Ladies, gents, we all know the scenario: Woman is waiting for her coffee at the café counter, guy behind her sidles up for the traditional rite of awkward small talk until the barista slings over a venti mocha caramel frappuccino, prompting the woman's departure. Afterwards, she thinks, "Well that was a friendly conversation." Meanwhile, he is smiling to himself thinking, "Oh yeah, she definitely likes me."
Men think women are more interested in sex, and more interested in them, than women really are. This has been shown across tons of different study methodologies from self-report to in-lab observations to even looking at photographs!
Why do guys mistake women's friendliness for sexual interest?
Why does this bias exist? One might say that the media sexualizes men and makes them see sex wherever they look. This can't be the whole answer, though, because guys don't overestimate ALL women's interest (e.g., they don't overestimate their sisters' interest in other men)—if I'm a man, I overestimate women's interest in me. But what of the argument that the media depicts women as less interested in sex and having a lower sex drive than men? If that's the case, we should see men assuming that women are just generally not that interested; and should see women perhaps holding the opposite bias: assuming that men are more interested. So these proximal causes have yet to be ironed out.
Evolutionary causes may also have an impact. In ancestral environments, the cost of missing a chance to reproduce was potentially the loss of an offspring; the cost of the other type of error, thinking a woman was more interested than she really was, was some embarrassment. In the currency of reproductive success, clearly the former error looms larger.
Perfect accuracy is not an option in this case since—as a woman and a human being—I can tell you that the cues we use to figure out if someone is interested, or to show our own interest, are far from perfectly predictive! Ladies, just think of the last time you flashed a big smile, made your voice more girlish, and giggled when asking someone for a favor (a la in Mad Men when Betty Draper asked the tow truck driver to fix her car on the cheap). So guys whose "error management" strategy was to overestimate women's sexual interest would have had a reproductive advantage (increasing reproductive success is certainly not implied here to be a conscious motivation).
Is men's overperception universal?
Along with my colleagues Judith Easton and David Buss, I designed a speed-meeting study to determine whether all guys misperceive in the same way. In this study, groups of five men and five women reported to the lab for an experiment on "first impressions" in a platonic setting. Each male-female dyad went into a lab room for a few minutes to make small talk. Afterwards they privately rated one another. These ratings assessed, among other things, their interest in their partner and their estimate of the partner's interest in them—allowing us to calculate misperception.
We found that men overestimated the women's interest overall, but some men did so more than others. There were two traits in men that predicted this difference: mating strategy and attractiveness.
Men who had a more short-term mating strategy (read: interested in casual sex and one night stands) were even more likely to overestimate how interested the women were. Also, guys who rated their own attractiveness higher also overestimated women's interest more.
Interestingly, though, guys whom the women in the study rated as more attractive were less likely to overestimate. These attractive men didn't overate women's interest because the women really were interested!
So before you think that all guys have taken a page from Lloyd at the end of Dumb and Dumber,
Lloyd: What are my chances?
Mary: Not good
Lloyd: You mean, not good like one out of a hundred?
Mary: I'd say more like... one out of a million.
Lloyd: So you're telling me there's a chance!
Keep in mind that some guys are less susceptible to this bias. Good-looking men who are interested in long-term relationships—a desirable bunch—seem to be least susceptible. But if you're looking to avoid the over-estimators, ladies, keep the flirtatious signals to a minimum—guys are more than willing to pick up on even the slightest hints of interest!