Why can't Susie add? It may be the nature of math tests--not her inherent ability--that's the problem. The belief in men's math superiority is supported by the fact that boys consistently outscore girls on the SAT and GRE by about 50 points. Still, girls get higher grades in math classes. To Robert Josephs, Ph.D., of the University of Texas-Austin, the numbers didn't add up. The assistant professor of psychology gave a GRE math section to undergraduates and found that women who believed it would expose academic flaws performed much worse than those who thought it would demonstrate ability. Men, however, performed worse when they thought the test would show their proficiency. While women worry about proving that they are bad at math, says Josephs, men are concerned with confirming that they are better at sums. So both sexes feel more pressure-and do worse, on tests which reinforce gender stereotypes of behavior. Which is why girls perform confidently in class but lose points on standardized tests: exams like the GRE are used to weed out weak students, but school math tests are designed to let them show what they know.