The editor’s introduction identifies the major issues which have traditionally concerned students of human thought, and provides an historical background. It describes how at first the subject was studied by introspection, and how this method fell into disrepute at the end of last century. A satisfactory alternative has not yet emerged, although much recent work is based on the information-processing model, which sees the brain as a sophisticated computer. Consequently the papers presented in this volume deal with a wide range of issues, and a number of different experimental tasks and paradigms. They cover most current approaches to the theory and methodology of cognitive psychology, including problem solving, the relationship between language and thought, and reasoning.