title: Extortion can outperform generosity in the iterated prisoner's dilemma.
abstract: Zero-determinant (ZD) strategies, as discovered by Press and Dyson, can enforce a linear relationship between a pair of players' scores in the iterated prisoner's dilemma. Particularly, the extortionate ZD strategies can enforce and exploit cooperation, providing a player with a score advantage, and consequently higher scores than those from either mutual cooperation or generous ZD strategies. In laboratory experiments in which human subjects were paired with computer co-players, we demonstrate that both the generous and the extortionate ZD strategies indeed enforce a unilateral control of the reward. When the experimental setting is sufficiently long and the computerized nature of the opponent is known to human subjects, the extortionate strategy outperforms the generous strategy. Human subjects' cooperation rates when playing against extortionate and generous ZD strategies are similar after learning has occurred. More than half of extortionate strategists finally obtain an average score higher than that from mutual cooperation.
authors.affiliation: Experimental Social Science Laboratory, Zhejiang University, Room 312, Dongsan Building, No. 866 Yuhangtang Road, Hangzhou 310058, China.|College of Economics, Zhejiang University, Room 326, Waijingmao Building, No. 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Experimental Social Science Laboratory, Zhejiang University, Room 312, Dongsan Building, No. 866 Yuhangtang Road, Hangzhou 310058, China.|College of Economics, Zhejiang University, Room 326, Waijingmao Building, No. 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Yanran
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Decision Sciences and Managerial Economics, The Chinese University of Hong Kong, Cheng Yu Tung Building, No. 12 Chak Cheung Street, Hong Kong 999077, China.|School of Economics and Management, Tsinghua University, Room 561, Weilun Building, Haidian District, Beijing 100084, China.
authors.forename: Jaimie W
authors.initials: JW
authors.lastname: Lien
authors.affiliation: School of Economics and Management, Tsinghua University, Room 561, Weilun Building, Haidian District, Beijing 100084, China.|Department of Economics, Esther Lee Building, Room 1013, The Chinese University of Hong Kong, Shatin, Hong Kong 999077, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
authors.affiliation: College of Economics, Zhejiang Gongshang University, Economics Building, No. 18 Xuezheng Street, Hangzhou 310018, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
mesh_terms: D003299:Cooperative Behavior; D006801:Humans; D008962:Models, Theoretical; D000068956:Prisoner Dilemma