Ego psychology was developed from the notion that personality cannot be solely defined as the dynamic interaction of sexual and aggressive drives with the conscious and unconscious minds, as Sigmund Freud (1856–1939) had suggested. Instead, ego psychology adherents focus on the ego as a major force in development and view the ego as serving several functions, including reality testing, the development of tolerance, the overseeing of defenses and coping capabilities, the development of judgment, and the managing of affect and impulse control. In addition, in contrast to Freud, who stated that personality developed through the psychosexual stages that encompass the first 5 or 6 years of life, ego psychology suggests that development occurs over the life span.