Note: This workshop was jointly held with Hokkaido Universiy Modern Eonomics Association and Center for Experimental Research in Social Sciences, Hokkaido University.

Date: March 26, 2010 (Friday) 13:00-15:00

Location: Hokkaido University, The Humanities and Social Science Building, room W309

Speaker: Tatsuyoshi Saijo (Osaka University, Japan)

Title: A Solution to Prisoner’s Dilemma: 100% Cooperation in the Experiment with Approval Stage
Tatsuyoshi Saijo, Yoshitaka Okano and Takafumi Yamakawa

Participants: Yoichi Hizen, Toshio Yamagishi, Tatsuya Kameda, Susumu Onuma, Nobuyuki Takahashi, Mizuho Shiandai, Others: Total 15 participants

Contents: 
Players can approve or reject the other choice of the strategy after playing a Prisoner’s Dilemma game. If both approve the other choice, the outcome is what they choose, and if either one rejects the other, it is the outcome when both defect called the Mate Selection Mechanism. The subgame perfect equilibria of this two stage game have the outcomes where both are cooperative and both are defective. However, the all pairs of weakly evolutionarily stable strategies coincide with the subgame perfect equilibria where both are cooperative and we observed 100% cooperation in the experimental session of prisoner’s dilemma game with approval stage, and 7.9% cooperation in the session of the game without the approval stage.