Fig. 2.

The PGG. Each game began with a prompt indicating that a new round was about to begin. Participants decided whether to keep or give $8.00. Participants then saw three stages of guided feedback: (1) each player’s contribution to the public good, (2) the total contribution multiplied by two, then (3) each player’s resulting payout. Each feedback stage was presented for 5 s. The next trial began immediately afterwards, for a total of 20 games. Each game consisted of a separate one-shot interaction with three new players. In the example above, the participant decides to keep and then learns, in the feedback stage, that the other three players chose to give. Decisions to keep and give were depicted in yellow and blue, respectively. Not shown to scale.