Analysis of Prisoner's Dilemma Strategies: Trust, Reciprocity, and Punishment

1. Module 1: Evolution and Economics An Analysis of You: Prisoner’s Dilemma

2. Prisoner’s Dilemma • This game is played by two people, designated A and B. • A plays first and can either cooperate or defect. • Knowing A’s choice, B can then either cooperate or defect.

3. B C D A:$30 B:$30 A:$10 B:$45 C A A:$15 B:$15 A:$45 B:$10 D Player A goes first without knowing what B will do. Player B goes second after learning A’s response.

4. Possible Strategies

5. Unconditional Cooperator: CCC

6. Friendly Tit-for-Tat: CCD

7. Optimistic Non-Cooperator: CDD

8. Pessimistic Tit-for-Tat: DCD

9. Unconditional Non-Cooperator: DDD

10. Wingnuts:CDC, DCC, DDC A DDC Player: “Player A will know I helped them and they might help me in the future.”

11. Your Population? T-4 1 3 T-4 2

12. What Have We Found?

13. TRUST • Cooperation by Player A demonstrates trust. A DCD Player: “I don’t think there are too many people in here who wouldn’t want $45 over $30 if we both decided to cooperate.” A CDD Player: “If my partner sees that I chose to cooperate, they may choose to be altruistic and cooperate too so that we both get thirty dollars.”

14. RECIPROCITY • Cooperating with a cooperative first mover demonstrates reciprocity. A CCD Player: “I would cooperate because that’s what I wanted somebody to do, and I’m a nice guy.” A CDD Player: “Because I will make more money this way and the first player can’t stop me.”

15. Self-Sacrifice • Cooperating with a non-cooperative first mover demonstrates self-sacrifice. A CCC Player: “The effect on me is minimal, but it helps the other person immensely.”

16. The Scientific Method • Intro: Ask a question, make a hypothesis. • Methods: Do an experiment. • Results: Analyze outcomes Topics for Today: Gender Punishment (& Gender) One Idea From Me A Few From You

17. Statistical Tests

18. Statistical Tests • Effect Size • The magnitude of the relationship between variables. • Specific to a particular test. • p-value • The probability that an effect size is observed by chance. • As the sample size increases, the p-value goes down.

19. Statistical Tests • t-test: • A t-test determines whether the means of two separate groups are equal or not. = ?

20. Do Males and Females Behave Differently in the Game? • Null Hypothesis • There is no relationship between gender and first mover behavior. • Alternate Hypothesis • One gender offers cooperation more often than the other. p < .05

21. Trust Behavior Between Genders

22. Do Males and Females Behave Differently … In trust behavior? Male Mean = .64 Female Mean = .65 Males = 58 Females = 57 p-value = .901 .901 > .05 Insignificant! Male Offers = Female Offers?

23. Reciprocity Between Genders

24. Do Males and Females Behave Differently … In reciprocity? Male Mean = .45 Female Mean = .57 Males = 58 Females = 57 p-value = .120 .120 > .05 Insignificant! Male Reciprocity = Female Reciprocity?

25. Punishment:Strategy Differences Without Punishment With Punishment

26. Using Variables • Independent Variable • Something that is controlled for by the researcher. • Dependent Variable • Something that is observed in terms of the independent variables. Independent Variable: Punishment Dependent Variables: Trust Reciprocity Altruism

27. What Punishment Does…Trust A CCC Player: “I would cooperate so I wouldn’t get punished.” Played DDD in the first game.

28. What Punishment Does…Trust Offers of Cooperation: w/o Punishment = .64 w/ Punishment = .90 p < .0001 Significant!

29. What Punishment Does…Reciprocity Offers of Cooperation: w/o Punishment = .50 w/ Punishment = .85 p < .0001 Significant!

30. What Punishment Does…Self Sacrifice A CCC Player: “Because if I don’t cooperate, A could punish me.” Played CDD in the first game.

31. What Punishment Does…Self-Sacrifice Offers of Cooperation: w/o Punishment = .09 w/ Punishment = .20 p < .012 Significant!

32. How Do People Punish?

33. Punishment:In-Class Study #2

34. Punishment Cooperative/ Non-Cooperative Behavior Investment in Punishment Male/Female

35. Selfish vs. Moralistic Punishers:Sex Null Hypothesis: Moralistic & Selfish Punishers are distributed equally between the sexes. Alternate Hypothesis: They are not. p = .272 Do not reject null hypothesis!

36. Punishment Cooperative/ Non-Cooperative Behavior Investment in Punishment Male/Female

37. Selfish vs. Moralistic PunishersInvestment in Punishment Null Hypothesis: Moralistic & Selfish Punishers punish equally. Alternate Hypothesis: They do not punish equally. p = .683 Do not reject null hypothesis!

38. Punishment Cooperative/ Non-Cooperative Behavior Investment in Punishment Male/Female

39. Selfish vs. Moralistic PunishersInvestment in Punishment Null Hypothesis: Males & Females punish equally. Alternate Hypothesis: They do not punish equally. p < .001 Reject null hypothesis! Males punish more!

40. Punishment Cooperative/ Non-Cooperative Behavior Investment in Punishment Male/Female

41. Predictors of Cooperation:In-Class Study #1 Social Dependency Risk Taking Behavior Social Integration Trusting People

42. First Mover Behavior:Based on Trust? Will People Reciprocate? First Mover Behavior p = .087 Risk Taking Behavior p = .378

43. Risk Behavior Score = 6 Most Risky

44. Risk Behavior Score = 3 Mildly Risky

45. Risk Behavior Score = 1 Least Risky

46. Risk Behavior

47. Risk Behavior and Gender:Discussion Section 1 Null Hypothesis: Moralistic & Selfish Punishers punish equally. Alternate Hypothesis: They do not punish equally. p = .061 Do not reject null hypothesis!

48. Ambiguity Behavior Are people… Pessimistic Or Optimistic?

49. Ambiguity Behavior

50. Ambiguity Behavior, Trust and Upbringing?Discussion Section 6 Trust Behavior? Reaction to Ambiguity p = .901 Rural/Urban p = .112