A brief critical review of longitudinal studies in developmental psychology is followed by presentation of the author's own extensive cross-cultural research of this type (social communication in the "mother - child" unit has been studied). Results of the study are in conflict with some oversimplistic behavioristic schemes of the process of socialization which assume the same valence of positive and negative reinforcement in the ontogenesis. It is possible to conclude therefore that the role of the identification and social imitation mechanisms in the development of personality and behavior becomes progressively greater with age.