Figure 3. Power and cooperation.

(a) Change of average power of the most powerful group member over rounds in the endogenous condition (blue). In the exogenous condition, power transfers were identical to the endogenous condition by construction, and thus, the average power of the most powerful group member was the same. In the fixed condition, power was fixed to 1 (grey). Error bars show the within-subject standard errors of the mean. (b) Distribution of correlations across rounds between maximum power and cooperation for each group in the endogenous and exogenous condition. Thick horizontal bars represent the medians.