Freud's psychoanalytic theory and stages of psychosexual development are summarized. His theory proposed that personality develops through five stages, each focused on a different erogenous zone: oral, anal, phallic, latency, and genital. Fixation in a stage can result in personality traits. Erikson's eight psychosocial stages across the lifespan are also outlined, describing the psychosocial crisis and related virtue at each stage. William James conceptualized the self as having two aspects: the "I" as thinker and actor, and the "me" as one's characteristics and capabilities. He described components of the self including the material, social, and spiritual aspects.