In recent years there has been a substantial growth of interest in parallel distributed processing among experimental psychologists and neurobiologists. Many hope that developments in formal analysis of neural networks will provide a bridge between psychological accounts of cognitive function and those at the neural level. This volume examines the implications of these developments and their influence on experimental psychology and neurobiology. It includes coverage of formal PDP models, providing an introduction to the approach, with full information on assumptions and algorithms. The psychological implications of these models for research on both humans and animals is also discussed. Each of the main parts is introduced by a chapter that outlines the key issues under discussion.