Proceedings of the Annual Meeting of the Cognitive Science Society

Hierarchical category systems evolve in response to a changing environment encountered over time. To better understand how such systems develop, we designed a task in which participants sequentially incorporated novel stimuli into an existing taxonomy. We manipulated presentation order, similarity to existing categories, and category system depth. All three factors shaped the hierarchical systems that emerged, and the likelihood of creating a new high-level category decreased as system depth increased. Our findings show that hierarchical category systems depend on the sequence in which items are encountered, and that sequence effects can result in hierarchical category systems that are skewed representations of the world.