Written for anyone who does or plans to do behavioral research, this book is based on the thesis that the psychological laboratory is a special place for people brought there as subjects. Accordingly, subjects act in ways that bear little relationship to their behaviours in the life situations to which psychologists seek to generalize their findings. An analysis is given of the motives, feelings and intentions common to people who assume the role of psychological subjects. The ways in which their responses confound data and lead to spurious conclusions are described