The Hess pupil dilation findings: Sex or novelty?

Pupil dilation research was initially focused upon emotional reactions and then shifted almost entirely to information processing. In the present study we return to the initial research and addresses the question of whether pupil dilation in response to nudity reflects general arousal or more specific sexual arousal. Among heterosexual participants, pictures of opposite sex nudes should produce sexual arousal, while pictures of nudes of either sex should produce a general novelty reaction. Pupil dilation was monitored among men and women viewing pictures of clothed men, clothed women, nude men, and nude women. Pupils dilated more to nude pictures than to the clothed pictures, regardless of the sex of the participant or the sex of the target person being viewed.