Source variables

Source credibility variables include:

• Source competence determinants and effects: perceived source credibility and therefore persuasive impact increase with general knowledgeability cues such as high level of education, intelligence, social status, etc.
• Forewarning effects on the subsequent communication's impact: The most interesting trustworthiness manipulation is forewarning of source's intent to persuade, which diminishes persuasive impact via some mediators and enhances it via others.
• Anticipatory attitude change effects of forewarnings: Most interesting of the forewarning effects is "anticipatory change" such that the warning itself, before any attack arrives, produces anticipatory attitude change.

Source attractiveness variables include: familiarity, likeability, and similarity.

Source power variables: Persuasion occurs through the compliance process when the receiver wants to get a reward or avoid punishment from a powerful source. Compliance-eliciting power may derive from many cues including: the source's perceived control over the receiver's rewards and punishments, concern about the receiver's complying, and ability to observe whether compliance occurs.