Dutch psychologists had males and females talk to strangers of both sexes and tested them on word games before and after the interaction. When men spoke to men, or women conversed with either sex, their mental abilities remained unchanged. However, a man gets considerably dumber after he talks to a woman — and the better-looking the woman, the stupider he becomes.
The researchers posit men can’t help but mentally exhaust themselves trying to pick up an attractive woman.
So I guess if a guy can talk to a girl endlessly and perform tasks and not become mentally exhausted, then she’s not attractive.