"I don't know why I would want to do that," says Geri, a college student in New Jersey who asked that her last name not be used. "I know I'm straight and I like my men, and it would just be too weird. I guess I was confused by it." She was 16 at the time, talking loudly at a party, her breath stained with alcohol. A boy at the party jokingly suggested that she kiss her friend, a girl she lived next door to for years. And suddenly, it seemed like a good idea. No, it was a great idea. Not just a peck, but a real kiss, the kind of genuine thing Clark Gable would applaud. As if on autopilot, Geri says, she told her friend of this new desire -- and then quickly pulled back. This wasn't her. She didn't know what she wanted.

Geri and her friend still laugh about that night, although she hasn't settled on what caused such an impulsive, erratic desire. Sometimes she blames the booze, but she's not convinced. Whatever it was, she says, she knows one thing for sure: if she were a guy, this probably wouldn't have happened. "Guys are programmed to fuck, and girls aren't like that," she says. "Girls are more sensual, and the mood has to be right. It doesn't matter who's doing it, it just has to be right." And on that night, somehow, the mood was right.

But if a study recently released from Northwestern University is correct, Geri's desire was almost more natural than her heterosexuality. In her case, and the cases of countless other women, her biological impulses spontaneously bubbled up. As the study shows, women may be naturally aroused by both sexes, and what turns them on may have little to do with their sexual orientation.

For the study, more than 90 gay and straight men, women and male-to-female transsexuals were shown erotic film scenes with a probe attached to their genitals to indicate when they were aroused. Both the men and the transsexuals were only aroused by scenes that featured members of their preferred sex, while women were aroused by all the films -- whether they featured lesbian scenes, gay male scenes or mixed-sexes scenes.

The results, which will be published in an upcoming issue of the journal Psychological Science, seem almost counterintuitive. Men have eagerly embodied their reputation as the sexually enthusiastic half of the population, and yet this study seems to suggest that women, deep down, are really thirsting for more. But, according to one of the study's coauthors, Northwestern psychology department chairman J. Michael Bailey, the study really just reinforces what we already know: Men are sexually simple, and women are not. "I think it really shows us how much we don't know about women more than it shows us what we do know," he says.

For one, he says, there appears to be a significant disconnect between what sexually and mentally arouses a woman. Many of the women in the study did not even recognize they were being aroused by some of the tapes, which leads Bailey to believe that women are somehow disconnected from their genitals -- and are perhaps fully aroused more by circumstance, such as an emotional bond or a sexy scenario, as something that engages their brains and emotions. When men get an erection, Bailey says, "it makes men motivated to have sex with whatever's causing the genital arousal. I don't think women have the same connection."

That may be because women don't package their sexual orientation the same way that men do, according to Lisa Diamond, assistant professor of psychology at the University of Utah. Unlike some other cultures, Americans tend to lump many different experiences into one category called "sexual orientation" -- including distinct desires such as who we love, who we want to marry, who we are attracted to and who we fantasize about. However, this comes more naturally to men than it does for women, Diamond says. Some women unconsciously dissect what defines their sexual interests, and find that they may want different things from different sexes. "You have a lot of cases of totally heterosexual women who may not be aroused by women, but their deepest emotional bond is with other women," she says. "They feel they fall in love with other women, without the sex."

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