Theres a social phenomenon that psychology professor Gurit Birnbaum often sees play out among people she knows and couples in the wild: Thinking theyre sly, one partner will try to make the other jealous or get a rise out of them by flirting or seeking attention elsewhere.

It made me wonder: Does this strategy actually work? Does it make the partner feel more desired, or does it prove counterproductive and damage the relationship? she told HuffPost.

With her interest piqued, she and her research team at Reichman University in Herzliya, Israel, teamed up with researchers at the University of Rochester in New York to explore that very premise. A new study published in the Journal of Sex Research reveals their findings.

The study revealed a surprising twist in the way we respond to others interest in our partners: At first we kind of like it, but that enthusiasm is short-lived. Once were coupled up and in a relationship, seeing someone flirt with our partner causes a dip in both our desire for them and our desire to invest further in the relationship.

Both men and women displayed similar defensive behaviors, including decreased desire for their partner, reduced investment in the relationship and increased vigilance towards potential rivals, Birnbaum said.

Prior research suggests that seeing someone flirt with our partners is actually a positive thing, up to a certain point. Thats because as social animals, we rely on social cues to help us search out a desirable partner. One specific cue, known as mate choice copying , occurs in humans and other animals: Seeing others interested in a potential mate makes that person appear all the more attractive and in-demand. Consider it the Ill have what shes having approach to dating.

Or imagine youre at a party, Birnbaum said. You might notice someone who seems attractive, but youre not sure about their personality or if theyd be a good partner. Thats where mate choice copying comes in. That outside interest convinces you that the person is worth your time, too.

Another example of mate choice copying, according to Birnbaum? Research has shown that women tend to perceive men as more desirable if theyre photographed in the company of other women (especially smiling women), as opposed to photos of guys alone or in the company of other men. (Do with that information what you will, dudes on dating apps.)

And she said men and women both are more likely to judge a potential mate favorably if they see that the persons exes were attractive.

We use this to make snap judgments about relationship building because other desirable traits how trustworthy a partner is, for instance, or how loyal they are arent as easily observable.

By noticing who others are interested in, we get a shortcut to figuring out who might be a good partner, minimizing the time, energy and potential risk involved in finding a compatible partner, the professor said.