Multiple Source Characteristics and Persuasion: Source Inconsistency as a Determinant of Message Scrutiny

It is argued that previous persuasion research has been concerned predominantly with the role of single source characteristics (e.g., expertise) for attitude change and thus has failed to consider the role of multiple source characteristics. This was done in two experiments that tested the hypothesis that recipients would scrutinize a message more effortfully when the combination of two source characteristics is unexpected (source inconsistency) than when the combination is less surprising (source consistency). In Experiment 1, source likability, source expertise, and argument quality were manipulated. In Experiment 2, honesty instead of likability was manipulated. Results from both experiments provide evidence supporting the predicted effects of source (in)consistency on message scrutiny; that is, argument quality affected attitudes and favorability of message-related thoughts in the case of inconsistent source characteristics but not in the case of consistent source characteristics.