Active Decisions and Prosocial Behaviour: a Field Experiment on Blood Donation


  •  Corresponding author: Alois Stutzer, Department of Business and Economics, University of Basel, Peter Merian-Weg 6, CH-4002 Basel, Switzerland. Email:

  • We are grateful to James Andreoni, Christine Benesch, Matthias Benz, Bruno Frey, Ralph Hertwig, Gilad Hirschberger, Dean Karlan, Simon Lüchinger, Susanne Neckermann, Pierre Salmon and, in particular, Karla Hoff for comments. Jayson Danton and Elodie Moreau provided excellent research assistance. We thank the Stiftung Zürcher Blutspendedienst SRK, especially Beat Frey, Heinz Jehle and Gertrud Stäheli, for their support of the project. Goette thanks the Swiss National Science Foundation for financial support under grant No. 124676.


Assigning a subjective value to a contribution to a public good often requires reflection. For many reasons, this reflection may be put off, reinforcing the underprovision of public goods. We hypothesise that nudging individuals to reflect on whether to contribute to a public good leads to the formation of issue-specific altruistic preferences. The hypothesis is tested in a large-scale field experiment on blood donations. We find that an ‘active-decision’ intervention substantially increases donations among subjects who had not previously thought about the importance of donating blood. By contrast, contributions of individuals who had previously engaged in such reflection are unchanged.