1. any theory based on the continuity of human development and the importance of early experiences in shaping personality. Examples are the psychoanalytic theory of psychosexual development, Erikson’s eight stages of psychosocial development, learning theories that stress early conditioning, and role theories that focus on the gradual acquisition of different roles in life.

2. the proposition that intellectual disability is due to slower than normal development of cognitive processes but that such processes are not otherwise qualitatively different from those of people without intellectual disability. Also called developmental orientation. Compare defect theory.