MJTH/Shutterstock
Source: MJTH/Shutterstock

Choosing to have sex with a total stranger is not something everyone would do. It probably takes a certain type of person. Quite a bit of evidence suggests that, at least when it comes to eagerly having sex with strangers, it might also take being a man.

Let's look at the evidence.

Over the last few decades almost all research studies have found that men are much more eager for casual sex than women are (Oliver & Hyde, 1993; Petersen & Hyde, 2010). This is especially true when it comes to desires for short-term mating with many different sexual partners (Schmitt et al., 2003), and is even more true for wanting to have sex with complete and total strangers (Tappé et al., 2013).

In a classic social psychological experiment from the 1980s, Clark and Hatfield (1989) put the idea of sex differences in consenting to sex with strangers to a real-life test. They had experimental confederates approach college students across various campuses and ask, "I've been noticing you around campus. I find you to be very attractive. Would you go to bed with me tonight?" Around 75 percent of men agreed to have sex with a complete stranger, whereas no women (0 percent) agreed. In terms of effect size, this is one of the largest sex differences ever discovered in psychological science (Hyde, 2005).

Twenty years later, Hald and Høgh-Olesen (2010) largely replicated these findings in Denmark, with 59 percent of single men and 0 percent of single women agreeing to a stranger's proposition, “Would you go to bed with me?” Interestingly, they also asked participants who were already in relationships, finding that 18 percent of men and 4 percent of women currently in a relationship responded positively to the request.

According to Strategic Pluralism Theory (Gangestad & Simpson, 2000), men of high physical attractiveness should be most able to successfully pursue a short-term sexual strategy (physical attractiveness fulfills women's evolved preferential short-term mating desires). For the average-looking man, short-term mating may not represent a viable reproductive option (Schützwohl et al., 2009).

OK, but Why?

Several scholars have modified the experimental "ask for sex" method to see if they could tell why men, but not women, agreed to sex with strangers. Clark (1990) was among the first to address the issue of physical safety. He had college-aged confederates call up a personal friend on the phone and say "I have a good friend, whom I have known since childhood, coming to Tallahassee. Joan/John is a warm, sincere, trustworthy, and attractive person. Everybody likes Joan/John. About four months ago, Joan/John’s five-year relationship with her/his high-school sweetheart dissolved. She/he was quite depressed for several months, but during the last month Joan/John has been going out and having fun again. I promised Joan/John that she/he would have a good time here, because I have a friend who would readily like her/him. You two are just made for each other. Besides, she/he has a reputation as being a fantastic lover. Would you be willing to go to bed with her/him?” Again, many more men (50 percent) than women (5 percent) were willing to have sex with this personally "vouched for" stranger. When asked, not one of the 95 percent of women who declined sex reported that physical safety concerns were a reason. 

Surbey and Conohan (2000) wondered whether worries of safety, pregnancy, stigma, or disease were holding women back from saying yes to sex with a stranger. In a "safe sex" experimental condition, they asked people, "If the opportunity presented itself to have sexual intercourse with an anonymous member of the opposite sex who was as physically attractive as yourself but no more so (and who you overheard a friend describe as being a well-liked and trusted individual who would never hurt a fly), do you think that, if there was no chance of forming a more durable relationship, and no risk of pregnancy, discovery, or disease, that you would do so?" On a scale of 1 (certainly not) to 4 (certainly would), very large sex differences still persisted with women (about 2.1) being much less likely to agree with a "safe sex" experience with a stranger compared to men (about 2.9).

So, sex differences in agreeing to sex with strangers are not just a matter of safety issues, pregnancy concerns, stigma, or disease avoidance. Controlling for all of that, researchers still find large sex differences in the willingness to have sex with a stranger.

Converging Lines of Evidence

In addition to these powerful experimental tests, a wide range of supportive evidence (literally hundreds of studies) confirms that men, on average, are more eager than women are for casual sex and tend to desire sex with more numerous partners, including complete strangers (Buss & Schmitt, 2011).

In terms of research on sexual attitudes, nearly all studies conducted have found that men have more positive attitudes toward casual sex than women, have more unrestricted sociosexuality than women, and generally relax their preferences in short-term mating contexts (whereas women increase selectivity, especially for physical attractiveness).

When considering attitudes toward mixed-sex threesomes, for instance, most people express very little interest, with the notable exception being men considering having sex with two women at the same time, even if they are strangers (Thompson & Byers, 2016).

Thompson & Byers (2016)
Source: Thompson & Byers (2016)

Many more men (24%) than women (8%) are willing to engage in a consensually non-monogamous relationship (i.e., a committed romantic relationship
wherein everyone consents to all partners having multiple sexual encounters with others; Sizemore & Olmstead, 2017).

Cognitively and emotionally, men are more likely than women to have sexual fantasies involving short-term sex and multiple opposite-sex partners; men perceive more sexual interest from strangers than women do; and men are less likely than women to regret short-term sex or “hook-ups.”

Considering sexual fantasies, men are much more likely than women to report having imagined sex with more than 1,000 partners in their lifetime (Ellis & Symons, 1990).

Ellis & Symons (1990)
Source: Ellis & Symons (1990)

Behaviorally, men are more likely than women to be willing to pay for short-term sex with (male or female) prostitutes; men are more likely than women to enjoy sexual magazines and videos containing themes of short-term sex and sex with multiple partners; men are more likely than women to actually engage in extradyadic sex; men are more likely than women to be sexually unfaithful multiple times with different sexual partners; men are more likely than women to seek one-night stands; and men are quicker than women to consent to having sex after a very brief period of time (for citations, see Buss & Schmitt, 2011).

Buss and Schmitt (2011)
Source: Buss and Schmitt (2011)

Is Patriarchy to Blame?

Many of these sex differences are culturally universal, having been observed in dozens of samples around the world (Lippa, 2009; Schmitt, 2005). One might claim universal features of "patriarchy" or "sex role socialization" are primarily responsible for this sex difference universality, and this is certainly partly true (though that doesn't make these sex differences a "myth" and merely adds more to be explained). Moreover, there are serious questions as to patriarchy and sex role socialization being the only explanations.

For instance, Schmitt (2015) found sex differences in the sociosexuality scale item, "I can imagine myself being comfortable and enjoying ‘casual’ sex with different partners,” were largest in nations with the most egalitarian sex role socialization and the greatest sociopolitical gender equity (i.e., the least patriarchy, such as in Scandinavia). This is exactly the opposite of what we would expect if patriarchy and sex role socialization are the prime culprits behind sex differences in consenting to sex with strangers.

How can this be? Why are these sex differences larger in gender egalitarian Scandinavian nations? According to Sexual Strategies Theory (Buss & Schmitt 1993), among those who pursue a short-term sexual strategy, men are expected to seek larger numbers of partners than women (Schmitt et al., 2003). When women engage in short-term mating, they are expected to be more selective than men, particularly over genetic quality (Thornhill & Gangestad, 2008). As a result, when more egalitarian sex role socialization and greater sociopolitical gender equity “set free” or release men’s and women’s mating psychologies (which gendered freedom tends to do), the specific item “I enjoy casual sex with different partners” taps the release of men’s short-term mating psychology much more than it does women’s. Hence, sex differences on “I enjoy casual sex with different partners” are largest in the most gender egalitarian nations.

Overall, when looking across cultures, reducing patriarchy doesn't make these and most other psychological sex differences go away; it makes them larger (Schmitt, 2015). So much for blaming patriarchy and sex role socialization.

Deceive, Inveigle, Obfuscate

Despite this wealth of confirmatory evidence--as evidenced in real life experiments (controlling for many confounds and alternative explanations), numerous meta-analyses of sexual attitudes, and decades of work on sex differences in sexual cognition, fantasy, emotion, and behavior--some scholars have deemed the notion that men are more eager than women are for sex with complete strangers as a total "myth" (Rudman, 2017). Like extreme climate change deniers, some of these scholars focus on a few contrived studies, torture the findings into a false narrative, and then claim that a few new empirical results completely refute a mountain of well-established evidence. Below I explain why two particular studies commonly used in this manner do not refute the mountain of evidence supporting sex differences in willingness to have sex with strangers. In fact, they are very much a part of the mountain.

Baranowski & Hecht (2015): Sex With Strangers at a Party and in a Lab

Baranowski and Hecht (2015) conducted two experiments relevant to assessing whether men and women differ in willingness to have sex with a stranger. In Experiment 1, they had confederates approach participants at a "party" (at the bar, dance floor, or a smoking area at night). Confederates were instructed to approach unknown members of the opposite sex who were without obvious company and say, "Hi, normally I don’t do anything like this, but I find you totally attractive. Would you like to have sex with me?"

In this "party" condition, Baranowski and Hecht found 50 percent of men (19 out of 38) agreed to sex with a total stranger (including 16 percent of men at the party who were already in a relationship—that’s a lot of willing male extra-pair copulators). In contrast, only one woman (4 percent) agreed to have sex with a stranger (and she was not in a relationship). In a second "on campus" condition, 14 percent of men and 0 percent of women agreed to sex with a complete stranger. Clearly requests at parties are more conducive to stranger sex than requests on campus (at least for men). Also clear from this first experiment is that men are more receptive to requests for sex from total strangers.

In a second experiment, Baranowski and Hecht presented participants with a complex sequence of "dating study" experiences over time. Eventually, participants were brought into a university lab and were shown pictures of 10 people who presumably had previously reported they wanted to either "date" or "have sex" with the participant. If the participant then chose any of the pictures to date or have sex with in return, the researchers said they would then film an hour discussion between the interested individuals and then leave them to have a date or have sex in a safe laboratory environment. (This is legal in Germany where the study was conducted.)

What were the amazing "there are no sex differences in desires for having sex with a stranger" findings? From the original article: “Of all male subjects, 100 percent agreed to have a date or sex with at least one woman. This rate did not differ from the female consent rate (97 percent).” Did you notice that? Those results were for "date or sex." Nowhere was it reported what the percentages were of men versus women specifically agreeing to have sex. As it stands, it might be that men agree to a date 1 percent of the time and to sex 100 percent of the time (unlikely, but possible), whereas women agree to a date 97 percent of the time and to sex 1 percent of the time. Because of this double-barreled reporting, we simply can't know what the truth is about sex differences in wanting to have sex with strangers from the published Baranowski and Hecht (2015) percentage results.

It's unbelievable that these results were published in this form, or that serious scholars would claim this published study is definitive proof that sex differences in consenting to sex with strangers are a "myth" (Rudman, 2017). Indeed, in order to do so they misinform readers about the findings, such as Rudman's (2017) claim "100 percent of the men and 97 percent of the women agreed to potentially have sex with at least one stranger, which did not statistically differ." Did you catch that? Rudman claimed the 100 percent versus 97 percent is just about sex with a stranger. Well, the Baranowski and Hecht published data specifically cited by Rudman were about the "date or sex" with a stranger findings. There were no percentage findings for just the sex condition in the published Baranowski and Hecht (2015) data.1

Most importantly, Baranowski and Hecht (2015) did report the raw number of strangers that men and women agreed to have sex with in their Experiment 2. These key data are actually relevant for evaluating Rudman's (2017) claim that sex differences in consenting to sex with strangers are a "myth." The findings? Men chose a larger number of strangers to have sex with (M = 3.57; SD = 1.16) than women did (M = 2.73; SD = 1.87), a moderately-sized sex difference, d = .56, even a little larger than the German sex difference in sociosexuality reported in the International Sexuality Description Project (d = .48; Schmitt, 2005). 

So sex differences in consenting to sex with strangers did not disappear in this research study: Baranowski and Hecht (2015) clearly found sex differences in consenting to sex with strangers in both of their experiments. And in Experiment 2, the only reported data with which they precisely evaluated that question — which is number of strangers chosen for sex — there was a moderately-sized sex difference, d = .56. This is even larger than meta-analytic sex difference in attitudes to casual sex, d = .46 (Petersen & Hyde, 2010). And again, it's also a little larger than the German sex difference in sociosexuality reported in the International Sexuality Description Project (d = .48; Schmitt, 2005). Converging lines of evidence, indeed.

Sex With Strangers vs. Sex With Celebrities

In 2011, Conley conducted an American version of the “ask for sex” methodology using hypothetical requests from unknown strangers and celebrities. (This study did not involve actual real-life requests.) Although her theoretical portrayal of evolutionary psychology was highly flawed (see Schmitt et al., 2012), her results were quite interesting (and again, supportive of the mountain of evidence that men and women differ in desires for sex with strangers).

Most importantly, Conley (2011) found in an "unknown stranger" condition there were very large sex differences in willingness to have sex with strangers. Using a rating scale, Conley found 74 percent of men would "entertain the possibility of the sexual offer" (rating between two and seven on a likelihood scale) whereas only 18 percent of women would. This is a key confirmation, of course, when it comes to directly testing whether there are sex differences in willingness to have sex with strangers. But it is often missed given the study's celebrity findings.

Within the highly attractive celebrities condition, Conley (2011) found women were much more likely to agree to a brief sexual encounter with a high-profile celebrity (e.g., Brad Pitt, Johnny Depp) compared with an unknown stranger, but men were relatively unaffected by a stranger's celebrity status (men were hypothetically asked for sex by Angelina Jolie or Jennifer Lopez, but men were rather willing to have sex regardless of a woman's celebrity status). As a result, sex differences in reactions within the celebrity requests for sex condition were minimal. However, these findings with celebrity requests for sex did not disconfirm or deem a "myth" that there are evolved sex differences in short-term mating psychology and desires for sex with strangers. In fact, these findings confirmed evolutionary perspectives on short-term mating psychology in several ways.

For instance, the celebrity findings confirm the view that women's (but not men's) short-term mating psychology is specially designed to obtain good genes from physically attractive partners (Thornhill & Gangestad, 2008). Brad Pitt and Johnny Depp are extremely attractive, as are Angelina Jolie and Jennifer Lopez, but as predicted by an evolutionary perspective, women's short-term desires for sex with strangers were more profoundly affected by this extreme attractiveness.

The Conley (2011) study also used participants who were only 22 years old on average to consider sex with much older celebrities, celebrities who also were married. As evolutionary psychologists have pointed out, women in their 20s generally prefer older partners as short-term mates compared to men (Buunk, Dijkstra, Kenrick, & Warntjes, 2001), and women tend to find already-mated prospective partners especially attractive (Parker & Burkley, 2009). Brad Pitt and Johnny Depp (highly attractive, more than 10 years older, married) are among the most adaptively-potent designed humans when it comes to fulfilling women’s (but not men’s) evolved short-term mate preferences as outlined by Sexual Strategies Theory (Buss & Schmitt, 1993).

In short, the Conley (2011) research method was highly contrived to provide a special set of conditions within which men and women would appear not to differ in choosing to agree to casual sex (celebrities who are attractive, older, married, etc.). But the sex-similar results within this special condition are expected from an evolutionary perspective.

Indeed, given other findings on women’s evolved short-term psychology, such as women who are nearing ovulation and are already in relationships with asymmetrical and submissive partners being more likely to consent to sex with extremely attractive men (Pillsworth & Haselton, 2006), there may be certain contexts in which women are more likely than men to consent to short-term sex. That's right, evolutionary psychologists argue that women are highly designed for short-term mating (Buss & Schmitt, 1993; Gangestad & Simpson, 2000; Kenrick et al., 1990). Just not designed in the same way as men.

So these special contextual factors utilized by Conley (2011) do not demonstrate that men and women have identical desires underlying their seemingly similar choices. The similar-looking choices result from a foundation of women (but not men) having specialized desires for short-term mating with highly attractive, older, and perhaps even married people; whereas men are interested in short-term mating regardless of these particular factors.

In the end, this is the key point of the Conley (2011) study: It takes Johnny Depp to get women to even consider agreeing to casual sex. For men, the difference between agreeing to sex with Jennifer Lopez versus a total stranger was minimal. The Baranowski and Hecht (2015) study clearly found sex differences in consenting to sex with strangers in both of their experiments. These facts should tell you a lot about the reality of sex differences in short-term mating psychology and willingness to have sex with strangers.

Footnote

1 I have been contacted by the first author of Baranowski, A.M., & Hecht, H. (2015). (A.M. Baranowski, personal communication, July, 24, 2017). It is confirmed that Rudman (2017) had not contacted the authors of Baranowski & Hecht (2015) to note the percentage of women (versus men) who agreed to potentially have sex with at least one stranger. It is perhaps possible Rudman had come to know the sex-specific data in some other way (e.g., at a conference or seminar), however the scientific citation provided by Rudman (2017) was to the original Baranowski & Hecht (2015) article. It is clear this reference in Rudman (2017) was inaccurate, and the very important actual test published in Baranowski & Hecht (2015) regarding the raw number of strangers that men and women agreed to have sex with was ignored (see above).      

References

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About the Author

David P Schmitt Ph.D.

David P. Schmitt, Ph.D., is a Caterpillar Inc. Professor of Psychology at Bradley University.

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