The nature of category formation is linked to the tasks applied to lea
rn the categories. To explore this idea, we investigated how three dif
ferent methods of category learning-Classification Learning, Inference
Learning, and Mixed Learning (a mixture of the two)-affect the way pe
ople form categories. In Classification Learning, subjects learned cat
egories by predicting the class to which an individually presented exe
mplar belonged given feature information about the exemplar. In Infere
nce Learning, subjects learned categories by predicting a feature valu
e of a stimulus given the class to which it belonged and information a
bout its other features. In Mixed Learning, subjects received the Clas
sification task on some trials and the Inference task on other trials.
The results of two experiments and model fitting indicate that infere
nce and classification, though closely related, require different stra
tegies to be carried out, and that when categories are learned by infe
rence or by classification, subjects acquire categories in a way that
accommodates these strategies. (C) 1998 Academic Press.