Researchers at Northwestern University have concluded what seems like an obvious fact to many: male bisexuality exists.

However unnecessary the study — testing whether men who labeled themselves as bisexual were truly aroused by both men and women — seemed to be, the researchers' findings actually contradicted a 2005 study, also at Northwestern, which concluded that it "remains to be shown that male bisexuality exists."

This conclusion outraged the LGBT community for its implication that bisexual men were either "gay, straight or lying." One flaw detractors pointed to was the recruitment of subjects from venues aimed at gay men. Subjects for the more recent study "were recruited using stringent criteria involving sexual and romantic experience with both men and women" and from venues catering to bisexual people, according to the abstract.

The study measured erectile response in subjects while they were shown gay and straight pornography.

Jim Larsen, chairman of the advocacy group Bisexuality Organizing Project, told the New York Times that the findings were only proof of what was already known.

"It’s great that they’ve come out with affirmation that bisexuality exists," he said. “Having said that, they’re proving what we in the community already know. It's insulting. I think it’s unfortunate that anyone doubts an individual who says, 'This is what I am and who I am.'"

The study is published in the most recent issue of the journal Biological Psychology.

Creative Commons image via flickr user juverna.