Nash equilibria in multi-agent motor interactions.
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When confronted with sensorimotor interaction tasks that correspond to the classical prisoner's dilemma and the rope-pulling game, two-player motor interactions led predominantly to Nash solutions.In contrast, when a single player took both roles, playing the sensorimotor game bimanually, cooperative solutions were found.Our methodology opens up a new avenue for the study of human motor interactions within a game theoretic framework, suggesting that the coupling of motor systems can lead to game theoretic solutions.
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PubMed Central - PubMed
Affiliation: Computational and Biological Learning Laboratory, Department of Engineering, University of Cambridge, Cambridge, UK. dab54@cam.ac.uk
ABSTRACT
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Social interactions in classic cognitive games like the ultimatum game or the prisoner's dilemma typically lead to Nash equilibria when multiple competitive decision makers with perfect knowledge select optimal strategies. However, in evolutionary game theory it has been shown that Nash equilibria can also arise as attractors in dynamical systems that can describe, for example, the population dynamics of microorganisms. Similar to such evolutionary dynamics, we find that Nash equilibria arise naturally in motor interactions in which players vie for control and try to minimize effort. When confronted with sensorimotor interaction tasks that correspond to the classical prisoner's dilemma and the rope-pulling game, two-player motor interactions led predominantly to Nash solutions. In contrast, when a single player took both roles, playing the sensorimotor game bimanually, cooperative solutions were found. Our methodology opens up a new avenue for the study of human motor interactions within a game theoretic framework, suggesting that the coupling of motor systems can lead to game theoretic solutions. Related in: MedlinePlus |
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Mentions: Here, we develop continuous sensorimotor versions of the prisoner's dilemmaand the rope-pulling game. In the classical prisoner's dilemma [16],two players (prisoners) have a choice (Fig. 1A) between cooperation (claiming the other player is innocent) anddefection (claiming the other player is guilty). If both cooperate, they eachreceive a short sentence (3 years) whereas if both defect they each receive amoderate sentence (7 years). But if one cooperates while the other defects, thedefector is freed and the cooperator receives a lengthy sentence (10 years). Theglobally optimal solution in which the players benefit the most is for both playersto cooperate. However, if one of the players decides to defect, the defector reducestheir sentence at the expense of the other player. In such a non-cooperative settingthe stable Nash solution is for both players to defect. This Nash solutionguarantees in this case that a player minimizes their maximum expected punishment(in this case 7 years) and the player does not have to rely on a particular actionbeing chosen by the other player. The dilemma arises because the Nash solution isnot identical to the globally optimal solution which is cooperative. The samedilemma occurs also in the rope-pulling game (given as a conceptual example in [15]) whereeach of two players is attached by a rope to a mass that they have to pull together.One player is rewarded according to how far he pulls the mass along one directionand the other player is reward according to how far he pulls the mass in anorthogonal direction. Thus, the globally optimal solution is to cooperate and pullthe mass along the diagonal. However, if one of the players defects and pulls intohis own direction he gains even more payoff at the expense of the other player.Therefore, the stable Nash solution in this case is for each player to pull alonghis own direction. In the following we address the question whether human motorinteractions in such motor games can be quantified using a game theoretic framework. |
View Article: PubMed Central - PubMed
Affiliation: Computational and Biological Learning Laboratory, Department of Engineering, University of Cambridge, Cambridge, UK. dab54@cam.ac.uk