In this paper. seven experiments are described in which the effect of contr
ast categories on the within-category structure of superordinate and basic
level natural language concepts was studied. intension-based and extension-
based predictors originating from both the target category and a contrast c
ategory were used to predict typicality ratings and response times in twt,
different speeded categorization tasks. Virtually no evidence for contrast
category effects was found in any of the experiments. These findings contra
st with what one would expect based on results reported by Rosch and Mervis
(1975) anti on many exemplar models. in which a contrast category effect i
s explicitly assumed, (C) 2001 Academic Press.