Persuasion is a method of changing a person’s cognitions, feelings, behaviors, or general evaluations (attitudes) toward some object, issue, or person. Although any change technique is sometimes referred to as persuasion regardless of the target of influence, the term more commonly refers to a method of change in which a person is deliberately presented with a message containing information intended to alter some general evaluative judgment (e.g., capital punishment is bad). Self-persuasion can occur when people generate their own messages in favor of or against something. Persuasive communication is readily used by advertisers, salespeople, politicians, ministers, attorneys, and people in everyday situations to produce change in others. In democratic societies, persuasion has replaced coercion as the primary means of influence.
Persuasion History and Background
The power and prevalence of persuasion have led to a great deal of scientific research investigating the factors that make a persuasive appeal effective. In the 1950s, Carl Hovland and his colleagues at Yale University conducted the first systematic analysis of persuasion in what was known as the Yale Communication Project. The Yale group determined that four elements are present in all persuasion settings: (1) a source who delivers the persuasive message, (2) the message itself, (3) a target person or audience who receives the message (recipient), and (4) some context in which the message is received. Adopting an information-processing approach to persuasion, the researchers proposed that for a persuasive appeal to work, the message recipient must pay attention to, comprehend, learn, accept, and retain the message and its conclusion in memory. People’s degree of engagement in these steps was thought to be determined by various characteristics of the source, message, recipient, and persuasive context. For example, a highly complex message might be too difficult to comprehend and therefore, unable to be learned, accepted, or retained.
Later research showed, however, that persuasion often does not depend on the specific arguments in a message that people learn and remember but, rather, on what unique cognitive (mental) reactions they have in response to those arguments. That is, what matters most when people are actively processing the message is not learning what is in the message but what people think about the message. According to this cognitive response approach, persuasion is more likely when the recipient has favorable thoughts toward the message and less likely when the recipient’s thoughts about the message are unfavorable. For example, two individuals may both learn the same details of a proposal to increase the interstate speed limit and yet have wildly different thoughts (e.g., “I’ll be able to get to work faster” versus “It will make driving more dangerous”).
Current Theories of Persuasion
The learning and cognitive response approaches to persuasion focused on attitude change through active, effortful thinking. However, research has also shown that sometimes people are persuaded to change their attitudes when they are not thinking much about the information in the message. Instead, they base their attitudes on simple associative or heuristic processes that require less cognitive effort. Incorporating these different ideas, Richard Petty and John Cacioppo’s elaboration likelihood model (ELM) and Shelly Chaiken’s heuristic-systematic model (HSM) are two similar theories introduced in the 1980s that propose that both effortful and non-effortful processes can produce attitude change in different situations.
According to these models, when people are motivated and able to evaluate all the information relevant to the message’s position (high elaboration), they will follow the central or systematic route to persuasion. This corresponds to the cognitive response approach, whereby people’s favorable or unfavorable thoughts about the message and their confidence in them determine the degree of attitude change. In contrast, when people are not thinking carefully about the merits of the message (low elaboration), they can still be influenced by processes requiring less cognitive effort. For example, people can rely on mental shortcuts (e.g., “The package is impressive—it must be a good toothpaste.”) to decide if they agree with or like something. In these cases, people are said to be taking the peripheral or heuristic route to persuasion. In this case, the models claim that individuals will use the central (systematic) route when they are both motivated and able to consider the contents of the message thoughtfully. If for any reason, they are unwilling or unable to engage in effortful thinking, they will follow the peripheral (heuristic) route to persuasion.
Research using the information-processing and cognitive response approaches identified a number of source, message, recipient, and contextual variables that affect persuasion. Nevertheless, it was not clear from those studies exactly when and how each variable would affect attitude change. For example, in some studies a highly credible source enhanced persuasion, but in others the source inhibited persuasion. However, the two different routes to persuasion outlined in the ELM and HSM provide a valuable framework for determining when and how these variables will lead to attitude change. In particular, the ELM holds that any variable within the persuasion setting may play one of several roles. First, when people are not thinking carefully about the message, the variable is processed as a simple cue that influences attitudes by rudimentary association or heuristic processes. Second, when people are thoroughly considering the merits of the message, the variable will be scrutinized as an argument, bias ongoing processing of the message, or affect confidence in the thoughts generated. Finally, when thinking is not constrained to be high or low by other factors, the variable may affect how much processing occurs by acting as an indicator of whether or not it is worth putting effort into evaluating the message. The multiple roles for variables as explained by the ELM provide the basis for how different source, message, recipient, and context factors affect persuasion.
Source Variables in Persuasion
The source is the person or entity who delivers the persuasive appeal, and a number of source characteristics have been shown to influence attitude change. Two of the most commonly studied source variables are credibility and attractiveness. Credibility refers to the source’s (a) expertise and (b) trustworthiness. An expert source is one who has relevant knowledge or experience regarding the topic of the persuasive message. A trustworthy source is one who lacks ulterior motives and expresses honest opinions based on the information as he or she sees it. You may consider a physician (expert) and your best friend (trustworthy) to be credible sources. Attractiveness refers to how physically or socially appealing and likable the source is. For example, television commercials often use fashion models and charismatic celebrities to get people to like their products. In general (but not always), credible and attractive sources are more persuasive than are noncredible and unattractive sources.
Consistent with the ELM’s multiple roles hypothesis, source variables have been shown to influence persuasion in several different ways in different situations. Consider, for example, an advertisement for a brand of shampoo that features an attractive person using the product. People often associate attractiveness with positive feelings, and under low elaboration conditions, when there is little effortful thinking about the message, they may decide that they like the shampoo simply because the source makes them feel good. Under high elaboration conditions, when thinking is extensive, people may use the attractiveness of the source as evidence that the product gives them beautiful hair. Or, the source might bias their thinking so that positive thoughts selectively come to mind. Or, they might have more confidence in the thoughts they have if they think that attractive sources know what they are talking about. And if people are not sure how much to think about the message, the beauty of the source may induce them to pay more attention to the advertisement and its message. This would increase persuasion if what the source says is compelling, but if the message is not very compelling, thinking more about it could lead to less persuasion. Other source variables affect persuasion by the same mechanisms.
Researchers have also documented a delayed persuasion phenomenon that frequently involves source variables. Generally, the effect of an initially compelling persuasive appeal decreases over time as information about the message decays in memory. However, it has been shown that messages associated with a cue that discounts or weakens the initial impact of a message containing strong arguments, such as a noncredible or untrustworthy source, may not change attitudes initially but can lead to persuasion at later. This is called the sleeper effect. It happens because the discounting cue decays in memory faster than do thoughts about the message itself, which allows the message to affect attitudes free from the influence of the discounting cue.
Message Variables in Persuasion
The message refers to all aspects of the persuasive appeal itself such as its length, complexity, language, and so forth. One of the central characteristics of the message is the quality of the arguments it contains. The effect of argument quality on persuasion depends on how much the recipient is thinking about the message. When people are unwilling or unable to effort-fully process the message, they are influenced by peripheral cues or heuristics rather than by their analysis of the strength or weakness of the evidence presented. Thus, under low processing conditions, a weak message may be persuasive if it is paired with certain factors, such as a credible source. In contrast, when people are motivated and able to think carefully about the message, they will base their attitudes on the analysis of the merits of the evidence. Thus, under high processing conditions, a weak message will be low in persuasiveness even in the presence of a highly credible or likable source. Self-generated arguments (in role-playing, for example) are especially strong because individuals tend to be less resistant to their own thoughts and ideas.
When thinking is high, the message generally becomes more persuasive as argument strength increases. However, if people feel too pressured to change their attitudes, they might respond unfavorably to the message despite the strength of the reasons for change. Also, fear appeals (such as those designed to curb unhealthy behaviors) that are too anxiety arousing can lead people to defensively avoid thinking about the message. In fact, research has shown that fear appeals are most successful when the message is personally relevant, the fear aroused is moderate, and a clear, attainable solution to the problem is presented.
As with source variables, the ELM’s multiple roles hypothesis holds that message variables can influence persuasion in several different ways. For example, messages that have been tailored to match the basis of the recipient’s attitude are generally more persuasive than messages that mismatch. For example, religious types are more persuaded by messages framed in a religious manner. Also, attitudes based on feelings or affect tend to be more influenced by affectively based messages, whereas attitudes based on thoughts and cognitions tend to be affected more by cognitively based messages. How does matching work? Under low processing conditions, matching may lead to persuasion through a heuristic that messages that match are good. Under high processing conditions, however, matching positively biases processing of the message. That is, strong arguments that match elicit more favorable thoughts than do arguments that mismatch. When the amount of thinking is not constrained to be either high or low, matching increases scrutiny of the message, which leads to persuasion if the arguments in the message are compelling. However, if a matched message is not strong enough to overcome the original attitude, a mismatched message that directs recipients to think about the attitude object in a new way may be more persuasive. Other message variables influence persuasion in a similar manner.
Recipient Variables in Persuasion
The recipient is the target person or audience who receives the persuasive message. As with the source and message, a number of recipient characteristics have been found to influence attitude change. Many of these recipient factors have been shown to follow the multiple roles hypothesis of the ELM and can affect persuasion in several different ways. For example, when effortful thinking is low, a person’s mood serves as a simple peripheral cue (“I feel good, so I must agree with the message”). When effortful thinking is high, however, mood has been shown to serve in other roles. For example, under high thinking conditions, mood has biased the recipient’s thoughts. That is, positive mood facilitates the retrieval of other positive thoughts or inhibits the retrieval of negative thoughts. Thinking more positive thoughts will then lead to more favorable attitudes. Under high thinking conditions, a person’s mood has also been analyzed as an argument and affected the confidence in people’s thoughts. When the amount of thinking was not constrained to be high or low, mood influenced the amount of processing. Specifically, people in positive moods tend not to engage in effortful thinking, presumably because they want to maintain their good moods. However, those in positive moods will think carefully about a message if it is expected to advocate something pleasant. People in negative moods have been shown to engage in effortful processing of the message, regardless of whether it is expected to be pleasant or unpleasant. One explanation for this is that people in bad moods are in a problem-solving frame of mind, and thinking is associated with problem solving.
Some recipient variables influence persuasion by affecting people’s motivation to process the message thoughtfully. Need for cognition is an individual difference that refers to how much people engage in and enjoy thinking. Those high in need for cognition tend to like thinking and seek out tasks and activities that are cognitively engaging. In general, these individuals are more likely to carefully consider the merits of the message even when it is not personally relevant. As such, they will base their attitudes on the strength of the evidence. Those low in need for cognition, however, do not enjoy thinking as much and tend to avoid tasks that require extensive thinking. Consequently, they are more likely to form their attitudes based on simple associations and heuristics rather than on effortful assessments of the evidence. Those low in need for cognition can be motivated to process the message carefully, but they require greater incentive to do so.
Context Variables in Persuasion
Contextual factors such as the manner and circumstances in which the message is given can also influence persuasion. That is, how the message is presented can be as important as what is presented. For example, a persuasive appeal that is introduced in a written format (e.g., in a newspaper) is generally easier to process than is one in an audio format (e.g., on radio) because people can slow the pace of their reading or reread to make sure they understand the arguments. If people are distracted by some variable (e.g., loud noise in the room), they may be unable to think critically about the message and will instead follow the peripheral route to persuasion. In addition, merely associating the message with something positive (e.g., a nice meal) or simply repeating it several times can be used to make the attitude object seem more positive with little or no effortful thinking.
Attitude Strength and Persuasion
As just described, there are a number of ways that source, message, recipient, and context variables can lead to persuasion. Although there are many avenues to attitude change, not all produce equally impactful attitudes. Regardless of the influencing variable, persuasion through effortful (central route) processing generally results in stronger, more durable, and longer-lasting attitudes than does persuasion through less effortful (peripheral route) processing.
- Brinol, P., & Petty, R. E. (2005). Individual differences in attitude change. In D. Albarracin, B. T. Johnson, & M. P. Zanna (Eds.). Handbook of attitudes and attitude change (pp. 575-615). Mahwah, NJ: Erlbaum.
- Petty, R. E. (1995). Attitude change. In A. Tesser (Ed.). Advanced social psychology (pp. 195-255). New York: McGraw-Hill.
- Petty, R. E., Rucker, D., Bizer, G., & Cacioppo, J. T. (2004). The elaboration likelihood model of persuasion. In J. S. Seiter & G. H. Gass (Eds.), Perspectives on persuasion, social influence and compliance gaining (pp. 65-89). Boston: Allyn & Bacon.
- Petty, R. E., Wheeler, S. C., & Tormala, Z. L. (2003). Persuasion and attitude change. In T. Millon & M. J. Lerner (Eds.), Handbook of psychology: Vol. 5. Personality and social psychology (pp. 353-382). Hoboken, NJ: Wiley.