Psychophysiological & psychological responses of frequent self-mutilation participants & an infrequent self-mutilation group to self mutilation imagery were compared to determine whether the reinforcement processes associated with the act itself alter as self-mutilative behavior becomes habitual. Results indicated that although psychophysiological benefits of the behavior are evident from the first episode, self-mutilation initially is perceived as a frightening experience which is associated with limited psychological benefits; psychological response alters as the behavior becomes habitual. (23 refs)