Effect of Expectation and Dis Confirmation on Post Exposure Product Evaluations an Alternative Interpretation
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Journal of Applied Psychology 1977, Vol. 62, No. 4, 480-486
Effect of Expectation and Disconfirmation on Postexposure Product Evaluations: An Alternative Interpretation Richard L. Oliver Department of Business Administration University of Kentucky Interpretations of the effect of expectation and disconfirmation on perceived product performance are reviewed. At issue is the relative effect of the initial expectation level and the degree of positive or negative disconfirmation on affective judgments following product exposure. Although the results of prior studies suggest a dominant expectation effect, it is argued that detection of the disconfirmation phenomenon may have been clouded by a conceptual and methodological overdetermination problem. To test this notion, 243 subjects responded to expectation and disconfirmation measures in a three-stage field study of reactions to a recently introduced automobile model. These measures were later related to postexposure affect and intention variables in a hierarchical analysis of variance design. Although the results support earlier conclusions that level of expectation is related to postexposure judgments, it is also shown that the disconfirmation experience may have an independent and equally significant impact. Implications of the findings are discussed.
The effect of confirmation and disconfirmation of expectations on perceived product performance has received scant attention in the literature, despite an apparent relationship between expectancy disconfirmation and product satisfaction (Anderson, 1973). This is evidenced by the fact that only five studies in the last decade exist to provide a foundation for a research tradition of the effects of expectation and disconfirmation on postexposure product reactions. This article reviews these investigations and suggests a new conceptual and empirical perspective to disconfirmation effects. Theories oj Reaction to Discrepancy A number of competing explanations have been proposed by Anderson (1973) to describe the effect of expectation and confirmation-disconfirmation on perceptions of product performance. All include the implicit assumption that consumers acquire cognitive expectations of the most probable level of Requests for reprints should be sent to Richard L, Oliver, who is now at the College of Business Administration, University of Iowa, Iowa City, Iowa 52242. 480
product performance. The extent to which these expectations are met determines the perceived disconfirmation experience. Note that one's expectations will be negatively disconfirmed if the product performs more poorly than expected, confirmed if the product performs as expected, and positively disconfirrned if performance is better than anticipated. Thus, confirmation is more properly the midpoint on a disconfirmation continuum ranging from unfavorable to favorable disconfirmation. The product performance predictions made by the competing theories differ in terms of magnitude of effect placed on expectation and disconfirmation (Anderson, 1973). For example, assimilation theory (Sherif & Hovland, 1961) and dissonance theory (Festinger, 1957) would predict that postexposure ratings are primarily a function of the expectation level because the task of recognizing disconfirmation is believed to be psychologically uncomfortable. Thus, consumers are posited to perceptually distort expectationdiscrepant performance so as to coincide with their prior expectation level. In comparison, contrast theory (Sherif & Hovland, 1961) would predict that outcomes deviating from expectations will cause the subject to favor-
EFFECT OF EXPECTATION AND DISCONFIRMATION
ably or unfavorably react to the disconfirmation experience in that a negative disconfirmation is believed to result in a poor product evaluation whereas a positive disconfirmation should cause the product to be highly appraised. In short, an assimilation model would predict that product performance perceptions are a function of the expectation level, whereas a contrast model would predict that performance ratings are primarily a function of the disconfirmation experience. The Evidence Five marketing studies have investigated the effects of expectation and/or disconfirmation on product evaluations. In two early investigations, Cardozo (196S) found that subjects who received a pen of expected quality rated the product significantly higher than a group expecting a higher quality writing instrument, whereas Cohen and Goldberg (1970) showed that subjects who received an unaltered cup of a new coffee brand rated it higher than subjects tasting the same brand with a poor-tasting additive. Thus, the latter study confirmed Cardozo's findings that a negative disconfirmation of performance expectations resulted in lower product ratings than were obtained under accurate expectation conditions in accord with the contrast model. The effect of positive disconfirmation was introduced by Olshavsky and Miller (1972) in a 2 x 2 design featuring high and low levels of subject expectations and the performance of a reel-type tape recorder. Unlike the results of the two prior studies, high expectation subjects in the low performance condition rated the product higher than subjects in the low expectation-low performance group, while the low expectation-high performance subjects evaluated the recorder lower than subjects whose expectations of a high quality recording were confirmed. Olshavsky and Miller concluded that performance evaluations "tended to be assimilated toward manipulated expectations whether positively or negatively disconfirmed (p. 21)." In a thorough analysis of the expectation effect, Anderson (1973) investigated the im-
pact of varying levels of expectation on ratings of a ballpoint pen and found that with the exception of a high expectancy extreme, subjects assimilated their postexposure judgments in the direction of the expectation treatment. Specifically, the ratings of a group receiving accurate expectations were higher than those of two lower expectation groups and lower than a moderately high expectation group. Mean evaluations of the highest expectancy group were equivalent to those in the accurate treatment. Finally, Olson and Dover (197S) manipulated subject expectations that an unfamiliar coffee brand would be free of bitterness and then permitted both the experimental group and a control group receiving no information to taste a very bitter coffee blend. When compared to their own pretrial expectations and the control group ratings, the experimental group evaluated the coffee as more bitter than expected but less bitter than indicated by the control group. In summary, the three most recent studies provide consistent evidence in favor of the predictive superiority of the assimilation model. In these investigations, the effects of positive and/or negative disconfirmation were compared to evaluations under conditions of accurate expectations. The results showed that the contrast effect is elusive. Rather than responding favorably to an unanticipated superior performance or unfavorably to an unexpected inferior product experience, subjects appeared to distort performance to coincide with their expectations. Although the two earliest studies found evidence for a contrast effect, the findings of the first study have been questioned by Olshavsky and Miller (1972, pp. 20-21) while Cohen and Goldberg (1970) did not provide for differing expectation levels. Accordingly, the weight of the evidence would appear to support the assimilation model. In response, it is argued that the assimilation and contrast predictions derived from communication theory may not be meaningful within the context of product exposure. Consider the implications of the findings to date in light of the relation between disconfirmation and perceived performance. The
RICHARD L. OLIVER
conclusions of the most recent studies indicate that a positive disconfirmation results in lower ratings and a negative disconfirmation in higher ratings than would be obtained under accurate expectations—a counterintuitive proposal. Rather,, the position taken in this article is that both expectation and disconfirmation explanations are needed to fully specify the level of postexposure evaluations in much the same way that any revised attitude can be explained in terms of initial position plus degree and direction of change. Consequently, it may be inappropriate to force an assimilation or contrast interpretation on any set of findings. This line of thought is pursued in the following discussion. The Case jor Independent, Effects Postexposure Evaluations
As noted by Weaver and Brickman (1974), research on the disconfirmation of expectations is confounded by conceptual overdeterrnination. Specifically, one's reaction to a disconfirmation experience is believed to be a function of three constructs (expectation, outcome, and disconfirmation), although only two can be manipulated independently as a practical matter. The nature of the third variable has been assumed from the following postulates: 1. An outcome given high expectations results in perceived negative disconfirmation. 2. An outcome given low expectations results in perceived positive disconfirmation. Note that an axiomatic negative correlation between expectation and disconfirmation is implied, in that high expectations are assumed to result in an unfavorable disconfirmation and low expectations in positive disconfirmation. Weaver and Brickman took issue with this interpretation and argued that a separate disconfirmation effect may exist independent of the outcome and expectation treatments and that studies manipulating only expectation and performance may have obscured this possibility. In the five studies cited in the preceding discussion, three varied expectation only (Anderson, 1973; Cardozo, 1965; Olson &
Dover, 1975), one manipulated performance (Cohen & Goldberg, 1970), and one examined expectation and performance (Olshavsky & Miller, 1972). In no study was disconfirmation measured per se; rather, the magnitude and direction of the disconfirmation experience were assumed from Postulates 1 and 2. To independently test the effect of disconfirmation, a design such as the following would be required: Negative Expectation disconfirmation Confirmation
Because no such design has been tested, the studies to date can be said to have only shown that (a) expectations influence postexposure product ratings and (b) that actual product performance influences product ratings. Strictly speaking, the inferences drawn in these studies regarding the predictive superiority of an assimilation over a contrast model or of the greater effect of expectation over disconfirmation may be due to the confounding inherent in Assumptions 1 and 2. Conditions facilitating independent effects. A defense of the notion of expectationdisconfirmation independence would require that the likelihood of either a positive, zero, or negative disconfirmation be the same at all expectation levels. It is argued here that the context of many overall product performance evaluations is sufficiently subjective so that this condition is satisfied from a perceptual standpoint. Although performance perception ratings may, in part, be based on objective criteria, one's overall assessment of many products usually involves a number of subjective attributes including those that are objective but are judged subjectively as a practical matter (e.g., the quietness of an automobile). Consequently, postexposure evaluations are likely to be highly subjective as well. Second, because expectation formation and disconfirmation occur at separate points in time, the assumed relation between the two variables may be attenuated for two reasons. First, the product usage experience itself may serve to interfere with the retention of expec-
EFFECT OF EXPECTATION AND DISCONFIRMATION
tation levels and, if usage takes place over a period of time, the time interval may enhance forgetting. Second, because aroused disconfirmation is in closer temporal proximity to the postexposure evaluation, its effect may be greater than that of expectation. In fact, it may be instructive to note that the relationship between expectation and evaluation over time has not been explored in a usage context. Finally, it is also suggested that one experiences feelings as opposed to mental calculations of overall disconfirmation based on subjective perceptions of disconfirmation on the individual attributes. Thus, in the event that one had very high expectations, he could still "feel" as if the product performed better than expected (e.g., "whiter than white"), whether these feelings were, in fact, accurate or not. In summary, the position taken here assumes that when expectations, performance, and disconfirmation are largely subjective, no necessary relation between expectation and disconfirmation would be expected even though one's expectation level may provide a baseline for disconfirmation in an objective performance situation. As a result, the separate disconfirmation effect posited by Weaver and Brickman (1974) may serve to mitigate the strong expectation effect predicted by the assimilation model. To address the issues raised above, a methodology is needed that tests for the disconfirmation effect independent of expectation. Because a laboratory solution to this problem is not easily executed (Weaver & Brickman, 1974) and because the external validity of the prior findings has not been assessed, a field investigation was conducted in a manner that would allow both expectation and disconfirmation to be related to postexposure evaluations. Method Sample Students at a Midwestern university voluntarily participated in a study of reactions to a recently introduced automobile model. Subjects were recruited both from campus housing units and from various locations around campus. After deleting the responses of seven subjects for incompleteness, the final sample
consisted of 243 undergraduates 57% of whom were male.
Design In an effort to adapt the traditional laboratory investigation of the effect of expectancy disconfirmation to the field, a three-stage cross-sectional design was employed whereby expectation and disconfirmation data were collected without treatment manipulations. Specifically, a quasi-realistic shopping experience was used in which subjects were asked first to complete a preexposure questionnaire, then examine the car in a test drive or stationary situation, and finally make a number of postexposure judgments. The data were later collapsed into a 2 X 3 X 2 unequal « factorial design consisting of expectation (low, high), disconfirmation (negative, zero, positive), and nature of exposure (drive and inspection, inspection only).
Measures Expectation and disconfirmation. As all prior studies have manipulated expectation and disconfirmation experimentally, the literature provides little precedent for measuring these constructs on a selfreport instrument. Consequently, expectation was measured on the preexposure questionnaire in two ways. First, subjects indicated their perceptions of the car's overall quality by responding to the item "Before you inspect (test drive) the , do you expect it to be . . .?" on a 7-point scale ranging from very poor, through average, to very good. Second, expectation was also viewed as the mean rating on fifteen 7-point bipolar scales measuring subject perceptions of the car's position on attribute;, selected from research summaries provided by the manufacturer. Examples include cramped-roomy, noisy-quiet, and uncomfortable-comfortable. The degree of commitment to these beliefs was believed to be similar to that obtained in prior studies. The first measure of disconfirmation was obtained in a straightforward manner on the postexposure questionnaire. Subjects were asked to rate the car in terms of their expectations on the following scale: My expectations were: Too high: It was poorer than 1 thought 8
Accurate: It was just as I had expected 8
Too low: It was better than I thought 8
In accord with the second measure of expectation, disconfirmation was also viewed as the average change in the attribute ratings between the pre- and postexposure questionnaires where positive and negative net changes were interpreted as favorable and unfavorable disconfirmation, respectively. To create distinct categories of the independent variables, the measures were collapsed to provide
RICHARD L. OLIVER
expectation and disconfirmation were assumed to operate to the same degree in the drive and inspection groups, however, the exposure effect was given the lowest priority.
Correlations Between Expectation, Disconfirmation, Affect., and Intention Measures Variable 1, 2, 3. 4. 5.
Affect Intention Overall expectation Pretest ratings Overall disconfirmation
6. Net ratings change
Note. N = 243. * p g .01.
two levels of expectation and three levels of disconfirmation. A median split was used to divide the sample into high and low expectation groups, but no effort was made to equally partition the disconfirmation measures as the natural categories of negative, zero, and positive disconfirmation were theoretically denned. Consequently, subjects were divided into those who selected the three negative disconfirmation scale points, those who indicated that their perceptions were accurate, and those who chose the the rightmost positive disconfirmation categories. This same procedure was used to partition the attribute ratings change continuum, although a margin of ± .25 scale points around zero net change was allowed to provide the same percentage of accurate subjects that was obtained with the overall disconfirmation scale. Attitudinal criteria. Two attitudinal dimensions, overall affect and intention to buy, were selected to assess the effect of expectation and disconfirmation. To obtain a postexposure evaluation of overall affect, subjects were asked to check their perceptions of the car on a 7-point scale ranging from very unappealing (1) to very appealing ( 1 ) . In a similar manner, subjects indicated their purchase intention by responding to the question "If you were 'in the market' for a car, what are the chances that you would buy a ?" on an 11-point scale ranging from zero, through SO-SO, to certain.
Analysis Because of the unavoidable necessity of unequal cell sizes in the design, a nonorthogonal analysis of variance (Overall & Spiegel, 1969) was required. The hierarchical technique was selected in the present case because a logical a priori ordering of main effects was considered defensible on grounds of temporal precedence and research tradition. Because expectations are antecedent to product trial and consequently to the disconfirmation experience, the expectation variable was given priority in the sum of squares partitioning. Moreover, the evidence to date suggests that the expectation effect is more potent than that of disconfirmation, a condition reflected in the hierarchical positioning. Because both
Results Correlations between the raw scale scores are reported in Table 1, which shows that postexposure affect and intention were positively related to both the overall and summed attribute expectation variables as well as both the overall and attribute change disconfirmation variables. Moreover, the expectation measures were uncorrelated with the disconfirmation variables except when the summed attribute pretest scores were used to represent expectation and the attribute change scores were used as a proxy variable for disconfirmation. This observed negative correlation, however, is more likely due to the common regression effect obtained when change scores are correlated with pretest scores (Lord, 1962). Note that even with the negatively correlated ratings scales, the dependent variables were positively correlated with both the expectation and disconfirmation measures. To show that the correlational findings generalize across disconfirmation categories and exposure conditions, the results of the hierarchical analyses of variance on postexposure affect and intention to buy using categories derived from the overall as well as the ratings scales are shown in Table 2. Because no main effect attributable to the nature of the product experience was significant in any analysis, the two exposure groups were combined for purposes of presenting the cell means in Table 2.1 Table 2 shows that both the expectation and the disconfirmation effects were significant. As measured by the partial F statistics, disconfirmation had a greater impact on affect regardless of how the independent variables were measured, whereas the effects on intention were more equally attributable to both independent variables. In all cases, higher mean evaluations were obtained in high 1 The complete hierarchical analyses of variance tables and cell sizes are available from the author.
EFFECT OF EXPECTATION AND DISCONFIRMAT.ION Table 2 Design Cell Mean Scores and Main Effect
F Levels Main effect F ratios
Disconfirmation level expectation level Affect Low High Intention Low High
Expectation Disconfirmation Exposure
2.97 3.21 3.87 3.91
3.88 4.24 5.06 4.94
5.06 5.19 5.93 6.03
1.82 1.84 2.69 3.00
1.71 2.05 4.64 4.47
3.76 3.83 5.47 6.03
Note. The upper mean scores and F ratios were obtained using the overall expectation and disconfirmation scales to form design cells, whereas the lower figures were determined using the attribute ratings to construct cells. *p < .05. **p < .01.
expectation groups at all disconfirmation levels. Similarly, higher mean scores on affect were obtained in the successively higher disconfirmation groups at both expectation levels. This latter finding was nearly true for the intention measure with the exception of one aberrant cell. Mean intention evaluations in the low expectation-confirmation group were slightly lower than those obtained in the low expectation-negative disconfirmation group when the overall scales were used to categorize subjects. To conserve space, no interaction F ratios are shown, and, in fact, none were significant in the analysis of the affect criterion. The analysis of intention did yield a marginally significant Expectation X Disconfirmation effect, which was attributed to the one aberrant cell mean noted above. Although significant, this would appear to be of minor consequence in the overall interpretation of the findings. Discussion The results have shown that the disconfirmation effect implicit in the expectation theories of consumer satisfaction can be a significant predictor of postexposure affect and intention to buy and may be viewed independently of product performance expec-
tations. Moreover, these findings generally support those of the four most recent studies in that the expectation effect was also significant. As the reader may recall, when expectation was manipulated while holding performance constant, product ratings were a positive function of expectation (Anderson, 1973; Olshavsky & Miller, 1972; Olson & Dover, 197S). Conversely, when expectation was held constant and a performance manipulation was used to create disconfirmation, ratings were inversely related to negative di;>confirmation and positively related to a positive disconfirmation (Cohen & Goldberg, 1970; Olshavsky & Miller, 1972, p. 20). Thus, all results show that perceived performance is a positive function of expectation and disconfirmation when other factors are held constant. Confusion in interpretation of the findings appears to be linked to a reliance on Postulates 1 and 2 to infer disconfirmation. In fact, in no prior study was disconfirmation measured directly even though the various measures of performance were subjective in nature. Rather, the disconfirmation experience was assumed from the treatments applied. As noted, prior interpretations would suggest a negative correlation between expectation and disconfirmation, an assumption that was not supported by the data reported here. Consequently, it is sug-
RICHARD L. OLIVER
gested that other avenues of thought be pursued in future studies. Implications
ity of a perceived negative disconfirmation is high. References Anderson, R. E. Consumer dissatisfaction: The effect
of disconfirmed expectancy on perceived product From a managerial standpoint, this reperformance. Journal of Marketing Research, 1973, search suggests that two stages of marketing 10, 38^4. effort may be required to affect postusage Cardozo, R. N. An experimental study of consumer evaluations and satisfaction maximally. In effort, expectation, and satisfaction. Journal of Marketing Research, 1965, 2, 244-249. addition to a proper positioning of the level of advertising claims (Anderson, 1973), the Cohen, J. B., & Goldberg, M. E. The dissonance model in post-decision product evaluation. Journal marketing manager may also wish to provide of Marketing Research, 1970, 7, 315-321. postpurchase information affecting consumer Festinger, L. A theory of cognitive dissonance. New perceptions of positive disconfirmation. This York: Harper & Row, 19S7, concept is implicit in many dissonance-reduc- Lord, F. M. Elementary models for measuring change. In C. W. Harris (Ed.), Problems of meaing messages aimed at current and potential suring change. Madison: University of Wisconsin users of the manufacturer's product and Press, 1962. would include claims similar to "I never Olshavsky, R. W., & Miller, J. A. Consumer expectations, product performance, and perceived prodexpected my Maytag washer to last so long." uct quality. Journal of Marketing Research, 1972, The author views these findings with mixed 9, 19-21. feelings, however, as they do not refute the Olson, J. C., & Dover, P. Effects of expectation creprevious observation that higher expectations ation and disconfirmation on belief elements of congitive structure. Proceedings of the Sixth beget higher postexposure judgments when Annual Conference of the Association for Conproduct performance is held constant. An sumer Research, 1976, 3, 168-17S. inspection of Table 2 shows this quite clearly: Overall, J. E., & Spiegel, D. K. Concerning least High expectations yielded higher ratings at squares analysis of experimental data. Psychoevery disconfirmation level. However, when logical Bulletin, 1969, 72, 311-322. the independent disconfirmation effect is Sherif, M., & Hovland, C. I. Social judgment: Assimilation and contrast effects in communication considered, the benefits accruing to the user and attitude change. New Haven, Conn.: Yale of inflated appeals may be diminished, parUniversity Press, 1961. ticularly when the disconfirmation experience Weaver, D., & Brickman, P. Expectancy, feedback, and disconfirmation as independent factors in outis negative. This possibility has been obscured come satisfaction. Journal of Personality and in previous investigations and suggests that Social Psychology, 1974, 30, 420-428. a high expectation promotional strategy may Received August 13, 1976 H not be strategically sound when the probabil-