The Elaboration Likelihood Model (ELM)

What is the Petty and Cacioppo ELM model?

In the early 1980s, Richard Petty and John Cacioppo developed a theory of persuasion and attitude change called the ELM or Elaboration Likelihood Model. They found that people reacted differently to a message depending upon whether that message was given peripheral processing (like an ad occurring in the background or full attention (like an ad being critically examined).

For example, an ad featuring puppies or babies and laughing, attractive people might produce warm, fuzzy feelings about almost any product, even life insurance, if a person is not paying much attention. But Petty and Cacioppo found that if people scrutinize the arguments in an ad, they are more likely to evaluate the quality of information and much less likely to be swayed by the atmospherics (such as the beauty of people advertising the product).

Why might an ad that receives superficial processing work better?

This is another line of research relating to the two modes of cognition discussed in Chapter 3 (States of Consciousness) and in Chapter 5 (Conditioning). Epstein (1995) suggested the two modes could be summarized as "the heart" and "the head." Emotional processing (the heart) often takes place out of consciousness through classical conditioning. Intellectual processing (the head) usually requires conscious attention and may be more analytical or critical.

Petty and Cacioppo tapped into this very basic distinction. They essentially showed that classical conditioning creates a warm and fuzzy emotional response to ads, but only when people do not have a reason to think analytically about the ads. If people have a conscious response, it might be critical (for example, "This advertiser is trying to manipulate me" or, "I don't need seven edges on my razor"). That could alter the emotional response. Then the ad might not create a positive attitude toward the product.

Of course, most people do not think critically about ads. Most ads only receive superficial or inattentive processing. Therefore ads that "say nothing" but surround a product with beautiful people (or puppies, or babies) may indeed work, most of the time. They create positive emotional associations to brand names and products. When a social scientist comes along and measures attitudes toward those brand names or products ("Which of these do you like best" or "Which brands to you trust") the heavily advertised products rate highest.

What did researchers discover about the effect of famous endorsers?

Petty, Cacioppo, and Schumann (1983) found that famous endorsers such as star athletes made advertising more persuasive only when people were in a low involvement condition, not very concerned about the product (a fictitious brand of disposable razor). When subjects were put into a high involvement condition (expecting to select a brand of razor given to them free) they paid more attention to the ad, and the celebrity endorsers lost their advantage.

This explains the name Elaboration Likelihood Model. The more likely people are to elaborate on an message (to relate it to other things they know, which means thinking about it) the less likely they are to show a non-specific positive emotional response to it. The likelihood of elaboration predicts the amount of attitude change.

How did these studies typify cognitive social psychology research?

The Petty and Cacioppo research illustrates cognitive social psychology, because it emphasized the type of information processing carried out by subjects and how this mental activity influenced the outcome of research. In contrast to earlier theories, which mostly tried to demonstrate that an effect could occur, research in the cognitive era tried to explain why and under what circumstances an effect might occur. We will discuss more examples of cognitive social psychology later in this chapter.

Write to Dr. Dewey at

Don't see what you need? Psych Web has over 1,000 pages, so it may be elsewhere on the site. Do a site-specific Google search using the box below.

Custom Search

Copyright © 2007 Russ Dewey