Do Americans Have a Preference for Rule-Based Classification?

Six experiments investigated variables predicted to influence subjects' tendency to classify items by a single property (rule-based responding) instead of overall similarity, following the paradigm of Norenzayan et al. (, Cognitive Science), who found that European Americans tended to give more "logical" rule-based responses. However, in five experiments with Mechanical Turk subjects and undergraduates at an American university, we found a consistent preference for similarity-based responding. A sixth experiment with Korean undergraduates revealed an effect of instructions, also reported by Norenzayan et al., in which classification instructions led to majority rule-based responding but similarity instructions led to overall similarity grouping. Our American subjects showed no such difference and used similarity more overall. We conclude that Americans do not have a preference for rule responding in classification and discuss the differences between tasks that reliably show strong rule or unidimensional preferences (category construction and category learning) in contrast to this classification paradigm.