Partner choice versus punishment in human Prisoner’s Dilemmas

Two factors that promote cooperation are partner choice and punishment of defectors, but which option do people actually prefer to use? Punishment is predicted to be more common when organisms cannot escape bad partners, whereas partner choice is useful when one can switch to a better partner. Here we use a modified iterated Prisoner’s Dilemma to examine people’s cooperation and punishment when partner choice was possible and when it was not....