Proceedings of the Annual Meeting of the Cognitive Science Society

Leading models of human categorization posit that an observed stimulus is classified according to its similarity to storedreference points. In the present study, we investigate a category structure that elicits human generalization behavior notpredicted by the reference point framework. In a supervised classification learning task, participants were presented withsimple continuous-valued stimuli (one- or two-dimensional) based on an underlying category structure with a strict patternof alternating regions assigned to each class (e.g., A A B B A A B B ? ?). The participants were then tested on newstimuli with dimension values beyond the range seen in training. A large portion of participants classified new items byextrapolating the alternation sequence they did not classify based on similarity to the nearby reference points. Theseresults pose a challenge to reference point models and raise important issues about concept formation and generalization.