1. 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

2. 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

3. 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

4. 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
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Approval vs. Costly Punishment

5. 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

6. 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): , 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
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Approval vs. Costly Punishment

7. 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
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Approval vs. Costly Punishment

8. 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
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Approval vs. Costly Punishment

9. Designs of the Experiments (2)
PD : Prisoners’ Dilemma game
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Approval vs. Costly Punishment

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

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

12. 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)
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Approval vs. Costly Punishment

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

14. 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
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Approval vs. Costly Punishment

15. 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
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Approval vs. Costly Punishment

16. 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
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Approval vs. Costly Punishment

17. 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
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Approval vs. Costly Punishment

18. 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
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Approval vs. Costly Punishment

19. Results : Behavioral Data (2)
PDCP-PD
PD-PDMC
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Approval vs. Costly Punishment

20. 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
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Approval vs. Costly Punishment

21. Approval vs. Costly Punishment
Results : Revenues
PD-PDMC
PDMC-PD
PD-PDMC
PD-PDCP
PDCP-PD
PDCP-PD
PD-PDCP
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Approval vs. Costly Punishment

22. 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)
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Approval vs. Costly Punishment

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

24. Approval vs. Costly Punishment
Results : STAI
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Approval vs. Costly Punishment

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

26. Approval vs. Costly Punishment
Results : STAI
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Approval vs. Costly Punishment

27. Approval vs. Costly Punishment
Results : STAI
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Approval vs. Costly Punishment

28. Results : Salivary Alpha-Amylase
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Approval vs. Costly Punishment

29. 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.
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Approval vs. Costly Punishment

30. Approval vs. Costly Punishment
Thank you.
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Approval vs. Costly Punishment