Many studies have shown that introverts and extroverts have brain differences which cause many of these behavioral differences. In one study published in the American Journal of Psychiatry, researchers measured cerebral blood flow of introverted and extroverted people while they thought freely. Introverts were found to have more blood flow in the brain regions involved with recalling events, while extroverts were found to have more blood flow in brain regions involved with interpreting sensory data. This supports Jung’s belief that extroverts focus their attention outward, while introverts focus their attention inward.
