London, Aug. 27: Revenge, reprimand and schadenfreude really do feel good, according to a brain scan study published today.

As well as explaining why Dirty Harry declared: “Go ahead, make my day”, today’s study is part of a scientific revolution in the use of scanners to reveal how people are influenced by emotions when they make choices.

The Swiss brain imaging study reveals how we draw satisfaction from teaching strangers a lesson when they have behaved badly, part of a rapidly-emerging field of neuroeconomics. As the journal Science puts it, the study reveals what goes on in Dirty Harry’s head when “he succinctly informs a norm violator that he anticipates deriving satisfaction from inflicting altruistic punishment”.

For the study, Dominique de Quervain, Urs Fischbacher and Prof Ernst Fehr from the University of Zurich scanned the brain activity of male volunteers participating in a game of exchanging money back and forth.

If one player made a selfish choice instead of a mutually beneficial one, the other could penalise him. The majority of the players chose to impose the penalty even when it cost some of their own money.