The association of pupillary constriction with negative valence stimulation was explored within the context of Eysenck's theory of extraversion. Three groups of 11 introverts, ambiverts, and extraverts observed the auditory presentation of 12 affective. 12 taboo, and 24 matched neutral words. Introverts yielded the largest average pupil size under all conditions and the largest magnitude of change in pupil size from prestimulus level. The results support Kysenck's general statement relating extroversion and cortical arousal in its postulate of a higher level of arousal in introverts. The general hypothesis that the pupil constricts to unpleasant stimulation was not affirmed.