Abstract
Self-formation was one of the most important processes in child development, although only few studies on this matter have been made by child psychologists. The purpose of this paper was to clarify the concept of the self and its significance for developmental studies on middle childhood. First, literature from the Journal and books edited by the Japanese Research Association of Psychological Science was examined to show that there appeared 3 terms, "jibun (I)", "jiko (self)", "jiga (ego)" in Japanese. The term "jiko" was at first seen on the topic of adolescent psychology and then seen in the realm of child psychology of school age. Second, a polyvalent feature of the self in primary school age was indicated by my own studies of social cognition, privacy, and ego development. That feature was notable and necessary for developmental transition from crowding to grouping during childhood. Third, the importance of intimate dialogue between brain science and clinical and developmental psychology was emphasized to realize the research on children whom we could see not only as individuals but also as peers.
