Girls need to be taught to be more competitive, new research from Université Paris-Saclay finds.

Professors José de Sousa and Guillaume Hollard studied more than three million games of chess from 154 countries to find that in games with comparatively equal opponents – same in age, nationality and ranking – women were more likely to lose against men. José de Sousa suggests that psychological reasons are behind these findings.

Male players seem to want to beat female players more, women know that. When women are told that they tend to do worse, they usually do.” He says. “Women often shy away from competition. Perhaps men push harder against women. The man thinks he controls the game and has to win.

Though the glass ceiling exists in chess as it does in business, studying chess eliminates the other reasons often given for the gender gap. As anyone can play, it removes discrimination, and the data can be compared across countries because it’s measured in the same way. So when comparable male players were compared to similar female players, there shouldn’t have been a difference. But men were 2 percent more likely to win across all countries.

The only variance is gender. This psychological effect of competition may translate into a massive under-representation of women at the top of the hierarchy because they drop out and stop putting in effort. Thus inducing an even more profound impact on the overall gender gap. Professor de Sousa advises us to be aware that in the likes of business and job interviews, men are more competitive. He suggests that we need to work on how boys and girls view competition – teaching girls to be more competitive, and boys to be less.