Eysenck conceptualized personality as three biologically based traits of temperament: extraversion, neuroticism, and psychoticism (H. J. Eysenck & M. W. Eysenck, 1985). Extraversion is characterized by being outgoing, talkative, high on positive affect, and in need of external stimulation. According to Eysenck's arousal theory of extraversion, there is an optimal level of cortical arousal, and performance deteriorates as one becomes more or less aroused than this optimal level. Thus, at very low and very high levels of arousal, performance is low, but at a more optimal mid-level of arousal, performance is maximized.1 Extraverts, according to Eysenck's theory, are chronically under-aroused and bored and are therefore in need of external stimulation to bring them up to an optimal level of performance. Introverts, on the other hand, are chronically over-aroused and jittery and are therefore in need of peace and quiet to bring them up to an optimal level of performance.