Do good actions inspire good actions in others?
  Actions such as sharing food and cooperating to reach a common goal have played a fundamental role in the evolution of human societies. These good actions may not maximise the actor's payoff, but they maximise the other's payoff. Consequently, their existence is puzzling for evolutionary theories. Why should you make an effort to help others, even when no reward seems to be at stake? Indeed, experiments typically show that humans are heterogeneous: some may help others, while others may not. With the aim of favouring the emergence of 'successful cultures', a number of studies has recently investigated what mechanisms promote the evolution of a particular good action. But still little is known about if and how good actions can spread from person to person. For instance, does being recipient of an altruistic act increase your probability of being cooperative with others? Plato's quote, 'Good actions give strength to ourselves and inspire good actions in others', suggests that is possible. We have conducted an experiment on Amazon Mechanical Turk to test this mechanism using economic games. We have measured willingness to be cooperative through a standard Prisoner's dilemma and willingness to act altruistically using a binary Dictator game. In the baseline treatments, the endowments needed to play were given by the experimenters, as usual; in the control treatments, they came from a good action made by someone else. Across four different comparisons and a total of 572 subjects, we have never found a significant increase of cooperation or altruism when the endowment came from a good action. We conclude that good actions do not necessarily inspire good actions in others, at least in the ideal scenario of a lab experiment with anonymous subjects. 
Valerio Capraro, Alessandra Marcelletti
physics.soc-ph cs.GT q-bio.PE