"Girls, ...are often praised for their "goodness." When we do well in school, we are told that we are "so smart," "so clever, " or " such a good student." This kind of praise implies that traits like smartness, cleverness, and goodness are qualities you either have or you don't. Boys, ...are given a lot more feedback that emphasizes effort (e.g., "If you would just pay attention you could learn this," "If you would just try a little harder you could get it right.") The net result: when learning something new is truly difficult, girls take it as sign that they aren't "good" and "smart", and boys take it as a sign to pay attention and try harder.
This tallies with previous research I've read. I need to work on praising my daughter based on effort rather than innate ability/ traits. So rather than saying "well done, aren't you clever" I say "well done, you worked that out really well/ you tired really hard there"