Investigation of context effects in iterated Prisoner's Dilemma game

Abstract

Context effects during Prisoner's Dilemma (PD) game playing are investigated. The Cooperation Index (CI) - a quantity computed as a relation between payoffs - defines a cooperativeness scale, along which PD games can be distributed. Context is selected by manipulating the CI range of the games played. It is found that the level of cooperation depends not only on the CI of the current game but also on the CI of the other games in the sequence. The influence of context on the full CI scale is investigated by introducing probe games covering the whole CI range. The results are compared with the prediction of a model that takes into account the current game, the previous play history, and the predicted opponent's move. The model is found to be sensitive to both the CI and to the CI of the other games form the game set and a very good agreement between the model and the experimental data was found. © Springer-Verlag Berlin Heidelberg 2005.