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Like Tinder, cats, and dying alone, flirting is usually associated with single people. 

But couples need to know how to flirt, too.

After studying 164 married people for a 2012 study, University of Kentucky researcher Brandi Frisby noted that most of them flirted — by playing "footsies" or whispering in their partner's ear, for example — as a means of maintaining and emphasizing intimacy. Oftentimes, she wrote in her paper, married couples flirted to "create a private world with the spouse." 

You probably already know that asking questions of the person you fancy is a good idea. 

But it's all about the kind of questions you ask. 

According to a widely cited 1997 study by State University of New York psychologist Arthur Aron, people feel more closely bonded when they ask each other intimate questions, as in "What roles do love and affection play in your life?" and "What, if anything, is too serious to be joked about?" 

Six months later, two of the participants (a tiny fraction of the original study group) even found themselves in love — an intriguing result, though not a significant one.

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Evidence from multiple studies supports the idea that, among heterosexual people, men tend to overperceive sexual interest from women, while women tend to underperceive sexual interest from men.

In other words, men tend to think women are into them when they aren't, and women tend to not notice when men are into them.

In a 2000 analysis of several of these studies, University of Texas psychologists Martie G. Haselton and David M. Buss offered several explanations for this finding, including that men are raised to see more sex in their environments while women are brought up to be more modest, but psychologists still haven't quite nailed down a perfect explanation for their observations.

There's no need for a full-on shoulder massage, but putting a hand on their arm might help.

In 2004, psychologist Nicolas Gueguen had 20-year-old men approach women pedestrians in a French city and ask for their phone number. Half the time, the men simply made the request; half the time they lightly touched the woman's forearm for one second while asking.

Sure enough, the men were more successful in getting the woman's digits when they'd touched her arm. 

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University of New Mexico evolutionary psychologist Steven W. Gangestad told Psychology Today that flirting is a "negotiation process" that happens after the first moments of attraction.  

It's a subtle sort of testing the waters. You don't just say I'm attracted to you; are you attracted to me?

"It works much better to reveal [your attraction] and have it revealed to you in smaller doses,"Gangestad says. "The flirting then becomes something that enhances the attraction."

The impulse to flirt doesn't necessarily end once you're in a relationship.

But a 2008 McGill University study found that men and women in relationships react differently after they've potentially flirted with someone else.

In one study, 71 male undergrads in committed partnerships met either an attractive woman who flirted with them or an unavailable woman who ignored them. The same experiment was repeated on 58 female undergrads and attractive or unavailable men.

After the encounters, researchers asked participants how they'd react if their partner had done something annoying. Men who'd met the attractive woman were 12% less likely to forgive their partners, while women who'd met the attractive man were 17.5% more likely to show forgiveness.

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It's about signaling that you're available. 

According to research from Webster University psychologist Monica Moore — who studied people's flirting behavior at singles bars, shopping malls, and other places where young people meet — women who smiled and made eye contact with others were more likely to be approached than those who were simply good-looking.

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Without being too much of a creep, staring into another person's eyes really does have effects.

In one study, researchers had 48 pairs of unacquainted, opposite-sex undergrads spend two minutes at each of the following tasks: 1) gazing at their partner's eyes, 2) gazing at their partner’s hands, and 3) counting how many times their partner blinked.

When both pairs were doing the eye-gazing task at the same time — meaning they were looking at each other — they were far likely to report feelings of affection than when they were doing any other task. 

When it comes to flirting, everyone's got a different M.O.

In 2010, Jeffrey A. Hall and Chong Xing published research that suggests there are five different styles of flirting. In 2015, they followed up on this research by breaking down each style into a series of verbal and non-verbal behaviors.

Here are some key behaviors of each type, as described by Susan Krauss Whitbourne onPsychology Today:

• Physical flirts tend to subtly touch the person they're interested in.
• Traditional flirts believe men should make the first move.
• Sincere flirts get other people to open up to them.
• Playful flirts see the interaction as a game and may be using the flirtation as a means to another end.

Read the original article on Tech Insider. Copyright 2016.