Iterated Prisoners' Dilemma Simulation

Player Counts

Iterations:
Pushover: Tit-for-tat: Suspicious Tit-for-tat:
GrimTrigger: Random: Tit for Two Tats:
Defector: Generous Randomizer: Double Tit for Tat:
GrimTrigger 75%: Very Suspicious Tit for Tat:
Score of Best Performing Player of Each Strategy vs. Rounds

Info:

The graphs plot the score of the top scoring player of each strategy. For example, if you have entered 50 players into the pool to play Tit-For-Tat, only the tit-for-tat player whose score was the highest will be graphed.

Instructions

How this works:

This app allows you to create a group of players who will play the group iterated prisoners' dilemma with each other. On the settings tab, you will specify how many players of each strategy will be entered into the pool and how many rounds of the tournament will be played.

Rules

At each round, each player plays one prisoners' dilemma game with every other player in the pool. After each individual game, each player updates his personal cumulative score that carries across every single game he plays. To clarify, in a tournament with R rounds, and N players, each player plays R games with each of the N - 1 players in the pool.

Payoffs

  • If both players cooperate, both get +1.
  • If player 1 cooperates and player 2 defects, player 1 gets -2 and player 2 gets +2.
  • If both players defect, both get -1.

Additional stipulations

This game has an additional twist. If a player's score drops below zero, the player is considered a "loser" and is removed from the pool. Every player starts off with a score of 50.

Explanation of Strategies

  • Pushover: Cooperates 100% of the time.
  • Defector: Defects 100% of the time.
  • Random: Cooperates 50% of the time, defects 50% of the time randomly.
  • GrimTrigger (Chris): Cooperates with opponent until the first time opponent defects. Then defect against opponent forever.
  • Double Tit For Tat (Dr. Schwab): Cooperates on the first two moves. On move t, look at opponent's move for t-1 and t-2. If they are both the same, perform the opponent's move. Else, make the move you made on the previous turn t-1.
  • Generous Randomizer (Nate): Cooperate with 90% probability, defect with 10% probability.
  • Tit For Tat (Scott): Cooperate on turn 1. For turns after turn 1, make the move that your opponent made on the previous turn.
  • Suspicious Tit For Tat (David): Defect on turn 1. For turns after turn 1, make the move that your opponent made on the previous turn.
  • Very Suspicious Tit For Tat (Robin): Defect for the first 7 rounds. Then play tit for tat.
  • Tit for Two Tats (Melissa): Cooperate on turn 1 and turn 2. If opponent's last two turns were defects, defect as well. Else cooperate.
  • Grim75 (Vickie): Play Grim Trigger for 75% of the game (after 75% of the turns have passed). Then always defect.