Researchers have demonstrated just how sensitive our brains are to sexual imagery, with a series of experiments that showed how we respond to hidden erotic images. Incredibly, although the test subjects in the experiments were not consciously aware of the sexy images, they still responded to them according to their gender and sexual orientation. The purpose of the experiments, conducted by University of Minnesota researchers, was to uncover the mechanisms by which the brain processes visual information that is not consciously perceived by the subjects. "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 researcher Sheng He.
Erotic pictures were chosen for the experiments as the researchers believed they would elicit strong responses and clear patterns in the data, but they said other imagery could also have similar effects. "This definitely doesn't just work for erotic pictures," said He. "But erotic images stand out in terms of potency to generate a response."
The experiments were conducted with the subjects seated at a stereoscope (a device which allows different images to be simultaneously displayed to the left and right eyes). Each eye was presented with a screen that was divided into two patches sitting side by side. One eye was presented with an intact picture of a nude person in one patch and the same picture scrambled in the neighboring patch. The other eye was presented with twin patches containing moving, high-contrast noise patterns. To the subjects, the screens from both eyes appeared to be overlapped, rendering the intact pictures invisible. The subjects were then tested to see if their visual attention had shifted toward or away from the part of the visual field containing the erotic image.
Responses were noted in all the test subjects but the strongest shift in attention toward the area where the image had been was in heterosexual men (who had been shown nude female images). Heterosexual women responded to nude male images but less strongly than the response of the heterosexual men. Gay men behaved similarly to heterosexual women, and gay/bisexual women came in somewhere between heterosexual men and women.
Reporting their results in the Proceedings of the National Academy of Sciences, the researchers said that the results provide evidence that the subjects' brains were processing the visual information in a selective manner. "Selective attention helps us to quickly process what is important while ignoring the irrelevant," the researchers write. "In this study, we demonstrate that information that has not entered observers' consciousness, such as [invisible] erotic pictures, can direct the distribution of spatial attention. Furthermore, invisible erotic information can either attract or repel observers' spatial attention depending on their gender and sexual orientation."
Could the procedure be used to assess an individual's sexual preferences? It's unlikely, say the researchers, as the responses from the test groups was clear, but individual responses were not reliable indicators.
Based on material from the University of Minnesota
