You know how sometimes you're talking to a guy you thought seemed smart and he is suddenly acting really, really dumb? Well, so did researchers at Radboud University Nijmegen in The Netherlands, and they set out to determine if it's more than just anecdotal experience and, if so, why.
And, unsurprisingly, they found that men's brains do tend to turn off when there's an attractive woman around.
They made participants – both male and female – talk with a stranger, of either sex, and complete a cognitive task, like mental arithmetic, before and after the interaction.
When men – whether single or not – spoke to women, their ability to carry out the task dropped. But when they spoke to other men, their abilities remained unchanged.
Want to guess how the women in the experiment fared?
Women's performance stayed the same throughout.
The researchers speculate that men are trying so hard to impress women that they're impairing their own cognitive function.
Since impression management isn't easy (it requires careful cognitive control as one is constantly monitoring and modifying one's behavior), it can be very effortful and cognitively demanding, thus depleting an individual's cognitive resources (consistent with Roy Baumeister's self-regulatory resource model) and therefore can result in declined cognitive performance after the interaction.
As for why effect was most pronounced in men, the researchers cite research that suggests that "compared to women, men are more likely to consider mixed-sex interactions in terms of a mating game.", and therefore "men in particular might therefore be prone to engage in effortful and cognitively demanding attempts to impress an opposite-sex partner."
In other words, it might be socially-ingrained in men to try to impress the opposite sex, but it generally makes them incapable of certain kinds of brain functions (which often then has the opposite effect of impressing women).
As someone subjected to male stupidity in the course of trying to impress me, I can only say, "Duh!"