Iris of the Beholder

Prompted by the idea that “beauty brings many social benefits,” researchers from the University of Amsterdam, the University of California, and City University of London have investigated how pupil size can affect a person’s attractiveness.

“Over the past 50 years, researchers have been unable to determine whether people appear more attractive with dilated (enlarged) pupils or constricted (smaller) pupils,” explains the University of Amsterdam’s Martina Cossu. “The primary goal of this study is to conclusively determine whether constricted pupils – compared to dilated pupils – enhance perceived attractiveness.”

The team enrolled over 3,000 participants across six experiments, asking them to judge pairs of photos using a slider scale from 0 (“very unattractive”) to 100 (“very attractive”). The paired photos, although identical in every other way, were manipulated by the study authors – in one photo the models had constricted pupils, in the other they had dilated pupils. The study participants looked at headshots and letterboxed eye shots; the female and male models in the pictures had either brown or blue irises.

All six of the experiments demonstrated that – even when factors such as color and lighting are accounted for – people are deemed more attractive when their pupils are constricted. The research reveals that “constricted pupils enhance physical attractiveness by making the eyes appear brighter,” says Zachary Estes, City University of London.

Going forward, Cossu suggests these experiments should be conducted on demographics outside of the study’s Caucasian models to see whether the results are replicated in different ethnicities.