The columns are strategies of the second player. Notice that the total payoff to both players is highest if neither confesses so each receives 5. So no matter what I think the other player will do, it is best to confess. The theory predicts, therefore, that each player following her own self-interest will result in confessions by both players. This example illustrates the central concept in game theory, that of an equilibrium .
Dominant strategy is the most persuasive notion of equilibrium known to game theorists.
In the experimental laboratory, however, players who play the prisoner's dilemma sometimes cooperate. The view of game theorists is that this does not contradict the theory, so much as reflect the fact that players in the laboratory have concerns besides monetary payoffs. An important current topic of research in game theory is the study of the relationship between monetary payoffs and the utility payoffs that reflect players' real incentive for making decisions. This is known as the Battle of the Sexes game. The story goes that a husband and wife must agree on how to spend the evening.