Before the month is out, I have to take note of a research article in the April issue of Psychological Science, which concludes that when it comes to reading women’s non-verbal signals—smiles, gaze, body language, tone of voice—men are complete and utter illiterates.

Especially when it comes to figuring out whether she is saying (in the family-friendly version): take me someplace where we can be horizontal and engage in activities that have been known to perpetuate the species. Or as scientists led by Coreen Farris and Richard McFall of Indiana University put it, “Men perceive more sexual intent in women’s behavior than women perceive or report intending to convey.”

I don’t mean to make light of this. Such misreading can lead to date rape, and telling the woman that she led the man on makes the victim feel complicit in her attack. Smiling, making eye contact, moving closer, or touching someone on the shoulder can indeed convey romantic interest—but all of these cues can also indicate “simple warmth, friendliness, or platonic interest,” the scientists note.

As is usual in questions like this, evolutionary psychologists have spun a theory to explain why men read “let’s have sex” into every nonverbal cue. If a man misses a signal to have sex, he loses out in the evolutionary sweepstakes. If he misreads an innocent signal as a sexual one, the worst that can happen (from the male reproductive point of view) is that he mates with a not-so-willing partner. In terms of evolution, erring on the side of “she wants sex” is a better, more adaptive strategy than erring in the other direction, missing such signals. As a result, goes this argument, men are programmed to read sex where no such message is intended.

No wonder “men consistently rate female targets as intending to convey a greater degree of sexual interest than do women who rate the same targets,” write the scientists. In a survey of university women, 67 percent said male acquaintance had misread friendliness as a sexual come-on.

According to the new study, however, it’s not just that men read sex where no sexual invitation is intended. Men can’t read any signals right. The scientists had 280 straight, undergraduate men and women look at a series of full-body photos of women, and categorize them as friendly, sexually interested, sad, or rejecting. The scientists selected the photos that were clearly one or another, then had a new group of 80 men and 80 women categorize the women in the photographs. A “correct” answer was one that agreed with the vast majority of raters in the first group, since only (seemingly) unambiguous photos were shown to this second, test group.

In every category, women categorized more images correctly than men did. Men were more likely than women to miscategorize a friendly-looking woman as indicating sexual interest, but—crucially—they also flunked out when it came to recognizing photos showing sexual interest: men were more likely than women to misidentify sexually interested targets as merely friendly, by 37.8% vs. 31.9%. In short, “men were more likely than women to misperceive friendliness as sexual interest, but they also were quite likely to misperceive sexual interest as friendliness,” the scientists found. “Men were significantly less sensitive to the distinction between friendliness and sexual interest”—in both directions, since they couldn’t tell when women were sad as opposed to rejecting, either. Men “oversexualized some women, but were quite likely to undersexualize other women.”

The take-home message is clear. Women can’t assume that men will understand anything they’re trying to convey.