Verbal feedback and the feature-positive effect in children

JOURNAL

OF EXPERIMENTAL

CHILD

PSYCHOLOGY

21, 249-255 (1976)

Verbal Feedback and the Feature-Positive Effect in Children C. BITGOOD

STEPHEN

Jacksonville State University

KERRY SEGFUVE McMaster

University

M. JENKINS

HERBERT McMuster

Unil,ersity

A pair of displays having common elements may be differentiated by the presence of a distinctive feature in one of the displays. When required to discriminate’ between such displays presented simultaneously, young children more readily learn to confine their responses to the display containing the distinctive feature (feature-positive condition) than to the display which does not contain the distinctive feature (feature-negative condition), The effect of explicit verbal feedback for incorrect choices on the learning of discriminations of this type was examined in 3- to .5-year-old children. In the featurepositive case, explicit feedback for incorrect responses increased the tendency to respond directly to the distinctive feature when responding on the positive display and greatly reduced errors. In the feature-negative case, explicit feedback for incorrect responses increased the tendency to avoid the distinctive feature in favor of a common feature when responding on the negative display. In this case+ however, consistent avoidance of the distinctive feature on the negative display was not always followed by the development of consistent choice of the positive display, and errors continued to occur at a high rate throughout training for most subjects. These results reflect the difference in the structure of the feature-positive and feature-negative tasks.

Jenkins and Sainsbury (1969, 1970) reported on the learning, in pigeons, of a successive discrimination between a pair of visual displays that shared common elements but were differentiated by a distinctive feature in one member of the pair. When responses to the display containing the distinctive feature were rewarded (feature-positive condition) responses shifted to the distinctive feature and the successive discrimination between the positive and negative display developed relatively quickly and completely. When responses to the display containing only common features were rewarded (feature-negative condition) responses shifted away from the distinctive feature to common features. In this case, however, the discrimination between displays developed only very slowly 249 Copyright 0 lY76 hy Academic Pres,. Inc. All rights of reproduction in any form rewwed,

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and incompletely. The greater ease of learning the discrimination in the feature-positive arrangement has been called the feature-positive effect. Sainsbury (1971, 1973) showed an interesting parallel in the learning of simultaneous discriminations between displays of this type in young (4- to 5-year-old) children. The children learned more readily to confine their responses (touching a display with their finger) to the display containing the distinctive feature than to the one containing only common features. The children, like the pigeons, shifted the location of their response to the distinctive feature in the feature-positive case. A tendency to shift away from the distinctive feature was also found in the featurenegative case, but the shift was not as pronounced as it was in the animal experiments. We attempted to replicate Sainsbury’s findings with a similar apparatus and procedure. However, a substantial fraction of the subjects in the feature-positive condition, as well as in the feature-negative condition, failed to solve the problem and a significant feature-positive effect was not obtained. The persistence of the same wrong response in some children suggested that the absence of explicit feedback for incorrect responses (the experimenter said “yes” for correct responses and said nothing for incorrect responses) was responsible for the high percentage of failures to solve the task in the feature-positive condition. This conjecture is supported in the literature on discrimination learning in children. Research on the relative effectiveness of reward and punishment on discrimination learning in young children has demonstrated that a rewardblank condition (reward for responding to the positive stimulus and no consequences for responding to the negative stimulus) results in poorer discrimination performance than either a reward-punishment condition (reward for responding to the positive stimulus and punishment for responding to the negative stimulus) or a blank-punishment condition (no consequences for responding to the positive stimulus and punishment for responding to the negative stimulus). This finding has been obtained both for verbal consequences (Curry, 1960; Spence & Senger, 1967; Williams, 1972) and for nonverbal consequences (Brackbill & O’Hara, 1958: Penny & Lupton, 1961). When children are explicitly told the meaning of no response from the experimenter (blank), the difference disappears (Spence, 1966), suggesting that in the reward-blank condition, the blank is interpreted as meaning “correct” when there are no explicit instructions or consequences. If reliable, the feature-positive effect could prove to be valuable for exploring some aspects of cognitive ability in children. In the hopes of increasing the reliability of the difference between performance in the feature-positive and feature-negative tasks, the effect of explicit verbal feedback for incorrect responses was examined in the present experiment. We reasoned that in the simpler feature-positive case, virtually all

FEATURE

POSITIVE

EFFECT

251

subjects would solve the problem easily after errors due to misinterpretation of the feedback were removed. At the same time, in the more demanding feature-negative case, many subjects would continue to fail despite explicit feedback. The difference in performance would therefore increase under explicit feedback. METHOD Subjects

Twenty children, male and femaIe, between the ages of 3 and 5 years were used as subjects. They were recruited from the Cariad Day Care Center in Dundas, Ontario, Canada. Apparatus

The apparatus consisted of a Gin. plywood panel painted gray and placed vertically on a table facing the child. At eye level were two Plexiglas screens 6-in.z centered 15in. apart. Each screen was divided into four 3-in.2 sectors by strips, IV&in. wide. Two Kodak slide projectors were used to back-project the displays. One control button operated both projectors simultaneously. The experiment took place in a semidarkened room. The experimenter always sat directly behind the child. The displays were similar to those used by Sainsbury (1973). The elements were solid black squares or triangles, X-in. on a side. They appeared centered, one in each quadrant. The triangle was the distinctive feature. It appeared in only one quadrant. In all other quadrants of both displays, the square (common element) appeared (Sainsbury has found no differences attributable to the use of a square or triangle as the distinctive feature). The side on which the display containing the distinctive feature appeared, and the location of the distinctive feature within the display, were randomly varied from trial to trial. Procedure

Subjects were instructed to find the “good” display and to touch it with their finger whenever it appeared. They were told that each time they picked the good display they would receive a poker chip, and that chips could be traded for a toy at the end of the session. The positive and negative displays were presented simultaneously. A response to any sector of the positive display resulted in termination of both displays and reinforcement, while a response to the negative display simply terminated the displays. The time between trials was approximately 5 sec. A training session consisted of 40 trials. At least two sessions were received by all subjects. Training was terminated after a subject performed correctly on 90% or more of the trials in the second or any

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subsequent session, or after ten sessions if the criterion was not reached earlier. In the yes-blank condition and in the yes-no condition, each correct response was followed by verbal feedback such as “good,” or “that’s right,” as well as by a poker chip. On incorrect trials the experimenter said nothing in the yes-blank condition, and said “no” or “that is wrong” in the yes-no condition. The two feedback conditions were factorially combined with the feature-positive and feature-negative tasks. Five children were assigned to each of the four groups in a way that kept the mean age for groups within narrow limits; from 3 years, 11 months to 4 years, 0 months. RESULTS The typical subject either solved the problem after very few errors (five or less), or continued to respond at or near a chance level throughout the ten sessions of training. Of the 20 subjects, 17 conformed to one or the other pattern. Certain results on errors in the first two sessions (received by all subjects), and the percentage of subjects solving the problem by the end of training are given in Table 1. It is evident that by far the fewest errors occurred on the featurepositive task with yes-no feedback. In this condition, all subjects met criterion in the first session. Errors in each of the remaining groups were much more frequent (40 errors in two sessions are expected by chance) and the differences among the remaining groups were not large. In the feature-positive group with yes-only feedback, one subject made the correct choice on the first trial and every trial thereafter, but none of the other subjects reached criterion within the first two sessions. None of the subjects who received the feature-negative task reached criterion within the first two sessions. The Kruskal-Wallis H test showed that error scores over the first two sessions differed significantly among the groups (H = 21.21, p < .OOl). Certain pairwise comparisons were made using the procedure TABLE ERRORS

AND

PERCENTAGE

1

OF SUBJECTS

REACHING

CRITERION

in first two sessions

Errors

Feature Feature Feature Feature

positive, negative, positive, negative,

Yes/no Yes/no Yes/blank Yes/blank

Median

Range

Percentage of subjects reaching criterion

3 42 36 49

l-5 40-49 o-43 37-80

loo 20 40 20

FEATURE

POSITIVE

253

EFFECT

proposed by Ryan (l%O) based on the Mann-Whitney U test with adjusted significance levels. With levels set to fix the overall type I error probability at .05, the difference between errors in the feature-positive and feature-negative arrangements proved significant only under the yes-no feedback condition. The differences between groups which received yes-no, or yes-only feedback did not prove significant by this conservative test. We consider now the choice between the distinctive and common features when the child responds to the display containing both types of features (correct responses in the feature-positive case and incorrect responses in the feature-negative case). A summary of the choice data for the first two sessions is given in Table 2. With explicit feedback, the distinctive feature was virtually always chosen in the feature-positive condition and virtually never chosen in the feature-negative condition. Without explicit feedback, the median percentages showed only a weak preference for the distinctive feature in both the feature-positive and feature-negative conditions. The Kruskal-Wallis H test showed that choices differed significantly among the groups (H = 20.00, p < ,001). Again, using the procedure proposed by Ryan, with a .05 Type I error probability, the difference between choices in the feature-positive and feature-negative arrangements was significant only under the yes-no feedback condition. The difference in choices associated with yes-no or yes-only feedback reached significance only in the feature-negative condition. Individual data were examined for the relation between errors and preference for the distinctive feature when responding to the display containing that feature. In the feature-positive case, the elimination of errors and preference for the distinctive feature always occurred together. Every child who solved the problem responded directly to the distinctive feature. Furthermore, consistent preference for the distinctive feature within the display was always associated with the elimination of errors. In the feature-negative case, the association between avoidance of the distinctive feature and solution of the problem was weaker. Although the two subjects who eventually reached criterion on the featureTABLE PERCENTAGE

2

OF RESPONSES TO DISTINCTIVE FEATURE IN FIRST RESPONSE IS MADE ON DISPLAY WITH THE DISTINCTIVE

Feature Feature Feature Feature

positive, negative, positive, negative,

Yes/no Yes/no Yes/blank Yes/blank

Two SESSIONS WHEN FEATURE

Median

Range

95.0 5.0 36.0 50.0

lz9.0-97.5 o.o- 15.0 31.5-100.0 21.0-100.0

34

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negative task avoided the distinctive feature when responding to the display containing it, several other subjects who also avoided the distinctive feature in favor of the common feature nevertheless continued to choose the incorrect display with the frequency expected by chance throughout training. DISCUSSION

The principal results may be summarized as follows. With explicit feedback for incorrect responses, the feature-positive task was solved by all subjects with no more than a few errors. The feature-negative task, on the other hand, was solved by only a small percentage of subjects and with many more errors. Thus, when feedback was explicit, the greater ease of solving the feature-positive task was evident and highly significant statistically. When incorrect responses were not accompanied by explicit feedback, there were frequent failures to solve the featurepositive task, as well as the feature-negative task. The superiority of the feature-positive arrangement was not as clear, and was not statistically significant. More explicit feedback resulted in a stronger preference for touching the distinctive feature in the feature-positive case and a stronger preference for touching a common feature in the feature-negative case. In the feature-positive case, preference for the distinctive feature within the correct display was uniformly accompanied by the elimination of errors. On the other hand. in the feature-negative case, preference for the common feature within the incorrect display was not always followed by the eventual elimination of errors. The present results support the following account of the greater ease of solving the feature-positive task. Children seek the solution of the tasks in terms of a single element on the display rather than in terms of attributes of the collection of elements. The displays could have been distinguished in terms of an attribute of the collection such as “elements the same” versus “elements different.” In experiments with somewhat different displays we have encountered solutions on a “same-different” basis, but not in the present experiment. Were the problems solved in terms of an attribute of the collection there would be no reason for unequal difficulty with the feature-positive and featurenegative tasks, and no basis of the within-display response preferences which accompanied correct performance in the present case. The feature-positive case is solvable in terms of a single element, The rule. “touch only the distinctive feature,” although not logically necessary for solution, is sufficient for solution. There is no strict counterpart in the feature-negative case. Rules such as “touch only the common feature” do not, of course. imply choosing the correct display since common features also appear on the incorrect display. The closest one can come to a single element rule for the feature-negative case is something

FEATURE

POSITIVE

EFFECT

2.55

like “respond to a common feature only if it is not accompanied by a distinctive feature.” Such a rule entails a conditional choice rather than a direct choice as in the feature-positive case. A similar account has been offered for the feature-positive effect in pigeons (Jenkins & Sainsbury, 1969, 1970; Jenkins, 1973: Hearst & Jenkins, 1974). The present results suggest that some children misinterpret the absence of a response from the experimenter following an incorrect choice of display as equivalent to an “OK.” The misinterpretation could explain the frequent errors, and frequent failures to solve the otherwise very easy feature-positive task. This extraneous source of errors can obscure the basic, s&u&Ural difference between feature-positive and feature-negative tasks. Our results indicate that it is desirable to use explicit feedback when studying the cognitive capacities of children through discrimination learning tasks. REFERENCES Brackbill, Y., & O’Hara. J. The relative effectiveness of reward and punishment for discrimination learning with children. Journa/ of Comparative and Physio/ogica/ Psychology3 1958, 51, J4J-J5l. Curry, C. The effects of verbal reinforcement combinations on learning in children. Journal of Experimental

Psychology,

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59, 434.

Hearst, E., & Jenkins. H. M. Sign-tracking: The stimulus-reinforcer relation and directed action. Austin, Texas: The Psychonomic Society, l9J4. Jenkins, H. M. Noticing and responding in a discrimination based on a distinguishing element. Learning and kfotivation, 19J3, 4, l15-13J. Jenkins, H. M., & Sainsbury, R. S. The development of stimulus control through differential reinforcement. In N. Mackintosh & W. Honig (Eds.), Fundamental issues in associafive learning. Halifax: Dalhousie University Press, 1969. Pp. l23- 167. Jenkins, H. M., & Sainsbury, R. S. Discrimination learning with the distinctive feature on positive or negative trials. In D. Mostofsky (Ed.), Afrenfion: Contemporary theory and analysis. New York: Appleton-Century-Crofts, 1970. Pp. 239-275. Penny. R., & Lupton, A. Children’s discrimination learning as a function of reward and punishment. Journal of Comparative and Physiological Psychology, l%l, 54, 449-451. Ryan, T. A. Significance tests for multiple comparison of proportions, variances, and other statistics. Psycho/ogical Bulletin, 1960, 57, 3 18-328. Sainsbury, R. S. The feature positive effect and simultaneous discrimination learning. Journal of Experimental Child Psychology, l9Jl. 11, 347-356. Sainsbury. R. S. Discrimination learning utilizing positive or negative cues. Canadian Journal

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1973, 27,46-57.

Spence, J. T. Verbal-discrimination performance as a function of instructions and verbalreinforcement combination in normal and retarded children. Child Development, 1%6, 37, 269-28 I. Spence, J. T., & Senger, L. L. Verbal versus nonverbal reinforcement combinations in the discrimination learning of middle- and lower-class children. Chi/d De\fe/opment, 1%7,

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Williams, B. R. Effects of verbal reinforcement combination blank trials. Journal of Experimental Child Psychology, RECEIVED: October 30, 19J4;

REVISED:

July 7, l9JS

on children’s 1972.

14, 30-42.

responses to