In case you needed more proof….

A recent study finds that gender stereotypes affect children’s performance in tasks like math and science. Tell a girl that boys are good at math, and watch her performance fall.

That, at least, is what happened in a study of some 150 children ages 4 to 7. As reported in Slate, they “played a game in which they looked at pictures of 3-D blocks shown from different angles, then matched pairs of images that showed the same block from a different perspective.” After the first round of this game, “the adult leading the experiment told some children that the other gender group was successful at that game (so girls heard, 'Boys are good at this game'). A second group was told about other individuals’ skills ('That girl is good at this game'), and a third group heard no further information.”

Children in the first group saw their scores fall an average of almost 13 percent in the second round. Those in the second group saw their scores remain steady. Those in the third saw their scores fall about 3 percent. Simply hearing that another group (as opposed to another individual) does well had a big impact on young children.

The problem, of course, is that children are hearing these stereotypes in countless subtle and not so subtle ways. Recent research has shown that girls internalize the message that “math is for boys” as early as second grade. It’s getting harder to ignore the possibility that pervasive stereotypes are a major reason for the paucity of women in science, technology, engineering and math (STEM).

It's not easy to combat gender stereotypes, because they're so pervasive. The worst thing we can do, however, is ignore them.