You stop at the mailbox and bump into the guy down the hall. Or you pull into the driveway just as your neighbour is getting home. Suddenly you're gabbing about nothing in particular and you end up frittering away 10 minutes. It's not a waste of time, according to research to be published in the February [2008] issue of the Personality and Social Psychology Bulletin. Ten minutes of talking, face-to-face or by phone, improves memory and boosts intellectual performance as much as doing crosswords. "There's a widespread belief in this culture that the way to maintain your sharpness is to do technical and intellectual activities," says Oscar Ybarra, a University of Michigan psychologist. But his study suggests an alternative to Sudoku or crosswords could be simply talking to one another.