Proceedings of the Annual Meeting of the Cognitive Science Society

Four experiments explored the effect of diversity of contrasting evidence on inductive inferences drawn from a multi-item target. In Experiments 1 and 2, increasing the diversity of a contrast set led to lower generalization of a novelproperty that was probabilistically associated with the target. Further, this effect was not sensitive to weak vs. strongsampling assumptions (Experiment 3). Critically, when the property was universal (all target items shared the feature),increasing contrast diversity did not affect generalization to novel members of the target category (Experiment 4). Post-testquestioning suggested that people believed that the probabilistic property indicated subordinate categories in the target set(in fact, there werent). Such a change in the default-level representationin this case, from basic to subordinatealters theperceived size of the setswith subordinate, there are more items. Differences in default-level may explain these findings.We discuss implications for accounts of inferential reasoning.