Stimulus class formation has been studied independently by two groups of researchers. One group has come out of a learning theory approach, while the second has developed out of a behavior analytic tradition. The purpose of the present volume is to further establish the ties between these two research areas while allowing for differences in approach to the questions asked. The book is loosely organized around four themes. The first two sections deal with what constitutes functional and equivalence classes in animals and humans. In the third section, the authors attempt to identify stimulus...