extroverted people Photo courtesy of Big ThinkOpens in new window

Among the most well-known and well-researched traits in personality psychology is extraversion, a collection of attributes that includes sociability, positive emotion, activity and assertiveness, excitement-seeking, and sometimes impulsiveness.

Extraversion is a trait continuum such that each individual possesses anywhere from very low amounts of extraversion (which is called introversion) to very high amounts (called extraversion).

Most people actually fall somewhere in the middle of the continuum, and neither label—”extravert” nor “introvert”—describes these perons very well. These individuals are called ambiverts.

The person who is extremely high in extraversion frequently experiences positive emotion. Some researchers (e.g., Watson & Clark, 1997) argue that the positive emotionOpens in new window causes many of the other subtraits of extraversion.

It is the extravert’s happinessOpens in new window, joyOpens in new window, and excitement that leads to sociability, activity, assertiveness, and other qualities. In conjunction with the positive emotionOpens in new window, extraverts have more positive experiences than people who are not extraverts.

For example, compared to introverts, extraverts live longer, are healthier, are more successful in relationships, are more satisfied in their jobs, and are more likely to be leaders (Ozer & Benet-Martinez, 2006). Perhaps counterintuitive, extraversion has nothing to do with negative emotionOpens in new window.

Although extraverts experience more positive emotion than introverts and ambiverts, they do not experience any more or less negative emotion. Therefore an extravert could experience low, moderate, or high amounts of negative emotion compared to other people.

Some researchers have hypothesized that extraversion may have a biological basis. For example, British psychologist Hans EysenckOpens in new window proposed that the trait continuum extraversion-introversion is related to activity of a brain structure, the reticular activating systemOpens in new window, a set of nerve fibers extending to from the spinal cord into the interior of the brain.

The reticular activating system is responsible for physiological arousal. Eysenck’s hypothesis was that extraverts’ brain activity in this area is low whereas introverts’ activity is high.

Because of the low activation in the brain, Eysenck argued, extraverts seek stimulation from the outside world. Conversely, introverts are over-aroused and thus choose to withdraw from stimulation.

In general, research has not supported this idea that brain activity associated with general arousal is any different in extraverts or introverts. More recent theories center on a chemical messenger in the brain that is implicated in pleasure and reward called dopamine.

Results of one study indicated that in a specific laboratory situation, dopamine was more active in extraverts’ than in introverts’ brains (Depue, Luciana, Arbisi, Collins, & Leon, 1994). If a reliable relationship exists between extraversion and dopamine, it is likely complex, and research in this area is ongoing.

See also:
  1. Depue, R.A., Luciana, M., Arbisi, P., Collins, P., & Leon, A. (1994). Dopamine and the structure of personality: Relationship of agonist-induced dopamine activity to positive emotionality. Journal of Personality and Social Psychology, 67, 485 – 498.
  2. Ozer, D.J., & Benet-Martinez, V. (2006). Personality and the prediction of consequential outcomes. Annual Review of Psychology, 57, 401 – 421.
  3. Watson, D., & Clark, L. A. (1997). Extraverion and its positive emotional core. In R. Hogan, J. Johnson, & S. Briggs (Eds.), Handbook of personality psychology. (pp. 767 – 793). San Diego: Academic Press.