A fit blonde woman disrobes feverishly and then leans back on a wooden bench lining the perimeter of a roof deck. A ripped, dark-haired man approaches.

She mouths, "Lick my pussy." He obliges. Moments later, she returns the oral favor.

After the erotic video clip concludes, through my headphones I hear the voice of Erick Janssen, PhD, a wisecracking, bespectacled Dutch researcher whose notable work in the field of arousal has earned him the moniker Dr. Feel Good. Janssen tells me to follow the instructions on the computer screen before me.

Seated in a comfy leather chair in a living room–esque lab in Indiana University's Kinsey Institute for Research in Sex, Gender, and Reproduction, I try to follow the computer prompts without thinking about Janssen in the adjacent room, where he sits alongside his colleague, evolutionary biologist Justin R. Garcia, PhD. By means of special technology called a vaginal photoplethysmograph, a small glass tampon-shaped instrument that measures blood flow, the two are privy to the inner workings of my private parts.

What led me to this institution—where the mission established by pioneering sexologist Alfred C. Kinsey in the mid-20th century of "advancing sexual health and knowledge worldwide" still resounds—is a simple but important question: Do I really know what turns me on?

Thanks to our internet-centric culture, sexual imagery is everywhere these days. If you tire of professional James Deen pornos, you can always pull up a saucy, classic celebrity sex tape. But the sheer volume of sexual imagery out there can lead to confusion about our real turn-ons. That's a problem because knowledge is power in the sack. The more you know about your body and sexual proclivities, the better you can communicate with a partner so that both your needs are met. "Pornography is designed as drama for the camera," says neuroscientist Barry R. Komisaruk, PhD, a leading expert on brain activity during sexual response and coauthor ofThe Science of Orgasm. And it can give less experienced people the wrong messages about what should turn them on. I've always thought of myself as self-aware sexually. At 32, I consider myself a nonjudgmental heterosexual woman who enjoys various positions and toys and is open to the possibility of a threesome if the urge strikes. On occasion though—like the night I learned my breasts have more orgasmic potential than I'd ever imagined—I've considered whether there's anything else I'm missing.

To find out if I really know what turns me on, I wondered whether I could lend my vagina to science like the human guinea pigs recruited by William Masters and Virginia Johnson, the famed research duo depicted in Showtime's Masters of Sex. Although the foundation established by Masters and Johnson closed in 1994, I learned that arousal was still a main research focus of its predecessor, the Kinsey Institute. Since no related clinical trial was underway when I contacted Janssen, I volunteered for a special experiment of his design, based on those he'd conducted in the past. By comparing my subjective impressions about what is and isn't sexy to objective data about what happens to me "down there," I hoped that the Kinsey researchers would reveal whether a vagina-brain disconnect was preventing me from reaching full satisfaction.

During our initial meeting, Janssen explained that part one of our experiment would involve testing whether I was more aroused by positive or negative moods. After handing me a small glass vaginal probe, he stepped out to give me privacy. The next time I heard from him, it was through headphones: "Please twist the probe a millimeter clockwise, then focus on the screen in front of you."

To my surprise, the first eight-minute "neutralizing" video featured kittens wrestling. Then an inspirational clip from the 1984 baseball film The Natural played, followed by the aforementioned porn scene. After each clip, I reached across the white sheet covering my lower half for the mouse to log the degree to which I experienced a range of emotions (excitement, relaxation, fright, sadness, guilt, shame, etc.) on a 5-point scale. Next, I rated my emotional state following a similar succession of videos—except that between a nature video (this time starring turtles) and erotica, I was shown a disturbing scene from Silence of the Lambs.

For part two of our experiment, Janssen announced that we could play a bit with stimuli of my choosing. He asked me which sex acts sounded appealing to me instinctively. Without overthinking, I picked: lesbian sex, a threesome (female-female-male), sixty-nine, bondage, and female masturbation. Then I named three deeds I didn't consider arousing: homosexual male sex, foot fetishism, and bonobos mating. Within minutes, Janssen sourced footage depicting each of these scenarios online. During 30-second pauses between videos, I jotted down my answers to the same three questions in a small notebook, using a scale of 1 to 10: How aroused am I? How much do I want to engage in this behavior? How much do I want to be aroused?

Aside from remaining as still as possible so the probe wouldn't slip and compromise the data, the hardest part was coming to grips with some of my automatic reactions. As a proponent of gay rights, for instance, I wanted to be turned on by sex between men, but I found the sight of two erect penises off-putting. And as much as I wanted to believe that neither animals nor feet could excite me, I had to concede a minimal level of attraction to both.

A few days later, Janssen and Garcia called with results. "Your vaginal pulse," Janssen revealed, "was strongest while watching lesbian sex, bondage, foot fetishism, and female masturbation. It was lowest during the bonobos and the threesome."

Two discrepancies stood out: I had rated myself as turned off (3 out of 10) by the bondage scene and turned on (7 out of 10) by the threesome. Turns out, I was wrong. (But it felt good to know for sure that bonobos aren't my thing.)

Arousal, Janssen explained, is a function of balance between two brain systems: sexual excitation (your arousal gas pedal) and sexual inhibition (the brakes). So even though I named bondage as arousing—and my physiological response confirmed that instinct—certain factors may have inhibited me from recognizing my taste for rough play when confronted by it directly. Perhaps I've been conditioned to associate domination by a man as antifeminist, so my conscious mind couldn't embrace BDSM as eagerly as my vagina. Our guilt, shame, and social pressures can interrupt our ability to decipher our real sexual desires.

As for the mood test, Janssen said, my physiological response was stronger after the anxiety-inducing film than the positive one.

I never would have guessed that a horror film would turn me on more than a rom-com. Sex and romance go together, right? But then I thought about what a terrifying movie does to me. It makes me thirst for cuddling and protection from my partner. According to Janssen, my response was consistent with some studies showing that negative emotions (fear, anxiety, distress) "tend to be associated with stronger arousal," pointing out that "a lot of people watch porn or pursue casual sex to cope with their negative moods." So there's some science behind the familiar narrative: Sad/angry/stressed-out person gets sloppy drunk and hops into bed with whomever.

Garcia added that my personal revelations speak to the significance of this type of work. "It's about getting people to understand that you may be conditioned to think you're not turned on by something, but you are."

One night a few weeks later, I was feeling frisky, so my boyfriend and I watched a thriller. It did the job, and we both felt empowered by the realization that there are environmental factors at our disposal that we hadn't considered using. The trick, it seems, is in questioning your assumptions (happy equals randy) and thinking about your individual tendencies.

In the following weeks, my boyfriend and I became more vigilant about tuning into our own—and each other's—emotions and letting that awareness drive the style of sex we had. When he came home late from work looking frustrated, I ripped off his pants and tackled him into bed. When I woke up feeling premenstrual and pouty, he spent 10 minutes massaging my back before making his next tender move. Being more mindful of each other's moods and turn-ons ended up enriching our sex life and deepening our bond.

Of course, not everyone can play sexual guinea pig with a magical glass tampon. So what can the everywoman do to get in touch with her own turn-ons?

The scientists I spoke to emphasized the importance of careful self-examination. Yes, that means masturbating! Janssen also recommended taking a hot bath alone "to free associate." When you close your eyes and fantasize, what scenarios or behaviors come to mind that make you feel hot and wanting more? The first step to expanding your coital boundaries is "to set your sexual self free," he says. There was also consensus that it could help to discuss arousal within a relationship early and often—before, during, or after sex—so you can understand how your triggers overlap, because focusing on the things that get you both going will provide a shared boost in the bedroom. However, Janssen advised that couples shouldn't rule out something simply because it turns on only one person. Pleasing a lover can be exciting in itself, so you might end up enjoying certain things once you see how they impact your partner. The key is to dabble together, so try introducing something new—a toy, position, role-play—once a week.

Accept that your turn-ons evolve over time, as a function of age and situation (a new job, a move, the addition of kids can all come into play). So resist the urge to pigeonhole yourself, and be sure to reflect on what turns you and your partner on—on an ongoing basis. Only by tuning into ourselves and tuning out all that societal noise can we keep the doors to amazing sex wide open.

This article was originally published as "I Lent My Vagina to Science" in the December 2014 issue of Cosmopolitan. Click here to get the issue in the iTunes store!

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