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Abstract

We have carried out a comparative analysis of data collected in three experiments on Prisoner’s Dilemmas on
lattices available in the literature.We focus on the different ways in which the behavior of human subjects can
be interpreted, in order to empirically narrow down the possibilities for behavioral rules. Among the proposed
update dynamics, we find that the experiments do not provide significant evidence for non-innovative game
dynamics such as imitate-the-best or pairwise comparison rules, whereas moody conditional cooperation is
supported by the data from all three experiments. This conclusion questions the applicability of many
theoretical models that have been proposed to understand human behavior in spatial Prisoner’s Dilemmas. A
rule compatible with all our experiments, moody conditional cooperation, suggests that there is no detectable
influence of interaction networks on the emergence of cooperation in behavioral experiments.