Sodium amytal and extraversion.

" Extraversion" and " introversion " are descriptive terms denoting two types of behavioural reaction and personality organization widely recognized and described in psychological literature (Guilford, 1934; Eysenck, 1953). "Extraverted behaviour " is characterized clinically by the outward expression of feelings and attitudes, in words; gestures, and acts, in a spontaneous and direct manner, little impeded by reflection, indecision, or reserve. The contrary, " introverted behaviour ", comprises a tendency to limit or moderate spontaneous outward expression, reflection, preoccupation, and rumination rather predominating. A reserved or even withdrawn attitude may be maintained. While individual people may be predominantly introverted or extraverted in their behaviour, fluctuation normally occurs from one form to the other. Introducing these types Jung (1923) writes: " But every individual possesses both mechanisms -extraversion as well as introversion-and only the relative predominance of the one or the other determines the type." (p. 10)