This document discusses the development of self from infancy through adulthood. It notes that infants begin to develop a basic sense of self around 8 months when they experience separation distress from caregivers. Between 18-24 months, most children can recognize their reflection in a mirror. During the preschool years, children understand themselves based on observable traits, but have unrealistically positive self-evaluations. Through school-age and adolescence, the self-concept becomes more complex and integrated as abstract thinking develops, though adolescents may be preoccupied with how others see them. By late adolescence/early adulthood, the conception of self is usually more coherent and internally defined.