Sexual Orientation Determined By Pupil Dilation

First Posted: Aug 06, 2012 06:14 AM EDT

A new study done by Cornell University researchers has found that sexual orientation can be distinguished based on an individual's pupil dilation. The way the pupils react when they see other people is an effective way to detect whether the person is straight, gay or bisexual.

Pupil dilation has long been known to track the level of someone's excitement. Pupils open slightly when a person sees a puppy dog or a friendly face.

The findings of the research, conducted by Ritch Savin-Williams, state that pupil dilation is an accurate indicator of sexual orientation. The way the pupils open up on viewing an erotic picture is a good indication for researchers to study the person's orientation and level of arousal without opting for traditional methods.

According to Savin-Williams, this is the first large-scale experiment to show that pupil dilation matches what people report feeling aroused by.

 In order to conduct the study, Savin-Williams and his colleagues selected 165 men and 160 women-gay, straight or bisexual-and showed them images of men masturbating, women masturbating, and neutral landscape scenes while monitoring their pupil dilation. They also showed videos of members of the opposite sex simultaneously and took note where the subject's focus primarily was.

Results also revealed that bisexual men were attracted to men and women, an idea that has been disputed, and that heterosexual women may be aroused by both genders, despite being straight.

"The pupil reacts very quickly, and it is unconscious, so it's a method that gives us a subconscious indicator of sexuality," said lead study author Gerulf Rieger, a researcher at Cornell University.  "Sex researchers don't always want to rely on people's own reports about who they are sexually attracted to, because cultural and societal pressures can influence what people say."

The study that was published Aug. 3 in the journal PLoS ONE can raise more concerns in the US where some organizations and individuals discriminate against homosexuals.  At the same time, there have been social movements for equal rights. Now, most of the states allow same-sex marriage after the state Senate voted for a measure that would allow gay and lesbian couples to marry.

Savin-Williams said, "This technology could be used to conduct cross-cultural studies of sexuality, given that pupil dilation is universal and doesn't depend on labels of sexual orientation that may not translate across all languages. The method could even be used to help people who are confused about their sexuality sort through their desires."

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