The classic version of the Prisoners' Dilemma is a non-zero sum game. It was first published in 1997 and the basic description of it is this:
Tanya and Cinque have been arrested for robbing the Hibernia Savings Bank and placed in separate isolation cells. Both care much more about their personal freedom than about the welfare of their accomplice. A clever prosecutor makes the following offer to each: “You may choose to confess or remain silent. If you confess and your accomplice remains silent I will drop all charges against you and use your testimony to ensure that your accomplice does serious time. Likewise, if your accomplice confesses while you remain silent, they will go free while you do the time. If you both confess I get two convictions, but I'll see to it that you both get early parole. If you both remain silent, I'll have to settle for token sentences on firearms possession charges. If you wish to confess, you must leave a note with the jailer before my return tomorrow morning.”
The “dilemma” faced by the prisoners here is that, whatever the other does, each is better off confessing than remaining silent. But the outcome obtained when both confess is worse for each than the outcome they would have obtained had both remained silent. A common view is that the puzzle illustrates a conflict between individual and group rationality. A group whose members pursue rational self-interest may all end up worse off than a group whose members act contrary to rational self-interest.
How would you behave in a similar situation? The Brain Games crew at National Geographic Channel has organized a similar setting: here two strangers have to decide whether they split or steal a bag of money. If they both decide to split (the cooperative strategy), then the amount is split equally. However if one of them chooses "steal" (the competitive strategy), then that person receives the whole amount and the other receives nothing. If both of them choose to steal then nobody gets anything... What would you choose in this situation: would you cooperate or compete?
See how some strangers have decided: