Page 40 - The Handbook of Persuasion and Social Marketing

Social Psychological Foundations of Social Marketing 33

The difficulty in such an approach is that the formula for successful
persuasion is not as simple as highly credible sources being more persua-
sive than less-credible sources, more arguments always being more per-
suasive than fewer arguments, or a recipient in a positive mood being
easier to persuade than a recipient in a negative mood. Indeed, excitement
about seemingly simple early findings on attitudes and persuasion became
momentarily marred by more complex and conflicting findings. For exam-
ple, whereas early research found that credible sources enhanced persua-
sion (Hovland & Weiss, 1951), later research found that the use of credible
sources could decrease persuasion (Sternthal, Dholakia & Leavitt, 1978).
Whereas initial research suggested that increasing the number of argu-
ments increased persuasion (Calder, Insko & Yandell, 1974), later research
found that enhancing the number of arguments either had no effect
(Norman, 1976) or could decrease persuasion (Petty & Cacioppo, 1984a).
And whereas research suggested negative emotions decreased persuasion
(Zanna, Kiesler & Pilkonis, 1970), other research found that negative
emotions could sometimes increase persuasion (Rogers, 1983).
The contradictory evidence for how the same variable affected persua-
sion had at least two noticeable effects. First, these findings crippled efforts
to link a particular variable (e.g., the use of a highly credible source) with
a single and unilateral effect on persuasion (i.e., more persuasion) (Petty,
1997; Petty & Briñol, 2008). Second, these findings raised the question of
whether there was a scientific manner to craft messages beyond trial and
error. In response to these findings, researchers moved away from trying to
understand whether a particular variable had a positive or negative effect
on persuasion and instead sought to understand when and why a variable
had a positive versus a negative effect on persuasion.

The Elaboration Likelihood Model

One of the most prominent solutions to understanding when the same
variable would have a positive versus a negative effect on persuasion and
why each effect would occur came with the introduction of the Elaboration
Likelihood Model (Petty & Cacioppo, 1981, 1986). The ELM is a model
of persuasion that focuses on how persuasion is affected by recipient elab-
oration—the amount of message-relevant thinking an individual engages
in when processing a persuasive message. Petty and Cacioppo (1981,
1986) introduced the idea that the amount of effort people put into
processing information rests on an elaboration continuum. At one end of
the continuum, people engage in relatively little scrutiny and thinking
about the information presented (low elaboration). At the other end of the