When it comes to understanding a lot of behavior in sexually-reproducing species, a key variable to consider is differential reproductive potential: what the theoretical upper-limit on reproduction happens to be for each sex. The typical mammalian pattern is such that males tend to have much higher potential reproductive ceilings, owing to how the process of internal fertilization works. When females become pregnant, their reproductive potential is essentially turned off until sometime after the infant is born, as pregnancy and lactation typically disable ovulation. Males, on the other hand, can reproduce about as often as they have an available female. In humans, this can translate into a woman having a child about every three years, whereas a man could – at least in theory – fertilize around 1,000 women in that three-year period if they managed one a day. In terms of realities, though these limits are rarely reached, the most prolific mother on record had around 70 children, as she had a knack for birthing twins and triplets; the most prolific father sired closer to 900 offspring.

“And I suppose you all want to go to college now too, huh?”

Given that males and females face different cost/benefit ratios when it comes to sex, we should expect that male and female psychology looks somewhat different as well, as each sex has had different problems to solve in that domain. One such problem is detecting sexual interest. Perceptions are not perfect, so the degree of sexual interest that another person has in us can only be estimated from behavioral and verbal cues. Accordingly, it follows that people might make mistakes in perceptions: we might see sexual interest where none exists, or fail to see sexual interest that does exist. For women, failing to perceive sexual interest when it is present would be less of a bad thing than it would be for men, as the costs of missing a sexual encounter are generally higher for males. Given the very real reproductive consequences to making these perceptual errors, we should expect some cognitive systems in place designed to manage our errors.

This brings us to the matter of how these errors might be managed. According to one popular view, men manage their errors by over-perceiving sexual interest in women. That is to say that men are likely to perceive interest to be there when, in many cases, it isn’t (e.g., “she touched my arm; she must be interested in having sex with me”). This explanation, while plausible sounding on the face of it (as it does help minimize the chances of missing a potential encounter), does suffer a theoretical weakness: it assumes that men’s perceptions should be inaccurate. That is to say that it posits that men’s cognitive systems overestimate how interest women actually are. The reason this is a problem is that, all else being equal, accurate perceptions tend to lead to better outcomes than inaccurate ones. If, for example, you’re overly-optimistic about your chances of landing that career in your dream field, you might spend an inordinate amount of time pursuing that goal – which you won’t obtain – when you could instead be using that time and energy to pursue outcomes with a higher expected payoff. Put more simply, your sincerely-held belief that you are likely to win the lottery will lead you to wasting more money on lottery tickets than you otherwise should. The same logic holds when it comes to perceiving sexual interest: if you see interest where it doesn’t exist, you’re likely to spend excessive amounts of time and energy pursuing dead ends. It seems that an altogether better system for men would be one that detected women’s interest as accurately as possible, but decided to pursue low-probability outcomes on some occasions anyway owing to their high reward. This system would maximize expected rewards.

Empirically, however, men do seem to over-perceive women’s sexual interest; that’s been the conclusion from past research, anyway. Specifically, if you have a man and a woman interacting, the man will tend to perceive that the woman has more sexual interest in him than she reports that she does. The explanation that men are over-perceiving only works, though, if one assumes that women’s reports are entirely accurate; if women are actually under-reporting their interest – either knowingly or not – then the gap between men and women’s reports might be more readily explainable. The idea that the women are under-reporting has some conceptual merit as well: it is possible that women’s reports underestimate their actual amount of interest as a form of reputation management, since there are consequences to sending signals of promiscuity.

 ”Figure A: just really good friends. Nothing to see here.”

Towards attempting to figure out whether this gap in reports is due to male overperception, female underreporting, or some combination thereof, Perilloux & Kurzban (2014) began by presenting a list of 15 behaviors to roughly 500 men and women. The male subjects were asked to estimate a woman’s sexual intentions if she had engaged in the behaviors; the female subjects were asked to estimate their own sexual intentions, given that they had engaged in the behaviors. This resulted in each of the 15 behaviors getting a mean rating from each sex that could range from -3 (extremely unlikely to indicate a desire to have sex) to 3 (extremely likely). As usual, the difference in reports emerged: men’s composite average collapsed across the 15 behaviors was 1.44, whereas women’s was 0.77. So men were perceiving more interest than women were reporting.

The author’s second study sought to examine whether these reports were consciously being over- or under-estimated by the subjects. In order to do so, another 500 subjects were recruited and given the same 15-item survey and asked to estimate how much each behavior indicated a desire for sex, given that a woman had performed it. However, half the subjects were told that, in addition to their payment for the experiment, they could earn some additional money for more accurate reporting (i.e., estimating the accuracy of sexual intentions within a certain margin of error). In this second study, the gap showed up as it did before: men reported an average of 1.47, whereas women reported an average of 1.14. Compared with first study, the men’s ratings in the second were no different, though the women’s estimates increased significantly. So, when incentivized to be accurate, men’s rating didn’t change, though women’s did and, further, they changed in the direction of being closer to the men’s. One plausible interpretation of the data, as put forth by Perilloux & Kurzban (2014) is that women know that other women will under-report their sexual intentions, just not by how much, the result being that women’s estimates resemble men’s estimates, but still don’t quite match up.

This brings us to the third study. Here, the authors asked another 250 men and women about the same behaviors, but in a slightly different fashion; they now asked what other women would actually intend if they engaged in the behavior, as well what those women would say they intend. In this final condition, the sex difference vanished: when considering what other women actually intend, men’s average (M = 1.91) did not differ statistically from women’s (M = 1.84); when considering what other women would say they intend, the men’s average (M = 1.42) again didn’t differ from the women’s (M = 1.54). A reasonable conclusion from this pattern of data, then, would be to say that both men and women believe that other women will under-report their sexual intentions and, given that the men’s average perceptions remained consistent across studies and women’s continuously shifting in the direction of the men’s average, that the men’s perceptions were probably accurate in the first place.

 ”Alright; I might have underestimated my interest by a little bit…”

Now, again, this is not to say that women are lying about their interest level, as lying implies some knowledge of the truth (though people likely do lie about such things explicitly from time to time); instead, it is probably more often the case that women unconsciously tend to report that they’re less interested in such things, perhaps owing to some kind reputation management. While I suppose it’s not impossible that men have biased views of women’s sexual interest and women have similarly-incorrect views, but for different reasons, it doesn’t seem particularly probable. It is worth noting that a similar pattern of results to the present studies turned up in an informal one I covered some time ago concerning whether men and women can “just be friends”. The gist of that informal study is that men tended to agree that men almost always have an ulterior sexual motive for befriending women. Women disagreed with these assessments, stating that men and women could just be friends; they disagreed, that is, until the idea of their male partner being “just friends” with another woman was brought into question. In that latter instance, women tended to agree with men concerning the sexual interest in such relationships. The present studies would seem to suggest that this isn’t just due to clever video editing. What it doesn’t show is that men are wrong in their perceptions.

References: Perilloux, C. & Kurzban, R. (2014). Do men overperceive women’s sexual interest? Psychological Science, DOI: 10.1177/0956797614555727