Mobile Social Dilemmas in an Experiment

Mobility Accelerates the Cycle, but does not Change Cooperation

抄録

     This paper sheds light on the role of mobility on cyclic processes in mobile social dilemmas. Olson argues that large groups will allow free-riders. Erhart and Keser's experiment revealed that people formed clockwise cycles of group size and cooperation when they can change groups. But they did not compare various levels of mobility. Thus, our research question is how mobility affects the cycle and the cooperative behaviors. We conducted a laboratory experiment (with 168 participants in 40 groups in 10 sessions). Three conditions (treatments) were introduced (immobile, high mobility costs, and low mobility costs conditions). We show the following findings. (i) Mobility did not change effects of size on cooperation (N=339 group-rounds). (ii) Still, mobility accelerated effects of cooperation on size (N=360 group-rounds). As people moved more easily, cooperative groups were more likely to expand. (iii) As a result, intergroup mobility accelerated the cycle (N=40 groups). Groups rotated faster when people moved more easily. (iv) However, mobility did not raise nor decline cooperation levels (N=40 groups). Therefore, to foster cooperation, first increase mobility to free cooperators. Then, restrict mobility to exclude free-riders.