Does mobility make people nicer?

In much of modern life, cooperation takes the form of people engaging in costly behavior that helps another. It is easy to understand how cooperation might be achieved in small communities where members interact repeatedly. However, in our modern world, there is a high degree of relational mobility – where individuals can easily change locations and/or social groups. How does this affect cooperative behavior? I examine this question from both theoretical and empirical perspectives. I first develop a model of repeated prisoner’s dilemma. Individuals are matched but have some ability to leave the relationship. This is sufficient to show that, perhaps surprisingly, greater relational mobility actually leads to more cooperation in equilibrium, and the model predicts a stronger effect when players are more patient. I take these predictions to the data by first conducting a meta-analysis of twelve prisoner’s dilemma experiments that varied the amount of mobility in and out of relationships. I also examine the predictions of the model using data from the World Values Survey and Gallup World Poll. I find that looking across individuals, more relational mobility in the region is associated with greater cooperation and that this relationship is stronger when individuals are more patient. Both the experimental and the observational evidence are consistent with the theoretical mechanism.

That is from the job market paper of Ziqi Lu of Harvard economics.  His entire portfolio looks interesting…