Sexual orientation revealed in the eyes

[Posted: Tue 07/08/2012 by Gillian Tsoi www.irishhealth.com]

US scientists have discovered that the dilation of a person's pupils is highly telling of whether they are gay, straight or bisexual.

Many people believe that sexual orientation can be revealed by how wide our pupils dilate when we see attractive people, yet until now there was no scientific evidence.

For the first time, scientists used a specialised infrared lens to measure changes in the pupils of people as they watched erotic videos.

The researchers - from researchers at Cornell University in New York - found that people's pupils were highly telling of whether they were gay, straight or bisexual: they widened most to videos of people who participants found attractive, thereby revealing where they were on the sexual spectrum from heterosexual to homosexual.

As expected, heterosexual men participating in the study showed strong pupillary reactions to sexual videos of women, and little to men.

However, the pupils of heterosexual women reacted to both sexes. This result confirms previous research suggesting that women have a very different type of sexuality than men.

The new study also feeds into a long-lasting debate on male bisexuality. The idea that most bisexual men do not base their sexual identity on their physiological sexual arousal but on romantic and identity issues were disproven in the study - bisexual men showed substantial pupil dilations to sexual videos of both men and women.

"We can now finally argue that a flexible sexual desire is not simply restricted to women - some men have it, too, and it is reflected in their pupils," says Ritch C Savin-Williams, co-author and professor in Human Development at Cornell.

"In fact, not even a division into 'straight,' 'bi,' and 'gay' tells the full story. Men who identity as 'mostly straight' really exist both in their identity and their pupil response; they are more aroused to males than straight men, but much less so than both bisexual and gay men," Savin-Williams said.

Previous research explored sexual orientation either by simply asking people about their sexuality, or by using physiological measures such as assessing their genital arousal. These methods, however, come with substantial problems.

The new Cornell study adds considerably more to the field of sexuality research than merely a novel measure.
"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 and research fellow at Cornell.

"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. This will give us a much better understanding how sexuality is expressed across the planet."

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.

The findings were published in the scientific journal PLoS ONE.