Proceedings of the Annual Meeting of the Cognitive Science Society

How can we quantify the degree to which a piece of evidence affects a person’s belief? Philosophers investigating theories of Bayesian Confirmation have identified a plurality of potential measures, each with their own virtues and shortcomings. Psychologists meanwhile have largely neglected this question, which has limited their ability to understand differential belief updating, cases where certain individuals or groups respond to the same evidence in different ways. In this study, we examine how competing Bayesian confirmation measures track commonsense notions of evidential strength. We demonstrate how these measures can be computed from participants’ belief reports, and identify cases where the measures come apart in their characterization of participants’ belief updating. In so doing, this project seeks to build connections between investigations of psychological belief updating processes and formal epistemic theories of confirmation.