In previous research, sexual orientation could only be explored either by simply asking people about their sexuality or by assessing genital arousal.
Now researchers of Cornell University have discovered a new way to measure where a person’s sexual response falls on the spectrum from gay to straight: pupil dilation.
“We wanted 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,” says Gerulf Rieger, lead author of the study.
The present study assessed the pupil dilation of 325 men and women of various sexual orientations while watching erotic videos. 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. According to the researchers, this result confirms previous research suggesting that women and men’s sexuality work differently.
Furthermore, the present study contradicts previous notions that most bisexual men do not base their sexual identity on their physiological sexual arousal but on romantic and identity issues. Bisexual men in the study showed substantial pupil dilations to sexual videos of both men and women.
“With this new technology, we are able to explore sexual orientation of people who would never participate in a study on genital arousal, such as people from traditional cultures,” says Rieger. “This will give us a much better understanding how sexuality is expressed across the planet.”
Rieger G, & Savin-Williams RC (2012). The eyes have it: sex and sexual orientation differences in pupil dilation patterns. PloS one, 7 (8) PMID: 22870196