Erik Erikson's 8-stage theory of personality

Although Erik Erikson (Berkeley and Harvard University) is considered one of the so-called Freudian ego psychologists and, like Freud, takes into account different stages of development in his 8-stage theory, his theoretical framework extends beyond adolescence into late adulthood. Erikson places less emphasis on purely instinctual drives or the unconscious, but instead also takes into account psychosocial and psychohistorical components. Furthermore, in his view of development, he tends to start from so-called epigenetic stages—that is, a sequence of stages in which the mastery of a developmental task and learning at one stage serve as the foundation for the next stage.

His theory posits that every developmental task may inherently involve conflicts and crises, and that, under certain circumstances, a task is not fully resolved at a single stage; rather, resolving the task as thoroughly as possible at one stage facilitates the transition to the next stage.