ComputerMediated Communication

1
Computer-Mediated Communication

• Iterated Prisoners Dilemma

2
Strategizing in repeated PD games
What strategy might you use if you had to play
this game over and over again with
others? Always Cooperate? Always
Defect? Something more complicated, perhaps using
past behavior?

• Consider two individuals who interact repeatedly
  over time
• No mechanisms for enforceable commitments.
• No way to be sure what the other will do on each
  turn.
• No way to eliminate the other player or leave the
  interaction.
• No way to change the other players payoffs.

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C C C C C C C C C versus D D D D D D D
D D
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PD tournament

• Round-robin format
• Each strategy competes one-on-one with every
  other strategy and itself
• Strategy with the most total points wins
• Number of turns per game unknown
• Other strategies unknown
• No persistent memory across games

5
Writing your strategy

• Work in groups of 25 people
• Need at least one person who knows Java
• Need a laptop with a working JDK installation
• IPDLX open-source package
• Moves represented as doubles
• COOPERATE 1.0, DEFECT 0.0
• Can return fractional values system will round
  them
• History of your moves, opponents moves available
   see handout

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Time for strategizing
7
Tournament time!