Cooperative behavior cascades in human social networks

Theoretical models suggest that social networks influence the evolution of cooperation, but to date there have been few experimental studies. Observational data suggest that a wide variety of behaviors may spread in human social networks, but subjects in such studies can choose to befriend people with similar behaviors, posing difficulty for causal inference. Here, we exploit a seminal set of laboratory experiments that originally showed that voluntary costly punishment can help sustain cooperation. In these experiments, subjects were randomly assigned to a sequence of different groups to play a series of single-shot public goods games with strangers; this feature allowed us to draw networks of interactions to…

• RW
  Robert Wood Johnson Foundation
• JT
  John Templeton Foundation
• UO
  University of Notre Dame
• NI
  National Institutes of Health

  Awards: P30 AG034420, P01 AG031093
• NI
  National Institute on Aging