05 Abr New paper out on critical size for PGG
I am happy to report that I have a new paper out with my friends María Pereda (Universidad Politécnica de Madrid) and Valerio Capraro (Middlesex University London) entitled «Group size effects and critical mass in public goods games«. Basically, what this is about is the issue of the effect of the size of the interacting group on cooperative behavior. We contributed to this problem by designing a two-treatment empirical study where subjects play a Public Goods Game with a Critical Mass, such that the return for full cooperation increases linearly for early contributions and then stabilizes after a critical mass is reached (the two treatments differ only on the critical mass). We believe this is a good approximation to real-life social dilemmas and, on top of that, previous work suggests that group size might have an inverted-U effect on cooperation, where the pick of cooperation is reached around the critical mass. We designed an online experiment using the IBSEN facilities in which the same subject plays in groups of different size (from 5 to 40 subjects), and they played once every two weeks for two months. We find that the critical mass has no effect on cooperation;, but group size does seem to have a positive effect on cooperation. As far as individual behavior is concerned, the most chosen option (played by about 50% of the subjects) is All Defection, followed by All Cooperation (about 10% of the subjects), whereas the rest have a slight trend to switch preferentially from defection to cooperation as the group size increases.