What mechanisms are involved categorization by children and adults?  We are interested in a fundamental question – namely, do people categorize on the basis of explicit rules that have become automated during learning, do they categorize on the basis of perceptive characteristics, such as, configural cues from individual exemplars, or is it a mixture of the two?  More generally, how do top-down and bottom-up processes interact during categorization?  We examine this question in a developmental framework, attempting to better understand how children generalize categorization rules that were learned from exemplars.  Our results show that the similarity of the learning items must be greater the younger the child is (Gelaes & Thibaut, 2006).  The data from this research indicates how children progressively integrate conceptual and perceptual information that is perceptually further and further removed from the stimuli from which the rule was originally derived.  French and Cowell (2007, 2010, in revision) have proposed a computational model of how these rules might arise from bottom-up processes and, thereafter, become part of the categorization process.  E. Bigand has conducted research on the categorization of musical styles.