A new study from the Karolinska Institute and Stockholm School of Economics shows that the brain has built-in mechanisms that trigger an automatic reaction to someone who refuses to share. In the study publishing next week in the online open access journal PLoS Biology, the subjects' sense of justice was challenged in a two-player monetary fairness game, and their brain activity was simultaneously measured using functional magnetic resonance imaging (fMRI). When bidders made unfair suggestions as to how to share the money, they were often punished by their partners even if it cost them. This reaction to unfairness could be reduced by targeting one specific brain region, the amygdala.
"If the sum to be shared is 100 SEK kronor and the suggestion is 50 each, everyone accepts it as it is seen as fair," says Dr Katarina Gospic. "But if the suggestion is that you get 20 and I take 80, it's seen as unfair. In roughly half the cases it ends up with the player receiving the smaller share rejecting the suggestion, even though it costs them 20 SEK."