Psychology
Sigmund Freud's Psychoanalytic Theory of Personality
Quick fact
Freud developed his theory after treating patients with 'hysteria' whose symptoms disappeared when they talked about their childhood, leading him to propose that our present personality is anchored in unresolved memories and impulses buried in the unconscious.
Why this is interesting
Ever wonder why you sometimes do something you know you shouldn't? Freud's theory suggests a tiny inner battle inside your mind is behind it.