Brain activity exposes broken promises

ZURICH, Switzerland, Dec. 21 (UPI) -- University of Zurich researchers say they have discovered the physiological mechanisms in the brain that underlie broken promises.

Dr. Thomas Baumgartner and Professor Ernst Fehr, both of the University of Zurich, and Urs Fischbacher, a professor at the University of Konstanz, said the promise is one of the oldest human-specific behaviors promoting cooperation, trust and partnership. Although promises are generally not legally binding, they form the basis for a great many everyday social and economic exchange situations.

The researchers carried out a social interaction experiment using a brain scanner in which the breach of a promise led both to monetary benefits for the promise breaker and to monetary costs for the interaction partner.

The researchers found 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 breaking a promise triggers an emotional conflict in the promise breaker due to the suppression of an honest response.

The study was published in the journal Neuron.