Sexualpedia 6: Why Do I Like Him To Dress Up As Smokey The Bear?

Sexualpedia is an open-ended series of articles that will explain the source of many common erotic interests using neuroscience, biology, and online behavioral data.

MASTER/SERVANT ROLE-PLAYING  (cued interest)

Prevalence: Very common

Cues: Female submission cue; female psychological cues for male dominance

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The Internet reveals a great deal about our sexual proclivities. When we are liberated from anxiety and shame by the anonymity of our web browser, our true erotic preferences become clearer, recorded as digital footprints left behind in searches, clicks, comments, and credit card transactions.

But certain erotic tastes don’t manifest as plainly in the virtual world as they do in face-to-face interactions. Online behavioral data is a powerful tool for determining which bits of anatomy men find most arousing and which qualities of the male personality turn on women the most; indeed, this flood of new online data is the most powerful research tool in the history of sex science. But there are still facets of human desire which remain difficult to analyze using online data. One of these is erotic role-playing in the bedroom—such as asking your man to dress up like Smokey the Bear.

I often participate on the Morning X radio show in Tampa (hosted by Drew Garabo and Seth Kush) where I respond to a segment known as Fetish Fridays that invites listeners to call in and describe their sexual activities. Though these phoned-in confessions are obviously anecdotal, constituting a highly non-random convenience sample, there is a consistent pattern in women’s professed playtime preferences, which include:

  • wanting boyfriend to dress up like Smokey the Bear.
  • wanting boyfriend to dress up like an auto mechanic.
  • wanting boyfriend to dress up  like a caveman.
  • wanting to pretend to be a hooker getting paid for sex.
  • wanting husband  to dress up like the UPS delivery man.
  • wanting boyfriend to pretend to be doctor.
  • wanting husband  to pretend to be daddy.
  • wanting boyfriend to pretend to be Nazi guard.
  • wanting boyfriend to pretend to be a werewolf.

Are these fantasies strange, unhealthy, or atypical? Not at all: in fact, such fantasies appear to be the very norm for the female sexual brain. Perhaps the single biggest discovery from our wide-ranging online research was the central importance of dominance and submissiveness roles in sexual arousal. Themes of domination and submission run through all of male visual pornography and through female erotic narratives; it’s one of the very few erotic interests that men and women share. Both sexes prefer sexual content with dominant males and submissive women, though some men appear to be born with a preference for male submission and a smaller portion of women appear to be born with a preference for female dominance.

The majority of women have submission fantasies. From classic romance The Flame and The Flower to classic erotica The Claiming of Sleeping Beauty to Twilight BDSM fan fiction to 50 Shades of Gray, submission themes are immensely popular in female erotica in every country from every era. Based on anecdotal evidence from callers on the radio show, this also runs through women’s face-to-face fantasies in the bedroom. Where does this interest come from?

Consider, for a moment, Rattus norvegicus, the Norwegian rat. The female performs stereotyped behaviors associated with sexual interest. First is pacing: running and stopping, inducing a male to chase her. This culminates in lordosis: assuming a submissive stationary posture with arched back and raised hips. Lordosis is controlled by a specific region of the hypothalamus, a subcortical brain structure. An analogous part of the brain controls submission postures in female primates. Though we can’t know what runs through a female rat’s mind during lordosis, it seems reasonable to assume there must be some pleasurable psychological quality associated with these submissive behaviors that reward the rat for performing them. In male rats, another part of the hypothalamus controls stereotyped dominance activity, such as mounting a female and performing intromission.

However, all rats and primates (both male and female) appear to be born with both dominance and submission systems intact; in fact, when scientists activate the submission system in male rats they behave like sexually submissive females and when they activate the dominance system in female rats they behave like sexually dominant males. (Some female primates have also been found to naturally engage in male sexual behaviors.) It seems highly likely that humans have inherited the same twin set of ancient dominance-submission systems. (It’s always worth mentioning that just because you like to be submissive in the bedroom has no relevance for what you want in the boardroom.)

In addition, almost every quality of dominant males triggers arousal in the female brain: dominant scents, dominant gaits, deep voices, height, displays of wealth, displays of physical strength. Role-playing master/servant roles is likely a way for women to activate ancient submissive cues shared with other female primates while also activating the female brain’s less ancient cues for strong males. That’s why so many women want their partner to pretend they are a savage beast, a powerful man, a brutal man, an authority figure, or an outright rapist—but always someone who takes charge in the bedroom and has his way with her.

Of course, the individual details of a woman’s “dominant male” fantasy are highly variable and depend on her own experiences, personality, and other erotic tastes. Whether you want your husband to pretend to be the family physician or a Nazi doctor might depend on your past medical experiences. Whether you want your boyfriend to dress up like a werewolf or a lion or Smokey the Bear might be influenced by your childhood literary preferences. But—based on online data gathered from millions of women from around the world—all of these submissive fantasies reflect a healthy, natural, and utterly normal sexual brain.

Dr. Ogi Ogas received his PhD in computational neuroscience from Boston University and was a Department of Homeland Security Fellow. His writing has been published in the Boston Globe, Wall Street Journal, Glamour, Wired, Baltimore Magazine, and Seed.  He used his knowledge of cognition to reach the million dollar question on Who Wants to Be a Millionaire and battle Ken Jennings in the finals of Grand Slam.

Sexualpedia Part 5: Why Do I Like Wetlook?

Sexualpedia is an open-ended series of articles that will explain the source of many common erotic interests using neuroscience, biology, and online behavioral data.

WETLOOK (uncued interest; some examples may be cued interest)

Prevalence: Rare

Cues: Likely an uncued interest; male anatomical and male dominance cues may be involved

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Derek Kroft is a financial manager in Boston. After returning home in 2009 (1), he surfs over to one of his favorite websites and scans a page of new photos. There’s a smiling blonde wearing a white cotton tee, a redhead in a maroon sweater kneeling on a stump, and a Hispanic girl in torn jeans and a tank top, which could work if he was pressed for time, but this evening Derek is looking for something special. He jumps to another website, then another, but nothing gets his blood pumping. Finally, he tries a slapdash British site that rarely posts new content—but this time, pay dirt: a startled brunette in a forest green evening gown. And an added bonus: matching satin gloves. The evening gown is an important part of the equation for Derek—the high point, you might say—but is not absolutely essential. What is essential is the particular state of the young woman’s wardrobe: her expensive dress is soaking wet. The rain-saturated gown clings to her legs and bosom; her carefully-coiffed chestnut hair is a drenched, matted mess; swollen droplets roll off the tips of her fancy gloves; and her pretty, goggle-eyed face expresses total shock from this ruinous state of affairs. Perfect!

Derek’s special predilection might seem a bit unusual, but it’s part of a well-defined erotic niche known as wetlook. Wetlook enthusiasts ogle images of women (and men) in soggy clothing. Before the Internet, the only way Derek could satisfy his exacting taste was the rare movie that featured a wetlook scene (Tarzan, the Ape Man with Bo Derek in a dripping white cotton dress was a magical favorite). Now, dozens of websites devote themselves to this niche, including WetlookPlanet.com, WetlookWorld.com, and WetlookCouples.com (1). But as Derek’s own particular affection for waterlogged evening gowns demonstrates, the wetlook niche can be broken down into even more narrow sub-niches: wet T-shirts are certainly most popular, but saturated jogging outfits have their own devotees, as do men in business suits rising out of swimming pools and women getting splattered by wet dogs. Some wetlook sites specialize in outdoor scenes; some focus on bathroom scenes. There’s celebrity wetlook and group wetlook, while ThaiWetlook.com, DutchWetlook.com, and WetlookRomania.com demonstrate the international diversity of the niche. Wetlook overlaps other erotic niches: muddy (men and women smeared with mud), messy (bespattered with various liquids, suds, and oils), and wam (wet AND messy).

But why in the world would anyone become sexually aroused—sexually fixated, you might say—on amateurs in wet clothing? The answer is somewhat different than the explanation of men’s predilection for breasts or women’s predilection for billionaires. Breasts and billionaires are both cued interests. Most wetlook, however, may be an uncued interest.

According to cue theory, we are all born with specific sexual predispositions—cues—that tend to draw our attention to certain physical and psychological features of potential sexual partners. Most male cues are visual, most female cues are psychological, though the full range of cues for both sexes are quite diverse. The top 50 most popular sexual interests (measured by the frequency of online sexual searches) are all cued interests; if we have a biological predisposition towards certain kinds of erotic interests, then these interests should be most common.

Wetlook, on the other hand, is a rare interest. It does not crack the top 100 list of the most common sexual interests. This fact alone hints at the operation of a different kind of sexual mechanism. But there’s another clue that sets wetlook apart from an interest in busty or billionaires: people who are fans of wetlook almost always have an “origin story”—a vivid memory of the very first time the sexual interest manifested itself. From our research, it’s possible to have origin stories for cued interests, but it’s the norm for uncued interests.

“When I was nineteen, I had a hydrocele, which is the accumulation of fluid around the testicle. The doctor needed to check how it was doing using ultrasound. So I was in the doctor’s office lying on the cot with my pants down, and the female technician rubbed this warm gel on my testicles,” explains Billy Chou (2), a Massachusetts government employee. “But then she took the ultrasound tool and began to roll it around my testicles. Instant hard-on. Ever since then, I get intensely turned on by doctor’s offices. Once I’m on the exam table I can even get hard around a male doctor.”

What’s going on? For men, there appears to be a special window of time when sexual interests can form—what biologists call a critical period. During the critical period, male sexual interests are acquired and consolidated during a process of sexual imprinting. While it’s not ethical to experimentally manipulate sexual imprinting in humans, biologists have been studying imprinting in animals for a long time.

In studies where male sheep were raised by goats, the young sheep sexually imprinted upon goats during the sheep’s critical period. Afterwards, the male sheep would only try to mate with goats. Other sheep were not sexually desirable. In contrast, when female sheep were raised by goats, their imprinting was reversible. The female sheep could become willing to mate with other sheep. This same pattern of irreversible male sexual imprinting and weak female imprinting was observed when young goats were raised by sheep.

A critical period for sexual imprinting is also supported by research on birds, including the “guinea pig of sexual imprinting research”: zebra finches. A male finch’s ideas about what a sexy partner looks like are strongly influenced by how its mother looks. However, this influence only operates during a few months when the bird is about a year old. During this critical period, a visual representation of the ideal female is burned into the male finch brain and will guide its sexual behavior for life. (Intriguingly, female finches are more likely than males to form “visual fetishes”, such as preferring a single brightly colored feather, if their father possessed such a cue. But, unlike humans, the male finch is more colorful and ornamented than the female.) When researchers prevented a male finch from seeing its mother during the critical period, it never developed a visual attraction to female finches.

Scientists have discovered two relevant discoveries in sexual imprinting in animals, especially birds. First, some things are more easily sexually imprinted than other things—it’s easier to sexually imprint a rooster on a chicken’s wattle than a chicken’s legs, for example, emphasizing the role of cues. Second, it’s not just the initial exposure that matters for imprinting (what is called “acquisition”) but also a period of “consolidation” where contextual factors influence whether a novel interest gets fixed. If other erotic contextual stimuli are present and highly salient—or, most powerfully of all, if ejaculation accompanies the exposure to the novel interest—then the male is much more likely to imprint.

In men, sexual imprinting seems more likely to occur when two different contextual factors are present. First, a strong tactile or olfactory stimuli. If a male is touched, especially around the genitals, or smells a strong odor this seems to increase the likelilood of imprinting. This may also contribute to many latex and leather fetishes. Second, if there’s a strong emotional response, this also serves to increase imprinting. Billy Chou was touched on his testicles during a striking emotional experience where he felt vulnerable and exposed.

There are several types of wetlook interests (3) and several of them appear to be examples of sexual imprinting on an uncued interest. Many wetlook fans are sexually aroused by being soaking wet themselves. These interests may have formed during an early incident when they were pushed into the water by someone or fell into the water with members of the opposite sex present. A strong tactile sensation (immersion) accompanied by a strong emotion (fear, embarrassment, pleasure). Other male wetlook fans (both gay and straight) had an early experience where they cuddled or kissed someone in the rain or in another situation where they were clothed but soaking wet (one man told us that when he was 12 he rolled around in the mud with a girl).

However, other men report no “origin story” for their interest and assert that they simply like the way women look when they are wet, muddy, or messy. It’s possible that this might reflect a form of cued interest—the natural male predilection for female gynoid curves, whose geometries are visually enhanced by the body-clinging and body-emphasizing effects of wet or muddy clothes. In addition, the male dominance cue might come into play, as some wetlook fans appreciate the look of surprise or concern on a women’s face when she is unexpectedly doused or muddied up.

Before the Internet, wetlook fans had a difficult time indulging in their interest, as the opportunities to ogle wet or muddy women were relatively rare. Today—as with so many other uncommon interests—it’s possible to obtain a near-constant supply of new wetlook material. Whether this should be celebrated or condemned is not something that science can decide.

(1) The websites mentioned here are from 2009.(1)

(2) We’ve changed the names of Billy Chou and Derek Kroft.

(3) The vast majority of wetlook fans are male. Though there are anecdotes of female wetlook fans, we couldn’t find enough relevant online behavioral data about them during our research to draw any conclusions about them.

Dr. Ogi Ogas received his PhD in computational neuroscience from Boston University and was a Department of Homeland Security Fellow. His writing has been published in the Boston Globe, Wall Street Journal, Glamour, Wired, Baltimore Magazine, and Seed.  He used his knowledge of cognition to reach the million dollar question on Who Wants to Be a Millionaire and battle Ken Jennings in the finals of Grand Slam.

Sexualpedia Part 4: Why Do I Like Billionaires?

Sexualpedia is an open-ended series of articles that will explain the source of many common erotic interests using neuroscience, biology, and online behavioral data.

Our first entry in the Men’s Sexualpedia was busty, one of the most prevalent erotic interests for male brains around the world. We open the Women’s Sexualpedia with the erotic interest that may serve as busty’s equivalent in the female brain: billionaires.

Billionaire Montage Sexualpedia

“Billionaire” is as prominent in the titles of romance novels and female-authored erotic tales as “busty” is in porn sites: The Billionaire’s New Assistant; Untamed Billionaire, Undressed Virgin; The Billionaire’s Baby Bargain. In the romance titles on Amazon in 2010, there were 286 billionaires (and 415 millionaires and 263 sheiks). The explosively popular erotic novel 50 Shades of Gray features a typical example of a fictional billionaire that stirs female arousal:

“Miss Kavanagh.” He extends a long-fingered hand to me once I’m upright. “I’m Christian Grey. Are you all right? Would you like to sit?”

So young – and attractive, very attractive. He’s tall, dressed in a fine gray suit, white shirt, and black tie with unruly dark copper colored hair and intense, bright gray eyes that regard me shrewdly. It takes a moment for me to find my voice. “Um. Actually–” I mutter. If this guy is over thirty then I’m a monkey’s uncle. In a daze, I place my hand in his and we shake. As our fingers touch, I feel an odd exhilarating shiver run through me. I withdraw my hand hastily, embarrassed. Must be static. I blink rapidly, my eyelids matching my heart rate.

“[Your paintings] are lovely. Raising the ordinary to extraordinary,” I murmur, distracted both by him and the paintings. He cocks his head to one side and regards me intently. “I couldn’t agree more, Miss Steele,” he replies, his voice soft and for some inexplicable reason I find myself blushing.

Fabulously wealthy heroes have always been mainstays of romance fiction. The 1740 book Pamela, arguably the first romance novel, follows the courtship of a fifteen-year-old servant-maid by her master, Mr. B, a wealthy nobleman. Jane Austen’s heroes usually boasted aristocratic wealth. If one goes back 20 years or more, millionaires and sheiks replace billionaires as romance heroes (especially in Harlequin books), but a million dollars just doesn’t carry as much weight with twenty-first century women. Billionaire sheiks still have cross-cultural appeal even for Americans; a scene in the first season of the TV show Homeland portrays dozens of beautiful American women auditioning to be a companion for a Saudi prince. Even paranormal romance, with supernatural characters and situations, often emphasize the financial authority of its paranormal characters such as the blind vampire prince Wrath in J.R.Ward’s Black Dagger Brotherhood series who controls vast international wealth.

Material resources are arousing to females all across the animal kingdom. Female chimpanzees prefer males with the largest quantity of meat. Female pelicans prefer males who give them the most fish. The female wolf spider prefers males who bring them the largest insect. The female bower bird famously prefers the male with the most sumptuous and elaborate bower. But it’s likely that the female interest in billionaires is predicated on something even more basic. As Henry Kissinger famously said, “Power is the ultimate aphrodisiac.”

Power is a reflection of a man’s rank in the dominance hierarchy, and women (like all female primates) are attracted to the men near the top. When romance heroines swoon and shiver over the sight of billionaires it’s not so much at their lavish expenditures (though that doesn’t hurt), it’s at their vibrant projection of unbridled power. Consider this passage from Ruth Cardello’s Maid for the Billionaire; even though he reeks of booze, the hero’s mere existence incites the heroine’s lust:

His back straightened and she caught her breath, reeling from the full impact of his attention. God, he’s beautiful. His dark gray eyes raked over her, flashing with irritation and then something else. He cut the distance between them in a few short strides. A hint of alcohol reached her as he stopped mere inches from her. She tipped her head back to look up at him.

“Did Jake send you?” he asked as he assessed her. “You don’t look like a model.”

She blinked a few times in surprise as some of her sympathy for him faded. “And you don’t smell like a man who should be wearing an Armani, but I wasn’t going to mention it,” she answered in a huff.

Her words stirred something in him; his shoulders squared and his eyes narrowed. This was a man who was not accustomed to people speaking back to him, but if he was trying to intimidate her, his nearness was creating the entirely wrong reaction in her body. Even in his rumpled suit, or maybe because of it, he was the sexiest man she’d ever seen in person.

She wanted to reach up and run a hand over the rough stubble on his cheek. “I didn’t say you were unattractive,” he growled. “You’re just not reed thin like the women I’m used to.”

That’s it. She put her hands on her hips and raised her eyebrows in a silent challenge. Time suspended as their standoff continued. His look of annoyance was steeped with an expectation that she should try to appease him in some way.

Study after study has demonstrated the erotic appeal of male dominance. Women prefer the voices of dominant men, the scent of dominant men, the movement and gait of dominant men, and the facial features of dominant men. Scientists believe that the ventrolateral prefrontal cortex may be responsible for processing cues indicating social status or dominance, and it appears that almost all female brains are susceptible to dominance cues. One woman who met Bill Clinton reported, “I met [Clinton] as part of a governmental panel while he was president. I’m a lesbian, but the powerful attraction I felt toward him for an instant made me question whether I really was!”

In the same way that bustyness provides a quick index of youth, health, and fertility (through estrogen-influenced gynoid fat deposits), billionaires succinctly imply status and power, even in the absence of any actions on the man’s part. It’s no wonder that erotic stories involving billionaires tend to involve the domination, seduction, and, forceful ravishing of heroines—women trembling and quivering beneath the masculine authority of the billionaire.

So if men like busty and women like billionaires, is there an erotic place where the two meet? We could find no books with both “busty” and “billionaire” in the title; neither could we find a porn movie or porn site with both words. Billionaires do not seem to hold much erotic charge with men (not even with gay men; we couldn’t find any gay porn featuring billionaire characters); while a heroine’s well-endowed bustline isn’t often emphasized in romance novels, female-authored erotica, or fan fiction. One might guess that a novel titled Carlos Slim and the Double-D Secretary Senorita would be a cross-over erotic hit—or, perhaps, would not find much traction at all.

Dr. Ogi Ogas received his PhD in computational neuroscience from Boston University and was a Department of Homeland Security Fellow. His writing has been published in the Boston Globe, Wall Street Journal, Glamour, Wired, Baltimore Magazine, and Seed.  He used his knowledge of cognition to reach the million dollar question on Who Wants to Be a Millionaire and battle Ken Jennings in the finals of Grand Slam.

 

Sexualpedia Part 1: Why Do I Like the Things I Like?

Why do you like to read paranormal romance novels? Why do you like to look at pictures of girls smeared with mud? Why do you find Adam Lambert so strangely alluring? Why do you get turned on reading stories about men who turn into women? Why do you find yourself compulsively downloading bukkake porn?

This is the first in an open-ended series of articles that will explain the source of many common erotic interests using neuroscience, biology, and online behavioral data. The goal is to provide you with a clear understanding of why you like the things you like—even if these things are embarrassing (they shouldn’t be), strange (they’re probably quite common), or befuddling.

Whether you are a heterosexual woman who finds Brokeback Mountain to be intensely arousing or a heterosexual man who searches PornHub for the largest penises you can find, this series is intended to provide you with knowledge and reassurance.

While the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty.

—Sherlock Holmes, Sign of the Four

Though sexual behavior is infinitely nuanced and complex, influenced by culture, experience, mood, free will, and what you gobbled down for breakfast, sexual desire appears to be bounded. The things that turn us on can be broken down into specific sexual cues. Our sexual cues are analogous to our taste cues (sweet, sour, salty, savory, bitter, possibly others): hardwired predilections shaped by evolution that perform specific functions and deliver varying degrees of pleasure. Even though human cuisine is infinitely variable, everything we eat can be resolved into its constituent taste cues. (Oreo cheesecake and baklava both trigger our taste for sweetness.) Similarly, though human sexual tastes are infinitely variable, everything that turns us on can be broken down into their constituent sexual cues.

There is one important difference between our gustatory tastes and sexual tastes, however. Whereas men and women share the same gustatory cues—lemons taste sour to all of us—men and women exhibit very different sexual cues. For this reason, each article in this series will address either a male sexual interest or a female sexual interest since they each require different kinds of explanations.

On the other hand, gay male sexual tastes are mostly identical to straight male sexual tastes, so a single explanation will suffice for both; for example, straight men’s interest in women’s feet can be explained in the same manner as gay men’s interest in men’s feet. Lesbian and heterosexual women’s sexual tastes also mostly share the same explanations. There are exceptions, of course.

Our understanding of sexual desire is derived from research in sexology, neuroscience, primatology, social psychology, neurology, community health, and an enormous quantity of online sexual data, delineated at the end of this article. This online data supplied us with many useful tools for understanding the relationships between different sexual cues, including the following two graphics.

 

fetish_graph_v3_b

 

pornhub_tags_map

They may look like constellations of the celestial heavens but they are actually constellations of human sexuality: correlation maps. The first visualizes the correlations between different sexual interests within individual search histories on the AOL search engine. The second visualizes the correlations between different tags on videos on PornHub. In the articles that follow, we will be discussing the significance of some of these correlations—such as why incest and bestiality seem correlated, and why an interest in feet and an interest in bondage seem correlated.

 

Online data used for the Sexualpedia:

Web searches (Dogpile; AOL; Excite; Google; Yandex.ru)
Individual search histories (AOL)
Website traffic (Alexa, Quantcast, Compete)
Website names
Erotic stories (Literotica, nifty, asstr.org, fictionmania, Hindi)
Fan fiction stories (fanfiction.net, adultfanfiction.net)
Digitized romance novels (including erotic romance)
Delicious tags
Erotic images and videos (fantasti.cc, PornHub, xhamster, many others)
Personal sex seeking ads (craigslist)
Online dating site survey and user data (OKCupid)
Adult site-specific data (PornHub, ssh.com, wasteland.com, others)
Credit card processing data (CCBill)
Other niche data (Webcam sites, adult star details, pirated porn downloads, others)
Most of the data was gathered in 2010. Since then, the number of porn subscription sites have dramatically diminished, while tube sites now dominate online visual erotica.

What Do Shemale Porn and the Twilight Novels Have in Common?

[ This article is based upon the 2012 Idea City talk “What do shemale porn and Edward Cullen have in common?” ]

During our expansive exploration of sexual desire, we encountered a number of popular erotic interests that defied academic predictions and evolutionary theory. For example, among heterosexual men, the stunning popularity of shemale porn (sometimes referred to as futanari), incest porn, and bukkake porn, three of the most searched for erotic genres in the world. Among women, slash fan fiction (romantic and erotic male-male stories), incest stories, and the phenomenal global popularity of paranormal romance, whose leading example is Stephanie Myers’ Twilight novels.

As computational neuroscientists, we turned to the design of the brain to attempt to explain these prevalent yet baffling erotic tastes. In particular, we considered the operation of “sexual cues,” hardwired sexual taste predispositions analogous to our hardwired gustatory tastes. Just as our brains come hard-wired with five different taste cues—salty, sour, sweet, savory, bitter (some researchers add metallic and fat), our brains also come hard-wired with a finite set of sexual cues. However, though male and female brains share the same taste cues, our brains come loaded with entirely different sets of sexual cues. It’s as if the male brain has salty and sour cues, and the female brain has bitter and sweet cues. If we each tasted the sexual equivalent of peanut brittle, a man would report a salty flavor while a woman would report its sweetness.

In previous computational neuroscience research, we had modeled how the brain manufactured optical illusions, such as the enigmatic Mona Lisa smile, by simultaneously juxtaposing two different visual cues to create a strange and beguiling gestalt that was perceptually “more than the sum of its parts.” (In the case of the Mona Lisa smile, da Vinci juxtaposed a low-frequency grin with a high-frequency flat expression to produce the beguiling smile that seems to appear or disappear depending on where your eyes come to rest on the painting.) Our brain can also be tricked by gustatory illusions: restaurants like Chili’s and T.G.I.Friday’s hire food engineers who craft culinary concoctions that combine different gustatory cues (salty, fatty, sweet, crunchy) into irresistible gustatory illusions that promote what the food industry calls cravability, such as Chili’s Texas Cheese Fries or Cheesecake Factory’s Oreo Dream Extreme Cheesecake.

It appears that our brains might also be tricked by erotical illusions. By combining (or distorting) multiple sexual cues into novel gestalts, it’s possible to evoke bewilderingly intense sexual arousal. Male erotical illusions are mostly visual, since the male sexual brain consists primarily of visual cues. Female erotical illusions are mostly psychological, since the female sexual brain consists primarily of psychological cues.

Erotical illusions account for one of the most popular and baffling sexual interests of heterosexual men: shemale porn. (Many transsexuals find the term “shemale” offensive when applied to an individual, though this is the common term for the genre within the adult industry.) Figures in shemale porn feature the body of a woman and a penis, often a large one.

In Japanese anime, transsexual characters are known as futanari. Futanari porn reveals exactly what appeals to straight men about shemales. Futanari characters are drawn with hyperfeminine bodies, typically very young, with large round breasts and hourglass figures, large eyes with long eyelashes and beautiful faces. They also possess giant horse-sized penises. Typical futanari features schoolgirls with giant protrusions beneath their plaid skirts, teenage girls with pink hair and a bulge in their jeans, slender ballerinas in tutus and sporting erections as long as their slender legs.

Recently, contemporary adult webmasters have found ways to manufacture “artificial shemales” that do not involve the use of actual transsexual actresses. The women are voluptuous and curvy, with enormous strap-on dildos that look like authentic if colossally oversized penises. The site is full of scenes of attractive, busty women stroking their giant artificial manhood.

The site makes the erotical illusion very clear: anatomical cues of femininity juxtaposed with the visual cue of a penis. (The penis is a prominent sexual cue for many heterosexual men.)

What about the opposite? What about someone with strong muscular arms, tattooed biceps, a bald head, a beard—and a vagina? The most famous transsexual male porn star is the cigar-puffing Buck Angel.

Buck Angel combines a number of visual cues of masculinity with the single feminine cue of a vagina. Straight men express no interest in Buck Angel, and some find him disquieting. But many gay men find him extremely intriguing. The sexual brains of most women, however, do not respond to Buck Angel as a visual erotical illusion. Instead, erotical illusions comprised of psychological cues are more effective at tricking the female sexual brain—such as paranormal romance.

Some of the psychological cues that consistently appear in the hundreds of thousands of female-authored erotic stories and the thousands of digital romance novels we analyzed include heroes who are alpha males (strong, confident leaders), intelligent and experienced, willing to protect women from physical harm, desired by many women (though they only love the heroine), who lust intensely after the inexplicably irresistible heroine, who hide a secret tender side, and whose aggressive nature is tamed by the heroine’s love. It turns out that these cues are all whirled together and amplified in the stories of paranormal romance.

Consider Edward Cullen, the vampire hero of Twilight. Since he is a vampire, he has the body of a 17-year old hotty—but the experienced, mature mind of a 107 year old. He is the ultimate alpha: an immortal warrior dispatches human bullies with ruthless ease, rescuing Bella Swan time and again. All the girls at Bella’s high school have crushed on Edward—but he is only interested in Bella, because of her inexplicably delicious smell. He lusts after Bella—literally, since he lusts after the blood coursing through her veins—but demonstrates his love for Bella by not acting on his primal urge to rip open her neck and drink her blood. Cullen is an Oreo Extreme Dream Cheesecake for the female sexual brain: a superalpha who eternally lusts after one uniquely special woman, but who forever demonstrates his kind and loving heart by not acting upon his savage impulses—at least, not when he’s around his beloved; he’s free to release his barbaric side when challenged by villainous opponents.

Unlike women, men are not aroused by romantic stories of vampire women with youthful bodies and elderly minds. The male sexual brain does not process the same sort of literary erotical illusion.

Erotical illusions make vivid one of the most fascinating aspects of human sexuality: that much of sexual arousal results from the integrative sorcery of our imagination. For more, watch the 2012 Idea City talk “What do shemale porn and Edward Cullen have in common?”

Dr. Ogi Ogas received his PhD in computational neuroscience from Boston University and was a Department of Homeland Security Fellow. His writing has been published in the Boston Globe, Wall Street Journal, Glamour, Wired, Baltimore Magazine, and Seed.  He used his knowledge of cognition to reach the million dollar question on Who Wants to Be a Millionaire and battle Ken Jennings in the finals of Grand Slam.