Here's Ariely's reasoning:
Consider a study conducted by group of Swiss researchers led by Ernst Fehr (and by the way don’t you think it’s ironic that the Swiss are the ones doing research on revenge?) who examined revenge using a game we call The Trust Game. Here is how it is set-up: You are paired up with an anonymous participant. You are kept in separate rooms and you will never know each other’s identity. The experimenter gives of you $10. You get to make the first move. You must decide whether to send your money over to your partner, or to keep it. If you keep it, both of you get your $10 and the game is over. However, if you send him the money, the experimenters quadruple the amount and add it to the $10 so that the other player has his original $10 plus $40 (10 multiplied by four). The other player then decides whether to keep all the money, which means that they would get $50 and you would get nothing or they could send half of it back to you, which means you would have $25 each. This is the basic trust game and the question, of course, is whether you and people like you will trust the other person and send them the money- potentially sacrificing your financial well being-and whether the other person will justify the trust and share their earnings with you.
But the Swiss version of this game did not end there. If you sent your money to the other player and if he or she did not send the money back, you would now the opportunity to punish the bastard. You could spend money to make them suffer. In fact, for each dollar that you spend, they would lose $2. What do you think, if you were playing the game and the other person betrayed your trust, would you choose this costly revenge? Would you sacrifice your own money to cause them to suffer? The experiment showed that many people punished and they punished severely Yet this was not the most interesting part of the study.
