  Do people discriminate between men and women when they have the option to
punish defectors or reward cooperators? Here we report on four pre-registered
experiments, that shed some light on this question. Study 1 (N=544) shows that
people do not discriminate between genders when they have the option to punish
(reward) defectors (cooperators) in a one-shot prisoner's dilemma with
third-party punishment/reward. Study 2 (N=253) extends Study 1 to a different
method of punishing/rewarding: participants are asked to rate the behaviour of
a defector/cooperator on a scale of 1 to 5 stars. In this case too, we find
that people do not discriminate between genders. Study 3a (N=331) and Study 3b
(N=310) conceptually replicate Study 2 with a slightly different gender
manipulation. These latter studies show that, in situations where they do not
have specific beliefs about the gender of the defector/cooperator's partner,
neither men nor women discriminate between genders.
