“There are lots of people at the place where I work, but there is one person who is really special. This person is really, really smart,” said Lin Bian. “This person figures out how to do things quickly and comes up with answers much faster and better than anyone else. This person is really, really smart.”

Bian, a psychologist at the University of Illinois, read this story out to 240 children, aged 5 to 7. She then showed them pictures of four adults—two men and two women—and asked them to guess which was the protagonist of the story. She also gave them two further tests: one in which they had to guess which adult in a pair was “really, really smart”, and another where they had to match attributes like “smart” or “nice” to pictures of unfamiliar men and women.

The results were stark. Among the 5-year-olds, both boys and girls associated brilliance with their own gender. But among those aged 6 or 7, only the boys still held to that view. At an age when girls tend to outperform boys at school, and when children in general show large positive biases towards their own in-groups, the girls became less likely than boys to attribute brilliance to their own gender. You could frame that as a good thing: While boys continued to believe in their own brilliance, the girls, on average, developed a more equal view. But that view has consequences—Bian also found that the older girls were less interested in games that were meant for “really, really smart” children.

“It was really heartbreaking,” she says.

The stereotype that brilliance and genius are male traits is common among adults. In various surveys, men rate their intelligence more favorably than women, and in a recent study of biology undergraduates, men overrated the abilities of male students above equally talented and outspoken women. But Bian’s study shows that the seeds of this pernicious bias are planted at a very early age. Even by the age of 6, boys and girls are already diverging in who they think is smart.

It’s an excellent, important, and well-designed paper,” says Alison Gopnik from the University of California, Berkeley, who studies the minds of babies and children. “The pattern it reports is very consistent with other studies which show the emergence of gender stereotypes at around age 6.”

These differences can have lasting consequences. In 2015, Bian’s colleagues Sarah-Jane Leslie from Princeton University and Andrei Cimpian at New York University showed that in many academic fields, like physics, math, and philosophy, people believe that success depends on “raw, innate talent” that “just can’t be taught”. And as the team found, the greater the emphasis on this “brilliance required” message, the fewer female Ph.D.’s there were, and the bigger the gender gap. That’s not because of any actual differences in aptitude. Instead, the team argued, a double whammy of stereotypes—that men are more likely to be brilliant, and that brilliance is required in some fields—creates an atmosphere that makes women feel unwelcome, and pushes them away.  

It begins early, Bian found. She offered 160 children a chance to play two new games—one for children “who are really, really smart” and another for those who “try really, really hard”.  At the age of 5, girls and boys were equally attracted to both games. But among those aged 6 or older, the girls were less interested than the boys in the game for smart kids (but not the one for hard-working ones). “They’d go from being really enthusiastic to saying: ‘Oh I don’t want to play it, this isn’t a game for me,’” says Bian. And those who had most strongly assimilated the stereotype of male brilliance showed the lowest interest in the smart game. They had already mentally assigned themselves to Hufflepuff instead of Ravenclaw.

“The stereotype has an immediate impact,” she adds. “In the long-term it will steer away many young women from careers that are thought to require brilliance.”

“Unfortunately, this reveals another hurdle for efforts to recruit more women and girls into STEM,” says Sarah Eddy from Florida International University. “Not only do we need to break down the ‘science is male’ stereotype, but now we need to break down a ‘brilliance is male’ stereotype, too.”

Why do these beliefs occur? It’s not to do with actual ability. At that age, girls tend to outclass their male peers—and the girls in Bian’s study knew it. When she showed them pictures of four children and asked them to guess who got the best grades, the older girls were actually more likely to pick girls than the older boys were to pick boys. “Everyone agreed that girls do better in school but that didn’t seem to matter,” says Bian.

Why? “That’s something we’re investigating,” says Bian, “and the answer won’t be simple.” Their parents, perhaps? Parents tend to think that their sons are brighter than their daughters, and they’re 2.5 times more likely to do a google search for “Is my son gifted?” than “Is my daughter gifted?” Their teachers could be another font of stereotypes. So could the characters in the movies they see and the books they read.

“We have to be more deliberate about presenting examples of brilliant women to girls and boys as young as five to help them avoid developing this association,” says Eddy. “Brilliant women exist, like Rosalind Franklin, Shirley Jackson, Ada Lovelace, Marie Curie, and Katherine G. Johnson, whose story is popularized in Hidden Figures.  We need to be talking about them more.”

“We can also emphasize the importance of hard work and effort in addition to brilliance,” says Bian. Psychologists like Carol Dweck have shown that many disadvantaged groups, including poor students and people of colour, suffer disproportionately from beliefs that intelligence is innate and fixed. “Simply changing disadvantaged high-school students’ perception of the malleability of IQ can cause substantial differences in drop-out rates,” says Gopnik.  

But Sapna Cheryan from the University of Washington notes that in Bian’s study, the 5-year-olds had a kind of gender arrogance, which persisted in the boys but disappeared in the girls. “Do we want a society where each gender thinks they are smarter, or do we want one where boys and girls think the genders are equally smart?” Cheryan asks. “If the latter, then it may be boys’ beliefs that we should try to change.”

“Similarly, do we want a society where people would rather play the game that requires being ‘being smart’ over the one that require ‘hard work?’” she says. “We as a society should figure out what we value before concluding that it is the girls we need to change.”