The principles behind it are relevant to many fields, including sociology, philosophy and political science. Amidst the clanking chains, scampering rodentia, and endlessly dripping water, a welcome light shines upon your forehead. The only door to the dungeon cell swings open, and a guard peers through the cobwebs spanning the door frame. He clambers inside and drags you out after him, mercilessly scraping your shins on the stones in his haste. The guard wishes to determine whether you and your friend committed the crime in question.
Payoffs are negative here as they represent a loss, rather than a gain.
You should first note that the punishment depends on both your response and that of your friend. In the interest of minimizing the prison time for both you and your friend, you would like to cooperate with him, staying silent and hoping he remains silent as well. However, if your friend were to take advantage of your silence and proclaim guilt, he would suffer no prison time while you would find yourself incarcerated for the maximum prison sentence. Worst of all, if you both attempt to take advantage of each other's expected trust, you will both be jailed 4 for a substantial, non-minimal period of time. The crucial realization is that each prisoner can gain by double-crossing the other.