Think global, act local: Preserving the global commons.
Preserving global public goods, such as the planet's ecosystem, depends on large-scale cooperation, which is difficult to achieve because the standard reciprocity mechanisms weaken in large groups. Here we demonstrate a method by which reciprocity can maintain cooperation in a large-scale public goods game (PGG). In a first experiment, participants in groups of on average 39 people play one round of a Prisoner's Dilemma (PD) with their two nearest neighbours on a cyclic network after each PGG round. We observe that people engage in "local-to-global" reciprocity, leveraging local interactions to enforce global cooperation: Participants reduce PD cooperation with neighbours who contribute little in the PGG. In response, low PGG contributors increase their contributions if both neighbours defect in the PD. In a control condition, participants do not know their neighbours' PGG contribution and thus cannot link play in the PD to the PGG. In the control we observe a sharp decline of cooperation in the PGG, while in the treatment condition global cooperation is maintained. In a second experiment, we demonstrate the scalability of this effect: in a 1,000-person PGG, participants in the treatment condition successfully sustain public contributions. Our findings suggest that this simple "local-to-global" intervention facilitates large-scale cooperation.
Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02139, USA.|Harvard Business School, Boston, MA 02163, USA.
Oliver P
OP
Hauser
Faculty of Business and Economics, University of Osnabrueck, 49069 Osnabrueck, Germany.
Achim
A
Hendriks
Department of Psychology, Yale University, New Haven, CT 06520, USA.|Department of Economics, Yale University, New Haven, CT 06520, USA.|School of Management, Yale University, New Haven, CT 06520, USA.
David G
DG
Rand
Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02139, USA.
Martin A
MA
Nowak
D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D038622:Internationality; D000068956:Prisoner Dilemma; D013850:Thinking