Several years ago, thousands of bright-eyed middle schoolers in China were asked a simple question: "Do you agree that boys' natural ability in studying math is greater than that of girls?" These children were chosen because they reflected the typical student in China, so their beliefs reflected those of kids across the country. And they should have disagreed on factual grounds. Girls outperform boys in mathematics at this age in China. Instead, more than half of these children agreed that boys have innately superior math abilities. Whether we like it or not, this notion of inherent gender-based math ability commonly exists in the minds of many schoolchildren.

My co-author and I wondered whether these beliefs might be responsible for a curious trend. While girls tend to outperform boys in math and other major subjects in elementary school and middle school, we have found that their superior performance disappears and even reverses in college. Perhaps the gender stereotypes children encounter in early adolescence put girls at a disadvantage in math as they progress through high school and college.

The Algebra of Peer Influence in Middle Schools

To study this, we took advantage of the random fates of more than 8,000 children across 208 middle school classrooms in China. These students were assigned to their classrooms by random lotteries. This means that each class was essentially equal on anything that could systematically influence students' academic performance such as their prior grades or their parents' education level. Indeed, at the beginning of the study, average math scores didn't differ between classrooms.

But purely by chance, these classes differed in an important way. Even though more than half of all the students believed that boys were innately better at math than girls, these beliefs were more common in some classrooms than others. In some classrooms, as few as 19% of the students started the year with that belief, but in other classrooms, as many as 93% believed it. Could this have set the stage for these classrooms to have different academic outcomes?

We found that the more a classroom's students believed that boys were inherently good at math at the beginning of the school year, the better boys did on standardized midterm math exams, and the worse girls did later on. In classrooms where the stereotype was strong, girls shied away from math-related extracurricular activities, like study groups. And in classrooms with stronger stereotypical beliefs about gender, girls thought they received less attention and less praise from their math teachers. They were also more likely to buy into the stereotype and report less math-related self-confidence and career ambition.

It's worth noting, though, that the presence of these stereotypes about gender and math didn't make girls underperform across the board—just in math. For example, we didn't see any evidence that "girls are bad at math" stereotypes affected how much girls participated in other extracurriculars such as Chinese, English, painting, or music.

The Gender Gap in Math in College and Beyond

Our analysis of those middle school students showed that gender stereotypes had negative effects on girls over time. We wondered whether reminders of these gender stereotypes could spark immediate effects on girls' math performance. So, we ran an experiment in which 500 college students took a tricky math quiz. They were mostly economics majors, so math shouldn't have scared them.

But there was a twist. Before the quiz, we showed half of the participants a 5-minute video showcasing statistics from national surveys that suggest (a) men outperform women in mathematics on average and (b) more men than women score in the top percentiles in standardized math tests. The point was to remind both women and men of society's expectations of them. The other half of the participants also saw a video before the quiz, but it was about human memory strategies and never referenced any gender differences.

The result? Just like we've seen under typical circumstances, women still did slightly worse than men on the quiz when nobody was explicitly reminded of gender stereotypes about math. However, women's scores got substantially worse when they were reminded of these stereotypes, which widened the gap between men's and women's math scores.

The Reality Check

When we surveyed very young students, most of them believed that boys are inherently better at math than girls. Indeed, our analysis of years of Chinese exam scores found that female college students routinely underperform relative to men. But we don't think those kids' beliefs were simply reflecting reality. We think they may have been at least partly responsible for creating that reality. The existence of these stereotypes makes disparities happen. Rather than focus on changing girls' attitudes and choices, it may be more fruitful to change the ambient social environment that children and young adults are embedded in. For example, introducing female role models and interventions that aim to shift what is normal and desirable in one's community or peer groups may prove useful in the long run.

For Further Reading

Wu., S. J., & Cai, X. (2023). Adding Up Peer Beliefs: Experimental and Field Evidence on the Effect of Peer Influence on Math Performance. Psychological Science, 34(8), 851–862.

Wu, D. J., Thiem, K. C., & Dasgupta, N. (2022). Female peer mentors early in college have lasting positive impacts on female engineering students that persist beyond graduation. Nature Communications13(1), 6837.

Sherry Jueyu Wu is Assistant Professor of Management and Organizations and Behavioral Decision Making at the University of California, Los Angeles. She studies group influence over long-lasting behavioral changes and issues around social inequality.