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Attitudinal effects of “mere exposure”: A reevaluation
JOURNAL.
OF
EXPERIMENTAL
Attitudinal
Effects THOMAS Department
SOCIAL
PSYCHOLOGY
of “Mere
D. G. of
BURGESS
7,
461472
Exposure”: II’
Psychology,
AND
STEPHEN
Carnegie-Mellon
( 1971)
A Reevaluation M.
SALES*
University
Zajonc has proposed that repeated “mere exposure” of a stimulus is a sufficient condition for enhancing the attractiveness of this stimulus. And Harrison has suggested a theory to explain the relationship between repeated “mere exposure” and attractiveness. However, while this area appears complex, a simple and parsimonious explanation based on classical conditioning can apparently account for the obtained data. This explanation assumes only that the contexts within which “mere exposure” occurs are not affectively neutral, but rather positively evaluated. Thus, the data gathered in “mere exposure” studies may indicate only that the positive affect which characterizes the exposure context is increasingly transferred to the exposed stimulus as the number of trials (exposures) increases. TWO experiments are presented in support of this general argument. In the first, the relationship between exposure frequency and attraction is shown to be stronger for Ss who find the experimental context relatively attractive; in the second, intentionally created positive contexts are shown to provide positive relationhip between familiarity and affect, while intentionally created negative contexts are shown to provide negative relationships between these variables.
Zajonc (1968) h as recently argued that repeated “mere exposure” of a stimulus is a sufficient condition for enhancing the attractiveness of this stimulus. In his original article, Zajonc (1968) reported a variety of data which support this hypothesis. And, although conflicting data have recently been presented (Perlman & Oskamp, 1970; Suedfeld & Epstein, 1970; Brickman & Redfield, 1970), Zajonc’s findings have also been replicated in a variety of settings (Harrison & Hines, 1970; Zajonc & Rajecki, 1969; Harrison, 196Sa; Harrison, 1969; Harrison & Zajonc, 1970). Fur1 Now at the University of Pittsburgh; Study II of this paper is based on a master’s thesis submitted by the senior author to Carnegie-Mellon University. Requests for reprints should be sent to Stephen M. Sales, Department of Psychology, CarnegieMellon University, Pittsburgh, Pennsylvania, 15213. ‘The authors are indebted to Daryl J. Bern, Sandra L. Bern, Esther G. Sales, Walter Swap, and the editorial board of the Jownal of Experimental Social Psychology for their helpful comments upon an earlier version of this paper. 461
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thermore, a theoretical explanation has recently been proposed for the “mere exposure” effect (Harrison, 196Sb), and this rationale has itself received some support (e.g., Matlin, 1970; Harrison & Zajonc, 1970; Harrison & Hines, 1970). This line of research has attempted to demonstrate that exposure “unencumbered by other processes or contingencies, such as positive and negative reinforcement,” is sufficient to cause attitudinal enhancement of the exposed stimulus (Zajonc, 1969, p. 7). And it has generated interest precisely because the studies involved do seem to demonstrate that such “unencumbered” exposure leads to increased liking. However, it may be that the “mere exposures” involved in these studies are, in fact, more encumbered than one would previously have supposed. If so, then the major thrust of the “mere exposure” investigations would be considerably weakened. To see the nature of the encumbrance involved, one must look carefully at the studies performed within the “mere exposure” paradigm. In these investigations, Ss are usually brought into a psychological laboratory, seated before a stimulus presentation device of some sort (e.g., a projection screen, a memory drum, an E), and then shown a variety of stimuli with various exposure frequencies. Thereafter, the Ss are asked to indicate their degree of liking for the stimuli involved. Because no immediately apparent rewards or punishments are present, research workers within this tradition have assumed that the stimuli are, in fact, “merely exposed.” However, this conclusion presupposes that the psychological laboratory itself is affectively neutral for the S’s used. And, as Orne ( 1962) has argued, this second assumption is probably untenable. Rather than being affectively neutral, the laboratory is likely to provide a highly positive context for the “mere exposure” of stimuli. If so, then the “mere exposures” involved should be very much encumbered by processes such as positive and negative reinforcement. For, in a sense, exposure of a stimulus within some affectively meaningful context can be seen as a trial in a classical conditioning experiment. And the literature provides a clear expectation relating frequency of exposure (i.e., number of trials) to resultant affect (i.e., strength of learning) in such situations. As the number of trials increases, the focal stimulus increasingly assumes the affect which is aroused by the context, This conditioning mechanism is surely familiar, and it requires no discussion here. The implications of this argument for the present concerns should be clear. Since the experimental laboratory is (presumably) an affectively positive context, then stimuli which are frequently exposed within that context should themselves acquire positive meaning. And the explanation
“MERE
EXPOSURE”:
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REEVALUATION
463
of this effect would rest not upon any complex mechanism, but rather upon simple classical conditioning. The present paper reports two experiments directed toward this general issue. In the first, the strength of the “mere exposure” effect is examined separately for S’s who feel either (a) relatively positive or (12) relatively negative toward “silent” contextual factors (such as the psychological laboratory) which might act as higher-order unconditioned stimuli in this situation. If the argument sketched above is correct, one would expect to see a positive relationship between exposure frequency and affect in the former group but a negative (or, at least, a nonpositive) relationship between these variables in the latter group. In the second study, the relative strength of the “mere exposure” effect is investigated in contexts which are known to have either (a) positive or (b) negative meaning for the Ss involved. If the present argument is correct, one would expect to see a positive relationship between exposure frequency and affect in the first situation but a negative relationship between them in the second situation. STUDY
1
Ooeroie~. Ss were employed in one trial of an apparent serial learning task. Five diRerent nonsense words, arranged as a serial list, were used as the items to be learned one of these words was presented at each of five different exposure frequencies within the list. The experimental design was intended to be a replication, with minor changes, of the paradigm described by Zajonc (1968, pp. 13-16). The major deviations of the present methods from those employed by Zajonc (1968) were (u) that a Patterson 1-B memory drum, rather than the E, was used to present the stimuli, and (11) that the task was explicitly described as a learning experiment. All Ss believed that, after the presentation of the list, they would be tested for their recall of the material. However, prior to the recall testing, the Ss were asked to indicate their liking for various stimuli which might have constituted the context for the exposure of the nonsense words. They then were asked to indicate the way they felt about the five nonsense words themselves. Sample. Forty-eight undergraduates (27 male, 21 female) at Carnegie-Mellon IJniversity served as Ss for this experiment. All Ss were enrolled in introductory psychology, and all received required experimental credit for their participation. Materials Stimulus muterials. To obtain aflectively neutral nonsense words, 19 stimuli (CVCVC, with leading capitals) were constructed and presented to 53 social psychology students. These 53 Ss were asked to rate each of the nonsense words on a seven-point scale anchored by “good” and “bad.” The 10 words with the largest standard deviations were eliminated; of the remaining nine, the five with the most nelltral average ratings were selected for use in the experiment. The retained stimuli, ;ml thtair nssociattzd scale valnrs, WYP Hoheb ( +0.38), Kodup ( -+O.ZS), Rikd
464
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(O.OO), Solok (-0.15), and Falip (-0.15). These nonsense words were then placed in five different learning lists; within each list one word appeared only once, one appeared twice, one appeared four times, one appeared eight times, and one appeared 16 times. Five lists were required to achieve counterbalancing of stimuli over the various exposure frequencies. Contextual ratings. When the experiment (described below) was completed, the Ss were asked to complete a “personal reaction” questionnaire. This instrument asked them to rate nine contextual factors on separate seven-point scales, each anchored by “good” and “bad.” Three of these attitude objects had been selected to judge the Ss’ feelings toward the experiment itself (“‘the present experimenter,” “the present experiment, ” “this experimental laboratory”); three had been selected to indicate the Ss’ feelings toward psychology and science (“psychology,” “psychological experiments in general,” and “science”); three had been selected to measure the Ss’ attitudes toward themselves and their overall environments (“yourself,” “life in general,” and ‘your experience here at the University”). It was originally hoped that these nine items would constitute three separate three-item scales. However, this expection was realized only for the first (“the present experiment”) and the third (“life in general”) of the indices. In the present sample, coefficient alpha for the first of these indices was .64, while the same statistic for the latter index was .61. The three items designed to measure the Ss’ feelings toward science and psychology, on the other hand, exhibited only low correlations with each other. Thus, it was decided to collapse the Ss’ responses to the postexperimental questionnaire into two separate indices measuring (a) reactions to the present experiment and (b) reactions to “life in general.” The remaining three items have been ignored in the analyses reported below. Each S’s responses to the three items on each scale were summed to provide two separate scores. The sample was then divided at its median into “high” and “low” groups on each index. To provide equal Ns in the two groups, Ss whose scores fell at the median were randomly allocated between the “high” and “low” subsamples. Procedure When S arrived at the laboratory, he was directed to a small cubicle equipped with a ,table and a memory drum. S was told that he would be shown 31 words through the memory drum, and he was informed that his recall would be tested as soon as the presentations had been completed. The E then initiated the memory-drum program. This program presented each nonsense word for an 8-set period, with no pause between presentations. When all 31 exposures had been completed, the E turned off the memory drum and handed S the postexperimental questionnaire (described above) designed to measure S’S attitudes toward the context within which stimulus presentation occurred. He then gave S a “recall” form. The first item of this form read: The way you feel about the unfamiliar words used in this experiment affect how well they were learned. To help me judge this, please below how “good” or “bad” each of the words seems to you.
might indicate
This item was followed by five seven-point scales, one for each nonsense word. As previously, these scales were anchored by “good” and “bad.” On this posttesting, the five nonsense words were presented in the same order for all Ss. When S had completed this rating, which served as the dependent variable for
“hIEHE
this study, about the
he was debriefed investigation.
and
Findings
and Discussion
was
465
A REEVALUATION
WCPOS~JHE”:
given
the chance
to question
the
experimenter
Over the entire sample, a significant linear trend between familiarity and liking was observed (F( 1,188) = 5.12> p < .05). This finding is a replication of data reported by others (e.g., Zajonc, 1968), and it requires no particular comment here. This result was not at all mediated by Ss’ scores on the “life in general” index. However, it was clearly affected by their feelings about the experiment. Ss who felt relatively positive about the experiment exhibited a strong linear relationship between exposure frequency and liking (F( 1,92) = 13.10, p < .OOl). Ss who felt relatively negative about the experiment, on the other hand, exhibited no linear relationship at all between familiarity and liking.” These findings are presented in Fig. 1. The F ratio for the interaction shown in this figure is 2.37 which, with 4 and 184 degrees of freedom, falls just short of significance at the .05 level. These findings appear reasonably self-explanatory. As expected, Ss who experienced the exposure context as relatively positive exhibited a strong “mere exposure” effect; Ss who experienced the exposure context as relatively negative, on the other hand, exhibited no such effect. This
oooj
FIG. relatively 3 The
1. Relationship positive and quadratic
trend
I
between relatively shown
exposure negative in these
frequency and liking toward the experimental data
was nonsignificant
among Ss who context.
(F = 1.82).
felt
466
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AND
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result is quite consistent with the contention that the “mere exposure” effect is due to a classical conditioning process. Indeed, the only point in the present data which appears to be controversial is the essentially flat slope of the frequency-affect relationship for Ss who experienced the exposure context as relatively negative. That is, since these Ss exhibited relatively negative affect toward the experimental context, one might have expected to see a negative relationship between familiarity and liking in this sub-sample. However, the failure to find such a negative relationship has a simple explanation. For these Ss did not, in fact, dislike the experiment; rather, their attitudes were essentially neutral toward it, They constitute a “relatively negative” subsample only because, as Orne (1962) suggested, most Ss liked the present experiment.-’ Study I thus indicates that intersubject differences in the evaluation of a constant exposure context can affect the magnitude of the frequencyliking relationship. However, if the argument proposed here is correct, then one would expect that an intentional manipulation of the exposure context would also have such an effect. Study II is oriented toward this issue. In particular, Study II involves the presentation of unfamiliar stimuli not merely in the context of a positively evaluated laboratory, but also in the context of meaningful words known to evoke positive and negative affect. In a sense, the methodology employed in Study II differs from that used in Study I. The first investigation reported here essentially involves “incidental learning” (the pairing of the laboratory cues with the nonsense words), while the experiment discussed below is directed toward “intentional learning” (the pairing of the meaningful words with the unfamiliar stimuli). However, this procedural variation does not seem incidental and intentional crucial. For, as Postman (1964) h as argued, learning situations are apparently similar in all functional characteristics; thus, the difference between the two paradigms appears to involve only details of the experimenter’s stated procedures. Since experimental control seems easier to obtain in the intentional than in the incidental learning situation, we have chosen to employ the former in Study II. ‘One might maintain that the “relatively negative” Ss possessed a tendency to respond neutrally. This hypothesis vitiates the present conclusions, since it parsimoniously explains these Ss’ essentially neutral ratings of the five nonsense words. HOWever, two facts suggest that these data cannot he ascribed to any such response patterns: (a) Ss who responded neutrally on the “life in general” index exhibited a strong exposure effect. This result would not obtain if these Ss possessed a tendency to respond essentially
sponded would
neutrally. the same
positively
be unlikely
( b ) The within-subject variability in, rating the five stimuli was for Ss who responded neutrally (MS = 1.74) as for Ss who re(MS = 1.68) on the “present experiment” index, This result if the former were characterized by a neutral response tendency.
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EXPOSURE”:
STUDY
A REEVALUATIOK
467
II
Oceroiezr; Ss were employed in what appeared to be the “study” phase of a “study-recall” paired-associate learning task. For this task, nonsense words served as the focal stimuli, while the associates were meaningful words. (The paradigm may be recognized as similar to one used extensively by Staats, Staats, and their associates, e.g., Staats & Staats, 1958.) Four separate paired-associate lists were employed, and each subject was exposed to only one of these. In two of the lists, the meaningful associate words (which served as the “contexts” for stimulus exposure) were known to evoke positive affect; in the other two, the meaningful associates were known to evoke negative affect. Within each affect condition, one set of meaningful words was selected because it evoked strong affect, while the other was selected because it evoked relatively weak affect. In all conditions, the list of word pairs was exposed only once. In each condition, the nonsense words were presented either 1, 2, 4, 8, or 16 times. Thus, a 4 X 5 design was created, with “contextual affect” and “exposure frequency” employed as the variates. Ss believed that the experiment was a standard pairedassociate learning task; however, prior to the recall testing, all Ss were asked to indicate their liking for the nonsense words. Methods Sample. Sixty undergraduates (50 male and 10 female) at Carnegie-Mellon University served as Ss for this experiment. They were randomly allocated among the four experimental conditions, and 15 Ss were used in each condition. All Ss were enrolled in introductory psychology, and all received required experimental credit for their participation.
Norxense words. The five nonsense words employed in Study I were also used for investigation. Paired-associate lists. Four affectively homogeneous sets of 16 words each were chosen from the material reported by Jenkins, Russell, and Suci ( 1958). These sets of stimuli, which served as the basis for the paired-associate lists, were selected to represent (a ) highly positive, ( b) moderately positive, ( c) moderately negative, and (cl) highly negative stimuli. The average evaluative rating within these sets, reported by Jenkins et al. ( 1958), was +2.47 in the highly positive condition, +0.79 in the moderately positive condition, -0.79 in the moderately negative condition and -2.47 in the highly negative conditions; as with the nonsense stimuli, these means have been based on a seven-point scale (midpoint = 0.00). For the experimental task, the meaningful words were paired with the previouslydescribed nonsense stimuli in four different paired-associate lists. Each of these lists contained 31 pairs, and in each list one of the nonsense words appeared once, one appeared twice, one appeared four times, one appeared eight times, and one appeared 16 times. To achieve the desired design, four orderings of the various nonsense words were chosen. These permutations were selected such that, for any two lists, no stimulus occupied the same position in both lists. These five-item lists were then rxp:inded (following the 1, 2, 4, 8, and 16 frequency distribution) to form lists of 31 items each; that is, the first nonsense word on each five-item list was used only once, the second was repeated twice, the third was repeated four times, and so forth. this
468
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The sets of 16 meaningful words were also expanded to four lists of 31 words each; in these lists, each word (with a single, randomly varied exception) was repeated twice. Each nonsense list and each list of meaningful words was separately randomized, and then the lists were combined into four different paired-associate lists of 31 pairs (one nonsense stimulus, one meaningful associate) each. This pairing was achieved under the single restriction that no meaningful words be paired with any particular nonsense stimulus more than once in any given list. This procedure yielded learning lists which varied the exposure frequency of the nonsense words within the lists and the affect of the exposure context between the lists. The experimental design represented by these four lists was an incomplete Latin square, with the specific nonsense words and the exposure frequencies confounded in the various contextual lists. Thus, every S in any contextual condition observed each nonsense word the same number of times as every other ‘S in that condition; however, no nonsense word was used at the same level of repetition for S’s in any two conditions. This confo un d’mg was necessitated by the size of the available subject population; complete counterbalancing among words, frequencies, and lists would have required an inordinate number of subjects.
The procedure of Study II essentially duplicated that of Study I. Thus, it will only be briefly sketched here. When S arrived at the laboratory, he was seated before a Patterson 1-B memory drum. S was told that he would be shown 31 pairs of words and that his recall would be tested as soon as the list had been fully presented. S was told that some of the words would be unfamiliar; however, he was ,encouraged to learn all of the words, regardless of their familiarity. E then initiated the memory-drum program. As previously, this program presented each word pair for an 8-set period, with no pause between presentations. When all 31 exposures had been completed E gave S the “recall” form used in Study I. This form asked S to rate each of the nonsense words on a separate seven-point scale anchored by “good” and “bad.” In this posttesting, the five nonsense words were presented in the same order for all Ss. When S had completed this rating, which served as the only dependent variable for the study, he was debriefed and was given the chance to question the E about the investigation. Analysis As indicated, the various conditions of the present investigation are arranged as an incomplete Latin square. However, a Latin-square analysis would be inappropriate, as such an analysis assumes that the interaction effects among the variables are negligible (Winer, 1962). Clearly, this assumption would violate the intent of this experiment, since the study is primarily oriented toward the Contexts X Repetitions interaction. For this reason, the present data have been subjected to a 4 X 5 repeated-measures analysis of variance (with contextual condition and exposure freis also inappropriate, since no quency as the variates). In a sense, this analysis unique group of Ss observed each of the nonsense words in each exposure frequency and each environmental context. Nevertheless, this violation does not seem critical. Any bias thus induced would result from the two-way interactions involving the specific nonsense words. There is no reason to expect that these interactions would be large, and visual inspection of the data revealed them to be quite negligible.
“MERE
Findings
EXPOSURE”:
A
469
REEVALUATION
and Discussion
In this study, unlike Study I, no main effect due to exposure frequency was observed. The F ratio for the “mere exposure” effect over the four different contextual conditions used here was only 0.84, clearly nonsignificant. However, and more important, the data from this study did indicate a significant interaction between exposure contexts and exposure frequency. The nature of this interaction is shown in Fig. 2: the F ratio for the effect in question was 3.82, which, with 4 and 210 df, is significant beyond the .OOl level. As may be seen from Fig. 2, the attractiveness of the stimuli used in this investigation did appear to be a function of their exposure frequency. However, the direction of the relationship between familiarity and liking clearly varied among the several contextual conditions employed here. Stimuli presented in the positive contexts became more positive with increasing exposure, and this was particularly true in the highly positive condition. Stimuli presented in the negative contexts became more negative with increasing exposure, and this was particularly true in the highly negative condition. Like the data presented in Study I, these findings are congruent with the argument that the previously reported “mere exposure” effect is due to a simple classical conditioning process. It is interesting to note that the slopes of the curves generated in the “positive” conditions ( +.591 and +.380 for the highly positive and moderately positive lists, respectively) were somewhat greater than the parallel slopes (-.343 and -.098) generated in the “negative” condi-
FIG.
experimental
2. Relationship contexts.
between
exposure
frequency
and
liking
in
four
different
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tions. One might have expected to see slopes of equal magnitude in the two cases since the contextual lists in the positive and negative conditions were equal in polarity. And one might be tempted to interpret this difference as an indication that something other than classical conditioning is operating in this situation. However, the data gathered in Study I suggest a simple explanation for this difference, and this explanation is itself consistent with the conditioning argument proposed here. For, as indicated in the postexperimental questionnaire employed in the highly similar Study I (performed in the same laboratory by the same experimenter), Ss did like the present experimental environment. Indeed, of the 48 Ss employed in Study I, none expressed a negative rating on the “present experiment” scale of this instrument (p < .OOl). The implications of this fact for the present argument should be clear. Ss in the positive conditions of Study II observed the various nonsense words in an environment which consisted of a positive contextual list and a positive contextual setting; subjects in the negative conditions of this experiment observed these stimuli in an environment which consisted of a negative contextual list but a positive contextual setting. Thus, the overall context in the positive conditions of the present study appears to have been much more polarized than the overall context in the negative conditions of this study. In retrospect, then, it appears reasonable that stronger conditioning effects should have been observed in the former conditions. It thus seems that a simple conditioning mechanism may be sufficient to explain the data generated in both studies reported here and, by extension, in previous “mere exposure” experiments (e.g., Zajonc, 1968) as well. In all cases, stimuli exposed in the presence of some context take on the affective value which characterizes this context; in all cases, this tendency is strongest for those stimuli which have been exposed the most frequently. It should be mentioned, of course, that this interpretation does not in any way invalidate the empirical conclusions which have been suggested by earlier “mere exposure” investigations. Since psychological experiments and psychological laboratories constitute positive contexts for most subjects (Orne, 1962), we (like Zajonc) would expect stimuli which are frequently exposed within these contexts to become relatively attractive. Indeed, we observed such an effect in Study I, reported above. And, since “life in general” seems to bc a positive context for most subjects,: we ‘Holmes (1970) found that Ss who were asked to keep diaries of their experiences judged the great majority of the events in their lives to be all’ectively positive. Similarly, Ss in the present Study I exhibited an overall rating of +1.9’7 on the “life scale of the postexperimental questionnaire: this value is significantly in general” ( p < .OOl ) more positive than the midpoint.
would expect stimuli which arc frequently exposed in ongoing life contexts also to become relatively attractive. Our only disagreement with previous “mere exposure” theorists, then, is at the theoretical level. Specifically, we believe that the “mere exposure” situation is hardly so “mere” as has previously been assumed. WC feel that experiments within this tradition are highly “encumbered by other processes or contingencies. such as positive and negative reinforcement” (Zajonc, 1969, p, 7), and we believe that it is these encumbrances which lead to the observed relationship between exposure frequency and attractiveness. It is for this reason, of course, that we have continued to place quotation marks around the term “mere exposure.” It should also be mentioned that the results of these investigations suggest a conclusion of some practical importance. Specifically, these data imply that repeated exposure of a stimulus in an unpleasant environment will not lead to greater liking of the exposed stimulus. The present findings thus offer no support to statements such as, “After repeated exposure, almost anything grows on you-even Spiro Agnew” (Psyclrology Today, 1970, p. 3). It is interesting to note that Brickman and Redfield ( 1970) and Perlmnn and Oskamp ( 1970), who have investigated the efl’ects of frequent exposure involving originally unpleasant stimuli, have recently reached a conclusion which parallels the present one. REFERENCES BHICKMAK, P., & REDFIELD, J. Drive and predisposition as factors in the attitudinal effects of mere exposure. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. HARRISON, A. A. Exposure, favorability, and item endorsement. Psychological Reports, 1968, 23, 1070. (a) HAHHISOK, A. A. Response competition, frequency, exploratory behavior, and liking. Jownal of Personality and Sociul Psychology, 1968, 9, 363-368. (b) HARRISOX, A. A. Exposure and popularity. Journal of Personality, 1969, 37, 359-377. HARRISOS, A. A., & HINES, P. The &e&s of frequency of exposure at three short exposure times on affective ratings and exploratory behavior. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. HARRISON, A. A., h ZAJONC, R. B. The effects of frequency and duration of exposure on response competition and affective ratings. Journal of Psychology, 1970, 75, 163-170. HOLMES, D. S. Differential change in affective intensity and the forgetting of unpleasant personal experiences. Journal of Personality and Social Psychology, 1970, 15, 234-239. JENKINS, J. J,, RUSSELL, W. A., & SUCI, G. J. An atlas of semantic profiles for 360 words. American journal of Psychology, 1958, 71, 688-699. MATLIN, M. A. W. Response competition as a mediating factor in the frequencyaffect relationship. Journal of Pemonality and Social PsychoEogy, 1970, 16, 53fS-552.
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ORNE, M. On the social psychology
of the psychological experiment: With particular reference to demand characteristics and their implications. American Psychdo&t, 1962, 17, 776-785. PERLMAN, D., & OSKAMP, S. The effects of picture content and exposure frequency on evaluations of Negroes and Whites. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. POSTMAN, L. Short-term memory and incidental learning. In A. W. Melton (Ed. ), Categories of human learning. New York: Academic Press, 1964. Psychology Today, 1970, 3(9), 3. STAATS, A. W., & STAATS, C. K. Attitudes established by classical conditioning. Jozrrnal of Abnormal and Social Psychology, 1958, 57, 3740. SUEDFELD, P., & EPSTEIN, Y. M. “Mere exposure”-plus set. Paper presented at the meeting of the American Psychological Association. Miami Beach, September, 1970. WINER, B. J. Statistical principles in experimental de.Ggn. New York: McGraw-Hill, 1962. ZAJONC, R. B. Attitudinal effects of mere exposure. Jozwnul of Personality and Social Psychology, 1968, 9, l-27. ZAJONC, R. B. Attraction, affiliation, and attachment. In Man and beast. Symposium presented at the Smithsonian Institution, Washington, May, 1969. ZAJONC, R. B. Brainwash: Familiarity breeds comfort. Psychology Today, 1970, 3, 32-62. ZAJONC, R. B., & RAJECKI, D. W. Exposure and affect: A field experiment. Psychonomic Science, 1969, 17, 216-217. (Received
November
25,
1970)
OF
EXPERIMENTAL
Attitudinal
Effects THOMAS Department
SOCIAL
PSYCHOLOGY
of “Mere
D. G. of
BURGESS
7,
461472
Exposure”: II’
Psychology,
AND
STEPHEN
Carnegie-Mellon
( 1971)
A Reevaluation M.
SALES*
University
Zajonc has proposed that repeated “mere exposure” of a stimulus is a sufficient condition for enhancing the attractiveness of this stimulus. And Harrison has suggested a theory to explain the relationship between repeated “mere exposure” and attractiveness. However, while this area appears complex, a simple and parsimonious explanation based on classical conditioning can apparently account for the obtained data. This explanation assumes only that the contexts within which “mere exposure” occurs are not affectively neutral, but rather positively evaluated. Thus, the data gathered in “mere exposure” studies may indicate only that the positive affect which characterizes the exposure context is increasingly transferred to the exposed stimulus as the number of trials (exposures) increases. TWO experiments are presented in support of this general argument. In the first, the relationship between exposure frequency and attraction is shown to be stronger for Ss who find the experimental context relatively attractive; in the second, intentionally created positive contexts are shown to provide positive relationhip between familiarity and affect, while intentionally created negative contexts are shown to provide negative relationships between these variables.
Zajonc (1968) h as recently argued that repeated “mere exposure” of a stimulus is a sufficient condition for enhancing the attractiveness of this stimulus. In his original article, Zajonc (1968) reported a variety of data which support this hypothesis. And, although conflicting data have recently been presented (Perlman & Oskamp, 1970; Suedfeld & Epstein, 1970; Brickman & Redfield, 1970), Zajonc’s findings have also been replicated in a variety of settings (Harrison & Hines, 1970; Zajonc & Rajecki, 1969; Harrison, 196Sa; Harrison, 1969; Harrison & Zajonc, 1970). Fur1 Now at the University of Pittsburgh; Study II of this paper is based on a master’s thesis submitted by the senior author to Carnegie-Mellon University. Requests for reprints should be sent to Stephen M. Sales, Department of Psychology, CarnegieMellon University, Pittsburgh, Pennsylvania, 15213. ‘The authors are indebted to Daryl J. Bern, Sandra L. Bern, Esther G. Sales, Walter Swap, and the editorial board of the Jownal of Experimental Social Psychology for their helpful comments upon an earlier version of this paper. 461
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HUIKESS
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thermore, a theoretical explanation has recently been proposed for the “mere exposure” effect (Harrison, 196Sb), and this rationale has itself received some support (e.g., Matlin, 1970; Harrison & Zajonc, 1970; Harrison & Hines, 1970). This line of research has attempted to demonstrate that exposure “unencumbered by other processes or contingencies, such as positive and negative reinforcement,” is sufficient to cause attitudinal enhancement of the exposed stimulus (Zajonc, 1969, p. 7). And it has generated interest precisely because the studies involved do seem to demonstrate that such “unencumbered” exposure leads to increased liking. However, it may be that the “mere exposures” involved in these studies are, in fact, more encumbered than one would previously have supposed. If so, then the major thrust of the “mere exposure” investigations would be considerably weakened. To see the nature of the encumbrance involved, one must look carefully at the studies performed within the “mere exposure” paradigm. In these investigations, Ss are usually brought into a psychological laboratory, seated before a stimulus presentation device of some sort (e.g., a projection screen, a memory drum, an E), and then shown a variety of stimuli with various exposure frequencies. Thereafter, the Ss are asked to indicate their degree of liking for the stimuli involved. Because no immediately apparent rewards or punishments are present, research workers within this tradition have assumed that the stimuli are, in fact, “merely exposed.” However, this conclusion presupposes that the psychological laboratory itself is affectively neutral for the S’s used. And, as Orne ( 1962) has argued, this second assumption is probably untenable. Rather than being affectively neutral, the laboratory is likely to provide a highly positive context for the “mere exposure” of stimuli. If so, then the “mere exposures” involved should be very much encumbered by processes such as positive and negative reinforcement. For, in a sense, exposure of a stimulus within some affectively meaningful context can be seen as a trial in a classical conditioning experiment. And the literature provides a clear expectation relating frequency of exposure (i.e., number of trials) to resultant affect (i.e., strength of learning) in such situations. As the number of trials increases, the focal stimulus increasingly assumes the affect which is aroused by the context, This conditioning mechanism is surely familiar, and it requires no discussion here. The implications of this argument for the present concerns should be clear. Since the experimental laboratory is (presumably) an affectively positive context, then stimuli which are frequently exposed within that context should themselves acquire positive meaning. And the explanation
“MERE
EXPOSURE”:
A
REEVALUATION
463
of this effect would rest not upon any complex mechanism, but rather upon simple classical conditioning. The present paper reports two experiments directed toward this general issue. In the first, the strength of the “mere exposure” effect is examined separately for S’s who feel either (a) relatively positive or (12) relatively negative toward “silent” contextual factors (such as the psychological laboratory) which might act as higher-order unconditioned stimuli in this situation. If the argument sketched above is correct, one would expect to see a positive relationship between exposure frequency and affect in the former group but a negative (or, at least, a nonpositive) relationship between these variables in the latter group. In the second study, the relative strength of the “mere exposure” effect is investigated in contexts which are known to have either (a) positive or (b) negative meaning for the Ss involved. If the present argument is correct, one would expect to see a positive relationship between exposure frequency and affect in the first situation but a negative relationship between them in the second situation. STUDY
1
Ooeroie~. Ss were employed in one trial of an apparent serial learning task. Five diRerent nonsense words, arranged as a serial list, were used as the items to be learned one of these words was presented at each of five different exposure frequencies within the list. The experimental design was intended to be a replication, with minor changes, of the paradigm described by Zajonc (1968, pp. 13-16). The major deviations of the present methods from those employed by Zajonc (1968) were (u) that a Patterson 1-B memory drum, rather than the E, was used to present the stimuli, and (11) that the task was explicitly described as a learning experiment. All Ss believed that, after the presentation of the list, they would be tested for their recall of the material. However, prior to the recall testing, the Ss were asked to indicate their liking for various stimuli which might have constituted the context for the exposure of the nonsense words. They then were asked to indicate the way they felt about the five nonsense words themselves. Sample. Forty-eight undergraduates (27 male, 21 female) at Carnegie-Mellon IJniversity served as Ss for this experiment. All Ss were enrolled in introductory psychology, and all received required experimental credit for their participation. Materials Stimulus muterials. To obtain aflectively neutral nonsense words, 19 stimuli (CVCVC, with leading capitals) were constructed and presented to 53 social psychology students. These 53 Ss were asked to rate each of the nonsense words on a seven-point scale anchored by “good” and “bad.” The 10 words with the largest standard deviations were eliminated; of the remaining nine, the five with the most nelltral average ratings were selected for use in the experiment. The retained stimuli, ;ml thtair nssociattzd scale valnrs, WYP Hoheb ( +0.38), Kodup ( -+O.ZS), Rikd
464
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(O.OO), Solok (-0.15), and Falip (-0.15). These nonsense words were then placed in five different learning lists; within each list one word appeared only once, one appeared twice, one appeared four times, one appeared eight times, and one appeared 16 times. Five lists were required to achieve counterbalancing of stimuli over the various exposure frequencies. Contextual ratings. When the experiment (described below) was completed, the Ss were asked to complete a “personal reaction” questionnaire. This instrument asked them to rate nine contextual factors on separate seven-point scales, each anchored by “good” and “bad.” Three of these attitude objects had been selected to judge the Ss’ feelings toward the experiment itself (“‘the present experimenter,” “the present experiment, ” “this experimental laboratory”); three had been selected to indicate the Ss’ feelings toward psychology and science (“psychology,” “psychological experiments in general,” and “science”); three had been selected to measure the Ss’ attitudes toward themselves and their overall environments (“yourself,” “life in general,” and ‘your experience here at the University”). It was originally hoped that these nine items would constitute three separate three-item scales. However, this expection was realized only for the first (“the present experiment”) and the third (“life in general”) of the indices. In the present sample, coefficient alpha for the first of these indices was .64, while the same statistic for the latter index was .61. The three items designed to measure the Ss’ feelings toward science and psychology, on the other hand, exhibited only low correlations with each other. Thus, it was decided to collapse the Ss’ responses to the postexperimental questionnaire into two separate indices measuring (a) reactions to the present experiment and (b) reactions to “life in general.” The remaining three items have been ignored in the analyses reported below. Each S’s responses to the three items on each scale were summed to provide two separate scores. The sample was then divided at its median into “high” and “low” groups on each index. To provide equal Ns in the two groups, Ss whose scores fell at the median were randomly allocated between the “high” and “low” subsamples. Procedure When S arrived at the laboratory, he was directed to a small cubicle equipped with a ,table and a memory drum. S was told that he would be shown 31 words through the memory drum, and he was informed that his recall would be tested as soon as the presentations had been completed. The E then initiated the memory-drum program. This program presented each nonsense word for an 8-set period, with no pause between presentations. When all 31 exposures had been completed, the E turned off the memory drum and handed S the postexperimental questionnaire (described above) designed to measure S’S attitudes toward the context within which stimulus presentation occurred. He then gave S a “recall” form. The first item of this form read: The way you feel about the unfamiliar words used in this experiment affect how well they were learned. To help me judge this, please below how “good” or “bad” each of the words seems to you.
might indicate
This item was followed by five seven-point scales, one for each nonsense word. As previously, these scales were anchored by “good” and “bad.” On this posttesting, the five nonsense words were presented in the same order for all Ss. When S had completed this rating, which served as the dependent variable for
“hIEHE
this study, about the
he was debriefed investigation.
and
Findings
and Discussion
was
465
A REEVALUATION
WCPOS~JHE”:
given
the chance
to question
the
experimenter
Over the entire sample, a significant linear trend between familiarity and liking was observed (F( 1,188) = 5.12> p < .05). This finding is a replication of data reported by others (e.g., Zajonc, 1968), and it requires no particular comment here. This result was not at all mediated by Ss’ scores on the “life in general” index. However, it was clearly affected by their feelings about the experiment. Ss who felt relatively positive about the experiment exhibited a strong linear relationship between exposure frequency and liking (F( 1,92) = 13.10, p < .OOl). Ss who felt relatively negative about the experiment, on the other hand, exhibited no linear relationship at all between familiarity and liking.” These findings are presented in Fig. 1. The F ratio for the interaction shown in this figure is 2.37 which, with 4 and 184 degrees of freedom, falls just short of significance at the .05 level. These findings appear reasonably self-explanatory. As expected, Ss who experienced the exposure context as relatively positive exhibited a strong “mere exposure” effect; Ss who experienced the exposure context as relatively negative, on the other hand, exhibited no such effect. This
oooj
FIG. relatively 3 The
1. Relationship positive and quadratic
trend
I
between relatively shown
exposure negative in these
frequency and liking toward the experimental data
was nonsignificant
among Ss who context.
(F = 1.82).
felt
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result is quite consistent with the contention that the “mere exposure” effect is due to a classical conditioning process. Indeed, the only point in the present data which appears to be controversial is the essentially flat slope of the frequency-affect relationship for Ss who experienced the exposure context as relatively negative. That is, since these Ss exhibited relatively negative affect toward the experimental context, one might have expected to see a negative relationship between familiarity and liking in this sub-sample. However, the failure to find such a negative relationship has a simple explanation. For these Ss did not, in fact, dislike the experiment; rather, their attitudes were essentially neutral toward it, They constitute a “relatively negative” subsample only because, as Orne (1962) suggested, most Ss liked the present experiment.-’ Study I thus indicates that intersubject differences in the evaluation of a constant exposure context can affect the magnitude of the frequencyliking relationship. However, if the argument proposed here is correct, then one would expect that an intentional manipulation of the exposure context would also have such an effect. Study II is oriented toward this issue. In particular, Study II involves the presentation of unfamiliar stimuli not merely in the context of a positively evaluated laboratory, but also in the context of meaningful words known to evoke positive and negative affect. In a sense, the methodology employed in Study II differs from that used in Study I. The first investigation reported here essentially involves “incidental learning” (the pairing of the laboratory cues with the nonsense words), while the experiment discussed below is directed toward “intentional learning” (the pairing of the meaningful words with the unfamiliar stimuli). However, this procedural variation does not seem incidental and intentional crucial. For, as Postman (1964) h as argued, learning situations are apparently similar in all functional characteristics; thus, the difference between the two paradigms appears to involve only details of the experimenter’s stated procedures. Since experimental control seems easier to obtain in the intentional than in the incidental learning situation, we have chosen to employ the former in Study II. ‘One might maintain that the “relatively negative” Ss possessed a tendency to respond neutrally. This hypothesis vitiates the present conclusions, since it parsimoniously explains these Ss’ essentially neutral ratings of the five nonsense words. HOWever, two facts suggest that these data cannot he ascribed to any such response patterns: (a) Ss who responded neutrally on the “life in general” index exhibited a strong exposure effect. This result would not obtain if these Ss possessed a tendency to respond essentially
sponded would
neutrally. the same
positively
be unlikely
( b ) The within-subject variability in, rating the five stimuli was for Ss who responded neutrally (MS = 1.74) as for Ss who re(MS = 1.68) on the “present experiment” index, This result if the former were characterized by a neutral response tendency.
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STUDY
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467
II
Oceroiezr; Ss were employed in what appeared to be the “study” phase of a “study-recall” paired-associate learning task. For this task, nonsense words served as the focal stimuli, while the associates were meaningful words. (The paradigm may be recognized as similar to one used extensively by Staats, Staats, and their associates, e.g., Staats & Staats, 1958.) Four separate paired-associate lists were employed, and each subject was exposed to only one of these. In two of the lists, the meaningful associate words (which served as the “contexts” for stimulus exposure) were known to evoke positive affect; in the other two, the meaningful associates were known to evoke negative affect. Within each affect condition, one set of meaningful words was selected because it evoked strong affect, while the other was selected because it evoked relatively weak affect. In all conditions, the list of word pairs was exposed only once. In each condition, the nonsense words were presented either 1, 2, 4, 8, or 16 times. Thus, a 4 X 5 design was created, with “contextual affect” and “exposure frequency” employed as the variates. Ss believed that the experiment was a standard pairedassociate learning task; however, prior to the recall testing, all Ss were asked to indicate their liking for the nonsense words. Methods Sample. Sixty undergraduates (50 male and 10 female) at Carnegie-Mellon University served as Ss for this experiment. They were randomly allocated among the four experimental conditions, and 15 Ss were used in each condition. All Ss were enrolled in introductory psychology, and all received required experimental credit for their participation.
Norxense words. The five nonsense words employed in Study I were also used for investigation. Paired-associate lists. Four affectively homogeneous sets of 16 words each were chosen from the material reported by Jenkins, Russell, and Suci ( 1958). These sets of stimuli, which served as the basis for the paired-associate lists, were selected to represent (a ) highly positive, ( b) moderately positive, ( c) moderately negative, and (cl) highly negative stimuli. The average evaluative rating within these sets, reported by Jenkins et al. ( 1958), was +2.47 in the highly positive condition, +0.79 in the moderately positive condition, -0.79 in the moderately negative condition and -2.47 in the highly negative conditions; as with the nonsense stimuli, these means have been based on a seven-point scale (midpoint = 0.00). For the experimental task, the meaningful words were paired with the previouslydescribed nonsense stimuli in four different paired-associate lists. Each of these lists contained 31 pairs, and in each list one of the nonsense words appeared once, one appeared twice, one appeared four times, one appeared eight times, and one appeared 16 times. To achieve the desired design, four orderings of the various nonsense words were chosen. These permutations were selected such that, for any two lists, no stimulus occupied the same position in both lists. These five-item lists were then rxp:inded (following the 1, 2, 4, 8, and 16 frequency distribution) to form lists of 31 items each; that is, the first nonsense word on each five-item list was used only once, the second was repeated twice, the third was repeated four times, and so forth. this
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The sets of 16 meaningful words were also expanded to four lists of 31 words each; in these lists, each word (with a single, randomly varied exception) was repeated twice. Each nonsense list and each list of meaningful words was separately randomized, and then the lists were combined into four different paired-associate lists of 31 pairs (one nonsense stimulus, one meaningful associate) each. This pairing was achieved under the single restriction that no meaningful words be paired with any particular nonsense stimulus more than once in any given list. This procedure yielded learning lists which varied the exposure frequency of the nonsense words within the lists and the affect of the exposure context between the lists. The experimental design represented by these four lists was an incomplete Latin square, with the specific nonsense words and the exposure frequencies confounded in the various contextual lists. Thus, every S in any contextual condition observed each nonsense word the same number of times as every other ‘S in that condition; however, no nonsense word was used at the same level of repetition for S’s in any two conditions. This confo un d’mg was necessitated by the size of the available subject population; complete counterbalancing among words, frequencies, and lists would have required an inordinate number of subjects.
The procedure of Study II essentially duplicated that of Study I. Thus, it will only be briefly sketched here. When S arrived at the laboratory, he was seated before a Patterson 1-B memory drum. S was told that he would be shown 31 pairs of words and that his recall would be tested as soon as the list had been fully presented. S was told that some of the words would be unfamiliar; however, he was ,encouraged to learn all of the words, regardless of their familiarity. E then initiated the memory-drum program. As previously, this program presented each word pair for an 8-set period, with no pause between presentations. When all 31 exposures had been completed E gave S the “recall” form used in Study I. This form asked S to rate each of the nonsense words on a separate seven-point scale anchored by “good” and “bad.” In this posttesting, the five nonsense words were presented in the same order for all Ss. When S had completed this rating, which served as the only dependent variable for the study, he was debriefed and was given the chance to question the E about the investigation. Analysis As indicated, the various conditions of the present investigation are arranged as an incomplete Latin square. However, a Latin-square analysis would be inappropriate, as such an analysis assumes that the interaction effects among the variables are negligible (Winer, 1962). Clearly, this assumption would violate the intent of this experiment, since the study is primarily oriented toward the Contexts X Repetitions interaction. For this reason, the present data have been subjected to a 4 X 5 repeated-measures analysis of variance (with contextual condition and exposure freis also inappropriate, since no quency as the variates). In a sense, this analysis unique group of Ss observed each of the nonsense words in each exposure frequency and each environmental context. Nevertheless, this violation does not seem critical. Any bias thus induced would result from the two-way interactions involving the specific nonsense words. There is no reason to expect that these interactions would be large, and visual inspection of the data revealed them to be quite negligible.
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Findings
EXPOSURE”:
A
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REEVALUATION
and Discussion
In this study, unlike Study I, no main effect due to exposure frequency was observed. The F ratio for the “mere exposure” effect over the four different contextual conditions used here was only 0.84, clearly nonsignificant. However, and more important, the data from this study did indicate a significant interaction between exposure contexts and exposure frequency. The nature of this interaction is shown in Fig. 2: the F ratio for the effect in question was 3.82, which, with 4 and 210 df, is significant beyond the .OOl level. As may be seen from Fig. 2, the attractiveness of the stimuli used in this investigation did appear to be a function of their exposure frequency. However, the direction of the relationship between familiarity and liking clearly varied among the several contextual conditions employed here. Stimuli presented in the positive contexts became more positive with increasing exposure, and this was particularly true in the highly positive condition. Stimuli presented in the negative contexts became more negative with increasing exposure, and this was particularly true in the highly negative condition. Like the data presented in Study I, these findings are congruent with the argument that the previously reported “mere exposure” effect is due to a simple classical conditioning process. It is interesting to note that the slopes of the curves generated in the “positive” conditions ( +.591 and +.380 for the highly positive and moderately positive lists, respectively) were somewhat greater than the parallel slopes (-.343 and -.098) generated in the “negative” condi-
FIG.
experimental
2. Relationship contexts.
between
exposure
frequency
and
liking
in
four
different
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tions. One might have expected to see slopes of equal magnitude in the two cases since the contextual lists in the positive and negative conditions were equal in polarity. And one might be tempted to interpret this difference as an indication that something other than classical conditioning is operating in this situation. However, the data gathered in Study I suggest a simple explanation for this difference, and this explanation is itself consistent with the conditioning argument proposed here. For, as indicated in the postexperimental questionnaire employed in the highly similar Study I (performed in the same laboratory by the same experimenter), Ss did like the present experimental environment. Indeed, of the 48 Ss employed in Study I, none expressed a negative rating on the “present experiment” scale of this instrument (p < .OOl). The implications of this fact for the present argument should be clear. Ss in the positive conditions of Study II observed the various nonsense words in an environment which consisted of a positive contextual list and a positive contextual setting; subjects in the negative conditions of this experiment observed these stimuli in an environment which consisted of a negative contextual list but a positive contextual setting. Thus, the overall context in the positive conditions of the present study appears to have been much more polarized than the overall context in the negative conditions of this study. In retrospect, then, it appears reasonable that stronger conditioning effects should have been observed in the former conditions. It thus seems that a simple conditioning mechanism may be sufficient to explain the data generated in both studies reported here and, by extension, in previous “mere exposure” experiments (e.g., Zajonc, 1968) as well. In all cases, stimuli exposed in the presence of some context take on the affective value which characterizes this context; in all cases, this tendency is strongest for those stimuli which have been exposed the most frequently. It should be mentioned, of course, that this interpretation does not in any way invalidate the empirical conclusions which have been suggested by earlier “mere exposure” investigations. Since psychological experiments and psychological laboratories constitute positive contexts for most subjects (Orne, 1962), we (like Zajonc) would expect stimuli which are frequently exposed within these contexts to become relatively attractive. Indeed, we observed such an effect in Study I, reported above. And, since “life in general” seems to bc a positive context for most subjects,: we ‘Holmes (1970) found that Ss who were asked to keep diaries of their experiences judged the great majority of the events in their lives to be all’ectively positive. Similarly, Ss in the present Study I exhibited an overall rating of +1.9’7 on the “life scale of the postexperimental questionnaire: this value is significantly in general” ( p < .OOl ) more positive than the midpoint.
would expect stimuli which arc frequently exposed in ongoing life contexts also to become relatively attractive. Our only disagreement with previous “mere exposure” theorists, then, is at the theoretical level. Specifically, we believe that the “mere exposure” situation is hardly so “mere” as has previously been assumed. WC feel that experiments within this tradition are highly “encumbered by other processes or contingencies. such as positive and negative reinforcement” (Zajonc, 1969, p, 7), and we believe that it is these encumbrances which lead to the observed relationship between exposure frequency and attractiveness. It is for this reason, of course, that we have continued to place quotation marks around the term “mere exposure.” It should also be mentioned that the results of these investigations suggest a conclusion of some practical importance. Specifically, these data imply that repeated exposure of a stimulus in an unpleasant environment will not lead to greater liking of the exposed stimulus. The present findings thus offer no support to statements such as, “After repeated exposure, almost anything grows on you-even Spiro Agnew” (Psyclrology Today, 1970, p. 3). It is interesting to note that Brickman and Redfield ( 1970) and Perlmnn and Oskamp ( 1970), who have investigated the efl’ects of frequent exposure involving originally unpleasant stimuli, have recently reached a conclusion which parallels the present one. REFERENCES BHICKMAK, P., & REDFIELD, J. Drive and predisposition as factors in the attitudinal effects of mere exposure. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. HARRISON, A. A. Exposure, favorability, and item endorsement. Psychological Reports, 1968, 23, 1070. (a) HAHHISOK, A. A. Response competition, frequency, exploratory behavior, and liking. Jownal of Personality and Sociul Psychology, 1968, 9, 363-368. (b) HARRISOX, A. A. Exposure and popularity. Journal of Personality, 1969, 37, 359-377. HARRISOS, A. A., & HINES, P. The &e&s of frequency of exposure at three short exposure times on affective ratings and exploratory behavior. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. HARRISON, A. A., h ZAJONC, R. B. The effects of frequency and duration of exposure on response competition and affective ratings. Journal of Psychology, 1970, 75, 163-170. HOLMES, D. S. Differential change in affective intensity and the forgetting of unpleasant personal experiences. Journal of Personality and Social Psychology, 1970, 15, 234-239. JENKINS, J. J,, RUSSELL, W. A., & SUCI, G. J. An atlas of semantic profiles for 360 words. American journal of Psychology, 1958, 71, 688-699. MATLIN, M. A. W. Response competition as a mediating factor in the frequencyaffect relationship. Journal of Pemonality and Social PsychoEogy, 1970, 16, 53fS-552.
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ORNE, M. On the social psychology
of the psychological experiment: With particular reference to demand characteristics and their implications. American Psychdo&t, 1962, 17, 776-785. PERLMAN, D., & OSKAMP, S. The effects of picture content and exposure frequency on evaluations of Negroes and Whites. Paper presented at the meeting of the American Psychological Association, Miami Beach, September, 1970. POSTMAN, L. Short-term memory and incidental learning. In A. W. Melton (Ed. ), Categories of human learning. New York: Academic Press, 1964. Psychology Today, 1970, 3(9), 3. STAATS, A. W., & STAATS, C. K. Attitudes established by classical conditioning. Jozrrnal of Abnormal and Social Psychology, 1958, 57, 3740. SUEDFELD, P., & EPSTEIN, Y. M. “Mere exposure”-plus set. Paper presented at the meeting of the American Psychological Association. Miami Beach, September, 1970. WINER, B. J. Statistical principles in experimental de.Ggn. New York: McGraw-Hill, 1962. ZAJONC, R. B. Attitudinal effects of mere exposure. Jozwnul of Personality and Social Psychology, 1968, 9, l-27. ZAJONC, R. B. Attraction, affiliation, and attachment. In Man and beast. Symposium presented at the Smithsonian Institution, Washington, May, 1969. ZAJONC, R. B. Brainwash: Familiarity breeds comfort. Psychology Today, 1970, 3, 32-62. ZAJONC, R. B., & RAJECKI, D. W. Exposure and affect: A field experiment. Psychonomic Science, 1969, 17, 216-217. (Received
November
25,
1970)