So did you know about the MRI Study of Normal Brain Development? Me neither but thanks to Echidne I do now.

Study director Deborah Waber says they are finding:

• Mental performance differs little by gender. "We found a few significant differences that we would have suspected," Waber said. "For example, boys are better at visual and spatial tasks, and girls are better at motor speed, but there are no differences in many other paths, like memory."
• Family income matters. Kids from more affluent homes do better than those from lower-income families, with average IQs of 105, 110 and 115, respectively, for children classified as low-, middle- and high-income. "But when we limit the groups to healthy children, the differences are not as great," Waber said. "That suggests that the difference has more to do with disparity in health care related to income."

While the full article is behind a pay wall in the Journal of the International Neuropsychological Society, you can find a good
summary in Forbes magazine (skip the welcome screen).

Forbes concluded: "It turns out that much-touted differences in the mental evolution of boys and girls aren't so pronounced after all."

How about that!