Figure 4

Cooperation in symmetric and asymmetric Prisoner’s Dilemma games. Participants’ average cooperation frequency for the three experimental treatments and for symmetric (lighter colors) and asymmetric (darker colors) interactions. Unbalanced interactions lead to lower levels of cooperation in RH treatments and, to a certain extent, in CH treatments (comparison of individual action distributions in symmetric and asymmetric interactions: SH treatments MW U = 2783500, p = 0.607; CH treatments MW U = 2866600, ^**p < 0.010; RH treatments MW U = 1687000, ^***p < 0.001). Error bars represent standard error of the mean over all dyadic interactions.