Ever find yourself chasing the hotties who play hard to get? There’s a reason you can’t get them out of your head: Uncertainty increases attraction.

In this study, 47 college women were told that male students at other universities viewed their Facebook profiles and rated how well they thought they’d get along.

Next, each woman saw four profiles of men who supposedly viewed her profile. One group of women was told that the men liked their profiles the most; a second group was told that the men liked them about average; and a third was told that the experimenter wasn’t sure how much the men liked them, but it was either a lot or average. In other words, there was a 50 percent chance that the men were really into them, but it wasn’t a sure-fire bet.

As you’d expect, women in the liked-most condition were in a better mood and were more likely to return the feelings than women in the average-liking condition. But cue the daisy-plucking: Women who weren’t sure if the men loved them or not reported the strongest attraction.

Why? The mystery men consumed women’s thoughts the most, which may have tricked the women into thinking they were enamored. Talk about playing mind games!