Group size effect on cooperation in social dilemmas.

I will present the article (Helene Barcelo, Valerio Capraro, arxiv 2014) that concerns the following question: does larger group size favour or prevent cooperation? The authors compare the predictions of two most widely used models of human behaviour (Fehr & Schmidt and Charness & Rabin's) with results of their own experiment and propose a different model which (according to their argumentation) suits the results better.