Dresden 2011 – wissenschaftliches Programm

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SOE: Fachverband Physik sozio-ökonomischer Systeme

SOE 16: Networks: From Topology to Dynamics III (with BP, DY)

SOE 16.5: Vortrag

Mittwoch, 16. März 2011, 16:30–16:45, GÖR 226

Evolutionary dynamics and conditional cooperation in the iterated prisoner's dilemma — •Jelena Grujić, José A. Cuesta, and Angel Sánchez — Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Madrid, Spain,

We have recently performed an experiment to test the emergence of cooperation in the presence of an underlying structure [Grujic et al., PLoS ONE 5(11): e13749 (2010)]. Human subjects played a PD with each of their neighbors in a 13x13 square lattice. The results show that the population consisted of cooperators and defectors, who respectively cooperate or defect with high probability regardless of their and their neighbors' previous actions, and conditional cooperators, whose behavior does depend on those previous actions.

Here we take a first step towards an evolutionary explanation of the experimental results. Specifically, we use replicator dynamics to describe the evolution of a set of strategies that mimics the observations, in a simplified context consisting of a well-mixed population of players confronted in iterated Prisoner's Dilemma games. The dynamics exhibits two attractors: one for a population consisting only of defectors, and an interior point with population frequencies comparable to those observed in the experiment. The former has a much smaller basin of attraction than the latter, which therefore becomes the most probable evolutionary outcome. This is the first hint that the experiment may be amenable to an evolutionarily explanation.