CORNELL UNIVERSITY --
If you want to know a person's sexual orientation, stare deeply into their eyes. Researchers at Cornell University had heterosexual and bisexual men and women watch erotic videos. They found the pupils heterosexual men only dilated when seeing sexual images of women. However, the pupils of bisexual men widened watching both men and women. And women have similar response to bisexual men.
The author hopes the findings will boost understanding of different sexual groups.