Why do we like the so-called 'nudes'?

(CNN) - She's sitting in a crowded subway car, checking her email on her phone, going about her business, when suddenly the penis picture appears of a man.

Sexting is so common that in a 2015 survey, 88% of respondents said they had done it. It's so common that psychologist Peggy Drexler wonders if there's any stigma attached to it, and it's so common that even someone as prominent as Amazon founder Jeff Bezos said a news outlet threatened to publish compromising photos of himself.

If it's done in a consensual relationship, like other sexual behaviors, it's not entirely harmful, the problem is that men often send unsolicited photos to women.

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There are several theories that try to explain the phenomenon.

Interprets misinterpretation

Man is simply not good at gauging a woman's level of interest in him, says Alexandra Katehakis, founder and clinical director of the Center for Healthy Sex in Los Angeles. "Yeah, they're bad at it. And photos aren't welcome," she told CNN.

Besides, says Katehakis, most women aren't interested in pictures of penises at all. "They find images of a man's eyes or his butt more arousing," she said.

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Joe Kort, a sex therapist in Royal Oak, Michigan, concurs: "Most men believe that women would like to see it (an image of the penis) and that it would arouse them sexually. Of course, in most women that doesn't work."

Attachment

New York psychotherapist Jeannette Stern said this misperception is also due to men's attachment to their private parts.

"I think that men, generally more than women, feel a connection to their genitals and want the person they are sexually interested in to share that interest. I think men perceive this to be more pleasurable to the recipient than they think." often is," Stern said.

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Exhibitionism

Some men are turned on by sharing photos of their private parts with strangers, Katehakis says. Often they do it through what is known as cyberflashing or cyber exhibitionism.

Some use the iPhone's AirDrop feature to do this, which allows iPhone users to receive photos from people nearby if the feature is turned on and set to receive photos from anyone.

Some lawmakers in New York have proposed a regulation to make cyberflashing a crime, reports CNN affiliate WPIX.

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He's today's version of the flasher from the past. "It's not that different from old-school flashing. We thought of the hideous guy in the trench coat. This is the modern version of that," says Katehakis.

The hostility

Katehakis sees it as an act of rage against women, now filtered through the cybersphere.

"For the man, it's very much about power and control. An act of sexualized hostility. Men take out their anger on women in erotic ways," he says.

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The shocked reactions of the women who receive these images are a big part of the excitement for the men who send them, says Kort, the sex therapist.

Dominance

Sex therapist Russell Stambaugh explained that sending images of genitalia is a combination of seeking acceptance and intimacy, showing off and seeking dominance.

"Since bragging and seeking dominance are less conventional expressions of female gender roles, it is not surprising that men do this much more frequently. Because it is often an unsolicited pursuit of dominance, photos of penises are considered aggressive," Stambaugh told CNN.

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Impulse

Many men lack impulse control, Stern says.

"Impulsiveness plays a role in this, as does drug and/or alcohol use. Someone who is more impulsive is more likely to send the photo, especially under the influence, while a less impulsive person might want to do it but then think better of it," he tells CNN.

"Seeking thrills like these with a partner may seem safe, but cyber communication is never really safe and seems like a lesson worth keeping in mind."

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Evolution

Is this ingrained in the genes? Are some men programmed to do this sort of thing? Stambaugh is almost certain. He argues that there is an evolutionary basis for this kind of behavior. He calls it "sexual signaling" which is designed to stimulate the conditions from which reproductive sexual behavior can occur.

Sex researcher and educator Justin J. Lehmiller agrees with that sentiment, commenting on how this theory works. "An evolutionary theory that suggests that males and females have evolved specific cognitive biases that may aid successful reproduction," Lehmiller writes.

"Having an exaggerated perception of a woman's interest in sex, whether on Tinder or in the real world, could be considered an adaptive trait in light of this theory, as it reduces the likelihood that men will pass up any reproductive opportunity.

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But Lehmiller adds that men shouldn't use that as an excuse for bad behavior.

"Even if we think this behavior is adaptive in an evolutionary sense, this doesn't mean it's okay or excusable for men to send photos to women who don't want to see them," he writes.

After all, said Katehakis, we have evolved. "It probably has some biological underpinnings," she said, "but we've evolved these huge brains to negate all of that."