We analyze pro-social behavior in an every-day context. Using unique data on users of all public libraries in Barcelona, we test whether we can incentivize pro-social behavior by sending email messages with different contents. We find that users return their items earlier if asked to do so in a simple email. Emails involving a component of threat are more effective than emails with pure moral suasion. We also investigate whether there are different reactions regarding gender, age, and nationality.
 

VIEW PAPER