- Be nice--no first strikes
- Be provokable--retailiate immediately if your rival cheats
- Be forgiving
- Be clear--make sure your rival can interpret your moves
- Dont be envious--focus only on your slice of the profit pie
In Nowak's experiment, the students played more than 8,000 games of prisoner's dilemma, using dimes to reward and punish. The normal game of prisoner's dilemma gives two players two options: cooperate or defect. If both cooperate, each ends up winning a dime. If both defect, each gets nothing. If one cooperates and the other defects, the cooperative player loses 20 cents and the defector wins 30 cents. Nowak then added a "costly punishment" component. A player could choose to punish someone who didn't cooperate. That penalized the non-cooperative person 40 cents, but the other player had to pay a dime to mete out the punishment. When Nowak compared how much money people earned or lost in the long run, there was a noticeable correlation between punishment and overall money. The players who punished their opponents the least, or not at all, made the most money. Those who punished the most made the least money.