ABSTRACT
Introduction As a developmentalist, it is interesting to characterize the field of psychology in terms of its stages of scientific advancement. For many years the theoretical efforts of individuals appeared to represent ex ercises in solitary play, idiosyncratic formulations which were pursued in isolation. As we came to define ourselves as a legitimate domain of scientific inquiry, we advanced to a stage more analogous to parallel play. Dimly aware that other branches of the field existed, we were content to promote the growth of our own specialty, be it learning, perception, physiological cognition, affect social psychology, person ality, or psychopathology. In our theoretical egocentrism we might have found ourselves occasionally talking to our colleague in the next laboratory or office, though rarely did we listen.
