Pupillometric assessment of arousal to sexual stimuli: novelty effects or preference?

The pupillary response of male and female subjects to various sexual stimuli was examined. Change in pupil size was compared using light and dark control slides and nude male and female, heterosexual, and homosexual stimulus slides. Attempts were made to control for the many confounds inherent in pupillometric research. Pupil size was measured using video-recording techniques that magnified pupils to an easily measured size. Greater pupil change was found when the stimulus slide was preceded by a relatively lighter control slide. In addition, pupil change was related to familiarity with the stimulus slide and the relative pupil response changed as subjects gained experience with the stimulus material. Explanations and implications for further research are discussed.