The vertical axis refers to the averaged cooperation rates of each group of two or four players (n = 97) over all 20 first rounds, for each treatment and across both the high and the low games (horizontal axis). Across all rounds, people were most cooperative in the control treatment (red), in both the high and the low game. Cooperation rates in the same-partner (yellow) and the different-partner treatment (green) are not significantly different from each other. Data are presented as mean values, individual data points are overlaid as dots and the SEM is represented by a vertical bar.
