PSY 333 — Assignment 15

More complex games

The Prisoner’s Dilemma

In the Prisoner’s Dilemma, two players decide whether to cooperate with the other person or not. Consider this version of the Prisoner’s dilemma that is played for money:

• If they both cooperate they both get a large reward (e.g. $10).
• If they both defect (i.e. don’t cooperate) they both get a medium reward (e.g. $5).
• If one cooperates and the other defects, the cooperator gets nothing ($0) and the defector gets a very large reward ($15)

Imagine playing this game once against a perfect stranger:

1. What’s the best thing to do if you know that the other person will defect? (1 point)
2. What’s the best thing to do if you know that the other person will cooperate? (1 point)
3. What’s the best thing to do if you don’t know what the other person will do? (1 point)

Now imagine playing the game repeatedly against the same person

4. Describe the tit-for-tat strategy for the repeated play Prisoner’s dilemma. (2 points)
5. Why tit-for-tat a good strategy? (2 points)

Randomness in Games

1. List three biases that people show in Rock-Paper-Scissors (2 points)
2. If a competitor is smart and is able to exploit these biases, what’s the best strategy you can use in Rock-Paper-Scissors? (1 point)