basic personality types according to the theories of the 20th-century Swiss psychiatrist Carl Jung (Jung, Carl). According to these theories, an introvert is a person whose interest is generally directed inward toward his own feelings and thoughts, in contrast to an extravert, whose attention is directed toward other people and the outside world. The typical introvert is shy, contemplative, and reserved and tends to have difficulty adjusting to social situations. Excessive daydreaming and introspection, careful balancing of considerations before reaching decisions, and withdrawal under stress are also typical of the introverted personality. The extravert, by contrast, is characterized by outgoingness, responsiveness to other persons, activity, aggressiveness, and the ability to make quick decisions.

This typology is now regarded as overly simplistic because almost no one can be accurately described as wholly introvert or extravert. Most persons fall somewhere between Jung's two types—i.e., they are ambiverts, in whom introversive and extraversive tendencies exist in a rough balance and are manifested at different times in response to different situations.