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In the canon of sex research, far more energy and attention has been devoted to the act of having sex—how, when, and with whom—than to how people think about it when they are on their own. Which is one reason why Justin Lehmiller, a research fellow at Indiana University’s Kinsey Institute for Research in Sex, Gender, and Reproduction and the author of the blog Sex and Psychology, decided to conduct the largest-ever research project on sexual fantasy and desire, and write a book about it—Tell Me What You Want, published earlier this month.

“If you look back to, say, Alfred Kinsey, he was focused much more on people’s behaviors rather than their desires. Same with [William] Masters and [Virginia] Johnson. They were focused more on studying the physiological side of sex,” Lehmiller told me in an interview. The last significant scientific publication on the topic dates to 1995, before the popularization of the internet, which has made pornography, sexual information, and sexual misinformation all much more widely available.

So Lehmiller created an online survey of more than 350 questions about the specifics of participants’ favorite fantasies, published the link on social media, and got responses from 4,175 Americans from all 50 states, ranging in age from 18 to 87, with virtually all sexual and gender identities, political and religious affiliations, and relationship types and statuses represented. The sample is not representative; Lehmiller is careful—Tell Me What You Want is nothing if not a careful, frequently hedged interpretation of his research findings—to point out that most participants in his study heard about it through a major social-media channel like Facebook, Twitter, or Reddit, meaning his sample skewed more toward the average social-media user than the average American. That means they’re slightly younger, for one thing, than the average American (by six years, to be exact). Additionally, Lehmiller writes, because the survey called for frank discussion of private desires, “the people who chose to take part tended to have positive views about sex in general and were willing to openly report on their sex lives.” (This, he adds, is and has always been a complicating factor in sex research.) But Lehmiller says the sample is substantial enough to discern certain big-picture trends. What he found was that, even in a time of changing cultural values and plentiful pornography, most Americans’ fantasies aren’t all that outlandish or elaborate; rather, most Americans fantasize about what you might just call “spicing things up.”

Some of the earliest prominent analyses of sexual fantasies came from Sigmund Freud, and while many of the Austrian doctor’s theories about sex have been debunked and dismissed, his notions about sexual fantasizing are key to understanding how earlier generations might have understood or tried to understand the meaning of their sexual fantasies. In general, Freud believed fantasizing to be a pastime of dysfunctional individuals: “We may lay it down that a happy person never phantasies, only an unsatisfied one. The motive forces of phantasies are unsatisfied wishes, and every single phantasy is the fulfillment of a wish, a correlation of unsatisfying reality,” he wrote in 1908. “Phantasies, moreover, are the immediate mental precursors of the distressing symptoms complained of by our patients. Here a broad by-path branches off into pathology.”

Skip forward to 1995, however, when the American Psychological Association’s Psychological Bulletin released an overview of the findings from the existing research on the subject, and it’s clear researchers had a slightly better grasp of what sexual fantasies were and what they meant. Contrary to Freud’s belief, the paper—written by Harold Leitenberg and Kris Henning, psychologists from the University of Vermont—asserted that sexual fantasy was not a sign of dissatisfaction or pathology; rather, people who exhibited the fewest sexual problems and least sexual dissatisfaction were found in studies throughout the 1970s and 1980s to fantasize the most. (“It is now considered a sign of pathology not to have sexual fantasies,” the paper reads.) The 1995 review also noted that the four most popular themes of straight men and straight women’s sex fantasies (little research on non-heterosexual subjects existed at the time) seemed to be “conventional” sex with past, present, or imaginary lovers; sexual power and irresistibility; new settings, positions, and sex activities; and scenes of submission and dominance.

Other widely held beliefs among experts at the time included that men’s fantasies were more likely to include “explicit and visual” imagery (as opposed to women’s “more emotional and romantic imagery”), that fantasizing declined steadily as adults got older, that men were more likely to fantasize about sex with multiple partners at the same time—and that women preferred romance novels to pornography as their commercial erotica of choice.

Lehmiller’s findings tell a different story, however. Whether it’s due to generational change, cultural and technological change, or just differences in research methods, Lehmiller finds that the innermost fantasies of Americans appear to have evolved: For example, Lehmiller says he was surprised by how often he found men fantasized about romantic or emotional fulfillment. He asked participants how often they’d had sexual fantasies in which a variety of emotional needs were met: feeling appreciated, receiving approval, feeling desired, feeling irresistible, feeling reassured, feeling sexually competent, and emotionally connecting with a partner. Women reported having these fantasies more often than men did, but the majority of men said they fantasized about meeting these needs at least some of the time. A clear majority of people—more than 70 percent of both men and women—said they rarely or never fantasized about emotionless sex.

Tell Me What You Want is peppered with compelling tidbits about the state of the American sexual fantasy; for example, in one chapter Lehmiller identifies 15 different demographic factors that correlate with fantasizing about one thing or another. According to his findings, being older (and thus more sexually experienced) might mean you fantasize more about group sex or non-monogamy more than a younger person would, and being religious might mean you’re more likely to fantasize about sex as an expression of love, and especially heterosexual love—but you might also be prone to fantasizing about particular sex acts frowned upon by many major religions (that is, anything other than monogamous, procreative sex).

But many Americans’ sexual fantasies remain remarkably tame, especially with regard to whom Americans fantasize about. Nine out of 10 Americans reported they had fantasized about their current partner; just over half said they did so often. “No one else comes close,” Lehmiller writes; only 7 percent reported they fantasized about any famous people—like celebrities, porn stars, or politicians—often. And favorite fantasies about simply trying a new sex act or engaging in a favorite one, statistically speaking, outnumbered favorite fantasies that fall under the category “taboo and forbidden sex” (like fetishism and voyeurism).

One particularly intriguing suggestion Tell Me What You Want makes is that increased exposure to pornography, given how widely available it is online, may change the content of people’s fantasies in concrete ways.

Reliable statistics on Americans’ pornography consumption are hard to come by, as numbers attained through self-reported data are often looked at skeptically due to the possibility that respondents might lie about or downplay their viewing habits. But it is widely believed that the mainstreaming of the internet has contributed to an increase in porn-watching; one study, published in 2015 by The Journal of Sex Research, found a “big jump” in pornography consumption when comparing adults born in the 1980s to adults born in the 1970s, and it chalked that difference up to the fact that “children born in the 1980s onward are the first to grow up in a world where they have access to the Internet beginning in their teenage years.” A representative for Pornhub—which The Pornography Industry author Shira Tarrant describes as having “somewhat of a monopoly on porn sites”—told me that Americans accounted for some 9.5 billion of the 28.5 billion total visits to its website last year.

The availability—and amount—of instantly accessible pornography online seems to have some effect on how Americans fantasize. Sixteen percent of Lehmiller’s study respondents said their favorite fantasy of all time was directly cribbed from something they saw in pornography. Lehmiller also asked respondents in his survey to answer specific questions about the body proportions of the people in their fantasies and found that the consumption of pornography, which often features actors with somewhat extreme bodily proportions and grooming standards, tended to coincide with fantasies about those same kinds of bodies:

Among heterosexual women, those who watched more porn tended to fantasize about male partners with less pubic hair and larger penises. Likewise, among heterosexual men as well as lesbian and bisexual women, those who watched more porn fantasized about female partners with larger breasts.

That said, of course, it’s worth considering that people’s pornography habits might just be reflecting their desires, not inspiring them; of Lehmiller’s respondents, a vast majority said they had looked for videos that depicted their favorite fantasy, and it’s certainly possible that people who watch pornography do so because they already fantasize about the body types particular to the genre, and not the other way around. “I suspect that the availability of online porn isn’t necessarily changing our deeper underlying sexual desires, but rather is more often just giving us new ways of fulfilling existing desires that we might not necessarily have thought of before,” Lehmiller wrote to me in an email.

In general, Lehmiller finds many of the the results of his study “reassuring.” “We’re not trying to replace our partners,” Lehmiller says. “We’re just trying to amp our sex life up a little bit.”

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