Experimental Design Details
1. Data collection methods
The study will use the traditional laboratory-based experiment with cash incentives (based on the subject's decision in the experiment). During the experiment, subjects made their entire decisions through the laptop software named Z-tree (http://www.iew.uzh.ch/ztree/index.php).
The experiment takes approximately 30-85 minutes to complete. Each subject only participates in the experiment once. They will receive 20 RMB as participation payment (1 U.S. dollar equals 6.54 RMB on 04/06/2021). They can get an additional 30 - 150 RMB, based on their decisions in the experiment. Subjects' estimated average payoff is 60 RMB, above the average salary for a student's part-time job.
2. Intervention and Experiment Design
Upon arrival, the subjects will read the study information sheet to decide whether to participate in the experiment (see attached the study information sheet). Once they decide to participate in the experiment, they will be assigned randomly to a computer terminal. There are six parts to the experiment and a questionnaire at the end. Each part was introduced sequentially after completion of the previous one. Instructions were distributed, and questions were answered in private (see attachment instruction).
The "Fixed-Opponent" Experiment
There will be ten subjects who participate in this experiment. In the experiment, subjects play the following two games.
• In the first game, each subject will be randomly paired with a different person in this room. They will not be told who of these people are either during or after the experiment. The game has two players: subjects and his/her matched opponent. Each decision-maker will choose an integer number between 50 and 110 as "effort." They will earn the RMB equal to the minimum effort level chosen by subjects and the person they are matched with, minus the cost of the subject's effort, which is 0.5 times the subjects' own effort choice. The payoff rule captures this: Payoff (RMB) = Minimum Effort - 0.5*Your Effort.
• In the second game, there are two players: sender and responder. Each subject will be randomly paired with a different person who is in this room. One person is assigned as the sender, and the other is assigned as the responder. The sender has an initial endowment of 50 RMB while the responder receives no endowment. The sender decides how much they give to the responder. X must be an integer between [0, 50]. The experimenter will triple the amount they give to the responder. For example, if the sender gives X RMB, the responder will get 3X RMB. However, the responder will decide without knowing how much the sender gives to them. The responder makes 51 decisions, one for every amount they could get from the sender, ranging from 0 to 50. The sender receives 50-X+Y RMB, and the responder gets 3X-Y RMB.
We randomly choose one decision to make the payment for subjects. Subjects know this in advance. To avoid subjects getting meager payment, for those who get less than 30 RBM (not including the participation payoff), we will ask them to play a lottery where they have a 30% chance to get 30 RMB and a 10% chance to get their original payoff minus 1 RMB. Subjects are not aware of the lottery when they make the decisions in two games.
The Main Experiment
There are two different games in the main experiment. For each game, the subject play three times in the following order: an isolated individual decision, an group decision together with an individual real-time decision, and an isolated individual decision.
Two games are almost the same with the "fixed-opponent" experiment, with one exception. Subjects were told that they would not play games against other subjects in the experiment. Instead, they play against the one randomly chosen subject from the "fixed-opponent" experiment, call her "outside opponent." To determine their payoffs, we will split participants in the main experiment randomly into two groups of equal numbers called Group1 and Group 2 and match each participant in Group 1 with a partner in Group 2. If subjects are in Group 1, their decision will be matched with the "outside opponent" and determine their payoff as the game described. However, at the same time, the outside opponent's payoff will become the pairing members' payoff in Group 2.
• Subject in the individual decision environment makes an isolated individual decision.
• Subject in the group decision environment participates in a group decision discussion through Chat Box in the z-tree software. There are three subjects in one group. They need to make two decisions: a united group decision and a real-time private individual decision. The group environment's decision time will be10 minutes.
o Group members can freely submit their public proposals for group decisions by typing the number and clicking the "Submit Button." In the united group treatment, before all group members decide to leave the group discussion or decision time is finished, all group members' last proposals must be the same. Or, a random number will be chosen as a group decision, and they only get 10% of the random choice payoff. In the leader treatment, the leader decides when to leave the discussion and the leader's proposal becomes a group decision.
o A real-time private individual decision. Subjects can update their individual decision by typing the number and clicking the "Submit button." The screen will show the lasted individual decision. The default decision is subject to" isolated decisions made in previous stages. The computer recorded the actualized choices during the 10 minutes (or 90s) group decision process and then randomly chose a one-time point following uniform distribution after the experiment.
We randomly choose one decision to make the payment for subjects. Subjects know this in advance. To avoid subjects getting meager payment, for those who get less than 30 RBM (not including the participation payoff), we will ask them to play a lottery where they have a 90% chance to get 30 RMB and a 10% chance to get their original payoff minus 1 RMB. Subjects are not aware of the lottery when they make the decisions in two games.
The “Control Experiment”
Subjects in this experiment will play two games in the “Main Experiment,” but they will play each game three times, all in the individual environment.