In heterosexual relationships, women on average are having fewer orgasms than men — a problem that University of Florida professor Laurie Mintz, author of the book “Becoming Cliterate: Why Orgasm Equality Matters — And How to Get It,” calls “the orgasm gap.”

According to a 2016 study from the Archives of Sexual Behavior that looked at over 52,500 adults in the U.S. — including those who are lesbian, gay, and bisexual — 95 percent of heterosexual men reported they usually or always orgasmed during sex, compared to 65 percent of heterosexual women, who were the least likely.

“The number-one reason for the orgasm gap — and it’s not the only one — is our cultural ignorance of the clitoris,” Mintz tells NBC News BETTER.

Anatomy of the clitoris

Picture a flower with closed petals. Within the flower is a nub that branches down into two bulbous legs.

This is the image feminist and artist Sophia Wallace conjures when she talks about the part of a woman’s body that experiences the most sexual pleasure. Not the vagina, she explains, but the vulva, and especially the external clitoris — the “nub” within the vulva which contains about 8,000 nerve endings.

“The bulbs of the clitoris surround the vagina, and that’s why — when the clitoris is engaged and aroused — penetration can feel amazing, but when it’s not aroused, it can feel really uncomfortable, or like nothing, because the sensation and pleasure comes from the clitoris, not the vagina,” Wallace says.

The clitoris is the only organ in the human body solely responsible for sexual pleasure. In Greek, it means “key.” According to Wallace, it’s usually seen as a small button-like organ within the vulva, but this, she says, is a misconception.

Sophia Wallace with her artwork, Άδάμας (unconquerable). Courtesy of Sophia Wallace

“The clitoris is not this little nub on the outside of the vulva,” she says, “but is actually this large internal organ comprised of erectile tissue that’s similar in scale to the penis.”

Wallace has spent the last seven years illuminating the importance of the clitoris through her project “Cliteracy,” currently on display at Project for Empty Space in Newark, NJ, and her mixed-media project “Cliteracy, 100 Natural Laws.”

The artist says most people are shocked when they see what the clitoris actually looks like.

“They never know the true anatomy,” says Wallace, whose 2015 TEDx Talk on the topic received nearly 120,000 views to date. “They never know anything about it. That tells me there’s so much more work that needs to be done.”

“Inequality in the bedroom”

Mintz, who teaches the psychology of human sexuality to hundreds of college students every year, blames what she calls “inequality in the bedroom” on depictions of “media images of sex,” especially in pornography, and a “cultural over-privileging of male sexuality and a devaluing of female sexuality.”

She says most women need direct clitoral stimulation — such as oral sex and touching — to orgasm, but this is rarely depicted.

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“Instead,” she says, “what we see is women having these fast and fabulous orgasms from intercourse alone.”

According to a 2015 internet-based survey published in the Journal of Sex & Marital Therapy, which received responses from over 1,000 U.S. women, 36 percent reported that clitoral stimulation helped them orgasm during intercourse, whereas slightly more than 18 percent reported they orgasmed from intercourse alone.

Women are also more likely to orgasm if they receive oral sex (in addition to other activities like deep kissing and intercourse), according to the Archives of Sexual Behavior study, but some studies show they are less likely to receive oral sex than they are to give it.

Dispelling the “g-spot”

At the center of the myth that women should orgasm from intercourse alone is what’s popularly known as the “g spot” — often depicted as a mysterious spot on the inside of the vagina, according to Mintz.

She says the “g spot” is real, but misunderstood.

“It’s an area in the upper right side of the vagina, and it’s an area which includes a lot of structures, including the legs of the clitoris, including the female prostate glands, including the wall of the vagina,” says Mintz.

Mintz says the external clitoris is the real center of female sexual pleasure, but she doesn’t dismiss the “g spot” — she says some women indeed find it pleasurable.

“What I’m trying to fight against is the pervasive myth that orgasms from vaginal penetration — including the ‘g spot’ — are better, more ideal, the right way …” says Mintz, “when in fact the vast majority of women need clitoral stimulation to orgasm.”

Women need to be aroused for sex

Like the penis, the clitoris becomes erect during arousal. "Women need to be aroused prior to penetration, according to Mintz — otherwise, the vagina doesn’t lubricate, and the cervix doesn't pull back out of the way of the penis."

“The overwhelming majority of women find that incredibly painful,” she says.

Every woman’s body is different when it comes to arousal, Mintz says, but the more time couples spend kissing, caressing, and engaging in oral sex, the more aroused she’s likely to be.

The most important thing is that women communicate to their partners what they like and don’t like, says Mintz, and that their partners are receptive to this.

“We need to be communicating what we need and feeling entitled to communicate that,” says Mintz.

Intercourse usually doesn’t last that long, and that’s ok

For the average heterosexual couple, penetration lasts 3-5 minutes, according to Mintz. But she says media depictions of sex, particularly in pornography, have led many to think it should last a lot longer.

“We have all these men calling into sex therapists worried that they’re not lasting long enough,” she says.

In some ways the male body, like the female body, is also misunderstood, according to Sarah Byrden, a sex educator and speaker.

The penis, she explains, moves in “rhythms and tides.”

“It is not designed to be consistently erect as it is depicted in all kinds of media — able to be erect inordinate amounts of time — and that is where huge performance pressure comes,” Byrden says.

For greater pleasure, mix things up

Both women and men enjoy greater pleasure when they receive a mix of acts, whether through oral sex or touching, before, during, and after penetration, according to Mintz.

“Forget this myth of orgasming from the same act at the same time,” says Mintz. “Adopt a different way of doing sex.”

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