Resilient cooperators stabilize long-run cooperation in Prisoner’s Dilemma

Re:Resilient cooperators stabilize long-run cooperation in P... by diziet on Saturday January 28, 2017 @05:51PM (#13510015)

Were conditional cooperators playing a tit-for-tat strategy or something different? I see you citing Axelrod and Rapoport but after reading through most of the supplementary material exit questions, I most often saw descriptions similar to “I chose to cooperate unless the other person chose the defect at which point I chose to defect too for the rest of the game.”

Also, how often is the number of rounds known in studies like this? From an algorithm perspective of maximization of points for computer agents, typically the number of rounds is random.

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Re:Resilient cooperators stabilize long-run cooperation in P... by mizzao on Saturday January 28, 2017 @06:23PM (#13510243)

First, hat tip to you for getting to those questions. Usually no one looks at the supplementary material at all.

So the cooperators' strategy looks like tit-for-tat, but I don't think it really is because tit for tat means if someone started cooperating again after defecting, they would switch. We think it's actually a strategy where if you get defected on, you just stop cooperating altogether in the future (at least for this length of a game). However, because we never see people switch back to cooperating after defecting (after the first day where people are trying random things), we can't distinguish between these two strategies. But effectively it doesn't really matter.

A game with a finite number of rounds is a finitely repeated PD, for which the NE is to all defect. An undetermined number of rounds is ~= an infinitely repeated PD with a discount factor, for which there are many ways to sustain cooperation according to the theory.

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