When your eyes are presented with erotic images in a way that keeps you from becoming aware of them, your brain can still detect and respond to the images according to your gender and sexual orientation, a team of University of Minnesota psychologists has found. The team, led by graduate student Yi Jiang and his adviser, psychology professor Sheng He, found that even when unaware of erotic images in their field of vision, research subjects shifted the focus of their visual attention according to whether they were straight males, gay males, straight women or gay/bisexual women. The researchers, who have published their findings in the Proceedings of the National Academy of Sciences online, stressed that while differences among the groups are clear, individual differences are not and so could not be used to determine a person's sexual orientation.
The purpose of the work was to uncover mechanisms by which the brain processes visual information that is not consciously perceived by the subjects. When subjects become conscious of images, the sequence of steps in brain processing becomes very complicated because neurons engage in all sorts of feedback and crosstalk--especially with emotionally charged information. The researchers were studying the flow of visual information at an earlier stage, while it is still traveling along a one-way path.
"We're trying to reveal what happens when one doesn't have a conscious visual perception. That is, how the brain processes visual information independent of consciousness," said He.
The researchers chose to generate brain activity by using erotic pictures because they promised to elicit strong responses and clear patterns in the data. But the researchers believe the mechanisms by which the brain processes such images are universal.
"This definitely doesn't just work for erotic pictures," said He. "But erotic images stand out in terms of potency to generate a response."