Mixed Signals

Men often misinterpret a woman's innocent smile or compliment as a sexual come-on—but why? Gender stereotypes imply that men are socialized to oversexualize the world. But research suggests there are real evolutionary reasons that men and women get their signals crossed.

In two studies reported in the Journal of Personality and Social Psychology, Martie G. Haselton, Ph.D., and David M. Buss, Ph.D., both University of Texas-Austin psychology professors, asked over 500 college students to picture themselves on a date. The students then used imagined acts like holding hands or giving compliments to rate their companion's and their own sexual interest and level of commitment.

The researchers discovered that men tended to overestimate women's sexual interest, while women underestimated men's willingness to commit. But interestingly enough, both men and women were more accurate in rating women's commitment levels, and when asked to imagine that the sexual target was their sister, men rarely misread sexual intent.

So why do men and women misjudge only certain cross-sex signals? They're adaptive biases, say the researchers. According to the theory of natural selection—in which only the fittest survive—males who falsely inferred a woman's sexual interest stood to gain descendants, and lost little if the woman was a suitable mate. "For ancestral men, it was more costly to miss a reproductive opportunity" than to face rejection, Haselton explains. But females who were abandoned after consenting to sex suffered far greater consequences: pregnancy, reduction in mate value and having to raise a child alone. "For women, it was more costly to be deceived by men, so selection favored skeptical women," he says, leading to their continued skepticism about men's willingness to commit.

Buss, who explores jealousy in his book, The Dangerous Passion: Why Jealousy Is as Necessary as Love and Sex (Simon & Schuster, Inc.), suggests scientists rethink the notion that human psychological mechanisms are always designed to be logical. "We're arguing that they're designed to be biased," he explains, particularly when it comes to issues of trust.