1. according to Erik Erikson, personality development as a process influenced by social and cultural factors throughout the lifespan. See Erikson’s eight stages of psychosocial development. 2. the development of both prosocial behavior (e.g., cooperation) and antisocial behavior (e.g., aggression). Psychosocial development involves changes not only in children’s overt behavior but also in their social cognition. For example, they become able to take the perspective of others and to understand that other people’s behavior is based on their knowledge and desires.