The psychodynamic approach views abnormality as arising from unresolved unconscious conflicts from childhood. Freud proposed that personality is composed of the id, ego, and superego, which are constantly in conflict. The ego uses defense mechanisms to resolve conflicts and reduce anxiety. Abnormality can result if a person becomes fixated during one of Freud's psychosexual stages of development such as the oral, anal, phallic, or genital stages. The psychodynamic approach has explanatory power but is difficult to test scientifically.