For some, affirmative action is righting one wrong by committing a wrong against another group. But this column presents new theory and evidence suggesting that the influence of social stigma on a person’s self-confidence, self-development and their ultimate success should not be ignored.

Some blame women’s under-representation in high-level jobs on differences between the sexes in risk aversion and competition. But are these differences in behaviour hardwired or learned? This column describes a study that tackles this thorny question with a controlled experiment in single-sex and mixed classrooms in a British university. Women are found to become far less nervous about uncertainty over time with the men out of the room.

Several countries have recently introduced gender quotas in hiring and promotion committees at universities. Evidence from promotions in the Spanish university system suggests that quotas are only effective at increasing the number of successful female applicants in promotions to top positions. This column argues that, given that sitting on committees reduces the available time for research, gender quotas should be implemented only for more senior academic positions.

Around the world, the pay and achievement gap between men and women remains significant, as shown by last week’s Global Gender Gap Report. This column explores whether this gap can be explained by attitudes towards competition. Using experimental evidence from math quiz competitions in primary schools, it finds that while males respond better to competition initially, this advantage is short-lived, as females are just as responsive over time.