A landmark study finds that when we look at sad faces, the size of the pupil we look at influences the size of our own pupil

Abstract

In a study certain to become a classic, Harrison et al. (see record 2007-02700-003) have demonstrated a role for pupil size in such mirroring. Their data are impressive: behaviorally, the pupil size of sad faces influences viewers' emotion judgments of the face, even in the absence of explicit awareness of the observed pupil size; the effect is correlated with regional brain activation of structures known to mediate emotions; and, perhaps most surprisingly, viewers' own pupils mimic the size of the pupils seen in the sad faces. As with the present study, it has also been found that emotional facial expressions in the viewer can be evoked by subliminal presentation of emotional face stimuli. But the fact that we have no voluntary control over our pupils makes them an especially good measure of automatic emotional response Aside from its theoretical importance, the study by Harrison et al. is likely to encourage future experiments to include pupillometry as a psychophysiological measure, since the technology to measure pupil size accurately is now widely available-even within the environment of fMRI experiments. (PsycINFO Database Record (c) 2007 APA, all rights reserved).