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Elaboration
Likelihood Model (ELM)
Petty
and Cacioppo's Elaboration Likelihood Model
Two
"Routes" to Persuasion
Involvement
and Cognitive Responses
Argument
Quality
Argument
Quantity
Source
Factors
Evaluation of the ELM
Glossary
References
Self-Test
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Evaluation
of the ELM
The
ELM is a very powerful theory of persuasion. It recognizes
that sometimes audiences are active, thinking about messages
and the arguments in those messages. However, the ELM also
realizes that at other times receivers are passive, being
persuaded by the peripheral route. The ELM identifies two
readily understandable conditions that determine whether the
listener is doing central or peripheral processing: Central
processing requires that receivers have both ability and
motivation to think about a message. The ELM identifies
several factors that influence the kind of thoughts listeners
are likely to have: involvement, argument quality, argument
quantity, credibility. Thus, conceptually this is a very good
theory of persuasion.
The primary weakness of this theory is the metaphor it picked.
Petty and Cacioppo state that there are two “routes” to
persuasion, central and peripheral. However, if someone says,
“There are two routes you can take from Los
Angeles
to San
Diego:
I-5 or I-15,” you would take one or the other -- but not
both in the same trip. However, “central” and
“peripheral” are not really two choices but the end points
of a continuum. A listener can think more thoughts (and be
closer to the “central” end of the continuum) or fewer
thoughts (and be closer to the “peripheral” end). It
isn’t an either/or choice, as the metaphor two “routes”
suggests. In fact, even peripheral processing requires some
thoughts. The receiver must notice, for example, “this
persuader seems to be an expert” and then think “if an
expert says so, it is probably true” for peripheral
processing to occur. So, Petty and Cacioppo inadvertently
created the impression that listeners do either central
or peripheral processing, but not both, by the metaphor
they chose to explain their theory.
Experimental research has produced a great deal of
experimental support for the ELM. I’ve cited some of that
research above.
Eagly and Chaiken (1993) provide a more global
summary of the research related to the ELM:
"The assumption
that systematic or central route processing requires
motivation and ability has been documented in many studies,
using a variety of motivational and ability variables:
Persuasive argumentation is a more important determinant of
persuasion when recipients are motivated and able to process
attitude-relevant information than when they are not.
There is also substantial empirical support for the hypothesis
of these models that heuristic or peripheral cues exert a
sizable persuasive impact when motivation or ability for
argument processing is low, but little impact when motivation
and ability are high" (p. 333).
Thus,
there is a great deal of research supporting the ELM approach
to persuasion and attitude change.
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