The office flirt is doing you more harm than you think. You might think he’s just being flirtatious or a creep but his actions could actually be harming your work performance, especially if you’re a woman.

Research conducted by the University of Nebraska found that women who were subjected to an “objectifying gaze” performed less well at tests than those who weren’t subject to the same actions.

The tests were conducted with 150 men and women. They took part in an exercise involving team work: they had to work on 12 math questions in 10 minutes.

As part of the study, some of the participants, both men and women, were looked at by an interviewer of the opposite sex who was under instruction to look at them in an objectifying manner.

Women who were leered at on average got less than five question right while those who weren’t got an average of six correct.

Doctor Sarah Gervais, the lead researcher for the study said, “It creates this vicious cycle for women in which they’re under-performing in maths or at work, but they’re continuing to want to interact with the person who’s making them under-perform in the first place.”

You can read more about the study in the journal Psychology of Women Quarterly.