Sigmund Freud

Meaning: Freud (1856–1939) founded psychoanalysis, the psychodynamic view that much of mental life is unconscious and that personality comes from conflict among three parts. The id holds instinctual drives and follows the pleasure principle. The superego holds internalized moral standards. The ego follows the reality principle and mediates between them. Anxiety from this conflict is managed by defense mechanisms such as repression, denial, projection, displacement, reaction formation, rationalization, and sublimation. His psychosexual stages are oral, anal, phallic, latency, and genital; fixation from unresolved conflict at a stage is thought to shape adult traits.

On the MCAT: A vignette describes behavior and asks you to name the defense mechanism (a person angry at a boss who then yells at family shows displacement) or the part of personality at work. Freud also appears as the example of the psychodynamic perspective, contrasted with behaviorist, humanistic, and biological perspectives. Critics note that many of his claims are hard to falsify.

Common confusion: Id, ego, and superego are concepts, not brain regions, and the ego is not self-esteem. Students also mix Freud's psychosexual stages with Erikson's psychosocial stages; Freud's stages center on where libido is focused, Erikson's on social crises across the lifespan.