(a) Average round of achievement. Round (mean and standard error of the mean) in which the group of six achieved the target. (b) Aggregated contributions per group composition. Contributions (mean and standard error of the mean) in the first and last five-rounds per number of individuals with MD in a group. There are significant differences (t-test p < 0.01) in contributions in the first part of the game. (c) Contributions per group of six. Total group contributions by number of individuals with mental conditions in the group. (d) Gini index of final payoff within groups. Level of inequality in final payoff based on the number of individuals with MD in each group.