Psychologists say little girls have about six years before they’re affected by harmful gender stereotypes about their intelligence. The researchers published their findings in the journal Science.

Belief in oneself is not just some fluffy idea. A multitude of studies have shown that girls and women who are confident in their abilities are more likely to succeed in school and in their careers. They’re more likely to take risks, score higher on tests, and advance in the world. But widespread sexism can make this confidence very difficult to come by.

Lead researcher Lin Bian is a doctoral researcher at the University of Illinois. "Our society tends to associate brilliance with men more than with women, and this notion pushes women away from jobs that are perceived to require brilliance," Bian said in a statement. "We wanted to know whether young children also endorse these stereotypes."

The research team recruited 400 children between the ages of 5 and 7 for a series of four experiments. In the first, the kids were told a story about someone who was “really, really smart” and were told about four different people, two men and two women. In the second study, they simply had to guess which of the four people was “really, really smart.”

The 5-year-olds were quite equitable-minded, believing that either gender could be the story’s “really, really smart” protagonist. But by age 6, girls were far less likely to guess that women could be “really, really smart.”

In the third experiment, the researchers showed some of the 6- and 7-year-old kids two very similar games. One was labeled for “children who are really, really smart” and the other for “children who try really, really hard.” Then each kid was asked which game interested them more. Girls and boys were equally interested in the game for hard-working children. The game for smart children was significantly less popular among the girls.

Kids in the last study were shown a game “for smart children,” then asked if they were interested in playing. The 5-year-old girls were all for it, but 6-year-old girls had substantially less interest than the boys.

Co-author Sarah-Jane Leslie studies philosophy at Princeton University. "In earlier work,” she said, “we found that adult women were less likely to receive higher degrees in fields thought to require 'brilliance,' and these new findings show that these stereotypes begin to impact girls' choices at a heartbreakingly young age.”