Monkeys in a Prisoner’s Dilemma Ju Tian, Naoshige Uchida  Cell  Volume 160, Issue 6, Pages 1046-1048 (March 2015) DOI: 10.1016/j.cell.2015.02.049 Copyright © 2015 Elsevier Inc. Terms and Conditions

Figure 1 Prisoner’s Dilemma Game (A) An example payoff matrix of a game. There are two players (A and B), and each has to choose one of two options (C and D). Each makes a choice without knowing what the opponent will do. Depending on one’s own and the other’s choices, each receives an outcome defined by the payoff matrix (e.g., the number indicates dollar amount that each receives). (B) The original prisoner’s dilemma game. Each prisoner is asked to either defect the other by testifying that the other committed the crime or cooperate with the other by being silent. (C) A payoff matrix in a general form. T > R > P > S and 2R > T+S define a prisoner’s dilemma. The latter criterion guarantees that the players cannot escape the dilemma simply by taking turns. (D) Two monkeys played an iterated prisoner’s dilemma game (defined by A in Haroush and Williams [2015]). Cell 2015 160, 1046-1048DOI: (10.1016/j.cell.2015.02.049) Copyright © 2015 Elsevier Inc. Terms and Conditions