The research shows men who spend even a few minutes in the company of an attractive woman perform less well in tests designed to measure brain function than those who chat to someone they do not find attractive.
Researchers who carried out the study, published in the Journal of Experimental and Social Psychology, think the reason may be that men use up so much of their brain function or 'cognitive resources' trying to impress beautiful women, they have little left for other tasks.
The findings have implications for the performance of men who flirt with women in the workplace, or even exam results in mixed-sex schools.
Women, however, were not affected by chatting to a handsome man.
Read more about the study here.