Figure 1

Loss probability (left) and average expected winnings per subject (right), as a function of group investment over ten rounds, for Treatment 1 (T1, a and d), Treatment 2 (T2, b and e), and Treatment 3 (T3, c and f). The maximum of the average expected winnings per subject occurs at the target sum of €120 in T1 and T2 and at €113.3 in T3 (asterisks; see Methods).