BIO150Y: Evolution of Cooperation Single-Move Game

Background to the single-move game

What is the Prisoner's Dilemma Game?
Imagine that you and a partner have been caught with stolen goods; a minor crime punishable with 2 years in jail. Police, however, think you did the robbery (a major crime with a prison term of another 8 years ), but they have no proof it was either of you. They bring you in separately for questioning.

Cooperation and defection
Keen to "solve" the major crime, Police offer each of you a choice. You can either:
  • Implicate your partner in the robbery. By betraying your partner, you have chosen to defect. For this, Police will drop the minor charges against you, and you could go free.
  • Or you could remain silent, and cooperate with your partner. You would get at least 2 years jail but your partner could not be convicted of the major crime.
    What does it mean to defect?
  • Your payoff matrix
    What should you do? Since you each have two options, there are four different outcomes. These outcomes can be organized in a payoff matrix. Study this matrix before you make your choice!

    How the payoff matrix is built

    What is the payoff for mutual defection?

    Your partner
    Cooperate Defect
    You Cooperate 2 years 10 years
    Defect 0 years 8 years

    "Do you understand your two options and the four possible outcomes? Are you ready to make your choice...?"
    Make your move:

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