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CHAPTER 9
The Elaboration Likelihood Model
Daniel J. O’Keefe
The elaboration likelihood model (ELM) of persuasion is a “dual process” approach to social information-processing phenomena that is focused specifically on persuasion (Petty & Cacioppo, 1986; Petty & Wegener, 1999). The central idea of the ELM is that two different basic kinds of persuasion processes can be engaged, depending on the degree to which the message recipient engages in “elaboration” of (systematic thinking about) information relevant to the persuasive topic. The development of the ELM has broken new ground in the study of persuasion processes, and offers important advances over previous work. In what follows, the nature of elaboration is described, the two persuasion processes are detailed, the ELM’s analysis of multiple roles for persuasion variables is described, and directions for future research are sketched.
Elaboration
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The ELM suggests that, under different conditions, receivers will vary in the degree to which they are likely to engage in issue-relevant thinking (“elaboration”). Sometimes receivers will engage in a great deal of elaboration—attending carefully to the message’s arguments and evidence, reflecting on other arguments they remember, and so forth. But on other occasions, receivers will not do so much thinking about the persuasive message.
The most straightforward means of assessing the amount of elaboration is the “thought-listing” technique: Immediately following the receipt of a persuasive message, receivers are simply asked to list the thoughts that occurred to them during the communication (for a broad review of such techniques, see Cacioppo, von Hippel, & Ernst, 1997). The number of issue-relevant thoughts reported provides at least a rough index of the amount of issue-relevant thinking. And those issue-relevant thoughts can also be classified in various ways, most notably in terms of their favorability to the advocated position.
The degree of elaboration thus forms a continuum, from extremely high elaboration to little or no elaboration. A variety of factors influence the amount of elaboration that message recipients undertake, with these usefully divided into influences on elaboration motivation (the desire to engage in issue-relevant thinking) and elaboration ability (the capability for issue-relevant thinking).
Elaboration motivation can be influenced by a great many factors, but two can serve here as illustrations. One is the receiver’s level of involvement with the persuasive issue, where involvement is understood as the degree of direct personal relevance of the topic to the message recipient. As involvement increases, elaboration motivation increases. That is, as a given issue becomes increasingly personally relevant to a receiver, the receiver’s motivation for engaging in thoughtful consideration of that issue increases (e.g., Petty, Cacioppo, & Schumann, 1983).
Second, elaboration motivation is influenced by the receiver’s level of need for cognition. “Need for cognition” is an individual-difference variable concerning the degree to which persons engage in and enjoy thinking. As need for cognition increases, elaboration motivation increases (for a review, see Cacioppo, Petty, Feinstein, & Jarvis, 1996, pp. 229–231). That is, people who generally enjoy thinking hard are on the whole more likely to be motivated to process persuasive messages closely.
Elaboration ability is also influenced by a number of different factors. One such influence is the receiver’s amount of prior knowledge about the topic. As receivers know more about the topic, they can engage in greater elaboration (e.g., Laczniak, Muehling, & Carlson, 1991). A lack of relevant background knowledge can plainly interfere with one’s ability to think carefully about an issue.
A second influence on elaboration ability is the presence of a distraction in the persuasion setting—some distracting stimulus or task. In experimental research, distractions have included such things as having an audio message be accompanied by static or beep sounds, or having receivers monitor a bank of flashing lights. Under conditions that would otherwise produce relatively high elaboration, distraction interferes with such issue-relevant thinking (for a review, see Petty & Cacioppo, 1986, pp. 61–68).
The amount of elaboration in which a receiver engages is influenced jointly by elaboration motivation and elaboration ability. A receiver might have the desire to attend closely to a message (elaboration motivation) but be prevented from doing so (e.g., by the presence of a distraction). When elaboration motivation and ability align, the contrast is striking. Imagine, on the one hand, a low need-for-cognition receiver, encountering a message that’s not very involving, on a topic about which the receiver knows relatively little, while keeping one eye on the television set—plainly the recipe for very low elaboration. By contrast, a knowledgeable and high need-for-cognition individual encountering a message on a highly involving topic, with nothing to distract from attending closely to the message, is likely to undertake considerable elaboration.
Now one might be tempted to think that where little or no elaboration is occurring, little or no persuasion can occur, given that the receiver is not very engaged with the message. But the ELM
proposes that persuasion can take place at any point along the elaboration continuum, even under conditions of very low elaboration—but it suggests that the nature of persuasion varies depending on the degree of elaboration. This idea is expressed by the ELM’s two “routes to persuasion.”
Elaboration and the Two Routes to Persuasion
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According to the ELM, different kinds of persuasion processes are activated, depending on how much elaboration occurs. To bring out the basic idea, the ELM describes two fundamentally different routes to persuasion: the central route and the peripheral route. As a brief overview: The central route is activated when elaboration is relatively high; when persuasion is achieved through the central route, it comes about through elaboration, that is, through issue-relevant thinking. The peripheral route is activated when elaboration is relatively low; when persuasion is achieved through the peripheral route, it commonly comes about through the receiver’s use of mental shortcuts (“heuristics”) rather than thoughtful examination of issue-relevant considerations.
The Central Route
In central-route persuasion (i.e., when elaboration is relatively high), the outcomes of persuasive efforts will depend most centrally on the predominant valence of the receiver’s issue-relevant thoughts. If the message evokes predominantly negative thoughts about the advocated view, then little or no attitude change is likely to occur. But if the message leads the receiver to have predominantly positive thoughts about the advocated position, then the message is likely to be relatively successful in changing the receiver’s attitudes in the desired direction.
Two notable factors influence elaboration valence (the relative positivity of the evoked thoughts). One is whether the message advocates a pro-attitudinal position—one toward which the receiver is already favorably inclined—or a counterattitudinal position. With pro-attitudinal messages, recipients will presumably ordinarily be inclined to have favorable thoughts about the position advocated; when the message advocates a counterattitudinal position, receivers will generally be inclined to have unfavorable thoughts about the advocated view. Thus, everything else being equal, one expects pro-attitudinal messages to evoke predominantly favorable thoughts, and counterattitudinal messages to evoke predominantly unfavorable thoughts.
A second influence on elaboration valence is argument strength, that is, the quality (strength) of the arguments advanced in the message. Under conditions of high elaboration, message recipients are closely scrutinizing the message contents, and the valence of receivers’ elaboration will naturally reflect the results of such scrutiny. If close examination of the message reveals weak arguments, dubious reasoning, poor evidence, and the like, predominantly negative elaboration is likely; if the message is found to contain powerful arguments, sound reasoning, good evidence, and the like, then predominantly positive elaboration is more likely. That is, under conditions of high elaboration, argument quality influences the evaluative direction of elaboration and hence influences persuasive success (e.g., Petty & Cacioppo, 1984; Petty, Cacioppo, & Goldman, 1981; Petty, Cacioppo, & Schumann, 1983).
The Peripheral Route
In peripheral-route persuasion (i.e., when elaboration is relatively low), the outcomes of persuasive efforts do not depend on the receiver’s issue-relevant thinking—after all, with low elaboration, there isn’t much such thinking. Instead, persuasive effects arise through some other mechanism. A variety of such peripheral-route mechanisms have been suggested, but the one with the greatest research attention is the receiver’s use of heuristics, that is, simple rules—which don’t require much thinking—for deciding whether to agree with the advocated view. These heuristics are activated by “peripheral cues,” extrinsic aspects of the communication situation.
These heuristics are not ordinarily consciously articulated, but the workings of heuristics can be inferred from the observable influence of peripheral cues on persuasive outcomes. The ELM underwrites a specific prediction about the effect of peripheral cues, namely, that the influence of peripheral cues will be greater under conditions of relatively low elaboration likelihood (e.g., lower involvement) or under conditions in which the cue is relatively more salient. The primary evidence for the operation of heuristic principles consists of research results conforming to just such patterns of effect (for some discussion, see Bless & Schwarz, 1999).
One such heuristic is based on the communicator’s apparent credibility, and if expressed explicitly, would amount to a principle such as “statements by credible sources can be trusted.” When this heuristic is activated, higher-credibility communicators are more persuasive than lower-credibility communicators. Consistent with ELM expectations, the peripheral cue of credibility has been found to have greater impact on persuasive outcomes when elaboration likelihood is relatively low (e.g., Petty, Cacioppo, & Goldman, 1981; Rhine & Severance, 1970) or when credibility cues are less salient (e.g., Andreoli & Worchel, 1978).
A second heuristic is activated by the recipient’s liking for the communicator, and might be expressed as “people I like usually have correct opinions.” When this heuristic is activated, liked communicators are more persuasive than disliked communicators. Consistent with ELM expectations, the persuasive advantage of liked communicators over disliked communicators diminishes as involvement increases (e.g., Chaiken, 1980, Experiment 1; Petty, Cacioppo, & Schumann, 1983) or as the salience of liking cues varies (e.g., Chaiken & Eagly, 1983).
A third heuristic is activated by other people’s reactions to the message, and can be expressed as a belief such as “if other people believe it, then it’s probably true.” When this heuristic is employed, the approving reactions of others enhance message effectiveness (and disapproving reactions should impair effectiveness). A number of studies have confirmed the operation of such a consensus heuristic in persuasion (for a review, see Axsom, Yates, & Chaiken, 1987).
As can be seen from these three examples, heuristics are mental shortcuts for message recipients. Rather than engaging in extensive thinking about the message topic and the merits of the arguments, instead receivers can decide what to think by relying on such simple considerations as the communicator’s expertise or likeability or the reactions of other people.
The Two Routes Illustrated
A classic illustration of the differences between the central and peripheral routes to persuasion is provided by Petty, Cacioppo, and Goldman’s (1981) experiment, in which three factors were varied: the receiver’s level of involvement, the expertise of the communicator, and argument quality. The participants were college undergraduates, and the persuasive messages advocated the adoption of senior comprehensive examinations as a college graduation requirement. Involvement was varied by having the message advocate adoption of that requirement either at the receiver’s own university (high involvement) or at a distant university (low involvement).
High-involvement receivers were significantly affected by the quality of the arguments (being more persuaded by strong arguments than by weak arguments), but were not significantly influenced by the communicator’s degree of expertise. By contrast, low-involvement receivers were more affected by expertise variations (being more persuaded by the high expertise source than by the low) than by variations in argument quality. That is, where receivers were inclined to engage in extensive elaboration (by virtue of involvement), argument quality was more influential than was the peripheral cue of expertise. But where receivers were not inclined to invest the cognitive effort in close scrutiny of the message, the peripheral cue had more influence.
As this study illustrates, persuasion can be obtained either through a central route (involving relatively high elaboration) or through a peripheral route (where little elaboration occurs). But the factors influencing persuasive success are different in the two routes.
It should be emphasized that the two routes to persuasion are not conceived of as two rigidly different categories of persuasion, but rather as prototypical extremes at the ends of an elaborati
on continuum. For example, at intermediate levels of elaboration, one expects some complex mixture of central-route and peripheral-route processes. Thus the ELM does not claim that (for example) peripheral cues have no influence on persuasive outcomes under conditions of high elaboration, but rather simply that as elaboration increases, the influence of peripheral cues decreases and the influence of elaboration valence increases.
Consequences of the Route to Persuasion
Although persuasion can be achieved either through central or peripheral routes, the ELM emphasizes that these two ways of achieving persuasion are not identical in their consequences. Broadly speaking, the attitude change obtained through central-route persuasion is likely to be more enduring over time, more resistant to counterpersuasion, and more directive of subsequent behavior (for reviews and discussion, see Petty & Cacioppo, 1986, pp. 173–195; Petty, Haugtvedt, & Smith, 1995; Petty & Wegener, 1999, pp. 61–63).
One way of characterizing these effects is to say that central-route persuasion produces stronger attitudes than does peripheral-route persuasion. The attitudes resulting from these two routes might not necessarily be evaluatively any more extreme (for example, central-route and peripheral-route persuasion might yield equally positive attitudes), but those attitudes could differ with respect to attitude strength. (For discussion of strength-related attitude properties and effects, see Bassili, 2008; Farc & Sagarin, 2009; Petty & Krosnick, 1995; Visser, Bizer, & Krosnick, 2006.)
The plain implication for persuaders is that central-route persuasion, though perhaps more difficult to achieve (because it requires ensuring greater elaboration by message recipients), brings long-term benefits, in the form of attitudes that are more stable over time and are more likely to exert an influence on behavior.
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