One episode in season five of How I Met Your Mother, called “Hooked,” revolves around people being kept “on the hook,” romantically speaking, by members of the show’s central gang of friends. “I can’t be with you…right now” is the phrase the pals keep using to string these people along, the “right now” leaving the door cracked open just enough that apparently some poor guy is willing to continue to do Robin’s laundry and rub her feet for the vague possibility of a someday relationship.

This does not make the friends look very good, obviously, but keeping track of and keeping in touch with alternative romantic prospects is a common thing for humans to do, even if it is rarely in such an exaggerated, sitcommy way. A recent study published in Computers in Human Behavior dubs these interactions “backburner relationships." A backburner, as defined by the study, is “a person to whom one is not presently committed, and with whom one maintains some degree of communication, in order to keep or establish the possibility of future romantic and/or sexual involvement.”

The lead study author, Jayson Dibble, an assistant professor of communication at Hope College, told me, “What originally inspired me to think about this is when you meet somebody at a club and trade numbers, you might go through your contacts [later] and say ‘Oh I remember that guy. I might zing him a note and see how he’s doing...It was inspired by my old days in grad school.”

“When you were meeting everybody at the club?” I asked.

“Well, I say research is me-search,” he replied, laughing.

The communication is key here. A backburner is not just someone who wanders into your thoughts every once in a while—the college sweetheart whose Facebook photos you occasionally browse, or the cute friend-of-a-friend you met on vacation and have always thought you’d really click with, if you lived in the same city. These “what-ifs” only become backburners if you actually reach out to them.

Dibble notes that sometimes backburners know they’re backburners and sometimes they don’t—I suppose it depends on whether the communication in question is more artful than a “hey, what’s up?” text sent at 1 a.m.

There are a couple of competing evolutionary imperatives at play when it comes to keeping people on the backburner. On the one hand, it makes a certain primal sense to explore all the potential mates available, to be sure to get the best deal. But having one long-term partner helps offspring survive, in the rough-and-tumble caveman world often invoked by evolutionary psychology. So commitment provides benefits, in exchange for letting go of other possibilities—the wouldas, the couldas, the shouldas.

According to the investment model of relationships, developed by social psychologist Caryl Rusbult in the 1980s, people who have invested more resources—time, energy, money—into a relationship should be more committed to it, and alternative partners should seem less attractive. One 2007 study found that love motivates people to shut down other options—people who thought and wrote about love for their partners were more able to suppress thoughts about attractive strangers. This is consistent with research that suggests people in relationships don’t pay as much attention to other members of the sex they’re attracted to, and tend to rate others as less attractive.

So, with all this as background, Dibble reasoned that people in committed relationships in his study would keep fewer people on the backburner.