Title: The gender gap cracks under pressure
Description: "Using data from multiple-period math competitions, we show that males outperform females of similar ability during the first period.  However, the male advantage is not found in any subsequent period of competition, or even after a two-week break from competition.  Some evidence suggests that males may actually perform worse than females in later periods.  The analysis considers various experimental treatments and finds that the existence of gender differences depends crucially on the design of the competition and the task at hand.  Even when the male advantage does exist, it does not persist beyond the initial period of competition"--National Bureau of Economic Research web site.