Totality of an individual's behavioral and emotional characteristics.
Personality embraces a person's moods, attitudes, opinions, motivations, and style of thinking, perceiving, speaking, and acting. It is part of what makes each individual distinct. Theories of personality have existed in most cultures and throughout most of recorded history. The ancient Greeks used their ideas about physiology to account for differences and similarities in temperament . In the 18th century Charles-Louis Montesquieu , and Giambattista Vico proposed ways of understanding individual and group differences; in the early 20th century Ernst Kretschmer and the psychoanalysts Sigmund Freud , Alfred Adler , and Carl Gustav Jung offered competing personality theories. Freud's model rested on the power of psychosexual drives as mediated by the structural components of the id , ego , and superego and the interplay of conscious and unconscious motives. Particularly important was the array of defense mechanism s an individual employed. Jung, like Freud, emphasized unconscious motives but de-emphasized sexuality and advanced a typal theory that classified people as introverts and extroverts ; he further claimed that an individual personality was a persona (i.e., social facade) drawn from the "collective unconscious," a pool of inherited memories. Later theories by Erik H. Erikson , Gordon W. Allport , and Carl R. Rogers were also influential. Contemporary personality studies tend to be empirical (based on the administration of projective tests or personality inventories), and less theoretically sweeping, and to emphasize personal identity and development. Personality traits are usually seen as the product of both genetic predisposition and experience. See also {{link=personality disorder">personality disorder ; psychological testing .