Page 189 - Media Effects Advances in Theory and Research

178 PETTY, PRIESTER, BRIÑOL

Multiple Roles for Source Factors. Consider first the multiple
processes by which source factors, such as expertise or attractiveness, can
have an impact on persuasion (see Petty & Cacioppo, 1984c). In various
studies, source factors have been found to influence persuasion by serv-
ing as a peripheral cue when the likelihood of thinking was low. For
example, when the personal relevance of a message was low, highly
expert sources produced more persuasion than sources of low expertise
regardless of the quality of the arguments they presented (Petty,
6
Cacioppo, & Goldman, 1981; see also Chaiken, 1980). On the other hand,
in several studies in which the personal relevance of the message was not
specified and nothing else was done to make the likelihood of thinking
especially high or low (i.e., moderate elaboration likelihood), the source
factors of expertise and attractiveness affected how much thinking people
did about the message (Heesacker, Petty, & Cacioppo, 1983; Moore,
Hausknecht, & Thamodaran, 1986; Puckett, Petty, Cacioppo, & Fisher,
1983). That is, attractive and expert sources led to more persuasion when
the arguments were strong, but to less persuasion when the arguments
were weak. The self-monitoring scale (see Snyder, 1987) has been used to
distinguish people who tend to think more about what experts have to
say (i.e., low self-monitors) from those who are more interested in what
attractive sources have to say (i.e., high self-monitors; DeBono & Harnish,
1988).
When the likelihood of thinking is very high, source factors take on
other roles. For example, if a source factor is relevant to the merits of a
message, it can serve as a persuasive argument. Thus, as noted earlier, an
attractive endorser might provide persuasive visual evidence for the
effectiveness of a beauty product (Petty & Cacioppo, 1984c). In addition,
Chaiken and Maheswaran (1994) demonstrated a biasing effect on infor-
mation processing of source expertise. When recipients under high-
elaboration conditions received an ambiguous message (i.e., not clearly
strong or weak), expertise significantly affected the valence of the cogni-
tive responses generated (i.e., expertise biased message processing).
When the likelihood of thinking was low (i.e., the message was on an
unimportant topic), expertise did not affect message-relevant thoughts
and simply acted as a persuasion cue (see also Shavitt, Swan, Lowery, &
Wanke, 1994).
Under high-elaboration conditions, source factors have also been
found to influence persuasion by affecting the confidence people have in
the validity of the thoughts they have in response to the message. In one
study (Briñol, Tormala, & Petty, 2001), college students read a persuasive

6 In studies varying expertise or attractiveness, source trustworthiness is assumed to be
high.