Attention to Prescriptive Norms Increases Dictator Game Generosity in Women but not Men: Using the 2D:4D Digit Ratio to Test the Role of Biology

Abstract

Some authors propose that gender norms pose divergent effects on generosity, usually being women the gender expected to be kinder. Indeed, some economic experiments show women to be more generous than men in the Dictator Game (DG). Despite some claiming these results to be determined by socialization into gender norms, data do not speak against a biological explanation of sex differences. In fact, there is evidence that DG generosity varies with the level of pre-natal exposure to testosterone and estrogens, as indirectly measured using participants´ 2D:4D digit ratios. In any case, it is unclear whether DG generosity expresses pure altruism or compliance with social norms. Socialization and biological factors may have diverse effects on these two different motivations. In the present study, we aimed atcontributing to this discussion. We randomly assigned participants to two independent conditions. In the prescriptivenorm condition, participants were incentivized to accurately estimate others´ opinion about the most socially appropriate option in the DG (i.e., the prescriptive norm), and then made their decisions as dictators. Participants in the control conditions made their decisions as dictators without any prior estimation. We found that the normative exercise increased generosity (relative to the control condition) in women but not in men. In a sub-sample, we also measured participants´ 2D:4D digit ratios as a proxy of a socialization-free sex-dimorphic hormonal influence on behavior. We found no evidence that the normative effect of the estimation exercise was modulated by participants´ digit ratios. In contrast, generosity in the control condition was higher, the more extreme (highest and lowest) the digit ratios were. Weconclude in favor of: 1) a socialization-modulated gender effect on responses to prescriptive norms of generosity; and 2) a biological effect of pre-natal hormonal levels on generosity when the norm was not elicited; in this last case, the relationship between pre-natal testosterone and empathic concern might be involved.