Persuasion: Motivational Factors Influencing Attitude Change

To assess the success of persuasive messages under different circumstances, an analysis of variance (ANOVA) is performed on the attitudes toward a topic presented via an oral message. Three factors were predicted to affect attitude change: motivational relevance, source, and argument content. By including the variable of motivational relevance, researchers can determine if source and argument content affect successful persuasion under high- versus low-motivational relevance. This is known as testing an interaction effect.

The results showed a main effect of argument quality: The strong arguments lead to greater agreement with the message than weak arguments. There was also a main effect of source: Averaged across the other conditions there was greater agreement for the message when the source had high expertise than when the source had low expertise. However, of particular interest was the discovery of an interaction effect (Figure 1). When participants were in the high-relevance group, the effect of argument quality was stronger than when the participants were in the low relevance group. The opposite was true for the source condition: when participants were in the low-relevance group, the effect of high-source expertise was greater than when the participants were in the high-relevance group.

Figure 1: The interactive effect of source expertise and motivational relevance (top) or argument quality and motivational relevance (bottom) on agreement toward the comprehensive exam message. Participants agreed with the message more if the source was an expert only when the motivational relevance was low. However, participants agreed with the message more if the argument quality was strong only when the motivational relevance was high.

In the debate over what factors lead to a message being persuasive, this experiment provides a careful test of the idea that motivational factors, such as personal relevance of the message, play a pivotal role in determining the impact of factors that generally affect persuasion, including source characteristics and argument quality. The result of this experiment and the Elaboration Likelihood Model that took hold because of its results, steered the field in a new direction when it was in a battle over whether source characteristics or argument quality were the most important factors influencing persuasion. These data suggest that the answer is they are both important, but the motivational context in which the message is embedded is important to consider to determine when the factors will exert their influence on persuasion.

These results have considerable implications for areas such as marketing, politics, and public health. In terms of marketing, businesses can use the findings of the study to help design effective campaigns that are designed to spread positive messages about their product. For example, if an ad campaign on some media outlet is targeted at an audience for which the product is personally relevant (e.g., a video game targeting a demographic of teenage boys), then the research suggests that the advertisement should include factual evidence the game is a good one to buy (e.g., statistics demonstrating that everyone is playing it). If the advertisement is being presented to another audience that may buy the game but is not personally relevant for them (e.g., parents looking to a buy a game for the kid), then the source of the advertisement message is more important (e.g., the advertisement is endorsed by a pro-gamer or a computer technician).

In terms of politics, political candidates can try to persuade people about their policies differentially based on what crowd they are speaking to. When the policies they are discussing are directly relevant to their crowd, such as the case of discussing one's position on abortion to a crowd of young women, the politicians should use high quality arguments rather than rely on personal anecdotes. In other cases where the crowd is less interested in the policy being discussed, as in the case of discussing retirement policies to a young college crowd, tactics that make the candidate appear to be the expert on the issue may be more important than crafting a quality argument.

Finally, in terms of public health and other related fields, the findings of this study can be used to create effective campaigns that attempt to get the public to behave different than their currently behavior. For example, if campaigns about hypertension are targeted in low-income African American communities where hypertension rates higher than average, constructing an argument that appears to be supported by data and facts may be more important than emphasizing the source of the public-service advertisement.