reality principle
in classical psychoanalytic theory, the regulatory mechanism that represents the demands of the external world and requires the individual to forgo or modify instinctual gratification or to postpone it to a more appropriate time. In contrast to the pleasure principle, which is posited to dominate the life of the infant and child and govern the id, or instinctual impulses, the reality principle is posited to govern the ego, which controls impulses and enables people to deal rationally and effectively with the situations of life.