1. University of California at Santa Barbara, IZA Bonn, and CESifo Munich charness@econ.ucsb.edu
2. Royal Holloway University of London Francesco.Feri@rhul.ac.uk
3. Universidad de Málaga melendez@uma.es
4. Max Planck Institute for Research on Collective Goods, Bonn, University of Cologne and University of Innsbruck matthias.sutter@coll.mpg.de