Presentation Information
[C17-02]Altruism does not always promote cooperation in repeated interactions
*Kai Kang1, Boyu Zhang1, Yali Dong2 (1. School of Mathematical Sciences, Beijing Normal University (China), 2. School of Systems Science, Beijing Normal University (China))
Keywords:
Cooperation,Altruism,Direct reciprocity,Prisoner's Dilemma game,Public goods game
Altruism and direct reciprocity are two most basic mechanisms for explaining human cooperation. In one-shot social dilemma games such as the Prisoner’s Dilemma (PD) game and the Public Goods game (PGG), a higher degree of altruism can lead to more cooperation. In contrast, in repeated social dilemma games, reciprocal strategies such as GRIM and Tit-for-Tat can help to sustain cooperation when the probability of another encounter between the same individuals exceeds a threshold value. In this paper, we study the joint effects of altruism and reciprocity on cooperation in the context of repeated PD games and PGG. We find that when all players are selfish, increasing the degree of altruism for some players may counter-intuitively make the conditions for sustaining cooperation through direct reciprocity more difficult to satisfy. Further analysis reveals that the non-monotonic effect of altruism on cooperation is more significant when the game is asymmetric where players have different cost-benefit ratios or productivities. In sum, our study reveals the complex interactions between different mechanisms in promoting cooperation.