Secondary Reinforced Behavior in an Operant Situation among Dogs

Three- to five-year-old children (N = 134) approached each other in two experiments investigating age, sex, and dyadic sex composition differences in a social manifestation of the awareness of the sex of self and of others. Children of both sexes and at all ages both stopped and oriented their bodies farther away from opposite-sex peers than from same-sex peers, regardless of age-status or familiarity. A nonverbal technique, which is readily reproducible and experimentally manipulatable, is presented which measures an aspect of early awareness of one's own sex and that of others in an obviously meaningful interpersonal context.