Fig. 2.

Determination of the next observer, average of number of coplayers punished, and average contributions of the individual players observed by the observer in the first block. Each symbol represents an individual player and indicates the player's group. (A) Groups in which the observer opted for a random choice of next block's observer. (B) Groups in which the observer actively chose next block's observer. Circled players are those selected as observers in the next round.