The Persuasive Effect of Source Credibility: Tests of Cognitive Response

Two experiments are reported identifying the circumstances In which high credibility either facilitates, inhibits, or has no effect on the communica-tors persuasiveness in relation to a less credible source. These data pro-vide support for the cognitive response view of information processing and suggest the importance of message recipients initial opinion as a determinant of persuasion. In experimental investigations of the persuasive ef-fect of source credibility, it has been frequently demonstrated that highly trustworthy and expert spokespeople induce a greater positive attitude toward the position they advocate than do communicators with less credibility (cf. Stemthal, Phillips, and Dholakia in press). This finding can be explained in terms of cognitive response (cf. Greenwald 1968, 1970; Petty, Ostrom, and Brock 1978). According to this formulation, a message recipients initial opinion is an important determinant of influence. In response to a persuasive appeal, individuals rehearse their issue-relevant thoughts, as well as those presented to them. Message rejection occurs when people opposed to the communicators advocacy review counterarguments to assertions made to the message. If a highly credible source inhibits counterarguing. whereas a less credible source does not, cognitive response predicts the su-perior persuasive power of a highly credible com-municator. Consistent with this interpretation. Cook (1969) reported less counterargumentation in response to a competent source than to an incompetent source. Despite the substantial number of studies indicating that a highly credible source is more persuasive than a low credibility source, this finding is less than univocal. • Brian Stemthal is Assistant Professor, Depanment of Marketing,