Traditional theories of associative learning have found no place for the possibility that an individual's perception of events might change as a result of experience. Evidence for the reality of perceptual learning has come from procedures unlike those studied by learning theorists. The work reviewed in this book shows that learned changes in perceptual organization can in fact be demonstrated, even in experiments using procedures (such as conditioning and simple discrimination learning) which form the basis of associative theories. These results come from procedures that have been the focus...