Fig. 1.

Setup of the multiplayer resource-dilemma game and an example harvesting opportunity. The photographs show (a) the positions of the four players (a participant and three confederates) around the workstation where the game was played and (b) a single participant viewing an example display. In the example harvesting opportunity (c), the letter A indicates the position of the participant at the workstation; the three confederates are represented by B, C, and D, respectively. Throughout the game, the current value of the resource was shown in the center of the pentagon. During the harvesting phase (left panel), participants had 5 s to choose how much to harvest from the resource and enter that amount in the box marked “Select your take:.” This was followed by the 1.5-s observation phase (middle panel), in which the amount each player chose was displayed in red next to his or her identifying letter, and then the participant’s chosen amount was added to his or her total points. The resource was then partially replenished (right panel). Replenishment was signaled by a mauve border appearing around the pentagon and the sounding of a 0.5-s tone.