Source factors and the elaboration likelihood model of persuasion

The Elaboration Likelihood Model of persuasion (ELM) is discussed as it relates to source factors in persuasion. The ELM proposes that under low elaboration likelihood, source factors serve as simple acceptance or rejection cues under moderate elaboration likelihood source factors guide the extent of thinking; and under high elaboration likelihood source factors are unimportant as cues or general motivators of thought but (if relevant) serve as persuasive arguments or help in interpreting arguments. Several experiments are described which provide empirical support for these propositions. Traditional analyses of persuasion have sought to identify how source, message, recipient, channel, and contextual factors affect a person's susceptibility to persuasion (e.g. , Hovland, Janis, & Kelley, 1953) . Over the past 30 years, a large number of theories have developed to account for the many different effects that have been observed when these variables have been manipulated in (see Insko, 1967; Kiesler, Collins, & Miller, 1969; Petty & Cacioppo, 1981). Although persuasion researchers have accumulated a vast quantity of data and an impressive number of theories, perhaps more data and theory than or. any other single topic in the social sciences (see McGuire, in press), there is surprisingly little agreement concerning how and why the traditional variables affect attitude change. This lack of agreement even extends to variables that or the surface, at least, would appear to be quite simple in terms of their operation. For example, although it seems reasonable to propose that by associating a message with an expert or an attractive source, agreement can be increased, the accumulated research literature suggests that source effects are considerably more complicated than this. Sometimes sources have the expected effects (e.g., Kelman & Hovland, 1953), sometimes no effects are obtained (e.g., Rhine & Severance, 1970), and sometimes reverse effects are noted (e.g., Sternthal, Dholakia. & Leavitt. 1978). Elsewhere we have outlined a general framework for understanding persuasion called the Elaboration Likelihood Model (ELM). The model proposes that people are neither universally thoughtful in evaluating persuasive messages nor universally mindless. Instead, a variety of individual and situational factors will determine how much cognitive effort a person devotes to processing a message. The ELM postulates a continuum of message elaboration anchored at the high enc by what we have called the central route to persuasion, and at the lowend by what we have called the peripheral route to persuasion. Under the central route, attitude changes result from a person's careful attempt to evaluate the true merits of the advocated position. Under the peripheral route, however, attitude changes occur because the person associates the attitude issue or object with positive or negative cues or makes a simple inference about the merits of the advocated position. based on various simple cues in the persuasion context. We have proposed that most previous analyses of persuasion can be understood as emphasizing one of these routes to persuasion (see Cacioppo & Petty, this volume; Petty & Cacioppo, 1981; 1983; for further details on the ELM). Our primary goal in the present paper is to discuss how the elaboration Likelihood Model accounts for the effects of source factors on persuasion. Of the many variables that might be manipulated in designing a product or public service campaign, one of the most important variables that is under the control of the campaign designer is the source of the message. When does it make sense to spend a great deal of money hiring a celebrity spokesperson? When is the endorser irrelevant? When will a positive source be helpful? When, if ever, will a positive source actually be harmful? The answers to these questions depend on the elaboration likelihood of the persuasion situation. SOURCE FACTORS UNDER HIGH AND LOW MOTIVATION TO PROCESS In our initial work on the Elaboration Likelihood Model, we have focused on therelatively pure case of either very high or very low elaboration likelihood. For purposes of testing our theoretical framework it was important initially to create two very different persuasion contexts: one in which the elaboration likelihood was very high (that is, a person was both highly motivated and able to engage in issue-relevant thought) and one in which the elaboration likelihood was very low (that is, either motivation or ability to think was absent or reduced substantially). In the experiments we describe next, a person's ability to think was held constant at a high level across the experimental conditions (i.e., the messages and issues employed were easy to understand, no extraneous distractions were present, etc.). Motivation to think was manipulated in each study by varying the personal relevance and consequences of the persuasive appeal (cf. Apsler & Sears, 1966) . Given that all subjects have the ability to think about the persuasive message, subjects in the high relevance conditions should follow the central route to persuasion, and subjects in the low-relevance conditions should follow the peripheral route. More specifically, under low relevance conditions source factors should operate as simple acceptance or rejection cues, but under high relevance conditions, source factors should not operate as simple cues. In an early test of the two routes to persuasion (Petty, Cacioppo, & Goldman, 1981) we told some undergraduate students that their university chancellor was considering the implementation of a new graduation requirement for next year. Specifically, all students would be required to pass a comprehensive exam in their major area as a prerequisite to graduation. Other students were told that the comprehensive exam requirement was being considered for 10 years in the future. For the first group of students, the elaboration likelihood f or a message on senior comprehensive exams would be quite high. It would be very important for them to understand and think about the consequences of the proposed exams because they would be affected personally by them. If they didn't pass the exams, the couldn't graduate! When the exams were proposed for 10 years in the future, however, they have absolutely no personal implications for the students, and therefore it is not particularly important nor adaptive for the students to think about the issue. In addition to manipulating elaboration likelihood by manipulating personal relevance in this study, we also varied the expertise of the source of the message and the quality of the issue-relevant arguments presented. For some subjects the source was described as a professor of education at Princeton University who chaired the Carnegie Commission on Higher Education (high expertise), whereas for other subjects the message was described as originating from a local high school journalism class. Finally, some subjects received a message containing cogent and compelling arguments, and other subjects received a message containing weak and specious arguments. The results of this study indicated that when the elaboration likelihood was low (low personal relevance), the expert source was beneficial in enhancing persuasion regardless of argument quality. When the elaboration likelihood was high, however, the expertise of the source had no effect 25 a simple cue, but the nature of the issue-relevant arguments had a large impact on agreement (see also Chaiken, 1980). In a recent study, we attempted to extend our analysis of source effects to advertising communications. In this study (Petty, Cacioppo, & Schumann, 1983), we varied elaboration likelihood by leasing some subjects to believe that a new product (a disposable razor) was going to be test marketed soon in their local area and that at the end of the experiment they would be given an opportunity to select a disposable razor from several brands available. Other subjects were led to believe that the new disposable razor would be test marketed in a distant city and that they would be selecting brands of toothpaste at the end of the experiment. Our goal was to have one group of subjects highly involved with the disposable razor product and have another group of subjects have low involvement with the product. In addition to this manipulation of involvement we also varied source and message characteristics. Specifically, some subjects were exposed to ads featuring well known and liked athletes (one male and female), whereas other subjects were exposed to ads featuring middle-aged average citizens Some subjects were exposed to ads featuring cogent arguments, others were e: posed to ads featuring weak arguments Similar to the study just described, in his experiment we found that when the elaboration likelihood was low, using famous athletes in the advertisement led to more favorable product attitudes regardless of the strength of the product attributes presented. When elaboration likelihood was low, however, only the argument strength manipulation affected attitudes SOURCE FACTORS UNDER HIGH AND LOW ABILITY TO PROCESS In the studies described briefly in the previous section, where the elaboration likelihood was low, experts were more persuasive than non-experts, and celebrities were more persUasive than average citizens when elaboration likelihood was high, however, these source factors did not serve as simple acceptance or rejection cues Although the two studies employed very different specific manipulations of elaboration likelihood (personal relevance, anticipation of product choice), both manipulations were concerned with affecting a person's motivation to think about a persuasive message however, as noted earlier, elaboration likelihood is also determined by a person's ability to process a persuasive message Cacioppo & Petty, 1979, 1980; Wood, 1982). According to the Elaboration Likelihood Model, manipulations of abil