extraversion or extroversion and introversion

extraversion (or extroversion and introversion

a personality trait (see TRAIT THEORY) characterized, in the case of extraversion, by orientation towards the outside world, sociability and impulsiveness, and, in the case of introversion, by orientation towards the inner world of the self, shyness and caution. The extraversion-introversion typology was first described by JUNG (1928). It is one of the three central dimensions of personality in the model of personality structure proposed by H. Eysenck (1953), and in this context may be measured using the Eysenck Personality Inventory (EPD. A biological basis for extraversion-introversion in terms of cortical inhibition-excitation has also been postulated (H. Eysenck, 1967).
Collins Dictionary of Sociology, 3rd ed. © HarperCollins Publishers 2000