Scientists have discovered the physiological mechanisms in the brain that underlie broken promises.
Boffins from the University of Zurich say the patterns of brain activity even enable predicting whether someone will break a promise.
The results of the study conducted by Dr. Thomas Baumgartner and Professor Ernst Fehr, both of the University of Zurich, and Professor Urs Fischbacher of the University of Konstanz, have been published in the journal Neuron.
To reach the conclusion, neuroscientist Thomas Baumgartner (University of Zurich) and economists Ernst Fehr (University of Zurich) and Urs Fischbacher (University of Konstanz) carried out a social interaction experiment in a brain scanner where the breach of a promise led both to monetary benefits for the promise breaker and to monetary costs for the interaction partner.
The study's results show that increased activity in areas of the brain playing an important role in processes of emotion and control accompany the breach of a promise. This pattern of brain activity suggests that breaking a promise triggers an emotional conflict in the promise breaker due to the suppression of an honest response.
Furthermore, the most important finding of the study enabled the researchers to show that "perfidious" patterns of brain activity even allow the prediction of future behavior.
Indeed, experimental subjects who ultimately keep a promise and those who eventually break one act exactly the same at the time the promise is made - both swear to keep their word. Brain activity at this stage, however, often exposes the subsequent promise breakers.
"We've discovered critical elements of the neuronal basis of broken promises," economist Fehr explains. "In light of the significance of promises in everyday, interpersonal cohabitation in society, these findings offer the prospect of being able to fathom and better understand the brain physiological basis of pro-social and especially of antisocial behavior in general."