The Comparative Statics and Dynamics of Beliefs: The Effect of Message Discrepancy and Source Credibility

Two models of belief change, Laroche's (1977) comparative statics model and the single-push with friction dynamic model (Kaplowitz, Fink, & Bauer, 1983), were combined and tested. Beliefs about two issues (criminal sentencing and tuition increase) were measured every 77 ms, N=95. Eleven time points from each participant's belief trajectory were analyzed. Message discrepancy and source credibility were manipulated. As predicted, belief change monotonically increased over time and the rate of belief change decreased for both issues. For the criminal-sentencing issue, the relationship between message discrepancy and belief change was found to be positive and monotonic for messages from a high-credibility source but nonmonotonic for messages from a low-credibility source. For the criminal-sentencing issue the predicted overtime increase of the effect of message discrepancy on belief change for a high-credibility source and an over-time increase of the effect of source credibility on belief change were found.