The elaboration likelihood model (ELM) of persuasion, developed by Richard Petty, John Cacioppo, and their collaborators, is an example of a “dual process” approach to persuasion (another example is Chaiken’s heuristic-systematic model, HSM). The ELM suggests that important variations in the nature of persuasion are a function of the likelihood that receivers will engage in elaboration of (that is, thinking about) information relevant to the persuasive issue. Depending on the degree of elaboration, two different kinds of persuasion process can be engaged – one involving systematic thinking and the other involving cognitive shortcuts. Different factors influence persuasive outcomes depending on which process is activated.
These two persuasion processes are called the “central route” and the “peripheral route” to persuasion. The central route represents the persuasion processes involved when elaboration is relatively high. Where persuasion is achieved through the central route, it commonly comes about through extensive issue-relevant thinking: careful examination of the information contained in the message, close scrutiny of the message’s arguments, consideration of other issue-relevant material, and so on. In short, persuasion through the central route is achieved through the receiver’s thoughtful examination of issue-relevant considerations.
The peripheral route represents the persuasion processes involved when elaboration is relatively low. Where persuasion is achieved through peripheral routes, it commonly comes about because the receiver employs some simple decision rule (some heuristic principle) to evaluate the advocated position. For example, receivers might be guided by whether they like the communicator or by whether they find the communicator credible. That is, receivers may rely upon various peripheral cues (such as communicator credibility) as guides to attitude and belief, rather than engaging in extensive issue-relevant thinking.
Influences On The Degree Of Elaboration
A number of factors have been found to influence the amount of elaboration (and hence to influence which route to persuasion is activated). These factors can be classified broadly as influencing either elaboration motivation or elaboration ability.
A receiver’s motivation for engaging in elaboration can be influenced by the relevance of the topic; as the personal relevance of the topic (the receiver’s degree of “involvement” in the topic) increases, the motivation to engage in elaboration also increases. Elaboration motivation can also be influenced by the receiver’s level of “need for cognition,” a personality characteristic reflecting the tendency to enjoy and engage in thinking; people higher in need for cognition generally have greater elaboration motivation. The receiver’s ability to engage in elaboration can be influenced by factors such as the presence of distraction in the persuasive setting or the amount of relevant background knowledge; a person who lacks prior knowledge of the subject matter or is distracted may be unable to engage in issue-relevant thinking.
So, for example, when a topic is personally relevant to a receiver, the receiver is generally predisposed to engage in careful thinking, the receiver has extensive relevant background knowledge, and the receiver is undistracted, elaboration will presumably be high – and the central route to persuasion will be engaged. By contrast, on a topic that is not especially relevant, with a receiver who does not enjoy thinking hard and has little information about the topic, and in a context where there is considerable distraction, elaboration will presumably be low – and peripheral persuasion processes will be activated.
Influences On Persuasive Outcomes
Because central-route persuasion and peripheral-route persuasion have different underlying processes, the factors determining persuasive success correspondingly differ.
Influences On Persuasive Outcomes In Central-Route Persuasion
Under conditions of relatively high elaboration, the outcomes of persuasive efforts will largely depend on the outcomes of the receiver’s thoughtful consideration of issue-relevant arguments (as opposed to depending primarily on the operation of simple decision principles). Broadly put, when elaboration is high, persuasive effects will depend upon the predominant valence (positive or negative) of the receiver’s issue-relevant thoughts. To the extent that the receiver is led to have predominantly favorable thoughts about the advocated position, the message will presumably be relatively successful in eliciting attitude change in the desired direction; if the receiver has predominantly unfavorable thoughts, then the message will presumably be relatively unsuccessful.
Two primary factors influence the predominant valence (the overall evaluative direction) of elaboration. One is whether the message’s advocated position is proattitudinal or counterattitudinal for the receiver. Everything else being equal, one expects proattitudinal messages (ones advocating views toward which the receiver initially feels at least somewhat favorably inclined) to evoke predominantly favorable thoughts, and counterattitudinal messages to evoke predominantly unfavorable thoughts.
The second factor is the strength (quality) of the message’s arguments. Under conditions of high elaboration, receivers are willing and able to engage in extensive issue-relevant thinking, including careful examination of the message’s arguments. If such scrutiny reveals weak evidence, slipshod reasoning, and the like, predominantly negative reactions are to be expected. But if the message is seen to contain powerful arguments, good evidence, sound reasoning, and so forth, then more positive thoughts are likely to result. That is, under conditions of high elaboration, the quality (strength) of the message’s arguments influence the predominant valence of elaboration and hence affect persuasive success.
Influences On Persuasive Outcomes In Peripheral-Route Persuasion
Under conditions of relatively low elaboration, receivers are not engaged in thoughtful consideration of the message’s arguments and evidence. Rather, receivers use heuristic principles (“heuristics”), simple decision procedures that require little information processing; heuristics are activated by “peripheral cues,” extrinsic features of the communication situation such as the characteristics of the communicator. A number of such heuristics have been identified.
One is the credibility heuristic, in which receivers are guided by the apparent expertise of the communicator. Rather than carefully considering the message’s arguments, receivers can simply rely on the communicator’s credibility as a guide to what to believe: where the communicator is judged to be an expert, receivers will be persuaded by the communicator’s view (and where judged inexpert, the communicator will be relatively unpersuasive). A second heuristic is based on the receiver’s liking for the communicator; when this liking heuristic is employed, liked communicators will be more persuasive than disliked communicators. A third processing shortcut is the consensus heuristic, in which the receiver’s views are influenced by the reactions of others to the message; when this heuristic is activated, seeing approving reactions of others enhances the message’s persuasiveness (and disapproving reactions impair effectiveness).
As elaboration increases, the influence of such heuristics diminishes. When receivers are engaging in close scrutiny of and thinking about the message, peripheral cues such as the communicator’s likeability, the communicator’s credibility, and the reactions of other people play smaller roles as influences on persuasive outcomes. But where receivers are unable or unmotivated to engage in message scrutiny, these cognitive shortcuts are relied upon.
Complexities And Consequences In Persuasion Processes
Tradeoffs Between Central And Peripheral Persuasion Processes
Although the distinction between central and peripheral-route persuasion is convenient, one should remember that in fact there is an underlying continuum of elaboration. The central route and the peripheral route represent idealized extremes of this continuum, but at intermediate levels of elaboration, complex combinations of central-route and peripheral-route processes can be expected.
Thus, broadly speaking, there is a tradeoff between elaboration valence and peripheral cues as influences on persuasion. As elaboration increases, the impact of peripheral cues declines, and the impact of the valence of the receiver’s issue-relevant thinking increases. For example, as variations in argument strength make more difference in outcomes, variations in communicator expertise play smaller roles as peripheral cues. This tradeoff creates the possibility that, at intermediate levels of elaboration, both central and peripheral processes might operate.
Multiple Roles For Variables In Persuasion
The ELM emphasizes that any given variable might play multiple roles in persuasion. Specifically, a variable might influence persuasion in three ways. First, it might affect the degree of elaboration (and thus influence the degree to which central-route or peripheralroute processes are engaged). Second, it might serve as a peripheral cue (and so influence persuasive outcomes when peripheral-route persuasion is occurring). Third, it might influence the valence of elaboration (and so influence persuasive outcomes when central-route persuasion is occurring).
The ELM recognizes that a given variable need not play only one of these roles. In different circumstances, a variable might influence persuasion through different mechanisms. For example, communicator credibility might serve as a peripheral cue (activating the credibility heuristic) or it might influence the amount of elaboration (as when receivers decide that the communicator’s expertise makes the message worth attending to closely).
The possibility of different persuasion roles for a single variable points to considerable complexity in persuasion. Consider, for instance, the effects (on persuasive outcomes) of varying the communicator’s attractiveness. The ELM suggests that the effects will depend on the role played by attractiveness in the particular persuasion circumstance. Increasing the communicator’s attractiveness might enhance persuasion (e.g., if attractiveness operates as a peripheral cue that activates the liking heuristic, or if attractiveness enhances message scrutiny and the message contains strong arguments, or if attractiveness reduces message scrutiny and the message contains weak arguments, or if greater attractiveness encourages positive elaboration by serving as an argument – as might be the case in advertisements for beauty products), or might inhibit persuasion (e.g., if attractiveness enhances message scrutiny and the message contains weak arguments, or if attractiveness reduces message scrutiny and the message contains strong arguments), or might have relatively little influence on persuasion (if other factors play larger roles).
Consequences Of Differing Persuasion Routes
Although persuasion can be accomplished at any point along the elaboration continuum, differing degrees of elaboration will make for corresponding differences in the nature of the persuasive outcomes obtained. Where people’s attitudes are shaped through centralroute processes, those attitudes are likely to be more persistent over time, more directive of behavior, and more resistant to counterpersuasion (compared to attitudes influenced through peripheral-route processes). That is to say, central-route processes create persuasion that is more enduring and more integrated with a person’s belief system – as might be expected, given the greater amount of issue-relevant thinking involved in central-route persuasion. Persuasion accomplished through peripheral-route processes is likely to be more evanescent.
Future Directions And Contributions
At least four lines of future development of ELM ideas can be identified. One is continuing articulation of the nature of involvement (personal relevance). Several commentators have suggested that different varieties of involvement can be usefully distinguished as having differing effects on persuasion processes. No consensus has yet emerged about exactly how to more carefully specify involvement variations, but this will plainly be a subject of continuing attention.
A second is clarification of the nature of argument quality. Although the ELM emphasizes the role of variations in argument quality as an influence on persuasive outcomes under conditions of high elaboration, the model has not given much attention to unpacking exactly what makes for stronger and weaker arguments. At least some research suggests that the key ingredient of high-quality arguments may be the relative desirability of the properties attributed to the advocated view (e.g., the desirability of the consequences claimed for a social policy, or the desirability of the characteristics of a consumer product); that is, “strong” arguments are ones that mention properties especially valued by the audience.
A third issue is clarification of the conditions under which a given variable plays one role or another in persuasion. The ELM has usefully drawn attention to the possibility that a given variable might, in different circumstances, play different roles in persuasion processes. But it is not yet clear how one might predict when a given factor will serve in one role or another. Fashioning such an account is obviously of some importance.
Finally, the relationship of central-route and peripheral-route processes needs some attention. One prominent alternative to the ELM has been Kruglanski and Thompson’s “unimodel,” which proposes that the ELM’s two persuasion routes are similar in a fundamental way: in each route, receivers try to reach conclusions about what views to hold, using whatever evidence is available to them. Different kinds of evidence are employed in the two routes (peripheral cues in the peripheral route, the carefully scrutinized message arguments in the central route), but – the unimodel argues – there actually are not two fundamentally different processes here. Rather, there is just the one process of reasoning to conclusions based on evidence – and thus a “unimodel” of persuasion will suffice.
The unimodel stresses that both peripheral cues and message arguments can vary in their complexity, ease of processing, brevity, and so forth. But, it argues, in ELM research, peripheral cues have typically been quite simple and arguments have typically been quite complex – thus giving rise to apparent differences in how cues and arguments are processed. But, the unimodel argues, if cues and arguments are equalized with respect to complexity, then cues and arguments will be seen to be processed in identical ways, thus removing any need to posit two persuasion processes.
The unimodel raises many complicated issues and the empirical evidence bearing on the model is not uncontroversial. For instance, ELM defenders and unimodel advocates each point to research findings they believe only their favored model can explain – and each believes its model can accommodate the other’s findings. It will be some time before these questions can be sorted out, in part because the issues are both empirical (identifying differing predictions of the two models) and conceptual (for instance, whether it is true by definition that peripheral cues are easy to process).
The ELM has contributed two key insights about persuasion. One is the recognition of the variable character of topic-related thinking (elaboration) engaged in by message recipients. Because the extensiveness of topic-relevant thinking varies (from person to person, from situation to situation, etc.), the underlying persuasion processes vary and hence the factors influencing persuasive success vary. The second is the recognition that a given variable may play different roles in persuasion – it might in one circumstance influence the degree of elaboration, in another influence the valence of elaboration, and in a third serve as a peripheral cue. Naturally, then, a variable might have very different effects on persuasion from one situation to the next – which can give rise to seeming inconsistencies in research findings concerning the role played by a given factor. Taken together, these two insights offer the prospect of reconciling apparently conflicting findings and mark the ELM as an especially significant contribution to our understanding of persuasion.
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