title: Peer pressure: enhancement of cooperation through mutual punishment.
abstract: An open problem in evolutionary game dynamics is to understand the effect of peer pressure on cooperation in a quantitative manner. Peer pressure can be modeled by punishment, which has been proved to be an effective mechanism to sustain cooperation among selfish individuals. We investigate a symmetric punishment strategy, in which an individual will punish each neighbor if their strategies are different, and vice versa. Because of the symmetry in imposing the punishment, one might intuitively expect the strategy to have little effect on cooperation. Utilizing the prisoner's dilemma game as a prototypical model of interactions at the individual level, we find, through simulation and theoretical analysis, that proper punishment, when even symmetrically imposed on individuals, can enhance cooperation. Also, we find that the initial density of cooperators plays an important role in the evolution of cooperation driven by mutual punishment.
authors.affiliation: Department of Physics, Fuzhou University, Fuzhou 350108, China.
authors.forename: Han-Xin
authors.initials: HX
authors.lastname: Yang
authors.affiliation: Institute of Computational Physics and Complex Systems, Lanzhou University, Lanzhou, Gansu 730000, China.
authors.forename: Zhi-Xi
authors.initials: ZX
authors.lastname: Wu
authors.affiliation: CompleX Lab, Web Sciences Center, University of Electronic Science and Technology of China, Chengdu 610054, China.|Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Zhihai
authors.initials: Z
authors.lastname: Rong
authors.affiliation: School of Electrical, Computer and Energy Engineering, Arizona State University, Tucson, Arizona 85287, USA.
authors.forename: Ying-Cheng
authors.initials: YC
authors.lastname: Lai
mesh_terms: D003198:Computer Simulation; D003299:Cooperative Behavior; D005717:Games, Experimental; D006801:Humans; D007398:Interpersonal Relations; D008960:Models, Psychological; D000067074:Peer Influence; D011678:Punishment; D013995:Time