Socializing may improve mental function

But only if it's friendly chat...competitive conversations don't result in the same improvement.  (Words With Friends  doesn't count either...)

They found that engaging in brief (10 minute) conversations in which participants were simply instructed to get to know another person resulted in boosts to their subsequent performance on an array of common cognitive tasks. But when participants engaged in conversations that had a competitive edge, their performance on cognitive tasks showed no improvement.
"We believe that performance boosts come about because some social interactions induce people to try to read others' minds and take their perspectives on things," Ybarra said. "And we also find that when we structure even competitive interactions to have an element of taking the other person's perspective, or trying to put yourself in the other person's shoes, there is a boost in executive functioning as a result."