Dresden 2006 – wissenschaftliches Programm
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AKSOE: Physik sozio-ökonomischer Systeme
AKSOE 6: Economic Models and Evolutionary Game Theory I
AKSOE 6.3: Vortrag
Dienstag, 28. März 2006, 11:15–11:45, BAR 205
Learning through social interactions — •Viktoriya Semeshenko1, Mirta B. Gordon1, and Jean-Pierre Nadal2 — 1Laboratoire Leibniz-IMAG, 46 av Felix Viallet, 38031 Grenoble Cedex 1, France — 2Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 7231 Paris cedex 05, France
We consider a simple market model in which a population of heterogeneous individuals, subject to local positive externalities, must choose repeatedly either to buy or not a unit of a single homogeneous good, at a price posted by a monopolist [1]. If the weight of externalities is strong enough, there are multiple Nash equilibria, revealing coordination problems. We assume that individuals learn to make their choices repeatedly using deterministic and trembling hand decision rules. We study the performances along the learning path and the reached equilibria for different learning schemes [2]. In the presence of multiple equilibria, coordination on the optimal one through learning is shown to be reached only with some of the learning schemes. The result of the learning rules depends crucially on the learning parameters and the agents’ initial beliefs. With a trembling hand dynamics the system is shown to converge to a stationary state, in which the decisions fluctuate close to the optimal ones. This equilibrium has the flavor of (but is not identical to)what is known as a ‘Quantal Response Equilibrium’ in the economic literature.
[1] Gordon M. B., Nadal J.-P., Phan D., Vannimenus J: Seller’s dilemma due to social interactions between customers. Physica A, 356, Issues 2-4:628-640, (2005).
[2] Camerer C. F. Behavioral Game Theory. Princeton Press, (2003).