Proceedings of the Annual Meeting of the Cognitive Science Society

We examined whether probability weighting in decisions madeunder risk changed depending on the difference in evaluationmethods. In particular, we focused on two methods, joint eval-uation (JE) and separate evaluation (SE). We conducted a be-havioral experiment and found that participants put more prob-ability weight on small probability when using the SE methodthan when using JE, and that for large probabilities, the inversewas observed (i.e., participants put more weight in JE). We an-alyzed these results using a cognitive model and found that par-ticipants’ subjective value of money does not change owing todifferences in evaluation methods. However, beliefs concern-ing uncertain events shifted depending on evaluation methods,which led to the differences in probability weight. In this paper,we also discuss psychological mechanisms that produce differ-ent judgments or evaluations between SE and JE.