Wed August 8, 2012 11:13am
THEY say your eyes will give you away. Now we know they do - when it comes to your sexual preferences.
An article in the scientific journal PLoS One describes how researchers at Cornell University were able to identify the sexual orientation of men and women through testing the response of their eyes when watching pornographic material.
Dilation of the pupils is an unconscious sign of arousal, and one which researchers hope will be a less invasive - and less embarrassing - means of determining sexual orientation.
Previous techniques focused on measuring genital arousal.
"The idea was to find an unconscious measure," lead researcher Gerulf Rieger told abcnews. "We tried to find measures that were not so invasive, but reliable.
"What if someone comes in and says one thing and responds a different way?" said Rieger. "We wanted to really find a measure of sexuality that goes beyond what people tell us."
The study assessed 325 men and women of various sexual orientations.
Men and women react differently to sexual stimulation: men are more influenced by erotic stimuli while women tend to be more influenced by other, nonsexual stimuli.
And the report reveals that the eyes follow this tendency.
An infrared eye-tracking camera was used to measure eye dilation while the subjects watched erotic or non-erotic videos.
Heterosexual men and homosexual women predictably showed more eye dilation when shown sexual images of women. Homosexual men's eyes responded to men.
The eyes of heterosexual women, however, responded to images of both sexes.
Mr Rieger said this did not mean women were generally bisexual. Rather, it represented an evolutionary difference in the way the eyes informed the brain.
"Their body is not connected to their mind, which is very different from guys," he said.
Bisexual men produced similar dilation responses to heterosexual women.