Testing an Information Processing Account of Message Intensity Effects.

A mathematical model of message intensity effects based on information processing theory was empirically tested and supported. Message intensity and source credibility were manipulated. Message intensity was a composite of language intensity and vocal intensity. Attitude change was a linear function of message discrepancy. Post-message liking multiplied the effect of discrepancy on attitude change for both the trusted and the distrusted source, ego-involvement inhibited attitude change for only the distrusted source. Path analysis indicated that message intensity prompted receivers to use source evaluation heuristics.