Approval vs. Costly Punishment Emergence of Cooperation in Prisoner’s Dilemma Experiments Masanori Takaoka, Yoshitaka Okano, Takehito Masuda & Tatsuyoshi Saijo Osaka U., Japan July 1, 2011 SAET, Faro

Approval vs. Costly Punishment Objectives Questions: What should we focus on when we judge good and bad of mechanisms? What is the range of mechanisms’ influence on behavior? We want: to confirm the range of mechanisms’ influence. to totally compare the two mechanisms: approval and costly punishment. We mainly focus on: the mental influence caused by mechanisms. the mechanisms’ robustness about history. We compared: Behavior : cooperation rates, reject rates, punishment rates Results : revenues, salivary alpha-amylase, STAI 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Objectives Mechanism Game Structure Game Structure Game Structure Incentive Incentive Results Results Incentive Incentive Results Results Behavior Behavior Behavior Behavior 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Objectives Mechanism Game Structure Game Structure Incentive Results Incentive Incentive Results Results そのような動機の変化を実験的に観測すること Behavior Behavior Behavior 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Objectives Questions: What should we focus on when we judge good and bad of mechanisms? What is the range about mechanisms’ influence on behavior? We want: to confirm the range of mechanisms’ influence to totally compare the two mechanisms: approval and costly punishment We mainly focus on: the mental influence caused by mechanisms the mechanisms’ robustness about history We compared: Behavioral data : cooperation rates, reject rates, punishment rates Results : revenues, salivary alpha-amylase, STAI We want: to confirm the range of mechanisms’ influence to totally compare the two mechanisms: approval and costly punishment 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Literatures Approval Mechanism T. Saijo, Y. Okano, and T. Yamakawa, “The Approval Mechanism Experiment: A Solution to Prisoner’s Dilemma,” mimeo., 2011 → high cooperation rate Costly Punishment E. Fehr, and S. Gächter, “Cooperation and Punishment in Public Goods Experiments,” American Economic Review 90 (4): 980-994, 2000 → Incentive to punish free-riders アプルーバルメカニズムを囚人のジレンマ構造のゲームに導入し、実験において非常に高い協力率を達成した 公共財実験においてCostly　Punishmentのメカニズムを導入し、人々のフリーライダーを罰する動機が存在することを実験的に示した 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Outline Designs of the Experiments Treatments Flow of the Experiments Results of the Experiments Behavioral Data Revenue, STAI and Salivary Data Conclusion 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments Three types of game treatments PD : Prisoners’ Dilemma game PDMC : Prisoners’ Dilemma game with Mate-Choice (approval) mechanism PDCP : Prisoners’ Dilemma game with Costly Punishment mechanism Features of Treatments Each treatment has ten rounds Stranger-treatment 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (2) PD : Prisoners’ Dilemma game 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (3) PDMC : PD game with Mate-Choice mechanism Points determined at Decision Stage Decision Stage Judgment Stage 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (4) PDCP : PD game with Costly Punishment mechanism Points determined at Decision Stage Decision Stage Judgment Stage 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (5) Date : June 9-12, 2011 # of subjects : 88 subjects (22 x 4 sessions) # of rounds : 10 rounds in each treatment # of choices : 220 choices in each treatment Sessions : PDMC (10) - PD (10) PDCP (10) - PD (10) PD (10) - PDMC (10) PD (10) - PDCP (10) 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (6) Flow of the Experiment STAI1 Instruction Salivary Game Treatment Salivary STAI2 Instruction Game Treatment Salivary Salivary STAI3 Questionnaire 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Outline Designs of the Experiments Treatments Flow of the Experiments Results of the Experiments Behavioral Data Revenues STAI and Salivary Data Discussions 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data メイトチョイスメカニズムが有効に効いたこと コストリィパニッシュメントはあまり協力率を上げなかったこと←ストレンジャーが要因 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data メイトチョイスメカニズムが有効に効いたこと コストリィパニッシュメントはあまり協力率を上げなかったこと←ストレンジャーが要因 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data メイトチョイスメカニズムが有効に効いたこと コストリィパニッシュメントはあまり協力率を上げなかったこと←ストレンジャーが要因 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data メイトチョイスメカニズムが有効に効いたこと コストリィパニッシュメントはあまり協力率を上げなかったこと←ストレンジャーが要因 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data (2) PDCP-PD PD-PDMC 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data (3) (20/220) (18/220) (17/220) (11/220) (7/220) (3/220) PDCP-PD PD-PDMC PD-PDCP PD-PDCP PDCP-PD 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Results : Revenues PD-PDMC PDMC-PD PD-PDMC PD-PDCP PDCP-PD PDCP-PD PD-PDCP 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data (3) PDMC-PD PD-PDMC (9/9) (9/9) C : cooperate D : non-cooperate (2/9) (1/9) (0/202) (1/202) 4/11/2019 Approval vs. Costly Punishment

Results : Behavioral Data (4) (10/11) PD-PDCP (8/18) C : cooperate D : non-cooperate (18/198) (14/184) (1/18) (0/11) 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Results : STAI 4/11/2019 Approval vs. Costly Punishment

Designs of the Experiments (6) Flow of the Experiment STAI1 Instruction Salivary Game Treatment Salivary STAI2 Instruction Game Treatment Salivary Salivary STAI3 Questionnaire 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Results : STAI 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Results : STAI 4/11/2019 Approval vs. Costly Punishment

Results : Salivary Alpha-Amylase 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Conclusion The range of the mechanisms’ influence We confirmed the existence of purely mental influence. We observed the difference about the stress index between mechanisms. Approval Mechanism Approval mechanism efficiently worked in all treatments. Costly Punishment We confirmed the existence of people’s incentives to punish free-riders. We also observed the incentives to punish free-riders depend on some history. 4/11/2019 Approval vs. Costly Punishment

Approval vs. Costly Punishment Thank you. 4/11/2019 Approval vs. Costly Punishment