The organization of sexual preferences

Kodi B. Arfer and Nicholas R. Eaton

Sexual preferences vary widely, but how are preferences for different features of sexual partners or sexual activities related to each other? We present a 65-item self-report inventory surveying a wide range of sexual preferences, from preferences regarding partner gender to preferences regarding the power relationship between oneself and one's partner. We propose to discover how sexual preference of all kinds are related with no a priori theoretical commitments. We describe possible patterns of results congruent with existing lay, feminist, and evolutionary theories. Our study should provide an empirical bedrock for comprehensive theory on sexual preference.

N.B. This is a research proposal that I (Kodi) wrote as a homework assignment. It may not bear much resemblance to any real future manuscripts.

Introduction

What kinds of sexual activities and sexual partners are people attracted to? As in all domains of human life, such as food, sports, and academic disciplines, there are widespread individual differences in what people like. The diversity of people's "sexual preferences"—by which we mean preferences concerning sexual activity, whether for particular kinds of partners, particular sexual acts, or even moods or themes, such as vulnerability or purity—is perhaps most obvious from surveys of Internet pornography (e.g., Ogas & Gaddam, 2011) and Internet communities devoted to particular sexual interests (e.g., Scorolli, Ghirlanda, Enquist, Zattoni, & Jannini, 2007) or even the lack of sexual interests (Chasin, 2011). On the other hand, sexual preferences are not entirely idiosyncratic. A familiar example is that, on average, people are more attracted to the opposite sex than to their own sex. In addition to group-level trends, it seems reasonable to expect that preferences will be systematically related to each other. If people who like camping are more probable to like crafts, perhaps men who like penetrative anal intercourse are more probable to like receptive fellatio. How, then, are sexual preferences organized? In other words, which sexual preferences predict each other?

A danger of comparing sexual preferences to hobby preferences is that it suggests sexual preferences are trivial. On the contrary, sexual preferences are socially consequential. For example, male–male sexual contact is a key route of HIV transmission in the United States (Centers for Disease Control and Prevention, 2012), possibly because HIV is more readily transmitted by anal copulation than vaginal copulation (Public Health Agency of Canada, 2012), and people who identify as gay, lesbian, or bisexual are at greater risk of mental illness (Meyer, 2003). Although sexual behavior (what people actually do) and sexual identity (how people describe themselves) are distinct from sexual preferences (what people are attracted to), the latter is presumably an important cause of the former two, suggesting an influential role for sexual preferences in human life.

There has been no shortage of theory and research on various aspects of sexual preferences. We review some of this work below. What is lacking is attempts to discover how sexual preferences of all types cluster, with no a priori commitment to particular ways of organizing sexual preferences, or focus on a single dimension of sexual preference. For example, it is generally assumed that partner gender is the only important aspect of sexual preferences, but we see this as an empirical question. In this study, we survey preferences for a wide variety of characteristics of sexual acts and partners. Our questionnaire includes items relevant to various theories, but our aim is less to confirm or refute a particular theory than to provide an empirical bedrock for future theorizing.

Partner preferences

Most research on sexual preference grants without question some degree of validity to a popular lay theory. This theory splits sexual preferences into a few discrete categories, which are called sexual orientations. Invariably, heterosexuality and homosexuality are counted as sexual orientations. Usually, bisexuality is also included. So ingrained is the sexual-orientation theory in how researchers and laypeople think about sexual preference that the terms "sexual orientation" and "sexual preference" are often considered synonymous.1 But debate continues on which sexual orientations exist: can men be bisexual (Rosenthal, Sylva, Safron, & Bailey, 2012)? Should novel orientations such as "mostly heterosexual" (Savin-Williams & Vrangalova, 2013), pansexuality (Kuper, Nussbaum, & Mustanski, 2012), asexuality (Bogaert, 2006), or pedophilia (Seto, 2012) be admitted? Other controversy includes whether discrete orientation categories should be replaced with continuous scales (Ellis, Burke, & Ames, 1987; Haslam, 1997) and whether continuous variation exists on top of latent discrete categories (Gangestad, Bailey, & Martin, 2000).

Research on preferences for partner features other than gender exists, but has been somewhat piecemeal, characterized only by a trend for evolutionary theorizing (consistent with evolutionary psychology's longstanding concern with mate choice). We begin by considering body parts. Singh (1993) showed that men prefer women with lower waist-to-hip ratios (i.e., an hourglass figure), theoretically because waist-to-hip ratio is negatively related to health and reproductive potential. Wiggins, Wiggins, and Conger (1968) and Dagnino, Navajas, and Sigman (2012) provided some support for the lay notion that men can be grouped into those attracted to women's breasts, buttocks, or legs. Consistent with the association of breasts with nourishment and health, Swami and Tovée (2013) found that poverty and hunger were positively associated with men's preference for larger breasts. Fessler et al. (2005) and Kushnick (2013) examined preferences for foot size, finding overall preference for small women's feet and intermediate-sized men's feet, but with cross-cultural variability. In women, small feet have evolutionary significance because they predict youth and nulliparity.

Sexual preferences per se for more general characteristics of partners, such as personality and wealth, have been studied less than preferences concerning long-term romantic partners. Figueredo, Sefcek, and Jones (2006) examined people's ideals for the personality of their romantic partner, and found that people preferred partners who were more similar to themselves, but also generally more socially desirable (more agreeable, less neurotic, etc.). Backus and Mahalik (2011) found that less feministic women were interested in men with more masculine personalities. Shackelford, Schmitt, and Buss (2005) performed principal-components analysis of a mate-preferences questionnaire administered to many different cultures. They retained four bipolar dimensions, which they labeled "Love vs. Status/Resources", "Dependable/Stable vs. Good Looks/Health", "Education/Intelligence vs. Desire for Home/Children", and "Sociability vs. Similar Religion".

Social status and wealth seem particularly important for women's sexual attraction (Ellis, 1992). For example, Dunn and Searle (2010) found that women rated a male model as more attractive when he was posed in a high-status car than a neutral-status car, but no significant difference emerged for men rating a female model. Ahmetoglu and Swami (2012) found that body postures indicating social dominance may also increase women's attraction to men. Women may be attracted even to violently aggressive tendencies in men ("The memory of the bloody injuries and pain that he inflicted the enemy, confirms him in his self-image of being a good combatant"), as least when considering them as potential casual sex partners rather than as relationship partners (Giebel, Weierstall, Schauer, & Elbert, 2013).

Activity preferences

Research on which sexual activities people say they desire has been sporadic. Nurius and Hudson (1988) performed principal-components analysis of an instrument asking subjects how often they would like to do (and how often they actually did) 78 activities, ranging from "I insert my penis in a woman's anus" to "I have sex on a boat". They selected six dimensions of activity, which they labeled "Heterosexual", "Homosexual", "Multiple Partners", "Autosexual", "Anal Sex", and "Locational Variety". Activity preferences among men have been studied as they relate to "top" and "bottom" identities in the gay community. About half of Wegesin and Meyer-Bahlburg's (2000) subjects, who were gay- and bisexual-identified men in New York City, endorsed one of these labels, and these labels related to their reports of anal-sex role: tops were insertive more often than bottoms, and bottoms were receptive more often than tops. Ogas and Gaddam (2011), examining men-seeking-men personal advertisements on Craigslist, described 65% as being from bottoms seeking tops and 35% as being from tops seeking bottoms. A small pilot study by Damon (2000) found that insertive–receptive preference was related to whether subjects liked exerting power or being overpowered during sex. However, Pachankis, Buttenwieser, Bernstein, and Bayles (2013), as well as Wegesin and Meyer-Bahlburg (2000), found that top–bottom identities commonly changed over the course of a few years.

While research on which sexual activities people say they find appealing is sparse, there is substantial work on which sexual activities people say they actually engage in. Herbenick et al. (2010) describe a recent large survey of Americans. Considering the reports of people aged 25–29 regarding which activities they had ever participated in, in men, masturbation, coitus, cunnilingus, and receptive fellatio were very common, mutual masturbation and insertive anal copulation were less so, and receptive anal copulation was uncommon. In women, coitus, fellatio, and receptive cunnilingus were more common than masturbation, which was more common than mutual masturbation, which was more common than anal copulation, and performing cunnilingus on other women was uncommon.

Miscellaneous preferences

In addition to preferences for partner features or particular sexual acts, we can consider preferences for more general phenomena. Themes of interpersonal power, for example, may be closely tied to sexual affect. Studies of sexual fantasy suggest that women play more passive roles in their fantasies than men, and in particular, women are more likely to fantasize of being raped (Leitenberg & Henning, 1995; Critelli & Bivona, 2008). Sadomasochistic practices have been theorized to be an exaggeration of evolved tendencies to be sexually attracted to power differentials (Jozifkova & Konvicka, 2009). Themes of intimacy and romance, because of their association with sexuality, are also obvious targets for preferences. There is evidence that intimacy and romance are particularly important for women's sexuality (Meana, 2010). Finally, interest in the very sexual interest and pleasure of one's partner are worth investigating. Ogas and Gaddam (2011) note that romance novels for women emphasize the heroine's sexual irresistibility, and that pornography for men emphasizes women's signs of sexual pleasure.

Method

Subjects

Subjects will be recruited on the Internet. They will complete the survey online and be compensated with small fees. We will recruit initially from Amazon Mechanical Turk, a crowdsourcing website, and supplement this with announcements on websites that cater to minority sexual interests if these appear to be poorly represented. We aim for a minimum total sample size of 200.

Instrument design

The focus of our study is our 65-item sexual-preference inventory (see appendix for items and instructions). It asks subjects to consider how sexually appealing they find various qualities of sexual partners or sexual activities. In line with our focus on sexual preferences, our instructions emphasize that subjects should "answer using only your sexual and romantic feelings", as opposed to considering whether, for example, they would actually be willing to perform a given activity. Of course, people are not entirely capable of controlling what criteria they use to make judgments (Wilson & Brekke, 1994), but we aim for the purest appeal ratings possible.

Here is an outline of the items, with explanations of the aspects of sexual preference they are intended to measure.

• Items 1–16 concern typical sexual activities: solo masturbation, coitus, anal copulation, oral sex, masturbating others, and frottage. Descriptions are provided in parentheses to disambiguate and in case subjects are unfamiliar with formal terms like "cunnilingus".
• Items 17–21 concern feelings and activities that could be construed as more romantic than sexual. These are designed to tap interest in themes of romance and intimacy.
• Items 22 and 23 concern interpersonal power.
• Items 24 and 26 concern sexual interest in the genuine sexual interest and pleasure of the partner.
• Item 25 concerns group sex.
• Items 27 and 28 concern rape.
• Items 29–33 concern pornography, exhibitionism, and voyeurism.
• Item 34 concerns incest.
• Item 35 concerns sex in committed relationships, whereas item 36 concerns anonymous sex. Men appear more interested in sex outside of committed relationships than women, as most famously demonstrated by Clark and Hatfield (1989).
• Items 37–44 concern features of the partner's body, such as foot size.
• Items 45–50 concern partner gender and gender prototypicality.
• Items 51–55 concern partner age.
• Items 56 and 57 concern the partner's social status, wealth, and violent tendencies (and therefore, indirectly, interpersonal power).
• Items 58 and 59 concern the partner's sexual purity, which is valued in many cultures (Francoeur & Noonan, 2004).
• Items 60–65 concern partner personality.

In addition, items 17, 45, and 64 are catch items. By this we mean that we expect very few people to rate these items highly, and so we will use high ratings as evidence of careless or dishonest responding. We do not provide any catch items in the reverse direction (i.e., items for which low ratings are suspect) because we do not wish to exclude from our study people who experience no strong sexual attraction at all.

Procedure

The survey begins by asking for the subject's gender ("Male", "Female", or "Other"), age, and ethnicity (free-response). While the gender choices we give subjects are coarse, since a gender of "Other" is mostly uninterpretable, investigating nonbinary genders is not a goal of this study, so this should not be problematic for our analyses. Then the sexual-preference inventory is administered. Next, subjects are asked the number of sex partners of each gender they have had in the past year, and for their sexual-orientation identity ("Heterosexual or straight", "Homosexual, gay, or lesbian", "Bisexual", or "Asexual"). The sexual-orientation item is prefaced with the remark "We know that you may not fully identify with any of these categories, but try to pick the single best-fitting one." Finally, subjects are asked "How honestly do you feel you were able to answer this survey? (We won't withhold payment based on your answer to this question.)" (5-point scale ranging from not at all honestly to entirely honestly).

Data analysis

A project like this one deserves a thoughtful data analysis that maximally exploits the obtained data, rather than a generic analytic procedure fully specified in advance. Here, however, is one proposal.

We filter the data by removing subjects from the analysis who specified "Other" as their gender, who rated their honesty (on the last question) as 1 or 2, or who gave particularly high ratings to one of the catch items (at least one point above the 95th percentile for the item in question).

The items of the sexual-preference inventory are modeled with a Bayesian hierarchical model. The idea is similar to confirmatory factor analysis, but with an emphasis on mutual prediction of items rather than the latent scores themselves. Let yis be subject s's response to item i, expressed as a z-score (the standardization being performed within items). Let xs be 1 if subject s is female and 0 otherwise. Let I be the number of items (viz., 65). Let $C ∈ \{1, 2, …, \operatorname{floor}(I/2)\}$ be the number of clusters into which the items are grouped; this is selected by cross-validation. Let ci ∈ {1, 2, …, C} be the cluster to which item i belongs; the ci s are selected by maximizing the sum of (within-cluster) multiple correlations, with the constraint that every cluster must include at least two items. Give the model parameters Σ (a real C × C matrix), σ1, σ2, … σC (positive scalars), μ1, μ2, …, μC (real scalars), and b1, b2, …, bC (real scalars) uninformative priors. Then the model is:

\begin{aligned} m_s &\sim \operatorname{Normal}([μ_1, μ_2, …, μ_C]^\text{T} + x_s[b_1, b_2, …, b_C]^\text{T},\; Σ) \\ y_{is} &\sim \operatorname{Normal}((m_s)_{c_i},\; σ_{c_i}) \end{aligned}

In a nutshell, the model posits that each subject has a latent score for each cluster which depends on their gender, and that the subject's responses to items in that cluster are normally distributed with mean equal to the cluster's latent score.

Substantive questions that can then be answered include:

• Which items belong to which clusters?
• How well can items within each cluster predict each other?
• How well can each cluster predict each of the others?
• How do typical cluster scores differ between genders?

To assess the model's stability in clustering items and its predictive accuracy, we use 10-fold cross-validation. Cross-validation estimates a model's out-of-sample performance, lessening the need for a separate test set or replication study.

One might ask how valid our sexual-preference inventory is, in the sense of how well it predicts actual sexual attraction (measured with something other than the inventory itself). We will check that subjects' sexual-orientation identity and gender of past sexual partners are related to reported gender preferences in the appropriate direction (e.g., identified-gay subjects should endorse greater attraction to their own sex than identified-heterosexual subjects do). Unfortunately, these relationships are unlikely to be strong considering the large discrepancies between preferences, attraction, and behavior observed in past research (Savin-Williams, 2006). Worse, there are no well-established preexisting tests for the constructs measured by the bulk of the other items. This said, because the overarching construct under investigation, sexual attraction, is close to being phenomenological (if it is not actually phenomenological), construct validity is implied by face validity. More meaningful investigations of validity can only take place with more substantive predictions about how sexual attraction relates to sexual behavior—predictions that can only readily be formulated given a theory of sexual attraction.

Discussion

Here we discuss three possible ways in which the items may cluster. We do not try to account for every item; it is likely that, rather than all items ending up in coherent clusters, there will be either a heterogeneous "wastebasket" cluster or a large number of tiny clusters.

Gender, intimacy, and deviance

Suppose our analysis created the following clusters:

• Androphilia: 4, 5, 6, 8, 13, 45, 47, 56, 57
• Gynophilia: 3, 10, 16, 37, 38, 41, 43, 48, 49, 59
• Intimacy: 17–22, 24, 26, 35, 63, 65
• Deviance: 1, 2, 15, 22, 23, 25, 27, 28, 29–34, 36, 46, 50–52, 55, 58, 61, 62

The first two clusters appear to concern sexual interest in males and females, respectively. These items concern not only interests that are by construction applicable to only one gender (e.g., "Sex with a woman"), but also interests that have been associated in past studies with interest in a particular gender (e.g., "Sex with someone with small feet"; Fessler et al., 2005). The Intimacy cluster concerns emotional closeness to the partner. Its items measure the appeal of romantic ideals, harmony, and the partner's own sexual feelings. The Deviance cluster concerns "kinky" activities, ranging from the only nominally proscribed (masturbation) to the unusual (sex with strangers) to the condemned (sex with prepubescents). We might expect Androphilia and Gynophilia to be closely related to subject gender and hence negatively related to each other, Intimacy to be positively related to Androphilia (because women should be higher in both), and Deviance to be positively related to all three other clusters (if interest in deviant sexual activities is driven by overall erotophilia).

These results would be generally supportive of past thinking on sexual preference. Most prominently, gender—of both the subject and the partner—looms large, in keeping with the traditional focus on gender preferences in the study of sexual preference. Similarly, intimacy being its own cluster suggests that the divergence of research on sexuality and on romantic relationships should not be as troublesome as might be expected. Finally, the lack of finer organization of sexual deviance justifies lumping the many kinds of unusual sexual expression together, rather than investigating them for more systematic covariation. However, homogeneity of sexual deviance also supports the idea that antisocial sexual behavior (such as rape) is caused by high erotophilia rather than some non-sexual personality trait—an idea that researchers have grown increasingly hostile towards in recent decades.

Interpersonal power

Suppose our analysis created the following clusters:

• Domination: 3, 5, 7, 9, 11, 12, 14, 15, 22, 24, 28, 30, 31, 41, 46, 49, 51, 55, 59
• Egalitarianism: 17–21, 35, 63, 65
• Submission: 4, 6, 8, 10, 13, 16, 23, 26, 27, 32, 33, 47, 50, 56, 57, 58

Suppose also that the Domination and Submission clusters are negatively related, and Egalitarianism is negatively related to both of the others. Overall, this pattern suggest a bipolar model of sexual preference in which sexual preferences are characterized by the ideal power relationship between oneself and the partner. People higher in Domination are masculine, prefer insertive roles, prefer to receive stimulation from their partner rather than provide it, and prefer watching other people's sexual activities to displaying their own. Contrariwise, people higher in Submission are feminine, prefer receptive roles, prefer to provide stimulation, and prefer displaying to observing.

This scheme is a natural generalization of the top and bottom roles of male–male anal copulation, and the dominating and submitting roles in BDSM. It is also consistent with feminist arguments (e.g., Brownmiller, 1975) that interpersonal power and sexuality are deeply intertwined. In fact, it suggests the value of investigating the relationship between sexual affect and (apparently non-sexual) social behavior. There is already evidence that, for example, the feeling of power can make some men more sexually attracted to women (Bargh, Raymond, Pryor, & Strack, 1995). Perhaps power-seeking in the real world is in part sexually motivated, in line with evolutionary thinking that mate access is one of the benefits of social status.

Mating strategy

Suppose our analysis created the following clusters:

• Short-Term: 25, 28, 34, 36, 47, 51, 52, 55, 57,
• Long-Term: 5–21, 24, 26, 29–33, 35, 46, 56, 59, 63, 65

Suppose also that the two clusters are negatively related. Again a bipolar model is suggested, with the central concept being mating strategy. People pursuing a short-term mating strategy aim to maximize the number of offspring conceived. They are motivated by the promise of more partners, even partners of potentially low value (such as relatives, who are likely to produce low-fitness offspring because of inbreeding), and are less interested in non-reproductive sexual acts or romance. People pursuing a long-term mating strategy, by contrast, focus on building and maintaining a relationship with one mate (or only a few mates). By concentrating resources in a single mate (and their offspring with their mate), they maximize the odds that what offspring they have will be healthy and reproductively successful. Because women are obliged to invest more resources in offspring than men (through pregnancy), they can be expected to be higher in Long-Term and lower in Short-Term.

This scheme is representative of sexual-strategies theory (Buss & Schmitt, 1993). Sexual-strategies theory posits that sexual behavior is largely guided by the two named mating strategies. It does not, however, assume that people are committed to a single strategy throughout their lives, but may change as circumstances change: for example, men with fewer resources are more likely to pursue a short-term strategy. If sexual preferences are largely determined by mating strategy, it follows that sexual preferences should change along with life circumstances. Perhaps "situational homosexuality"—that is, cases of people who have sex only with the opposite sex in ordinary life but who take up homosexual activity in certain institutionalized same-sex settings (e.g., Gagnon & Simon, 1968; Evans-Pritchard, 1970)—results from a short-term mating strategy induced by the sense of stress and poverty in, for example, a prison. Homosexual activity could result from a short-term mating strategy if said strategy functions by decreasing overall partner selectivity.

Appendix

Subjects are given the following instructions for completing the sexual-preference inventory:

Below is a list of various activities. We would like you to consider how sexually appealing you find each of these activities. Importantly, we are not asking you about whether you'd really do these things, or if you've already done them. So much as you can, put aside concerns such as safety, morality, social obligations, and long-term consequences, and answer using only your sexual and romantic feelings.

We use the word "sex" to mean any kind of partnered genital contact (not just sexual intercourse, but also, for example, oral sex). We use the phrase "your partner" to mean a hypothetical person (not necessarily a long-term relationship partner) you are having sex with or are about to have sex with.

You may notice that the activities aren't described in much detail. For example, "Sex with two or more other people" doesn't specify the sexual practice or the identity of the other people. Mentally fill in these details in whatever way that makes the scenario most appealing to you.

Below are the items of the inventory. Responses are on a 5-point scale (no appeal to very appealing, midpoint labeled somewhat appealing). Items marked [M] or [F] are only displayed for subjects who previously indicated they were of the corresponding gender; subjects of gender "Other" are not shown any of these items.

1. [M] Solo masturbation (touching your own penis)
2. [F] Solo masturbation (touching your own clitoris or vagina)
3. [M] Sexual intercourse (vaginal penetration with your penis)
4. [F] Sexual intercourse (being vaginally penetrated by a man's penis)
5. [M] Insertive anal sex (anal penetration with your penis)
6. Receptive anal sex (being anally penetrated by a man's penis)
9. [F] Receptive cunnilingus (having your clitoris or vagina licked)
10. Performing cunnilingus (licking a woman's clitoris or vagina)
11. [M] Being masturbated (having your penis touched by your partner's hands)
13. Masturbating a man (touching a man's penis with your hands)
14. [F] Being masturbated (having your clitoris or vagina touched by your partner's hands)
16. Masturbating a woman (touching a woman's clitoris or vagina with your hands)
17. Holding hands
18. Hugging
19. Kissing
20. Feeling emotionally close to your partner
21. Feeling in love with your partner
23. Being totally controlled by your partner
24. Being sexually desired by your partner
25. Sex with two or more other people
26. Giving your partner sexual pleasure
27. Having sex against your own will
28. Having sex against your partner's will
30. In photographs or videos, seeing other people nude, masturbating, or having sex
31. In person, seeing other people nude, masturbating, or having sex
32. In photographs or videos, having other people see you nude, masturbating, or having sex
33. In person, seeing other people nude, masturbating, or having sex
34. Sex with someone you're related to
35. Sex with a long-term relationship partner
36. Sex with a total stranger
37. Sex with a woman with small breasts
38. Sex with a woman with large breasts
39. Sex with someone with small buttocks
40. Sex with someone with large buttocks
41. Sex with someone with small feet
42. Sex with someone with large feet
43. Sex with a person with an hourglass figure
44. Sex with a limbless person
45. Sex with a man
46. Sex with a stereotypically feminine man
47. Sex with a stereotypically masculine man
48. Sex with a woman
49. Sex with a stereotypically feminine woman
50. Sex with a stereotypically masculine woman
51. Sex with a 5-year-old
52. Sex with a 10-year-old
53. Sex with a 15-year-old
54. Sex with a 19-year-old
55. Sex with a 70-year-old
56. Sex with a wealthy person with a prestigious profession
57. Sex with a violent criminal
58. Sex with a person with lots of previous sexual experience
59. Sex with a person with no previous sexual experience
60. Sex with a reliable, organized person
61. Sex with an unpredictable, spontaneous person
62. Sex with an outgoing, adventurous person
63. Sex with a kind, warm person
64. Sex with a distant, cold person
65. Sex with a cheerful person

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Notes

1

In fact, it has been argued that the term "sexual orientation" should be preferred because "sexual preference" "suggests a degree of voluntary choice" (Committee on Lesbian and Gay Concerns, American Psychological Association, 1991). By this, presumably, it is meant that the term "sexual preference" suggests people can choose to whom they are attracted. This objection does not make sense. Preferences are construed as determining choices, not the other way around. People's "seating preference" for airplane flights determines whether they choose aisle seats or window seats; we do not expect people can freely choose whether they like aisle seats better than window seats.