In game 1, you are going to play a game within a group. You will be randomly matched with 3 other players. None of the four group members knows the identity of the other group members and no one will knowingly meet each other.
Each group member is endowed with 10 experimental currency units (ECUs, henceforth). As a member in the group, you need to decide how much of your endowment you want to keep for yourself and how much you want to contribute to a group account. You can choose to contribute any amount between 0~10 ECUs (the minimum unit is 1ECU). Note that each group member is facing the same decision and the decision is made in private.
Your choice influences your own and the other group members’ payment. Likewise, the group members’ choices influence your payment.
• The amount you keep simply remains in your possession: For every 1 ECU you keep, you will receive 1 ECU in payment.
• The amount you and the other group members contribute to the group account will be summed up, doubled, and then split equally among all group members. Thus, for every ECU contributed, each group member will receive 0.5 ECU
The game will be repeated for five rounds (fixed matching). At the end of each round, you will be informed of the total contribution to the group account, as well as your payment in this round.
Your payment in a certain round = the amount you keep + 0.5 * total amount in the group account.
We will randomly draw one round for as your final payment in game 1. A lucky player in each group will receive the actual payment, with an exchange ratio of 5 ECU → 1 chocolate