In psychoanalytic theory, the part of human personality that combines innate biological impulses (id) or drives with reality to produce appropriate behavior.
Sigmund Freud believed that human personality has three components: the id, the ego and the superego. In his scheme, the id urges immediate action on such basic needs as eating, drinking, and eliminating wastes without regard to consequences. The ego is that portion of the personality that imposes realistic limitations on such behavior. It decides whether id-motivated behavior is appropriate, given the prevailing social and environmental conditions.
While the id operates on the "pleasure principle," the ego uses the "reality principle" to determine whether to satisfy or delay fulfilling the id's demands. The ego considers the consequences of actions to modify the powerful drives of the id. A person's own concept of what is acceptable determines the ego's decisions. The ego also must "negotiate" with the superego (conscience) in the often bitter battle between the id's drives and a person's own sense of right and wrong. Repression and anxiety may result when the ego consistently overrides the id's extreme demands.
Atkinson, Rita L.; Richard C. Atkinson; Edward E. Smith; and Ernest R. Hilgard. Introduction to Psychology. 9th ed. San Diego: Harcourt Brace Jovanovich, 1987.
Zimbardo, Philip G. Psychology and Life. 12th ed. Glenview, IL: Scott, Foresman, 1988.