(Phys.org) —Nice people are not always good people. Those who have always felt this intuitively can feel vindicated by the results of a recently published theoretical study: For the so-called Prisoner’s Dilemma there are shrewd strategies a player can employ to force an opponent to cooperate before systematically exploiting this same cooperativeness in the end. But how successful is such exploitative behaviour in real life? Scientists from the Max Planck Institute for Evolutionary Biology in Plön have now developed an experiment to study this question in detail. It turns out that extortioners are only successful in the short term: many people do not allow themselves to be permanently exploited.