Diversity of sexual preferences is to be expected

In the contemporary West, it is taken for granted that sexual preferences—that is, what things people find sexually appealing—fall into a few discrete categories, which are called sexual orientations. Invariably, heterosexuality and homosexuality are considered sexual orientations (although some consider the word "homosexuality" stigmatizing for historical reasons). Usually, bisexuality is included. Many other extensions to this taxonomy exist, although none are popular among laymen. Among these extensions are a four-orientation model in which asexuality is included as a fourth orientation; the Kinsey scale, in which there is "Exclusively heterosexual with no homosexual", "Exclusively homosexual", and five intermediate points (Kinsey, Pomeroy, & Martin, 1948, p. 638); an added distinction between "tops" and "bottoms" (insertive or dominating versus receptive or submissive); a dual-axis model in which preferences for age are distinct from preferences for gender (Seto, 2012); and the Klein grid, which comprises 27 seven-point items (on gay–straight axes) organized into seven features and three time-points (Weinrich et al., 1993).

So, how well are real people's real sexual preferences described by these taxonomies? In everyday life, we rarely ask this question—we assume that the gay–straight dichotomy or gay–bi–straight trichotomy is correct and thence do all our reasoning about people's sexual preferences. Should these models be wrong, it is easy to see how great harm could arise from slavish application of them, from trying to pound square pegs into round holes. I need not provide any anecdotes about the misery people undergo when they feel unsure about their sexual orientation: popular media and likely the reader's own life are full of such anecdotes. How much more inescapable this suffering would be if the root problem were not mere ambiguity about which sexual orientation one belonged to, but the nonexistence of a sexual orientation that fits! The situation could then only be resolved with stoic apathy, denial of one's own feelings, or the invention of yet another sexual orientation. (As if we needed another letter added onto "LGBTQAOMGWTFBBQ".)

I'm tempted to claim that sexual orientation, considered as a psychological theory, is wrong. But I can't, because, as I was saying earlier, sexual orientation isn't any one theory or model; it's more like a big family of models with the lay dichotomy as common ancestor. The family as a whole can't be falsified. Faced with falsificatory evidence for any one model, one could extend the model into a new one that can handle the new evidence. Falsification is yet more difficult because sexual orientation, although often employed in an explanatory fashion (particularly by laymen), is more descriptive than explanatory: it says a lot more about the exact phenomena of interest (sexual attraction and behavior) than about any supposed causes. A careful thinker wouldn't claim that Joe has sex with Bob because Joe is gay; they would instead attribute the causal power to whatever they think causes male–male sexual attraction and behavior to begin with, and say that the attraction that led Joe to have sex with Bob is part of what constitutes Joe's homosexuality. There are then few causal chains within these models to test, and the only way they're accountable to empirical reality is that they have to include everybody, or at least, every sexual-preference pattern that can be found in more than a dozen people. The only other constraint on these models is that they have to be models, in the sense that they need to make only finitely many distinctions and they need to have halfway-coherent theories behind them.

There exists a more sophisticated philosophy for scientific models, which is to assume that all models are, in the final analysis, false, and change the focus from finding a correct model to finding the most useful model (see Arfer & Luhmann, 2015, for a related discussion). How exactly usefulness should be measured is, of course, context-dependent. It then becomes difficult to talk about how good a model is in abstract terms. A model that's excellent for one purpose could be poor for another. I think, however, that the onus is very much on the proponents of sexual orientation to demonstrate it is useful for anything other than breeding confusion and hatred among ordinary people.

At any rate, I can't falsify sexual orientation. The most I can do here is to enumerate some potential problems for any sexual-orientation taxonomy. These gotchas will mostly be ways sexual preferences can be diverse, which may remind you of the lists of non-reproductive sexual practices in the previous chapter. (But I'll give much less attention to animals than last time, because, for reasons that aren't clear to me but might just be differences of discipline (e.g., ethology versus sociology), scientists are much less hasty to classify the sexual preferences of animals than of humans.) Some are more specifically problematic to one model than another. Taken together, though, they're strong reason not to put too much faith in the idea of sexual orientation.

Instead of sex, let's think about ice cream for a moment.1 As a rule, people like ice cream. But they don't all like ice cream in exactly the same way. Consider yourself. Maybe you like vanilla. Maybe you like chocolate. Maybe you like both. Maybe you like vanilla a lot but chocolate only a little. Maybe you like chocolate in ice-cream sodas but when you're getting a cone it's vanilla with rainbow sprinkles or nothing. Maybe you enjoy the idea of vanilla but chocolate always seems to taste better in practice. Maybe you have pleasant associations with chocolate because it reminds you of your happiest childhood days, but vanilla appeals to you in a more direct, less sentimental way. Maybe you have much stronger opinions about soft-serve versus hard ice cream than flavor, so flavor, by contrast, is immaterial. Maybe you like strawberry. Maybe you like Pan-Galactic Gargle Chip (not that you have any idea what it tastes like, since it doesn't exist, but it sounds delicious for some reason). Maybe ice cream in general fails to excite you. Maybe you're just not a fan of ice cream, however good it tastes, and at times you wish that man had never domesticated the cow.

While we can classify people's ice-cream preferences in all sorts of ways, it would clearly be absurd to take such a taxonomy too seriously. People's preferences, examined in sufficient detail, are bound to be eccentric and varied, as is to be expected considering the wide variety of things that could somehow affect their preferences. There's no accounting for taste. (While we psychologists assume that there must be some causal chain behind a person's preferences, it can be arbitrarily obscure in any individual case.)

Simply put, why should we expect sexual preferences to be fundamentally different from ice-cream preferences? Correlations with respect to gender don't make idiosyncrasy disappear.

To make this ice-cream analogy more concrete, consider two simple stimulus-norming studies I conducted on Amazon Mechanical Turk in May and June of 2012 (Arfer, 2012). In each, subjects were shown 12 images and were asked to pick the image they found most appealing, the image they found second-most appealing, and the image they found third-most appealing. The primary difference between the two studies was that the first used photographs of desserts and the second used photographs of women, most of them semi-nude and in sexually provocative poses. Another relevant difference was that the second study was open only to Americans, whereas the first had no restrictions on country, so it probably included a lot of Indians, for example (Ipeirotis, 2010).

• The dessert study had 94 subjects. All but one of the images were selected at least once as a first choice, and all the images were selected at least twice as a second choice and as a third choice. There were 84 unique first–second–third selections in the sample, or 66 disregarding order.
• The sex study had 155 subjects (some of whom had also participated in the dessert study). Considering only subjects who stated they were male and sexually attracted to women (who should, of course, have had less diverse preferences than the whole sample), there were 88 subjects. Among these subjects, every image was selected at least twice for each of the three choices, and there were 86 unique first–second–third selections, or 70 disregarding order.

These findings don't exactly prove my point, considering issues such as how subjects had no way to indicate indifference and the lack of random assignment to studies, but I consider them supportive. Certainly, the second study flies in the face of the stereotype that men have homogeneous and predictable sexual preferences.

One additional lesson can be drawn from the ice-cream analogy described above. Even though ice-cream preferences can be affected by many things, from one's genes to other people's opinions, we know of no reliable way to change our preferences deliberately. We can't freely choose our preferences. On the contrary, preferences are, by definition, one of the fundamental causes of our choices. The moral is that despite popular belief, even if genes had no influence on sexual preferences, it wouldn't follow that sexual preferences are freely chosen, nor that sexual preferences are otherwise easy to change when one wants to. From this perspective, the APA task force's (Glassgold et al., 2009) conclusion that no existing gay-to-straight conversion therapy is effective, and Quinsey's (2008) conclusion that treatment can't change the true preferences of sex offenders, aren't surprising. And the claim that "sexual orientation" is a better term than "sexual preference" because "preference" "suggests a degree of voluntary choice" (Committee on Lesbian and Gay Concerns, American Psychological Association, 1991, p. 973) is nonsensical.

Just how fickle preferences can be is perhaps best demonstrated by Ariely, Loewenstein, and Prelec (2006). In a series of three experiments on college students, some subjects were asked whether they would pay money to attend a poetry recital by their instructor and others were asked if they would attend the recital for a fee paid to them. This manipulation affected how people evaluated the poetry recital. In Experiment 1, for example, 35% of subjects initially asked to pay said they would attend the poetry recital if it were free, compared to only 8% of subjects initially offered money to attend it. Experiment 3 showed that, amazingly, similar changes in valuation persisted even if subjects heard a sample of the poetry recital first (so they had a concrete sense of what it would be like) and were shown the two experimental conditions and how they were assigned. We are obliged to believe that subjects did not have a firm preference about whether attending the poetry recital was a desirable or undesirable experience. They were so uncertain about their own likes and dislikes on the matter that they stuck to whatever cue had been handed to them, even when they knew that the cue was completely uninformative. I submit that if people can be so uncertain and confused about their preferences for an experience as simple as a poetry recital, they are likely to be all the more confused about their preferences for romantic partners and sexual experiences.

Often, sexual orientations aren't considered exactly classes of sexual preferences. They may construed as classes of sexual behavior, whereby one's sexual orientation describes who one has sex with rather than who one finds attractive. Or they may be construed as identities, whereby one's sexual orientation is whatever group one says one belongs to. Or they may be construed as some combination of all three. While it makes sense that epidemiologists should group people according to who they've had sex with, and sociologists should group people according to who they identify with, it can be dangerous to conflate the three characteristics. Such conflation happens, for example, every time a researcher tries to measure sexual preferences by asking subjects what they identify as, which is the most common way of measuring sexual preferences (oops).

Mock and Eibach (2012) examined change in stated sexual orientation over a ten-year period in a large probability sample of adults, the National Survey of Midlife Development in the United States. The options were "heterosexual", "homosexual", and "bisexual". The vast majority of subjects chose "heterosexual" both times, but 18 of 1,342 women and 9 of 1,152 men who were straight in Wave 1 switched to gay or bi in Wave 2. Gay men were also reasonably but not perfectly stable: of the 21 in Wave 1, 1 switched to straight and 1 switched to bi. But Wave 1's lesbians (11) and bisexuals (17 female and 17 male) were overall no more likely to stay their initial orientation than switch to one of the other two. Similar results was obtained by Ott, Corliss, Wypij, Rosario, and Austin (2011), who used 5,887 males and 7,953 females from the four-wave Growing Up Today Study and an orientation item with options "completely heterosexual", "mostly heterosexual", "bisexual", "mostly homosexual", "completely homosexual", and "unsure". Over two-year periods starting during adulthood, complete heterosexuals were highly unlikely to change (no more than 7%), gay men were slightly more likely to change (11%), lesbians were somewhat more (35%), and other orientations were at most a little more likely to stay the same than change. Finally, similar results were also obtained by Savin-Williams, Joyner, and Rieger (2012), who used 5,527 men and 6,556 women from waves 3 and 4 of the National Longitudinal Survey of Adolescent Health, and similar orientation categories as Ott et al. (2011). Over a six-year period, stability was observed in 97% of completely heterosexual men, 88% of completely heterosexual women, 71% of completely homosexual men, 67% of completely homosexual women, and no more than 53% in every other category.

So, while rates of change differ by gender and starting sexual orientation, and change is rare overall, it happens nontrivially: orientation isn't fixed. Change seems particularly common among people who aren't heterosexual to begin with. I would expect people are more willing to change their mind about their orientation if they've already made the mental leap of identifying as something other than the default.

Since all studies I know of on change in sexual orientation over time have relied on self-report, it's hard to say what's actually changing. When a man stops calling himself straight and starts calling himself gay, has he merely changed how he interprets his own feelings, as laypeople assume, or is it actually his sexual preferences that have changed? And what if not only can preferences affect identity but identity can affect preferences? How does honest-to-God sexual behavior fit in here?

In ancient Greece, pederasty was a social institution. Although there was controversy among contemporaries as to whether pederasty aided in the development of the boy's character or was merely a means of sexual gratification for the adult, just as modern scholars debate its role in ancient society, it was widely acknowledged and not generally stigmatized (Percy, 2005). Since the adult was typically married to a woman at the same time (Stearns, 2009), and the boy presumably married a woman himself in adulthood, neither partner confined their sexual activity to males. Nor are such specialized arrangements consonant with the idea of gender-blind bisexuality.

One aspect of sexual preferences that lines up poorly with the idea of sexual orientation is preferences targeted to specific acts, objects, or personal characteristics.2 de Silva (1999) mentions sexual fantasies, feelings, and behaviors concerning garments, cross-dressing, urine, feces, prepubescent children, animals, dead bodies, and pain and humiliation.3 Scorolli, Ghirlanda, Enquist, Zattoni, and Jannini (2007), in a survey of Yahoo! Groups (online message boards and mailing lists), concluded that body parts (such as feet) are particularly popular. Scorolli et al. also mention Yahoo! Groups devoted to things as oddly specific as "smoking girls playing with balloons", but at this point it becomes difficult to distinguish parody from reality, as Poe's law would suggest.

Tying in with the previous theme of instability, Hoffmann (2012) mentions several reports of successful conditioning of sexual appeal in animals and humans, although she adds that in humans, the conditioning is "often weak and short-lived" (p. 67) and seems to depend on several individual differences.

Not everybody experiences enough sexual feelings or behavior to satisfy popular notions of straight or gay.

Note that most identified-heterosexual men masturbate (Herbenick et al., 2010) although there's nothing heterosexual about masturbation. (Yes, one can have heterosexual fantasies while masturbating, but one can have heterosexual fantasies while doing anything.) The incidence of masturbation in children under 6 and asexuals also suggests that masturbation is caused by sexual preferences that are distinct from the sort of sexual preferences we usually think about.

By no means. Truth be told, when I was doing the research for this chapter, I was sometimes surprised to find more consistency in sexual preferences for gender than I'd expected. I thought, for example, that I'd readily find (perhaps in Francoeur & Noonan, 2004) examples of sexual identities accepted as normal by non-Western cultures that didn't involve gender-bending (as two-spiritism does) but clearly didn't line up with hetero-, homo-, or bisexuality. Instead, the above section "Cultural differences" has only the one example of Greek pederasty. It seems that non-Western cultures tend only to have heterosexuality (perhaps with a bit of not-very-systematic homosexuality on the side), situational homosexuality, and (more rarely) fairly exclusive homosexuality or fairly even bisexuality. Also, I found three papers showing surprisingly good concordance between sexual identity and lower-level phenomena, at least in men. Snowden, Wichter, and Gray (2008) found that gender preference implied by performance in priming tasks is strongly predictive of identity. Jiang et al. (2006) found that identity predicted whether subliminal perception of a nude picture of a man or a woman would attract attention to its location. Finally, Ponseti et al. (2009) were able to predict individual identity with fMRI using group differences in BOLD response between 12 straight men and 14 gay men.

What moral, then, we can draw from all this? I suggest the following:

• Sexual orientation is not a natural kind, that is, a fundamental natural taxonomy.
• Don't confuse descriptions of sexual preferences with their causes.
• Don't assume that gender is the only important aspect of sexual preferences.
• Don't assume that sexual preferences are stable over time, but don't expect to be able to change them at will, either.
• Don't forget that preferences, behavior, and identity are distinct. In both everyday life and in research, examine what you're actually interested in. As Savin-Williams (2006) says (p. 43), "To assess STDs or HIV transmission, measure sexual behavior. To assess interpersonal attachments, measure sexual/romantic attraction. To assess political ideology, measure sexual identity."
• Decide whether to construe unusual sexual preferences as pathological by considering their consequences, not the degree to which they're unusual. (But now I'm practically repeating myself from the earlier chapter about practices.) Relatedly, if somebody's upset about their sexual preferences (whether they're a man disgusted at his desire for other men or a woman frustrated by her lack of desire), consider that either the preferences themselves or the subject's attitudes and reactions towards those preferences, or even some combination of both, could be fruitfully construed as the root problem. There is no magical dividing line between sexual preferences that are good and natural and that you just have to learn to tolerate and sexual preferences that are horrible and vile and that you must figure out how to change.

In summary, don't be essentialist about sexual preferences.

If we absolutely must construct taxonomies of sexual preferences, the case of discrete emotions might be a good model of how to proceed. Despite our many intuitions about what emotions exist, what causes them, what they do, and so on, researchers haven't hesitated to dream up new models of discrete emotion that bear little resemblance to lay concepts. There are even people who think about discrete emotions roughly the way I think about sexual orientations. For example, Barrett (2012) argues that emotions exist partly as "social reality", the same way that I would say that "gay" as a kind of person, an identity, exists only as a social construct even though it has a basis in trends in sexual preferences that exist independently of anybody's beliefs. Arguably, the field of emotion has too many competing theories, but this is surely better than everybody being unreasonably committed to a particular culture's lay theory.

An ongoing study by me and a collaborator (http://arfer.net/projects/galaxy) demonstrates another strategy. We are giving subjects a long list of types of sex partners, sexual activities, and sexual themes and asking how attractive they find each. We will then investigate statistically how these many individual preferences are organized. By avoiding a priori commitment to any particular taxonomy of sexual preference, we will hopefully maximize our chances of detecting whatever trends really exist.

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