The United States and Norway are working together to figure out what forms of flirting are most effective.

The results of the international collaboration are based on questionnaires, not experiments, which means we have to assume participants are honest about what they find attractive.

There was one way of flirting that stood out among heterosexual relationships in Norway and the US.

The most effective way to find a fling or long-term romance was with humor.

Laughing at someone else's jokes was considered good for both genders. Cracking jokes was seen as the most useful strategy for men looking for long-term relationships.

It is important that you show your potential partner that you think they are funny, because it is not only effective to be funny, but for women as well.

We are not endorsing anyone to try these kind of strategies at home. There are some interesting things to look into from a scientific perspective. The sexual strategies theory for flirtation came about in the 1990s.

Studies show that women looking for short-term relationships are the most effective at flirting when they make their sexual availability known.

While flirting with the opposite sex, men are better off showing commitment and generosity.

The theory says that sexual selection is the reason for this. Evolutionary theory says that men are more likely to have multiple partners because sex comes with minimal obligations. Women need to be pickier about their prospects.

The most effective female flirts were those who made sexual advances obvious and known.

Those who reigned in their sexual desires and promoted the best parts of their person were the most effective male flirts.

Researchers in the US and Norway have tried to reproduce that underlying theory by using a set of common flirtation tactics.

The responses to the 40 flirtation tactics were measured by a questionnaire given to participants.

Non-intimate communication, like asking for your help, and humor production are some of the flirting tactics on the list.

Despite the US and Norway being ranked very different when it comes to sexual liberalism, the results were the same in both cultures.

Both men and women in the study agreed on which flirtation tactics were the most effective.

The study found that signals of sexual availability, like dressing sexy or physical contact, were the most effective for women looking for a fling. Friendly contact was not less sexual.

The most effective flirting tactics for men were intimate conversations and spending time together. When men were looking for a long-term relationship, this was especially true.

When men were looking for a short-term relationship, the authors found that contact through comments, chats and compliment were not as effective as flirting.

In a long-term relationship, these tactics were just as effective as intimate conversations.

The authors admit that verbal investment or committed attention, such as light conversations/chats, compliment, random comments, and texts, even if it is not long or intimate, may signal continued investment.

It was expected that humor would be an effective flirtation tactic.

Laughing at a joke is good for both men and women. It's thought that this type of flirting is more useful for men who are looking for long-term relationships.

The authors think humor is a sign of intelligence, creativity and agreeableness. It shows a future partner with a positive influence on a woman's well-being.

The results of the questionnaires are interesting, but they are not irrefutable. The surveys give an interesting view into heterosexual relationships, but the ranking system is simplistic and doesn't take into account the complex realities of flirting, which are based on far more than what a person says or does.

According to the surveys, our ideas about flirting are gendered and situation-specific, and that these notions exist across western cultures.

Evolutionary Psychology published the study.