RECENT STUDIES of families of schizophrenics have reported that family interaction plays an important role in the development and maintenance of the thought disorder of schizophrenia. The present paper is an introduction to a series of experiments that have been designed and executed to answer part of the more general question raised by these studies: the relationship between family process and individual thought and perception. The experiments were designed to answer the following questions in particular. (a) Can we demonstrate, in the laboratory, that family interaction does affect the thought and perception of its individual members? (b) If so, how is this influence effected? (c) Are there special forms of such influence in families of schizophrenics ? In order to answer these questions we studied the performance of a number of families working together on experimental puzzles. We developed objective, quantitative, and reproducible