The prisoners dilemma was described in Robert Axelrod's book titled "The evolution of co-operation" (1984). I've created an online version to try at the bottom of this page.
Its called the prisoners dilemma because it models this problem. 2 criminals are caught and charged with robbing a bank. Both prisoners are in separate cells and can't communicate. They law doesn't have enough evidence to convict either one of the prisoners if they don't testify against each other, but the prisoners don't know that. The Autorny tells each prisoner if they testify he will charge them with a lesser crime. Now if your a prisoner do you risk not testifying and hope that the other prisoner does the same thing so you'll both go free? If you don't testify and the other one does you end up in jail for a long long time. If you testify against your partner you will end up with a shorter sentence.
Another example is OPEC. If all members cooperate the price of oil goes up. But if all member cooperate and drive the price up and you cheat and pump more oil you make a lot more money. If everyone cheats the price of oil plummets. So to maximize the price per gallon, countries shouldn't cheat, but when the price goes up it easy to see the temptation in pumping more oil.
This is a interactive version of the prisoners dilemma game with 20 turns. Your oponent is the computer. Each turn you and the computer pick to Cooperate (1) or not to Cooporate (defect). Infomation about how the computer moves can be found in the Algotihms page (but don't look until after you've played...) .
Scoring
| User Move | |||
| Cooperate | Don't Cooperate | ||
| Computer Move |
Cooperate | 3/3 | 4/1 |
| Don't Cooperate | 1/4 | 2/2 | |
Scores in Bold are points received by user.
Note the objective isn't to score more points, but to get the highest average score per turn (ie. highest $ pergallon of oil).