Extraversion and introversion

Extraversion and introversion are a central trait dimension in human personality theory. The terms were introduced into psychology by Carl Jung, though both the popular understanding and current psychological usage are not the same as Jung's original concept. Extraversion (also spelled extroversion) is typically associated with sociability, talkativeness, and high energy, while introversion is linked to introspection, reserve, and a preference for solitary activities. Jung defined introversion as an "attitude-type characterised by orientation in life through subjective psychic contents", and extraversion as "an attitude-type characterised by concentration of interest on the external object".

While often presented as opposite ends of a single continuum, many personality theorists, such as Carl Jung, have suggested that most individuals possesses elements of both traits, with one being more dominant. Virtually all comprehensive models of personality include these concepts in various forms. Examples include the Big Five model, Jung's analytical psychology, Hans Eysenck's three-factor model, Raymond Cattell's 16 personality factors, the Minnesota Multiphasic Personality Inventory, and the Myers–Briggs Type Indicator.

In September 1909, Swiss psychiatrist Carl Jung used the term introverted in a lecture at Clark University. A transcript of this lecture was then published with two others in a journal in 1910, the first time the term appeared in print. In the lecture he mentions that love that is "introverted", "is turned inward into the subject and there produces increased imaginative activity".

His 1921 book Psychologische Typen was published as Personality Types in English in 1923. It described the "introverted" in detail for the first time. In his later paper, Psychologische Typologie, he gives a more concise definition of the introverted type, writing:

He holds aloof from external happenings, does not join in, has a distinct dislike of society as soon as he finds himself among too many people. In a large gathering he feels lonely and lost. The more crowded it is, the greater becomes his resistance. He is not in the least "with it," and has no love of enthusiastic get-togethers. He is not a good mixer. What he does, he does in his own way, barricading himself against influences from outside. He is apt to appear awkward, often seeming inhibited, and it frequently happens that, by a certain brusqueness of manner, or by his glum unapproachability, or some kind of malapropism, he causes unwitting offence to people...

For him self-communings are a pleasure. His own world is a safe harbor, a carefully tended and walled-in garden, closed to the public and hidden from prying eyes. His own company is the best. He feels at home in his world, where the only changes are made by himself. His best work is done with his own resources, on his own initiative, and in his own way...

Crowds, majority views, public opinion, popular enthusiasm never convince him of anything, but mere make him creep still deeper into his shell.

His relations with other people become warm only when safety is guaranteed, and when he can lay aside his defensive distrust. All too often he cannot, and consequently the number of friends and acquaintances is very restricted.