The paradoxical consequences of revenge.

People expect to reap hedonic rewards when they punish an offender, but in at least some instances, revenge has hedonic consequences that are precisely the opposite of what people expect. Three studies showed that (a) one reason for this is that people who punish continue to ruminate about the offender, whereas those who do not punish "move on" and think less about the offender, and (b) people fail to appreciate the different affective consequences of witnessing and instigating punishment.