Specifying the ELM The Elaboration Likelihood Model and the Sleeper Effect: An Assessment of Attitude Change over Time

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1 Forum Specifying the ELM The Elaboration Likelihood Model and the Sleeper Effect: An Assessment of Attitude Change over Time by Mike Allen and Rodney Reynolds Since the late 1970s, the Elaboration Likelihood Model (ELM) has become a major focus of persuasion research. The originators of the ELM (Petty, 1977; Petty & Cacioppo, 1981,1984, 1986a, b) have extensively tested and revised the model. Petty and Cacioppo (1981) claim the model to be one step toward a general theory of attitude change (p. 255) that incorporates many of the major classic and contemporary approaches to attitudes and persuasion. According to the ELM, two routes of persuasion exist: the central route and the peripheral route (an early version of the ELM had three routes ; Petty & Cacioppo, 1981). The central route results in attitude change that is relatively permanent, resistant to counterpersuasion, and predictive of behavior (Petty & Cacioppo, 1986a, p. 29). Peripheral route processing causes attitude change that is relatively temporary, susceptible to counterpersuasion, and less predictive of behavior (1986a, p. 29). The emphasis placed on persistence of attitude change in the ELM offers an opportunity to explore the model. The question guiding this article is whether the ELM offers a reasonably precise explanation for the persistence of attitude change. Answering this will hinge on the conceptual and operational parameter(s) necessary for testing and supporting attitudepersistence predictions consistent with the ELM. Understanding the ELM is extremely difficult as is evident in the disagreement over the interpretation of the effects of evidence and involvement within this model (Johnson & Eagly, 1989; Petty, Cacioppo, Kasmer & Haugtvedt, 1987; Petty, Kasmer, Haugtvedt & Cacioppo, 1987; Reynolds, 1986; Stiff, 1986; Stiff & Boster, 1987). The difficulty is compounded by the fact that the ELM has undergone many successive alterations. The test of the value of the theory and subsequent changes are whether there is (a) an increase in the falsifiability of the theory (Stiff and Boster, 1987, point out that the changes deny falsifiability), or (b) a change in the scope of the theoretic predictions (Eagly and Chaiken, 1984, note that the ELM is overwhelmingly encompassing), In order to facilitate this examination of the ELM, an interpretation of the current state of the ELM must be provided. This essay proposes a reasonable and consistent interpretation of ELM. Since prior comments have noted concern over the way that vagueness and modifications in the ELM allow for otherwise unanticipated defenses of the model (Stiff & Boster, 1987, p. 25), we feel compelled to note that the interpretation of the ELM provided here is not intended as a definitive and final account. Following the interpretation of the ELM, data on the sleeper effect will be shown to be inconsistent with the ELM. We begin by defining the two methods or processes by which 73

2 Communication Theory persuasion occurs: the central route and the peripheral route. Defining the Central Route of Attitude Change The central route derives from Petty and Cacioppo s early advocacy of Greenwald s (1969) cognitive response approach to persuasion (see Petty, 1977; Petty & Cacioppo, 1977). Reynolds (1986, pp ) details changes in the notion of cognitive responses prior to and concurrent with the evolution of the ELM. The general definitions provided for elaboration tend to argue for a thoughtful, effortful, or deliberative processing of the message content. The underlying assumption of attitude change resulting from the central processing route requires that recipients thinking about issue-relevant information is viewed as being the most direct determinant of the direction and amount of attitude change (Petty & Cacioppo, 1986a, p. 29). Petty and Cacioppo explain that the central route... emphasizes the information that a person has about the attitude, object or issue under consideration (1981, p. 255; in 1986a, p. 21, the phrase issuerelevant arguments substitutes for attitude, object or issue ). The conclusion they offer is, persuasion [via the central route] is based on a thoughtful consideration of the object or issue at hand (1981, p. 256). For Petty and Cacioppo the central route involves drawing upon prior experience and knowledge to scrutinize and elaborate the issue-relevant arguments in the persuasive messages along the dimensions that are perceived central to the merits of the attitude object. This central processing creates cognitive responses that are rehearsed and stored in long-term memory (Petty & Cacioppo, 1981, p. 266). With respect to time, persuasion resulting from central processing should be relatively permanent, resistant to counterpersuasion, and predictive of behavior (Petty & Cacioppo, 1986a, p. 29). By contrast, peripheral route persuasion should be relatively temporary, susceptible to counterpersuasion, and less predictive of behavior (p. 29). This indicates one consideration for distinguishing between the routes: the effect over time each route has on attitude change. The result should be viewed as relative rather than absolute. A visual comparison of this effect over time is provided in Figure 1, taken from Petty and Cacioppo (1986a, p. 28). This figure is Petty and Cacioppo s own representation of the decay curves. Defining the Peripheral Route of Attitude Change The central route contrasts with the peripheral route, which is pairing the recommendation with a simple cue that either alters recipients moods directly, or provides them with the basis for a simple inference as to the appropriate attitude (Petty & Cacioppo, 1986a, p. 29). Petty and Cacioppo s 1981 text refers to the peripheral route of attitude change as attitude change without issue-relevant thinking (p. 267). In this section they point out that the temporary effects induced as a result of the cues associated with peripheral processing (credibility is mentioned as one) can lead to permanent changes. They conclude that what begins, then, as a temporary attitude change via the peripheral route, may end up being a more per- 74

3 Favorable 8 4 Unfavorable 3 2 Figure 1 Petty and Cacioppo s (1986a) hypothetical decay functions for attitude changes induced via the central and peripheral routes (p 28) Reprinted with permission, Time of Measurement after message manent change via the central route (1981, p. 267). Types of cues associated with peripheral processing are pleasant smells, attractiveness of the message source, physiological arousal, prestige suggestion, speech rate, or number of arguments (Petty & Cacioppo, 1981, p. 256; 1986a, p. 35). The common feature seems to be that peripheral cues trigger relatively primitive affective states that become associated with the attitude object (Petty & Cacioppo, 1986a, pp. 33,35). What basis is there for the concept of a peripheral cue? One note in Petty and Cacioppo (1981, p. 256) suggests that Kelman s (1961) notions of identification and compliance are peripheral processes while internalization is suggested as a central route. Kiesler, Collins, and Miller (1969, pp ) point out a conceptual ambiguity in Kelman s distinction. Identification, for example, might take the form of attraction to a rewarding source. but attraction to a rewarding source could be considered quite rational and mindful (internalization) or rewarding (compliance). Another note (Petty & Cacioppo, 1981, p. 256) characterizes peripheral processing as shallow, au- tomatic, heuristic, scripted, and mindless (1981, pp ). Defining the peripheral route assumes that a cue is not associated with message content and that the attitude change is temporary. Distinguishing Between the Two Routes Two assumptions separate the routes of persuasion in the model: (a) an assumption about the process of attitude change, and (b) an assumption abut the effects of messages utilizing one or both of these two routes. In other words, an experimental test of the ELM must not only demonstrate that the processes operate with the effects suggested but that the processes contain the proper elements. The differing temporal effects of the processing routes remain empirical issues and can be resolved by appropriate research, assuming that distinct operational tests of each route of message processing exist. The distinction between routes of processing remains both a theoretical and a methodological issue. The theoretical issue is whether or not the conceptual distinction between the two methods of processing is recognizable. 75

4 Communication Theory Can the routes of processing be defined as separate entities permitting independent operationalizations? The methodological issue involves the question, Can the effects of a message on a receiver be separated into effects due to central and peripheral processing? The only methodological distinction offered by Petty and Cacioppo considers the difference in the temporal effects of the message: Central processes have long-term impact whereas peripheral cues have only a temporary impact. Methodologically Distinguishing Between Processing Routes Petty and Cacioppo (1986a) state that the difference in persistence of persuasion for the central and peripheral routes can be represented by two decay curve functions. Central processing decays gradually while peripheral processing decays rapidly. Several features of these decay curves need to be noted. First, the curves are hypothetical, based on the theoretical parameters of the ELM. At the current time no clear empirical data support the existence of these curves. Second, both the beginning and ending points of the curves show the same attitude for central and peripheral attitude effects. This means that the immediate posttest and final posttest of attitudes should, theoretically, not differ as a result of method of processing. (It should be noted that most studies of the ELM involve only immediate posttest attitude measurement, hence no difference in effect should exist between routes of processing.) Any comparison of the central and peripheral routes must include a comparison of the rates of attitude decay, not the amount of attitude change. The dis- tinction between routes is not based on the amount of initial or final attitude change-those should be the same. The distinction between routes stems from the rate of decay for each curve. The peripheral decay starts more quickly and is initially more rapid than the decay for the central route. However, over time the peripheral route s decay slows, and the decay for the central route accelerates until the two eventually coincide at some final point. The empirical test of the theoretical assumption would require a minimum of a 2 (central, peripheral) x 3 (immediate, short delay, long delay) repeated measures design and would probably need more than just three measurements. Ideally, the patterns of decay would show equivalence at the immediate posttest, divergence at the short delay, and then convergence over time to a final point. Third, the distinction between the routes methodologically requires a sophisticated sense of timing that is not present in the theory. No specific time frames are suggested either theoretically or as examples. As Petty and Cacioppo (1986a) admit, since the exact decay functions of attitude changes induced by central versus the peripheral routes are not known, administration of one immediate and one delayed posttest does not provide a strong test (p. 29). The conclusion advanced by the authors is then to consider that one key to the solution of this problem lies in examining the distinctive underlying processes postulated by these two routes (Petty & Cacioppo, 1986a, p. 30). The result is a reliance on understanding the processing of the receiver exposed to the message. The problem of distinguishing routes of persuasion is compounded 76

5 Forum by Petty and Cacioppo s (1986a) proposition 5: Variables can effect the amount and direction of attitude change by (a) serving as persuasive arguments, (b) serving as peripheral cues and/or (c) affecting extent or direction of issue and argument elaboration (p. 16). Petty and Cacioppo (1986a) later explain that (a) any variable can serve as a persuasive argument, (b) any variable can serve as a peripheral cue, and (c) any variable can affect the extent of direction of issue and argument elaboration (pp ). Proposition 5 generates an indeterminate statement about the simple ability to identify some variables as relating to central and some variables as relating to peripheral processing. The elaboration evidence gathered in some studies may not assist in determining the route of persuasion. The thought-listing evidence can be arguably a measure of affect (even Greenwald, 1982, recognizes a correlation of.80 between pro- and counterargument though listings and attitudes). Additionally, the argument-quality manipulations used in many of the ELM studies can be seen as confounded with affect because the strong arguments were selected from a pool that elicited primarily favorable thoughts in a pretest, and the weak arguments were selected from a pool that elicited mainly counterarguments in a pretest (Petty, Cacioppo & Heesacker, 1981, p. 435) (that is, selection of highllow quality arguments was based on positive or negative thought-listing responses rather than standards of argument quality; see Reynolds, 1986). Finally, it is unclear whether self-report elaboration measures can distinguish between elaborative and peripheral pro- cessing (e.g., Petty et al., 1981, asked participants how distracted they were from thinking about the message, p. 436). It could be argued that a selfreport of elaborative processing actually accesses peripheral processing since the available cues (e.g., university research setting, persuasive message, questions about messageprocessing ability) suggest that it is appropriate to report an elaborative response. The need-for-cognition instrument (Cacioppo & Petty, 1982) may also fail to distinguish habitual elaboration from wishful thinking about elaborative ability (see Aune & Reynolds, 1991). The ELM allows for the possibility that the likely to elaborate may not elaborate. Therefore, even if the need-for-cognition measure gives a valid prediction of who is likely to elaborate, the ELM does not allow specification of when likely-toelaborate persons do not in fact elaborate. Operationally, therefore, no clear separation between the routes exists consistent with the theory. Or, to put it another way, a scientist cannot reasonably determine that the effect of any message is attributable to a particular route of processing. Theoretically Distinguishing the Processing Routes Distinguishing theoretically between routes requires the ability to examine a persuasive situation and determine those features belonging to the central or the peripheral route. Unless some clear distinction can be made a priori, the ELM becomes only a post hoc method of explanation, and much of its predictive scientific value is lost. The critical feature for any theory is that of prediction. Is there a basis for 77

6 Communication Theory predicting which cues are central and which are peripheral? One must concede that complete identification of the cues is not required. The classification of any cue may depend on future research. This discussion is intended to argue only that some basis must exist on which to categorize cues clearly as central or peripheral. The threshold that Petty and Cacioppo (1986a) set is, if we can distinguish attitudes that are based on argument elaboration rather than peripheral cues, we will distinguish the central and peripheral routes to persuasion (p. 31). The critical question, then, is what constitutes and contributes to argument elaboration. It should be remembered that all variables can be either peripheral or central; what must be distinguished is some qualitative feature of the situation. The key to elaboration or central processing is whether the cue is issue relevant. Petty and Cacioppo (1986a) generally treat source credibility as ;I peripheral cue (p. 4). However, consider Nixon s famous Checkers speech, in which the central issue was the credibility of the speaker. Was the credibility of the speaker an issuerelevant consideration that could be elaborated on? It could be argued that the Checkers speech had no central issue and was only a collection of peripheral cues. However, in the absence of evidential substance, the audience of such a message is likely to fill in the substance that they expected or find reasonable for the message (Hample, 1977; Petty, 1977; Petty & Cacioppo, 1981). Thus, the ELM denies access to what is issue relevant and what is issue irrelevant. Under any circumstances the credibility of the speaker could be considered as issue relevant and not simply as a peripheral cue. Considering the Sleeper Effect The sleeper effect is an example of an effect involving a relationship between time and attitude change. The sleeper effect posits that the relationship between attitude change and credibility is not a constant over time but changes from the immediate message reception to a different configuration after some period of delay. Existence of the Sleeper Effect Both sophisticated experimental evidence (Cruder, Cook, Hennigan, Flay, Alessis & Halamaj, 1978) and a quantitative literature summary or meta-analysis (Allen & Stiff, 1989) confirm the existence of the sleeper effect (SE). The particular SE model supported posits that participants exposed to a low credible message source show an increase in attitude change over time, measured from an immediate to a delayed posttest. The result can only be demonstrated experimentally under conditions involving no change in attitude in the low credible message condition from the pretest to the immediate posttest. Thus, only a small number of experiments can provide evidence for the SE, but such experiments consistently support this conclusion (Allen & Stiff, 1989). Timing of the Discounting Cue Petty and Cacioppo (1986a) interpret the evidence as consistent with the ELM position. Their position is that under narrow conditions it is possible for both cues and arguments to act independently of each other. They assume that the best evidence for a sleeper effect comes from studies [in] which a discounting cue is presented 78

7 Forum after rather than prior to message exposure (p. 183). They cite as examples several studies (Gruder et al., 1978; Hovland & Weiss, 1951; Pratkanis & Greenwald, 1985). They argue that the existence of the sleeper effect should be difficult to demonstrate because either (a) the topic will be of low involvement so no change occurs initially, or (b) the discounting cue after the message may be judged as irrelevant. An examination of the studies used in the Allen and Stiff (1989) meta-analysis does not support the conclusions drawn from a smaller sample of the available studies. While the Gruder et al. (1978) study did have the source manipulation after the message, other relevant experiments with the same findings had the source manipulation before the message (Watts & McGuire, 1964). It should be noted that all relevant studies demonstrated the SE; the effect is not a difficult one to produce. The available data demonstrate an SE that is not dependent on the timing of the discounting cue. Not Important to the Real World The conclusion offered by Petty and Cacioppo (1986a) is that while the sleeper effect is of considerable conceptual significance, obtaining it may require conditions that are infrequently present in either the real world or in persuasion research (p. 183). This claim seems to be overstated. The SE experiments (meeting the conditions established by Allen & Stiff, 1989) deal with general issues in persuasion (Watts & McGuire, 1964). Examples of low credible message sources are relatively common, not extremely rare. Statements coming from George Bush, Dan Quayle, Saddam Hussein, or Jim and Tammy Bakker, for a certain seg- ment of the population, would be determined as high or low in credibility. The point is that low credible sources are commonly involved in public discourse. Time Required for Disassociation The time required to observe the SE varies. Hannah and Sternthal(l984) obtained the effect in less than 4 hours. Other experimenters take weeks to document the effect. The result is a set of experiments that do not require complex and sophisticated methodological techniques to separate the effect over time (Mazursky & Schul, 1988). The effect has been shown to be reproducible and in a theoretical manner, contrary to the claims of Petty and Cacioppo (1986a, p. 183). Consideration of the content may cause elaboration, but the ELM in its current state does not provide for the timing mechanisms necessary to predict the eventual disassociation. Discounting in the ELM The effect of the eventual disassociation in the observed SE is that low and high credibility message recipients attitudes initially diverge and then converge over time. It is important to note that the observed curve is not the one specified by the ELM. The current data indicate an initial separation or spread that over time results in convergence at a final value (Allen & Stiff, 1989). The initial spread could be the result of different strengths of cues associated with the particular processing routes, but no relevant information exists. An important overlooked aspect is the part that memory plays in this process. Nothing in the current ELM explains how discounting cues are held in memory. The ELM does not explain when a discounting cue will be 79

8 Communication Theory intrinsic to the interpretation of a message and when a discounting cue will maintain a separate identity from the message. All that is claimed is that the separation of cues is rare. The ELM does not explain bow the forgetting and disassociation processes take place. Conclusion The ELM is one of the dominant theories in persuasion. The model has been carefully researched and considerable effort has been devoted to developing its assumptions. The ELM integrates large bodies of apparently contradictory literature in a consistent manner. The separation of emotion and cognition into separate processing routes allows for a rethinking of the available research. A valuable theory is not only accurate but specific. To be useful a theory should make assumptions and recommendations that translate into expectations about experimental results and prescriptions for how people ought to act. A theory that correctly identifies and outlines causal forces and the results of action is one to be valued. The ELM contains many ambiguities and points of complexity that make application difficult. In the case of the sleeper effect, the ELM makes fairly clear statements. One claim is that the presentation of the discounting cue is after the message. Experimental research demonstrates that the sleeper effect occurs regardless of whether the discounting cue is presented before or after the message. The experimental results call into question some of the expectations of the model. It may be possible to revise the model to consider other routes of persuasion. Perhaps the complexity involved in the model is unwarranted. The results of meta-analyses conducted to date suggest that simple summary statements about the literature make the complicated requirements of processing routes unnecessary (Allen, 1991; Boster & Mongeau, 1984). A simpler, more parsimonious theory, consistent with the available meta-analyses, may provide a better explanation for persuasion. This critique and evaluation of one specific feature of the model has focused on three basic analyses: (a) methodological, (b) conceptual, and (c) experimental. Concerning the ELM methodologically, even the authors of the theory admit that it may not be possible to test its tenets because of the difficulty of separating the processes involved. Thus, at the level of empirical data, no clear evidence for or against the theory can be provided. This means that no really critical empirical test of the ELM is possible. Concerning the ELM conceptually, the ability to draw clear distinctions in all cases can be lost given a few counterexamples. While asking a person what they do with the information may avoid this problem, this assumes that an individual can accurately report the relevant processes. The ability of an individual to access and report reasoning processes is suspect and highly controversial at best. Many times an individual will not have the reflective capacity necessary to identify sources of influence or processes used to make a determination. Experimentally, the summary of results on one aspect of this issue (the sleeper effect) do not support the predictions of the ELM. Even if the logic 80

9 Forum of the theory is correct, the application in this case does not match the empirical data. This is particularly troublesome because the example is relevant to an important method of determining the distinction between the two routes to persuasion within the theory. One critical distinction made between the central and peripheral processing routes is the temporal effects of a message on the recipient s attitudes. The ELM is going through a period of challenge and reformulation. As more data are gathered and analyzed and literature summaries (particularly meta-analyses) are produced, the ability to test assumptions of the theory will grow. Any good theory will be challenged. Empirical tests will not always support the theory. The result will be the origination of new explanations (theories) and changes to the old theory. Authors Mike Allen is an associate professor in the Department of Communication, University of Wisconsin- Milwaukee, Milwaukee, WI Rodney Reynolds is an associate professor in the Department of Speech, University of Hawaii at Manoa, 326 George Hall, 2560 Campus Road, Honolulu, HI References Allen, M. (1991). Meta-analysis comparing the persuasiveness of one-sided and two-sided messages. Western Journal of Speech Communication, 55, Allen, M., & Stiff, J. (1989). Testing three models for the sleeper effect. Western Journal of Speech Communication, 53, Aune, R., &Reynolds, R. (1991, February). Communication and cognitive vogue: PPM research asks, % need for cognition confounded with linguistic style? Paper presented at the Western States Communication Association Convention, Phoenix, AZ. Boster, F., & Mongeau, P. (1984). Feararousing persuasive messages. In R. Bostrom (Ed.), Communication yearbook 8 (pp ). Beverly Hills: Sage. Cacioppo, J. T., & Petty, R. E. (1982). The need for cognition. Journal of Personality and Social Psychology, 42, Eagly, A. H., & Chaiken, S. (1984). Cognitive theories of persuasion. In L. Berkowitz (Ed.), Advances in experimental social psychology (Vol. 17, pp ). New York: Academic Press. Greenwald, A. (1969). Cognitive learning, cognitive response to persuasion and attitude change. In A. Greenwald, T. Brock, & M. Ostrom (Eds.), Psychologicalfoundations of attitudes. New York: Academic Press. Greenwald, A. C. (1981). Cognitive response analysis: An appraisal. In R. E. Petty, T. M. Ostrom, 8( T. C. Brock (Eds.), Cognitive responses in persuasion (pp ). Hillsdale, NJ: Lawrence Erlbaum. Cruder, C. L., Cook, T. D., Hennigan, K. M., Flay, B. R., Alessis, C., & Halamaj, J. (1978). Empirical tests of the absolute sleeper effect predicted from the discounting cue hypothesis. Journal of Personality and Social Psychology, 36, Hample, D. (1977). Testing a model of value argument and evidence. Communication Monographs, 44, Hannah, D. B., & Sternthal, B. (1984). Detecting and explaining the sleeper effect. Journal of Consumer Research, 11, Hovland, C. I., & Weiss, W. (1951). The influence of source credibility on communication effectiveness. Public Opinion Quarterly, 15, Johnson, B. T., & Eagly, A. H. (1989). Effects of involvement on persuasion: A meta-analysis. Psychological Bulletin, 106, Kelman. H. C. (1961). Processes of ooinion change. Public Opinion Quarterly, 25, Kiesler, C., Collins, B., & Miller, N. (1969). Attitude change: A critical analysis of theoretical approaches. New York: Wiley. Mazursky, D., & Schul, Y. (1988). The effects of advertisement encoding on the failure to discount information: Implications for the sleeper effect. Journal of Consumer Research, 15,

10 Communication Theory Petty, R. E. (1977). A cognitive response analysis of the temporal persistence of attitude change induced by persuasive communications. Unpublished doctoral dissertation, Ohio State University, Columbus, OH. Petty, R. E., & Cacioppo, J. T. (1977). Forewarning, cognitive responding, and resistance to persuasion. Journal 0.f Personality and Social Psychology, 35, Petty,R. E., & Cacioppo, J. T. (1981). Attitudes and persuasion: Classic and contemporary approaches. Dubuque, IA: W. C. Brown. Petty, R. E., & Cacioppo, J. T. (1984). Source factors and the Elaboration Likelihood Model of persuasion. Advances in Consumer Research, 11, Petty, R. E., & Cacioppo, J. T. (1986a). Communication and persuasion: Central and peripheral routes to attitude change. New York: Springer-Verlag. Petty,R. E., & Cacioppo, J. T. (1986b). The Elaboration Likelihood Model of persuasion. L. Berkowitz (Ed.), Advances in experimental psychology (Vol. 19, pp ). New York: Academic Press. Petty, R. E., Cacioppo, J. T., & Heesacker, M. (1981). Effects of rhetorical questions on persuasion: A cognitive response analysis. Journal of Personality and Social Psychology, 40, Petty, R. E., Cacioppo, J. T., Kasmer, J., & Haugtvedt, C. (1987). A reply to Stiff and Boster. Communication Monographs, 54, Petty, R. E., Kasmer, J., Haugtvedt, C., & Cacioppo, J. T. (1987). Source and message factors in persuasion: A reply to Stiffs critique of the Elaboration Likelihood Model. Communication Monographs, 54, Pratkanis, A. R., & Greenwald, A. C. (1985). A reliable sleeper effect in persuasion: Implications for opinion change theory and research. In L. F. Alwitt & A. A. Mitchell (Eds.), Psychological processes and advertising effects: Theory, research, and applications (pp ). Hillsdale, NJ: Erlbaum. Reynolds, R. (1986). The effects of cognitive elaboration, valid arguments, evidence, and message style in persuasive discourse. Unpublished doctoral dissertation, Michigan State University, East Lansing, MI. Stiff, J. B. (1986). Cognitive processing of persuasive message cues: A metaanalytic review of the effects of supporting information on attitudes. Communication Monographs, 53, Stiff, J. B., & Boster, F. J. (1987). Cognitive processing: Additional thoughts and a reply to Petty, Kasmer, Haugtvedt, and Cacioppo. Communication Monographs, 54, Watts, W. A., & McGuire, W. J. (1969). Persistence of induced opinion change and retention of the inducing message contents. Journal of Abnormal and Social Psychology, 68,