Dresden 2011 – scientific programme

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SOE: Fachverband Physik sozio-ökonomischer Systeme

SOE 10: Focus Session: Experimental Methods

SOE 10.3: Invited Talk

Tuesday, March 15, 2011, 14:30–15:00, GÖR 226

Human behavior on networks: lessons and perspectives from game theory — Jelena Grujic¹, Constanza Fosco^1,4, Lourdes Araujo⁵, José A. Cuesta¹, and •Angel Sánchez^1,2,3 — ¹GISC/Matemáticas, Universidad Carlos III de Madrid, Spain — ²ICMAT, CSIC-UAM-UC3M-UCM, Madrid, Spain — ³BIFI, Universidad de Zaragoza, Spain — ⁴Economía, Universidad Católica del Norte, Antofagasta, Chile — ⁵NLP-IR/Lenguajes y Sistemas, UNED, Madrid, Spain

One of the most often invoked mechanisms to explain how cooperation can emerge is the existence of a population structure that determines the interactions among individuals. We present results of the first experiment designed to test the emergence of cooperation when humans play Prisoner's Dilemma on a network whose size is comparable to that of simulations. We find that cooperation is not sustained by the network: the cooperation level declines to an asymptotic state with low but non-zero cooperation. Regarding players' behavior, we observe that the population is heterogeneous, consisting of a high percentage of defectors, a smaller one of cooperators, and a large group that shares features of the conditional cooperators of public goods games. We do not observe significant learning as the experiment progresses. We propose a computational model showing that both heterogeneity and a ``moody'' conditional ooperation strategy, in which the probability of cooperating also depends on the player's previous action, are needed to explain all our experimental results.