It's All In The Eyes

A new study suggests pupil dilation reveals where a person’s sexual response falls on the spectrum from gay to straight.
Although there was a popular belief that sexual orientation can be revealed through studying the eyes via pupil dilation in response to attraction, there was no scientific evidence until now.

Researchers used a specialized infrared lens to measure pupillary changes to participants watching erotic videos. Previous research explored these mechanisms either by simply asking people about their sexuality or by using such physiological measures as assessing their genital arousal. These methods, however, come with substantial problems.
The goal was to find an alternative measure that would be an automatic indication of sexual orientation but without being as invasive as previous measures. Pupillary responses are exactly that. With this new technology, it is possible to explore sexual orientation of people who would never participate in a study on genital arousal, such as people from traditional cultures across the planet.

The new study adds considerably more to the field of sexuality research than just a new measurement. As expected, heterosexual men showed strong pupillary responses to sexual videos of women, and little to men; heterosexual women, however, showed pupillary responses to both sexes. This result confirms previous research suggesting that women and men’s sexuality work differently.

The researchers are confident that their new measure will aid in understanding these groups better and point to a range of sexualities that has been ignored in previous research.