upon his action, it is typically perceived as the result of luck, chance, fate, as under the control of powerful others. or as unpredictable because of the great complexities of the forces surrounding him.” Conversely, internal control was defined as, “When a person perceives that an event is contingent upon his own behavior, or his own permanent characteristics . . . .” The possible relationship to our findings is almost inescapable. Mary McNair, with the help of Russel Penrod, conducted an extensive study of all 89 fourth-grade students at Sagamore Hills Elementary School, DeKalb County, Georgia. This school is in a uniformly upper-middle-class neighborhood. Measures on the following tests were obtained from each subject: ( 1 ) Bialer Locus of Control Scale (Bialer, 1961), ( 2 ) Level of Aspiration Board (Rotter, 1942), ( 3 ) the reward preference procedure using the 25% and 100% choices described in Experiment VI of this report, ( 4 ) Otis Lennon Mental Ability Test, Elementary 11 Level, Form J, ( 5 ) Stanford Achievement Test, Intermediate I Level, Form W, and ( 6 ) the Adjective Check List (Gough & Heilbrun, 1965) filled out by each teacher. Using all subtest scores, the alternative scoring techniques of the behavioral data, several composite test score differences, and subject categories such as sex and age, a 43-variable correlation matrix was obtained. The results were unfortunately not very informative. Locus of Control correlated significantly (r = .24) with the Achievement Scale of the Adjective Check List. A dependent variable, defined as the difference between the Otis Lennori I.Q. score and the Stanford Achievement Test score (underachievement) was significantly correlated with the Defensiveness ( r = - . 3 4 ) , Self-control ( r = -.38), Achievement (r = -.32), and Succorance ( r = .27) Scales of the Adjective Check List. Performance on the two behavioral tasks, reward preference and Level of Aspiration Board, did not correlate with any other variables. The search is being continued for procedures to alter learning strategies. The goal is to design training techniques that teach specific learning strategies without producing perseveration on one strategy. REFERENCES

Abraham, F. D., Corrnezano, I . , & Wiehe, R. Discrimination learning as a function of prior relevance of a partially reinforced dimension. Jourtlal of Ewprrimrnfal Psychology, 1964, 67, 242-249.

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Archer, E. J. Concept identification as a function of obviousness of relevant and irrelevant information. Jorrrnal of Experimental Psychology, 1962, 63, 616-620. Bernstein, B. Social structure, language, and learning. Educational Research, 1961, 3, 163-176. Bialer, I. Conceptualization of success and failure in mentally retarded children and normal children. Jorrrnal of Personality, 1961, 29, 303-320. Brackbill, Y., & Bravos, A. Supplementary report: The utility of correctly predicting infrequent events. Journal of Experimental Psychology, 1962, 64, 648-649. Bresnahan, J. L., & Blum, W. L. Chaotic reinforcement: A socioeconomic leveler. Developmental Psychology, 197 I , 4, 89-92. Bresnahan, J . L., Tvey, S. L., & Shapiro, M. M . Developmentally defined obviousness in a concept formation task. Developmental Psychology, 1969, 1, 383-388. Cohen, J . Chunce, skill, and /rick. Baltimore: Penguin, 1960. Deutsch, M. The disadvantaged child and the learning process. In A. H. Passow (Ed.), Education ii7 depressed areas. New York: Teachers College, Columbia University, Bureau of Publications, 1963. Pp. 163-179. Epworth, A. The effect of socioeconomic level during extinction. Unpublished master’s thesis, Emory University, 1969. Erickson, J. R. Hypothesis sampling in concept identification. Journal of Experimental Psychology, 1968, 76, 12-1 8. Espenschadi, A. A note on the comparative motor ability of Negro and white tenth grade girls. Child Development, 1946, 17, 245-248. Frankmann. J . P., & Adams, J. A. Theories of vigilance. Psychological Brillefin, 1962, 59, 257-272. Goodnow, J. J., & Pettigrew, T. F. Effect of prior patterns of experience upon strategies and learning sets. Journal of Experimental Psychology, 1955, 49, 38 1-389. Gordon, E. W. Characteristics of socially disadvantaged children. Review of Edrrcational Research, 1965, 35, 377-388. Cough, M. G., & Heilbrun, A. B. The adjective check-list manual. Palo Alto: Consulting Psychologists Press, 1965. Gregg, L. W., & Simon, H. A. Process models and stochastic theories of simple concept formation. Journal of Mathematical Psychology, 1967, 4, 246-276. Gruen, G., & Zigler, E. Expectancy of success and the probability learning of middleclass, lower-class, and retarded children. Jorrrnal of Abnormal Psychology, 1968, 73, 343-352. Hess, R. D., & Shipman, V. C. Early experience and the socialization of cognitive modes in children. Child Development, 1965, 36, 869-886. Hilliard, J . Response time as a function of reinforcement and cue. Unpublished honor’s thesis, Emory University, 1970. Holland, J. G. Human vigilance. Science, 1958, 128, 61-63. Karp, J. M., & Sigel, I. Psychoeducational appraisal of disadvantaged children. Review of Educational Research, 1965, 35, 401-412. Kass, N. Risk in decision-making as a function of age, sex, and probability preference. Child Development, 1964, 35, 577-582. Krechevsky, I. “Hypotheses” in rats. Psychological Review, 1932, 39, 516-532. Lashley, K. S. Brain mechanisms and intelligence: A quantitative study of injuries to the brain. Chicago: University of Chicago Press, 1929. Levine, M. Cue neutralization: The effects of random reinforcements upon discrimination learning. Journal of Experimental Psychology, 1962, 63, 438-443.

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Levine, M., Yoder, R . M., Kleinberg, J., & Rosenberg, J. The presolution paradox in discrimination learning. Journal of Experimental Psychology, 1968, 77, 602-608. Lewis, M., Wall, A. M., & Aronfreed, J. Developmental changes in the relative values of social and nonsocial reinforcement. Jorrrnal of Experimental Psvclrology, 1963, 66, 133-137. McCandless, B. Environment and intelligence. American Jorrrnal of Mental Deficiency, 1952, 56, 674-691. McCarthy, D. Language development in children. In L. Carmichael (Ed.), Manria/ of child psychology. New York: Wiley, 1954. Pp. 492-630. Montague, D. 0. Arithmetic concepts of kindergarten children in contrasting socioeconomic areas. Elementnry School Jorirna/, 1964, 64, 393-397. Moore, J. E. A comparison of Negro and white children in speed reaction on an eyehand coordination test. Jorrrnal of Genetic P~yclrology,1941, 59, 225-228. Moore, J. E. A comparison of Negro and white preschool children on a vocabulary test and eye-hand coordination test. Child Development, 1942, 13, 247-252. Passow, A. H. (Ed.) Edrrcation i n depressed areas. New York: Teachers College, Columbia University, Bureau of Publications, 1963. Raph, J. Language development in socially disadvantaged children. Review of Edrrcalional Research, 1965, 35, 389-400. Review of Edrrcational Research, 1965, 35, 377-440. Rhodes, A. A. A comparative study of motor abiilties of Negroes and Whites. Child Development, 1937, 8, 369-37 1 . Riessman, F. The overlooked positives of disadvantaged groups. Jortrnal of Negro Edrrcation, 1964, 33, 225-23 1. Rotter, J. B. Level of aspiration as a method of studying personality. Jortrrral of Experimental Psychology, 1942, 31, 410-433. Rotter, J . B. Generalized expectancies for internal versus external control of reinforcement. Psychological Monographs, 1966, 80( 1 , Whole No. 609). Siegel, S. Theoretical models of choice and strategy behavior in the two-choice uncertain outcome situation. Psychometrika, 1959, 24, 303-3 16. Silverman, S. M., & Shapiro, M. M . Magnitude-probability preferences of preschool children from two socioeconomic levels. Developniental Psychology, 1970, 2, 134-139. Suppes, P., & Ginsburg, R. A fundamental property of all-or-none models, binomial distributions of responses prior to conditioning, with application to concept formation in children. Psychological Rertiew, 1963, 70, 139-161. Warner, W. L., Meeker, M., & Eells, K. Social class in America. Chicago: Science Research Associates, 1949. Wilcoxon, F. Probability tables for individual comparisons by ranking methods. Biometrics, 1947, 3, 119-122. Wycoff, L. B., & Sidowski, J. B. Probability discrimination in a motor task. Jortrrial of Experirnental Psychology, 1955, 50, 225-23 1.

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TIME AND CHANGE IN THE DEVELOPMENT OF THE INDIVIDUAL AND SOCIETY'

Kluus F . Riegel UNIVERSITY OF MICHIGAN

I.

INTRODUCTION

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

11. THE CONCEPT O F TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. THE CONCEPT OF TIME IN THE NATURAL SCIENCES . . B. T H E ANALYSIS OF PSYCHOLOGICAL TIME IN DEVELOPMENTAL STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . .

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83 83 87 95

111. DEVELOPMENTAL CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

96 A. PROPERTIES OF QUALITATIVE GROWTH MODELS . . . . . 97 B. APPLICATIONS OF QUALITATIVE GROWTH MODELS . . . 99 C. RELATIONS BETWEEN QUALITATIVE AND QUANTITATIVE GROWTH MODELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 D. APPLICATION OF A QUANTITATIVE GROWTH MODEL 103 E. INTERACTIONS BETWEEN CHANGES IN THE INDI107 VIDUAL AND SOCIETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . 109

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 This paper was presented on June 2, 1970 at a colloquium at the Laboratory of Psychology, National Institute of Mental Health, Bethesda, Maryland upon the invitation by Dr. Jacob Gewirtz. The author gratefully acknowledges the continued support by Dr. Gewirtz as well as the encouragements and critical comments by Donna Cohen, Clinton Fink, William Gekoski, Wilbur H a s , William Looft, and Ruth Riegel.

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I.

Introduction

Any discussion of time and change is bound to be entangled in philosophical difficulties. Indeed, since the beginning of philosophy, these topics have been at the center of speculations, in that some philosophers emphatically denied time and change as essential attributes of the universe (Parmenides, Melissus of Samos, Zeon of Elea) , while others regarded them as the most basic properties (Heraclitus, Empedocles, Democritus) . The distinction implied here, that between an idealized universe (of which the observable world af changes is an incomplete reproduction) and phenomenal changes (from which idealized systems are but empty abstractions), still permeates our thinking and is expressed, one way or the other, in all modern systems of philosophy and sciences. Locke, for instance, considered substance, space, time, causality, etc., as universal, primary qualities which (in contrast to the views of the earlier “naive realists”) are supplemented by secondary qualities of psychologically and socially dependent interpretations. With this distinction, Locke reintroduced the option for a study of perception of time (as well as substance, space, causality, etc. ) but, independently, maintained that there are substances, space, causality, time, etc., that these are not mere inventions. On the contrary, through their existence they make perception possible at all. Locke’s successors, step by step, reduced and modified the list of primary qualities. Hume explained causality as a regular succession of spatial events in time. Kant considered these qualities as a priori forms of the mind rather than as physical properties of the universe. Finally, the positivism of the early 19th Century (Comte) and its various representatives in the late 19th Century (PoincarC, Mach, Avenarius) denied the necessity for such “metaphysical” entities altogether by reemphasizing that all our knowledge is derived from the senses and is perceptual. The “real” world, which hitherto had been regarded as providing the foundation and cause for these sensations, now was being seen as a construct and an abstraction from the sensory information given. Statements concerning the “true” nature of the “real” physical world were being considered as metaphysical and, therefore, as unscientific. Among the basic attributes of the “real” world, i.e., the primary qualities of Locke, causality was already reduced by Hume. Space was not seen any longer as a metaphysical whole into which perceptions are cast nor as a prerequisite of an absolute and universal type for the study of all natural processes (see Jammer, 1954). Prior to this conceptual shift, the analysis of events was restricted to Euclidean space and geometry. Now, the concept of space became relative and dependent upon the direction of

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the research undertaken; a researcher could operate within the space model of Euclid, Riemann, Loboschevsky, or any others. Similarly, the concept of substance as representing the smallest building blocks of the universe gave way to relativistic views alternating between interpretations in terms of particles, waves, quanta, or combinations of these (see Cassirer, 1910). While, increasingly, philosophers and scientists realized the dependency of concepts like causality, space, substance, and time on sociocultural conditions (see Sarbin, 1968), they did not abandon these concepts altogether but proposed basic reformulations. Their preservation can be observed in the explication of measurement systems, e.g., the cgs system. Among these reformulations, vigorously promoted by Reichenbach ( 1958) and translated into developmental sciences by Reichenbach and Mathers (1959), the concept of time is of greatest interest for our present purpose.

Time is born out of my relationship to things - Merleau-Ponty

11.

The Concept of Time

A. THECONCEPT

OF

TIMEIN

THE

NATURAL SCIENCES

In his famous First Scholium of the Principiu, Newton (1687) described, closely in line with Locke’s viewpoints, the space and time concepts appropriate to his physics, which, subsequently, dominated the sciences so thoroughly that it has been hard for anyone ever since to form independent concepts for himself (Park, 1967). He started with the idea of a particle, defined as a body small enough that its internal structure can be ignored but as occupying a definite region of space at a given time. Extended bodies are made up of infinitesimals and their laws are derived by summation. The concept of time, as introduced by Newton, is by no means the simplest one possible. He burdened it further by distinguishing between “absolute” and “relative” time, a distinction which refers to the dichotomy between time as a primary and secondary quality. Absolute real and mathematical time, in itself and in its very nature, proceeds or flows steadily without relation to anything external you care to mention, and to give it another name, is called “duration.” Relative, apparent and common time is a perceptible, external form of measurement of some sort of duration derived from movements, either regular or uneven, which the layman uses instead of real time, such as an hour, a day, a month, or a year [Newton, 1687, Definition VII, Scholium Mathematical Principles].

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1. Zero points Time in the natural sciences has an absolute zero point which, nevertheless, is arbitrarily determined by the initiation of a particular process, for instance by the activation of a watch. Absolute zero points are not given by “nature” but are delineated through the development of scientific theories and techniques. They are, ultimately, dependent upon the observers’ perceptions and choices. Only a few theories elaborate rationales for absolute “natural” zero points, for example, those for temperature, electrical conductivity, as well as for such complex variables as saturation, using absolute black as its zero point. In regard to the time dimension, modern cosmologies (e.g., the “Big-Bang’’ theory) have proposed a rationale for an absolute, “natural” zero point, implying also the notion of an absolute, “natural” upper limit, represented by the speed of light. When considering psychological and social processes, zero points in time are always arbitrarily defined. In experimentation, zero points are defined by the start of the clock; in development analysis, zero points represent the moments of birth or the commencement of schooling; in historical-sociological analysis, zero points are the founding of Rome, the Birth of Christ, the beginning of the French or Russian revolution, etc. Since behavioral and social sciences are unlikely to advance sufficiently far to provide rationales for absolute, “natural” zero points in time, it is reasonable to turn our attention to less ambitious attempts and to discuss time measurements along scales with relative zero points.

2 . Intervals and Cycles If we ask ourselves whether time is primarily and originally experienced as a continuum or as periodicity, we will have to conclude that the latter represents the information immediately given. For instance, a child alternating from a state of hunger or thirst to one of drive satisfaction. then back to hunger or thirst, will develop some notion about the periodic up and down in his conditions. The experience of the changes from day to night, from lunar month to lunar month, or around the annual seasons all impress upon the child a notion of periodicity. For this reason it is not surprising that until modern ages the concept of time was intimately tied to this notion. Greek philosophers and scientists, especially of the Pythagorean, Platonic, and Stoic schools, rarely viewed time as a continuous dimension but emphasized its wavelike and cyclic nature. The same has been shown for Indian and various “primitive” cultures on the basis of linguistic analyses (see Nakamura, 1966; Whorff, 1956). By defining its units, the periodicity of time represents the basis for time measurements. These units could be the solar year, the lunar month, the terrestrial day, etc. Practical measurements rely on the isomorphism between these astronomical units and those more directly accessible for

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our manipulations, such as the swing of the pendulum or the vibration in quartz molecules. Further on in this chapter, we will have to examine how we might define time units of psychological and sociological processes.

3 . Order and Direction If we take one step further down in the hierarchy of measurement, we are considering systems in which order and direction play a role but not the periodicity and intervals of measurements. Commonly, our recordings of time and change in psychology are more ambitious. But all that these measurements imply is a blind adaptation of the periodicity of physical systems. Whenever less ambitious attempts are made by restricting judgments to ordered sequences of earlier and later events or to developmental interpretations in terms of stages and periods, they are considered with less esteem. Scientific knowledge, it is argued, ought to progress to the more advanced levels of observations. The concepts of order and direction can best be demonstrated by an example from physics frequently used for this purpose. Let us assume that we record a physical event, such as the movement of a billiard ball, by taking a film strip with a camera mounted above the pool table. If we cut the frames apart and randomize them, we could, thereafter, reconstruct the order of the event but would not be able to determine the direction of the move. In other words, we can line up the frames in a systematic manner, but we do not know which one of the two end points of the reassembled film strip is the first and which one is the last frame of the sequence. In such considerations, as in the “classical natural sciences” in general, time does not imply direction and irreversibility. For instance, the free fall of a body can be viewed as proceeding in either direction (whereby, of course, the reversal of the fall represents the throwing of the body). The law that describes these processes, i.e., the law of gravitation, is the same in both instances; only the signs have been changed from plus to minus. The development of “modern natural sciences” is characterized by the attempt to deal with the problem of directionality and irreversibility of time. The reorientation brought about can best be explained by extending the example given before. Let us assume that many balls are moving randomly within a confined area, such as a pool table, bouncing off from one another and from the edges, and that, moreover, two equal subareas are sectioned off by a bar placed across the table, one containing a greater number of balls than the other. If we remove the bar, the balls, after a lapse of time, will be completely mixed, i.e., will be equally distributed over the whole table. If, after the removal of the bar, we had taken pictures again and separated the frames, we could now reconstruct the sequence of the frames as well

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as the direction of the event. The condition in which the two sets of balls are separated is less likely than the one in which they are mixed. The former will precede the latter in time. The separate states can be recreated only through the intervention of some external, ordering forces. During the normal course of events the separate states will merge into a mixed one but not vice versa. Our example implies the notion expressed in the second law of thermodynamics providing a new conception of time. Eventually, time is reduced to probable sequences of spatial conditions. By enumerating some properties of these conditions, for instance the distribution of balls in the two sections of the table, estimates of time can be obtained. Of course, such a procedure relies again on extrinsic periodic systems, in this case the regular exposure of film material in the camera. However, the periodicity of the camera is not a necessary but only a convenient prerequisite. Time estimation could be based on randomly selected frames. Any two of them allow for inferences about the direction of the process. Of course, the fewer observations there are, the less reliable these estimates will be. Provided that a sufficiently large sample of frames is given, we can put them into the proper order, and by chopping off equal segments of frames beginning at the less likely end, we redefine our time measure on the basis of the sequence of spatial states. 4. Simultaneity The modern concept of time began to emerge with the development of thermodynamics and through the works of Boltzmann and Clausius. Whereas Newton postulated particles, space, and time as independent and necessary properties of the universe, modem natural science has reduced time to succession of spatial conditions of particles, for instance the molecules of an enclosed ideal gas. Similarly, Maxwell described electromagnetic fields in terms of amplitudes of space-time instances. Here, in comparison to the reduction of the time variable in thermodynamics, the particle substance loses its place. In his attempt to harmonize electromagnetic field theory with Newtonian mechanics, Einstein in his relativity theory introduced the concept of a space-time compound measured in terms that refer to the observer as well as to the object observed. In further extension, Planck consolidated the notion of particle with its counterpart, the notion of wave, which, like for Einstein, is depicted in a space-time system. Thus in all these theories, the three basic units of classical natural sciences-particles, space, and time-are compounded or reduced to one another and their relativity is stressed. In spite of all these modifications, the properties of order and direction remain essential parts of the time concept. To abandon these properties

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would lead to systems of unrelated classes. Although time without order and direction seems unthinkable, its discussion raises the problem of simultaneity which is of central importance for relativity theory as well as for developmental studies in the behavioral and social sciences. When, for instance, can we consider two children as being equal (simultaneous) in psychological age? Can comparable reaction time measures be obtained from the same individual but (therefore) at different times? Questions like these reveal some of the difficulties with which we are faced in a psychological analysis of time and change. Therefore, it may seem disillusioning as well as surprising that some modern natural scientists feel compelled to consider psychological knowledge rather than physical and, perhaps, formalized systems as fundamental for their analysis of time, space, and substance. The following quotation from Milne, as well as Einstein’s inquiry with which we begin our next section, reveals this orientation quite clearly. The reason why it is more fundamental to use clocks alone rather than both clocks and scales or than scales alone is that the concept of the clock is more elementary than the concept of the scale. The concept of the clock is connected with the concept of “two times at the same place,” whilst the concept of the scale is connected with the concept of “two places at the same time.” But the concept of “two places at the same time” involves a convention of simultaneity, namely, simultaneous events at the two places, but the concept of “two times at the same place” involves no convention; it only involves the existence of an ego [Milne, 1952, p. 461.

B. THEANALYSIS OF PSYCHOLOGICAL TIMEIN DEVELOPMENTAL STUDIES Several years ago, Einstein raised the questions “Is time immediate or derived?” and “Is it integral with speed from the very outset?” Piaget ( 1946), to whom these questions were addressed, tentatively suggested that the notions of speed and distance are psychologically most basic, without denying, of course, that theories of physics might be more readily formulated when time rather than speed or movement is regarded as its fundamental unit (Piaget, 1946). Nowadays, with our increasing preference for cognitive and phenomenological interpretations, Piaget’s reply seems to warrant few further explanations. During earlier periods of philosophy and science, however, such viewpoints would have caused consternation. Kant, for instance, maintained firmly that space and time are a priori givcn whereas the concept of motion is derived through experience. In contrast to Kant, many psychologists have argued that our perceptions of substance, space, and time are not direct but derived. Thus, an individual

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needs the experience of many different spatial clues before he recognizes the organziation of a display and before he develops an adequate notion of space. Similar arguments have been made for the perception of substance, mass, and weight. In particular, it has been argued that these notions develop only under conditions of change, i.e., through temporal variations. We do not gain full knowledge of weight unless pressure is changed and comparisons become possible. Similarly, static space is insufficient for its perception. Only movements through space and changes of space make its appreciation possible. Thus, while time and change are intimately tied to the perception of space and substance, the latter two, nevertheless, are directly accessible through the senses of touch and vision. Time perception, in contrast, has to rely on memory. We perceive one event, then a second event, and compare the second with the memory image of the first. Thus, we do not experience time itself but events and their successive changes, i.e., we experience transformations. Time is an abstraction from immediate experience and the conception of changes is prior to that of time. The psychological investigations of time have proceeded from several different angles (Cohen, 1964; Fraisse, 1963; Ornstein, 1969; Wallace & Rabin, 1960). First and oldest, the perception of time has been analyzed by comparing one interval with others slightly longer or shorter in duration. Second and comparable to the threshold of detection, the shortest noticeable intervals have been determined, i.e., intervals experienced as “unitary.” None of these laboratory explorations is of direct interest for our analysis. They will not be reviewed here nor will we discuss the work by Piaget (1946, 1955) and Fraisse (1963) on the development of time concept in children. Of greater interest for our present purpose are the studies in which subjects are asked to recollect events of the past. Studies of this type are concerned with much longer periods than those on the perception of time. They use a retrospective methodolgy which, though rarely applied in developmental research, represents a naturalistic form of inquiry in which individuals are engaged at all times, i.e., when they compare their present experiences with those of the past. Undoubtedly, retrospective retrievals are not only crucial for clinical and historical explorations, but also for experimental studies of learning and memory in which subjects receive some stimulus material and then, after the passage of time, are requested to recollect the information given. Of course, these experiments differ from clinical-historical studies in that the stimuli and the intervening passage of time are controlled by the experimentcr; they differ more sharply from developmental investigations, however, in which, predominantly, enactive methodologies have been applied.

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In these enactive studies, the states of individuals differing in age are either cross sectionally assessed o r individuals are longitudinally followed through portions of their lifespans. In both cases the here-and-now of subjects is evaluated. Rarely has it been attempted to have subjects recollect events of the past. I n three recent studies, the present author used a retrospective methodology; these studies may serve to demonstrate some of the theoretical issues raised, especially ( a ) on the compatibility of retrospective and enactive time estimates, ( b ) on the steadiness of the flow of psychological time. and ( c ) on its periodicity and zero points. 1, Psvchologicnl Time In the first study, 26 undergraduate students in psychology wrote down as many names of persons (relatives, friends, acquaintances) as they could recall during a six-minute session. After the completion of this task, they indicated the years at which they had first met each of the persons named. Furthermore, they recorded their birth date and the years during which they attended the various types of schools. I n Fig. 1 , the number of persons recalled is plotted as a function of school ages. The results resemble a serial position curve whereby the serial order represents subjects' school age. Recency has a strong effect, i.e.. persons met in very recent years are recalled much more often than those met earlier in life. A primary effect is also revealed, i.e., persons met during the first years of life are recalled more often than those met during the intermediate years (but not as often as those met during the very recent years). The results shown in Fig. 1 raise some questions on the congruence be-

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tween such retrospective data and the enactive data commonly obtained. In order to answer these questions, we ought to obtain “objective” records on the number of persons whom an individual meets during the various periods of his life: during the preschool years, at home, in the elementary school, in the high school, etc. Although such data are not available to us, it seems reasonable to speculate about the reconstructions of these “objective” contingencies without access to records. As shown in Fig. 2, an individual born at time to faces a social environment with aO persons (parents, siblings, friends, neighbors). During the early years the rate of physical-psychological mobility ( a o ) will be small. The individual is bound to the immediate environment of his home and to the social interactions provided there. During the following years, when the child is entering the various types of schools, successive ecological expansions (ai)occur at times ti. Also his rate of mobility aiincreases. Instead of sticking close to his home, he explores his street block, goes to different parts of the city, travels to the neighboring towns and through the country. While, thus, the rate of mobility increases with age (ai to a,) the ecological expansion also progresses in ever bigger steps ( a , to a , ) . At first, in the nursery or kindergarten, he finds himself among few other children. The group size increases from the elementary to the junior high to the senior high school. He enters college with several hundreds or thousands of other freshmen, all of whom he can potentially meet. Figure 2 depicts the changes in the social possibilities of what we might call the “official child,” i.e., the child regulated by educational policies and laws. Aside from this role, the growing individual is exposed to various other social contingencies. He might engage in religious, political, recreational, and occupational activities. Each of these settings will provide for

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Fig. 2. Hypothetical model of the expansion of the social environment during the school years.

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other, partially independent expansions. In conjunction, these settings will smooth the stepwise progression shown in Fig. 2 and transform it into an exponential function ( y = 2” a,,) which, on another occasion, was suggested as one potential model of historical growth, a “branch structure model” (Riegel, 1969). Thus far we discussed the growth of the environmental potential for social interactions. Any event or any person entering into the growing repertoire of an interacting individual is subjected to forgetting. Using the simplest interpretation possible, we propose a linear decay, drop out, or forgetting of the persons encountered. We also stipulate that at a particular point in time the number of persons retrieved by their names will amount to 50% of the names accumulated at any point earlier in life. This point, measured in years, might be called the “half-life” of the specific social contingencies. According to this assumption the later in life an event is experienced, the faster the rate of forgetting will be. Figure 3 shows several forgetting lines originating at those points in time at which individuals enter new educational settings. Extrapolating these lines beyond the “half-life” provides for an inference congruent with Ribot’s law which states that items learned last during the period of growth are forgotten first; childhood experiences are best retained, adulthood experiences least. More important for our present considerations, the free recall task of our subjects can be represented by the cross-section at ti, indicated by a heavy vertical line in Fig. 3. If we plot, in a noncumulative manner, the

+

Point of R e c a l l ( t , )

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’S

ES Jt

TIME PERSONS MET

Fig. 3 . Hypothetical model of the expansion of the social environment during the school years and of the recall of persons during the life span.

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average number of persons predicted to be recalled at t , , we obtain the curve shown in the upper right part of Fig. 3. This curve is closely similar in shape to that for the empirical data plotted in the upper section of Fig. 1 . Our predictions fit our empirical data almost perfectly. The preceding discussion served the purpose of contrasting subjective, retrospective recall data with those that might have been obtained through more “objective,” enactive inquiries into social contingencies and their changes with the age of subjects. The suggested mechanisms for forgetting and retrieval together with our interpretations on the changes of the social environment with the age of subjects seem to predict the observed recall surprisingly well. Therefore, it seems justified to make some comparisons between the flow of psychological and chronological time. Such an analysis will be based on another study in which subjects from three different age groups were engaged in the same task described above. 2. Age Differences in Psychological Time Twenty subjects each from three consecutive generations wrote down as many names of persons as they could recall during a 10-minute session. Most members of the youngest group (average age z 23.1 years) belonged to the same kin, the middle group (average age z 50.0 years) included their parents, aunts, and uncles; the oldest group (average age = 73.3 years) included their grandparents, grandaunts, and granduncles. Increasingly from the youngest to the oldest generation, the groups had to be supplemented by persons unrelated to the kin. After the completion of the recall task, subjects listed behind each name the years at which they had met these persons for the first time. An analysis of the results is shown in Fig. 4. Here, the ordinate indicates the number of persons recalled. The abscissa indicates the years at which these persons were met for the first time. Since the average age of the three groups, I, 11, and 111, were related in ratios of about 3:2: 1, the scales were compressed accordingly. Thus, along the abscissa, three different age scales are used. As in the preceding study, the youngest group (111) shows a very strong recency effect and a less strong primacy effect; the curve is J-shaped and the data points are almost bisected by the influence of these two factors. The middle-aged group (11) reveals a strong recency effect but the primacy effect has disappeared; the curve has the shape of a boomerang. For the oldest group ( I ) , the primacy effect reappears slightly, while the recency effect has almost disappeared; the curve resembles a straight line. Thus, in their retrospective perception the oldest subjects attend to all five time periods most evenly; the names of persons recalled are almost equally spread over the full age range. The retrospections of the middle-aged group

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