2014.5.20 Social cycling and conditional responses in the Rock-Paper-Scissors game
报告题目：Social cycling and conditional responses in the Rock-Paper-Scissorsgame
How humans make decisions in non-cooperative strategic interactionsis a challenging question. For the fundamental model system ofRock-Paper-Scissors (RPS) game, classic game theory of infinite rationalitypredicts the Nash equilibrium (NE) state with every player randomizing herchoices to avoid being exploited, while evolutionary game theory of boundedrationality in general predicts persistent cyclic motions, especially for finitepopulations. However, as empirical studies on human subjects have beenrelatively sparse, it is still a controversial issue as to which theoreticalframework is more appropriate to describe decision making of human subjects.Here we observe population-level cyclic motions in a laboratory experiment ofthe discrete-time iterated RPS game under the traditional randompairwise-matching protocol.The cycling direction and frequency are not sensitiveto the payoff parameter a. This collective behavior contradicts with the NEtheory but it is quantitatively explained by a microscopic model of win-lose-tieconditional response without any adjustable parameter. Our theoreticalcalculations reveal that this new strategy may offer higher payoffs toindividual players in comparison with the NEmixed strategy, suggesting that highsocial efficiency is achievable through optimized conditionalresponse.