We are all familiar with the following scenarios: a woman and a man are having a conversation. She is warm and friendly and clearly interested in the conversation. He interprets her behavior as sexual interest. Or she is warm and friendly and clearly interested in the conversation and he thinks she is just being friendly and then she wonders if he's gay.

Same behavior, different interpretations. 

Men and women misunderstand each other a lot and psychologists in the Department of Psychology at the Norwegian University of Science and Technology (NTNU) believe that we are built that way by biology and time - we have evolved to get the wrong idea about sexual interest.

When it comes to Ryan Gosling, the wrong idea is a lot less wrong to a lot more women. Why does Ryan Gosling invoke a biological imperative when other men do not? It is a mystery of psychology. See The Science Of Romantic Comedy Behavior: A Love Ode To Weak Observational Studies

Why is sex special? It's how we reproduce but in other areas that are biologically-based, like intelligence and food preferences, there is no gender difference, so why are so many differences claimed to be biological function when it comes to sexual behavior?

That's evolutionary psychology, which posits that behavior has biologically evolved just like our bodies. And the one thing that all evolutionary psychologists love to think about is sex. Evolutionary psychology can explain why men can wrongly assume that women who smile and laugh during conversation may want to sleep with them and thus why women will assume they are gay if men do not. 

The reason is, as the old saying goes, 'beggars can't be choosers.'

In an old joke, a curious duo of a boy and a girl show each other their genitals. The boy is delighted he has a penis and thinks the girl should be jealous. She replies that she needn't be jealous because with one of what she has, she can get as many of what he has as she wants. That biological imperative - men can't be picky - is the foundation of evolutionary psychology, even in a world with a metropolis the size of New York City, where man can have sex with a new woman every day for 8,000 years and never meet the same one twice, even without new ones being added every year.

Regardless, if it is built into biology, the social construct becomes less relevant, in evolutionary psychology. Many biologists believe little behavior is functional while many evolutionary psychologists believe most of it is. In the world of evolutionary psychology, a man's ability to reproduce is all about seizing every opportunity. He has to spend both money and time on courtship, which still may not lead to sex. But it costs even more to not try, because then he won't be able to reproduce.

Most men do not consciously think any of those things, of course. It's innate, you can't control it, according to evolutionary psychology.

 A woman can have sex with multiple men over a short period of time without producing any more children than if it were one. So for men trapped in the evolutionary psychology  prison of reproductive drive, it is a low-risk, potentially high-reward situation for men to have sex with women whenever the opportunity presents itself.  On the other hand, the cost is potentially great for a woman if she thinks that a man is more sexually interested than she is. A woman risks pregnancy, birth, nursing and raising the child, as well as lost opportunities to reproduce with others. Across thousands of generations, women's psychology has evolved to set the bar higher, which means they need much clearer signals than men before they consider sex, believe evolutionary psychologists. 

"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," Mons Bendixen  explains. "Even though these processes aren't conscious, we can still empirically measure the results." 

Empirically measure in evolutionary psychology means survey college students.

The recent survey at NTNU included 308 heterosexuals ages 18 to 30. 59 percent of participants were women. The participants were all heterosexual because sexual intercourse between men and women is necessary for reproduction. Half of the women and 40 percent of the men were in relationships. The questions were identical to questions asked in a similar American surveyed from 2003. Here are a few examples:

Have you ever been friendly to a person of the opposite gender, and had your actions interpreted as sexual interest? If yes, how many times has this happened?

Have you ever been sexually attracted to someone and shown interest, and had the other person misinterpret your signals as friendliness? If yes, how many times has this happened?

The results showed that both men and women find that their social signals are misinterpreted by the opposite sex. Women in the study answered that they had acted friendly towards a man and had this misinterpreted as sexual interest about 3.5 times over the past year on average. The men in the study also reported having been misinterpreted by the opposite sex in this way, but far less often.

The survey results also showed that men rarely misinterpret women who actually do signal sexual interest. The study shows that this is independent of whether or not the person is in a steady relationship or not.

"The results are no surprise, seen from an evolutionary perspective," Bendixen explains. "The fascinating thing is that our results are identical to a study done in the USA, even though Norway is one of the most gender-equal, sexually liberal countries in the world."

Bendixen says that the World Economic Forum's list for equality around the world lists Norway among the most gender-equal countries in the world. The USA is ranked as 20th.

"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," he says.

They now want to use data collected from high school students to see if the results of this study are also valid for people aged 16-19, and if that miscommunication might lead to 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. 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 says.

Citation: Mons Bendixen (2014) 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, 12(5), 1004-1021.