The Early Development of the Interpersonal System of Personality (ISP).

This note sketches aspects of the development of the Interpersonal System of Personality (ISP), using information appearing in dissertations, theses, notes, correspondence, and publications prior to the classic 1951 paper by M. B. Freedman, T. F. Leary, A. G. Ossorio, and H. S. Coffey. Topics include the setting and the creation of the ISP, the authors' objective empirical investigation of the process of group therapy, and the accompanying growth in understanding from an initial, largely psychoanalytic orientation, to an explicitly interpersonal theory. Kurt Lewin's "field" and "vector" theories, Harry Stack Sullivan's "interpersonal force field," relevant classification schemes by others, and some neglected or poorly understood details of this history are presented.