Verbal report and judgment of an unstructured stimulus[1]

William Robert Hood and Muzafer Sherif
Institute of Group Relations, University of Oklahoma


One of the established experimental methods in social psychology is measurement of changes in judgment accompanying variations in social influence. Procedures have been applied to judgment of a variety of stimulus dimensions (e.g., apparent movement, warmth, length, numerosity, affectivity) and have utilized different social influences (e.g., judgments of other persons in various prestige and status relationships to S, or with membership in social aggregates and groups).

During the last decade, interest in psychological processes involved in behavioral changes and a healthy concern with the validity of laboratory results have led to certain pertinent questions. Does the individual who changes his verbal reports with the introduction of a social influence actually see the stimulus situation differently, or is he simply reporting in a way calculated to avoid disapproval and to appear agreeable? Is there a discrepancy between his perception or judgment of the situation and his verbal report to E? That discrepancies do occur is shown by studies in which stimuli to be judged clearly differ and S faces a number of other individuals (planted Ss) stating, in effect, that they do not differ (1, pp. 451-483.) Here the typical finding is that a minority of the Ss agree with the planted Ss' judgments and that most of these later say that they did not in fact "see" the situation as they reported it.

Festinger (3) suggested a behavioral criterion for evaluating whether or not a discrepancy between S's experience and his verbal report occurs, viz., determining whether or not convergence to an experimentally introduced standard continues following its removal. On the basis of this criterion, experimental evidence of a discrepancy is lacking when the stimuli are unstructured in the dimension judged, i.e., when stimulus determinants are such that alternative perceptual organizations are feasible. The original studies on judgments of extent of autokinetic movement in interaction situa-

( 122) -tions (6) revealed no discrepancy between judgment and verbal report by this criterion. After judging extent of movement with others, Ss subsequently adhered to the range and norm developed in the interaction situation when making judgments alone on a different day. More recently, the maintenance of judgments formed in social situations was reported in individual sessions held after intervals of 28 days (2) and a year (5).

If lack of correspondence between judgment and verbal report were the general finding in experiments on social influence, it might be concluded that such experiments reveal merely responses expected of agreeable, socialized individuals to direct social pressures or demands from others in the situation. If so, findings obtained by this laboratory method would not be pertinent to the more lasting changes produced by social influences in actual life. Thus the correspondence or lack of correspondence between judgment and verbal report is a crucial problem in social psychology. The problem may be stated snore specifically: Under what conditions is a discrepancy found or not found? What is the nature of the social influence in these conditions and how is it perceived by S?

As a first step, it may be noted that discrepancies are sometimes reported in situations where the stimulus dimension is definitely graded in clear alternatives (structured situations). Judgments of other individuals contrary to perceived stimulus differences contribute to S's perception of "social pressures" to conform. At an opposite pole, when facing a situation whose stimulus determinants permit many alternatives, S is influenced by an experimentally introduced standard and may be unaware of the influence. In the latter situation, it may be misleading to speak of "social pressures." The problem of the present experiment concerns this latter pole, which may be conceived as an end segment in the range of gradations of structure in social influence situations.

The experimental situation was defined by the following guides: (a) The stimulus dimension judged permits varied alternative modes of experience and behavior. (The autokinetic situation was chosen.) (b) Procedures eliminate as much as possible any suspicion that the experiment has anything to do with any kind of social influence. (c) Immediate social pressures, in the form of the presence of another person making judgments or the sound of his voice, are eliminated. The social influence is perceived by S as coincidental to his presence in the situation and is absent when he renders judgments. (d) S does not "commit" himself in the presence of a planted S and is encouraged to judge as he sees fit. (e) Extensive data are collected on S's experiences in the experiment as reported after he makes judgments. Such

( 123) data are a basis, in fact the only available basis, for inferring his experience at the time.

The hypotheses were that under the conditions stated above: (a) S's judgments would converge toward those of a planted S to which he was exposed prior to rendering judgment, and (b) there would be no discrepancy between experience of the stimulus and verbally reported judgments.


Ss were told that the purpose of the experiment was the design of tests of visual abilities under low illumination. E identified himself as a graduate student employed to work on a research contract and avoided any mention of psychology. The experimental darkroom was located in an Army Reserve building. Before entering the darkroom, E explained to S:

We've found it takes the average person's eyes about three to 15 minutes to adjust to the dark enough to see the light. I left the observer who started before you in the darkroom while I came to get you so that we could save that 15 minutes. He has about that many estimates to make in order to finish his series. I'll bet he's asleep by now. You can just sit in the darkroom and let your eyes adapt while he finishes, and then you and I will he ready to go to work.

The room was dark when S entered and he never saw the planted S. F asked the planted S if he had taken a nap. The planted S answered : "No, but this would be a good place to take one. It sure is dark in here." Except for his judgments, he said nothing else in the naive S's presence. The naive S was led to a chair at one side of a table where the planted S was seated, facing the light source. Then he was told:

I'll tell you what we are doing before we start again so that it won't be quite so boring--just sitting there. The observer who is working now has a box in front of him with a button on it. His job is to watch for the light to come on down at the other end of the room-off to your right. I will say "ready" about three seconds before the light appears. He watches the light, and as soon as it starts to move, he punches the button. After a few seconds the light goes off, and then he tells me how far it moved-just the distance it moved through space; the direction doesn't matter.

The planted S then gave a series of 18 judgments, spoken in a clear voice but with a degree of assurance planned to approximate that conveyed by naive Ss in pre-tests. For half of the Ss, these 18 judgments were distributed between 1" and 5" with a mode of 3". For the other half of the Ss, the 18 judgments were distributed between 6" and 10" with a mode of 8". When

( 124) the series of 18 judgments was completed, S was asked to wait in the darkroom (two minutes), while the other observer was paid. Then S moved behind the table and the instructions for judging movement were repeated. E avoided any comment on the planted S's judgments. A few Ss expressed disagreement with them after the "plant" left, and they were told: "You call them the way you see them."

Following four trial judgments, each S gave a series of 50 judgments at one minute intervals. Then S was taken to where a questionnaire was administered.


The autokinetic apparatus exposed a pinpoint of light automatically through a circular hole 1 min. in diameter (see Sherif and Harvey, 1952, for specifications). The brilliance of the light was reduced approximately to half, and exposure time was set at two seconds. Pretests of these adjustments resulted in relatively small and consistent judgments of extent of apparent movement. The darkroom was 15' X 30' with S-to-light distance of 20'.

The questionnaire administered following the judgment included several linear scales to secure estimates of confidence, influence of the planted S and extent of agreement with him, as well as open-ended items concerning purpose and possible utility of the experiment, role of the planted S, descriptions and estimates of apparent movement.


Ss were 24 male college students paid as "observers" and unfamiliar with the autokinetic phenomenon. Random assignment to the two experimental conditions was restricted only by matching for age. Pre-test data indicated differences in response to the experimental conditions related to age, which factor probably summarizes several related characteristics of college students, e.g., classification, academic success, ease in an experimental situation. In each condition, five Ss were between 17 and 19 years old, two Ss were 20 years, and five Ss between 21 and 27 years. The planted S was the same person in each session (age, 20 years).


Data bearing on three general questions are pertinent to the hypotheses: 

1. Do S's judgments conform to the mode and range of the planted S's judgments previously overheard?

2. Do S's experiences as reported immediately after the experimental

( 126) session agree with his verbally reported judgments?

3. Is S aware of any influence from the prior judgments of the planted S?

Table I gives the median judgments by Ss in each condition. The median of all judgments for the sample exposed to the 1-5" range is 3.98", and that of the sample exposed to the 6-10" range is 6.79".

1-5" Range 
 6-10" Range
2.6 3.1
2.7 4.3
3.2 4.9
3.4 6.5
3.5 6.6
3.8 6.8
3.9 6.8
4.1 7.5
4.3 7.6
4.9 7.7
5.1 8.5
5.7 11.5
Mann-Whitney U = 16
p < .001 (one-tailed test)

The differences between the medians for the two conditions were tested by the Mann-Whitney statistic, U, and were significant (p < .001 ).

Figure 1 shows the proportion of Ss' judgments which were 5" or less and 6" or more. Ss exposed to the 1-5" range placed the bulk of their judgments below 5" and Ss exposed to the 6-10" range concentrated their judgments above 6". In the 1-5" condition, 81.1 per cent of the judgments fell between 1-5" and the range of judgments was 10". In the second condition, 70.5 per cent of judgments were 6" or greater, and the range was 24".

Responses to questionnaire items concerning the purpose of the experiment were identical or entirely consistent with the instructions for all but one S. The latter, a bright young physics student, had already observed to E that overhearing another person might affect one's judgments. However, this S estimated that he himself was influenced by the plant in only about 25 per cent of his judgments. Actually 74 per cent of his judgments fell within the plant's range. Explanations of the procedures by other Ss were in terms of tests for "night flying," "night driving" and the like. All Ss accepted E's explanation of the plant's presence.

In inferring correspondence between Ss' verbal reports and experiences of


Figure 1.


apparent movement, a crucial comparison is between medians of the obtained judgments and Ss' responses to the questionnaire item: How far did the light seem to move usually?" The summary in Table 2 reveals small differences between the two. The significance of differences between each S's median judgment and his subsequent report of "usual" extent of perceived movement was tested by the Wilcoxon Matched-Pairs Signed-Ranks Test. The resulting 7's of 21 and 26 for Ss in the 1-5" and 6-10" conditions, respectively, were not significant (p > .05, two-tailed test). Thus the hypothesis that Ss reported movement as they saw it is supported.

Ss accepted the planted S, whom they never saw, as another student like themselves. Only one of the 24 Ss believed that the plant judged accurately,

( 127)

Condition Obtained
Usual extent
T* Range of 
1-5" range 3.98 3.88 21 -1.2 +3.3
6-10" range 6.79 7.00 26 -1.5 +1.3
* Wilcoxon test: p > .05
** Difference between Ss median judgment and usual extent of movement he reported having perceived.

while another stated that he was uncertain as to his accuracy. The remaining 22 Ss stated either that the plant overestimated or underestimated.

Asked to estimate on a linear scale the proportion of his judgments influenced by the plant, only one S overestimated the extent to which his judgments actually fell within the prescribed range of the plant. The median difference between the proportion of judgments falling within the prescribed 1-5" range and the proportion which Ss in that condition estimated to be influenced was 64 per cent (range: -7-100). The median discrepancy for the 6-10" condition was 57.5 per cent (range: 16-80). Since all but one S underestimated the extent of agreement between his judgments and those of the plant, the direction of differences is clearly significant (p < .005, twotailed Wilcoxon Matched-Pairs Signed-Ranks Test). The size of the discrepancy between the proportions of judgments actually falling within the prescribed ranges and the proportions Ss thought were influenced was significant for both conditions (p = .005, two-tailed Walsh test).

The distributions of responses on a 5-category scale concerning amount of agreement between plant's judgments and S's own judgments were practically identical for the two conditions. One S in each condition rated his agreement with the plant between "Agreed some of the time" and "Much agreement." Of the remaining 22 Ss, half checked "Agreed some of the time" and half checked "Positively no agreement" or "Little agreement."


Analysis of the results has indicated that the prescribed range of a planted S, overheard briefly prior to rendering judgments, did influence the norm and range adopted by S in this situation. The purpose of the experiment and the role of the plant were accepted as genuine. There was no significant discrepancy between S's reported judgments and his experience of extent of movement. On the whole, Ss were not aware of the extent to which their

( 128) judgments coincided with the plant's. Thus we may consider the main hypotheses supported. In a situation lacking clear-cut determinants in the stimulus dimension judged, the spoken judgments of another person serve to anchor experience of the individual, and this experience is accurately reflected in his verbal reports while rendering judgment.

While much experimentation on social influence has quite properly focussed on interaction situations, it is apparent that even in the absence of interaction between individuals or the immediate sound of another's voice, the judgments of another person overheard previously may exert a categorizing effect, delimiting the scope of perceived alternatives and affecting the modal value. This conclusion is consistent with the experimental findings concerning the categorizing effect of linguistic concepts (4). In such situations, it would seem misleading to conceptualize the influence process in terms of arbitrary "social pressures," particularly when S is unaware of being influenced.

The situation in this study represents near-minimal social influence whose strengthening by the ascription of authority or prestige should lead to even more striking differences in judgments by Ss overhearing different prescribed ranges.

The use of a minimal social influence in the present experiment permits analysis of some of the stimulus determinants operating even in so unstructured a situation as the autokinetic set-up. Under the usual conditions of autokinetic experiments as to size of room, distance from light, length of exposure and brilliance of light, Ss ordinarily center judgments around a mode of 3-6", the individual who exceeds a mode of 8-10" being exceptional. In comparison, judgments made in a large, empty auditorium are greater in both mode and range (7). In the present experiment, the brilliance of the light was reduced, which resulted in pre-test judgments of small movement within a narrow range.

Certain differences in the responses by Ss exposed to the l-5" range and the 6-10" range are worth noting. In a situation more conducive to the perception of small movements, the introduction of the 6-10" range not only set a level considerably higher than "normal" for these viewing conditions, but also resulted in a range (24") unusually large for these conditions. In the autokinetic situation or other situations conducive to various alternative modes of perceptual patterning, possible conflict among alternatives can be resolved rather easily. In the present case, Ss in the 6-10" condition estimated distance to the light as farther (median: 19') than Ss in the 1-5" condition (median: 14'). This estimate is congruent with their larger median judgment of perceived movement (viz., 6.79", as compared to 3.98"). The

( 129) limits imposed by stimulus determinants are strikingly apparent when the social influence diverges from them increasingly. Whittaker (8) has shown that when the social influence diverges widely from the S's mode, he ignores the social standard completely.


The validity of experimental methods for studying lasting changes in judgment as a function of social influence requires that verbal reports of judgment reflect S's experience of the stimulus dimension. This paper discusses factors determining whether or not a discrepancy between verbal reports and S's experience will arise. An experiment is presented in which the stimulus dimension judged (extent of autokinetic movement) permitted alternative modes of experience and report. Procedures were designed so that Ss would not suspect that a study of social influence was in progress. S did not "commit" himself in the presence of another person, and immediate "social pressures" were eliminated. S was exposed, as though accidentally, to the prescribed judgments of a planted S prior to rendering judgment.

In this experimental situation, judgments of Ss exposed initially to different prescribed ranges did differ significantly in the predicted directions. "There was no significant difference between verbal reports in rendering judgment and experiences of movement, as inferred from other behavioral data. On the whole, Ss accepted E's account of the purpose and procedures as genuine, and were unaware of the extent to which their judgments had been influenced.

This situation is contrasted with those at an opposite pole, in which determinants in the physical stimulus situation are predominant and discrepant social standards are introduced.


1. ASCH, S. E. Social Psychology. New York: Prentice-Hall, 1952.

2. BOVARD, E. W., Jr. Social norms and the individual. J. Abnorm. & Soc. Psychol., 1948, 43, 62-69.

3. FESTINGER, L. An analysis of complaint behavior. In Sherif, M. & Wilson, N. O. (Eds.), Group Relations at the Crossroads. New York: Harper, 1953, 232-256.

4. GIBSON, J. J. The reproduction of visually perceived forms. J. Exp. Psychol., 1929, 12, 127-155.

5. ROHRER, J. H., BARON, S. H., HOFFMAN, E. L., & SWANDER, D. V. The stability of autokinetic judgments. J. Abnorm. & Soc. Psychol., 1954, 49, 595-597.

6. SHERIF, M. A study of some social factors in perception. Arch. Psychol., 1935, No. 187.

7. SHERIF, M., & HARVEY, O. J. A study in ego functioning: Elimination of stable anchorages in individual and group situations. Sociometry, 1952, 15, 272-305.

8. WHITTAKER, J. O. The effects of experimentally introduced anchorages upon judgments in the autokinetic situation. Unpublished doctoral dissertation, University of Oklahoma, 1958.

Institute of Group Relations The University of Oklahoma
Norman, Oklahoma


  1. Received in the Editorial Office on April 2, 1962, and published immediately at Provincetown, Massachusetts. Copyright by The Journal Press.



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