Studies of people's preferences, such as whether they prefer risk and safety, show considerable variation between cultures and genders. If we knew what caused these differences, we'd probably understand ourselves a lot better. A large-scale comparison between countries indicates that the richer and more equal a country becomes, the more preferences between men and women differ, strongly contradicting some explanations of the origins of these differences.

According to one theory of gender-based differences in preferences, the gap between what men and women want should be smaller in societies with little variation in wealth and opportunity between the sexes. An alternative proposes the exact reverse. The two hypotheses are based on opposing ideas of what is causing the gap in the first place.

Fortunately, this is now something we have the data to test. The Gallup World Poll asked 80,000 people across 76 countries for their preferences on matters such as risk, altruism, and desire to reward or punish others' behavior. In line with past results, women’s responses tended towards “prosocial” responses, being more likely than men to favor collective benefits over their own. Professor Armin Falk of the University of Bonn and PhD student Johannes Hermle of the University of California, Berkeley analyzed the data and reached a remarkably clear conclusion.

Falk and Hermle report in Science that across six different categories, the more gender equality (based on four rating schemes) a nation has, the larger the difference in expressed preferences. On some criteria, the change was small, but on others it was dramatic.

Participants were invited to play a game where they could give money to another (anonymous) player and hope their counterpart responded in a way that would benefit both sides. Differences between men and women were modest across three-quarters of the countries surveyed, but in the most equal quarter of countries, women’s trust responses became far greater than men’s.

An even larger factor in shaping the preferences gap between men and women was national wealth. On five of the six preferences tested, the differences between men and women were greatest in wealthy countries and least in the poorest ones surveyed. 

Some psychologists had anticipated this result, arguing that in very unequal societies women feel unable to express their preferences, instead fitting into the dominant narrative. Greater equality, they argued, brings increased capacity to express desires that differ from men’s. Others, however, expected the exact opposite. Men’s and women’s preferences are only different in the first place because of the different roles society pushes us into.

Extrapolating, particularly from a single study, is fraught, but the findings raise the question of what the preferences would look like in a society that achieved true gender equality.