Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We examine whether competitiveness in women is influenced by biological factors. Female participants in a laboratory experiment solve a simple arithmetics task first under a piece rate and then under a competitive tournament scheme. Participants can then choose which compensation scheme to apply in a third round. We find that the likelihood of selecting into the competitive environment varies strongly and significantly over the menstrual cycle and with the intake of hormonal contraceptives. The observed patterns are consistent with a negative impact of the sex hormone progesterone on competitiveness. We show that the effect of the menstrual cycle and hormonal contraceptives on competitiveness is due neither to an impact on performance, nor to an impact on risk aversion or overconfidence.