In 2003, an American study found men and women often think the opposite sex misinterprets their friendly behavior as something more. And now, a Norwegian study — a country where gender equality exceeds the U.S., a sign its population is more developed, productive, and has a better economy — found this is the case everywhere.

The study comes from the Norwegian University of Science and Technology, where 308 heterosexual men and women between the ages of 18 and 30 answered a variety of questions. Some examples include: “Have you ever been friendly to a person of the opposite gender and had your actions interpreted as sexual interest?” and “Have you ever been sexually attracted to someone and shown interest, and had the other person misinterpret your signals as friendliness?” If men and women answered yes, they were then prompted to report how many times this had happened.

The results showed women answered their friendly actions — laughing at jokes, standing close to the opposite sex, possibly patting or lightly touching their arm — were misinterpreted by men about 3.5 times over the past year; men answered women were guilty of the same, though less often. However, both men and women reported their social signals were often misinterpreted.

"The fact that the hypothesis in evolutionary psychology is supported even when the study is in a society where gender equality is strong, weakens alternative claims that the social roles of men and women in different cultures determine their psychology in these situations," Mons Bendixen, study author, said in a press release.

Bendixen added from an evolutionary perspective, these results aren’t a surprise. Evolutionary psychology focuses on how the human mind has evolved, developed, and adapted over time, including but not limited to the way men and women interact with one another. It all comes down to reproduction (which is why the study only included heterosexual couples).

"A man's reproductive fitness, meaning the amount offspring he produces, is dependent on how many women he is able to make pregnant. But that's not how it works for women," Bendixen said. It costs men more not to try and reproduce with women (think of courtship and time) than it does for women to.

Bendixen explained it like this: It’s a low-risk, potentially high reward situation for men to have sex with women whenever possible — women, on the other hand, face the risk of pregnancy and parenthood. And OK, lost opportunities to reproduce with other men. So over time, women have raised the bar and resort to only clear signals from men.

The problem, too, is when social signals are misinterpreted as sexual interest, it borders on sexual harassment.

"Even though evolutionary psychology and our findings can help account for some sexually inappropriate behavior in men, it doesn't mean that evolutionary psychologists defend this happening,” Bendixen said. “Measures can be taken to prevent sexual harassment. It will help if we just teach men that a woman who laughs at your jokes, stands close, or touches your arm at a party doesn't mean that she's sexually interested, even if you think she is," Bendixen said.

Source: Bendixen M. Evidence of Systematic Bias in Sexual Over- and Underperception of Naturally Occurring Events: A Direct Replication of Haselton (2003) in a More Gender-Equal Culture. Evolutionary Psychology. 2014.