Some research looking into the systems of the brain involved in nonbinding agreements has been done but there are still more questions than answers regarding of this topic. Using promises as a premise for research opens a unique door because promises can either be kept or broken. They can be made for many reasons but there are two justifications for keeping a promise. The first is to ensure future trust and cooperation and is referred to as an instrumental reason. The second rational is because it is the right thing to do and is called the intrinsic reason. The study in this paper focuses on the latter of these two explanations.
Each trial of the experiment had two subjects, a trustee and an investor. The trustee's brain activity was measured. First the trustee promises the investor to always, mostly, sometimes, or never keep their promise. In this study to be trustworthy means sharing the money made equally. The investor could choose to invest or not and then the trustee could choose to keep or break their promise to share the money. The trustee could choose both the strength of their promise and whether or not to keep their promise. These freedoms of choice led to two main groups of trustee subjects: both groups almost unanimously promised to "always" keep their promise but when it came to keeping the promise the subjects split into either the group who honored their promise or who was dishonest.
This study was the first to create a design looking at three different processes that play a role in promises. The first stage is the promise stage where the promise is made, then there is what is called the anticipation stage while they wait for the commitment of the investor, and finally the decision stage where the promise is either kept or broken. Researchers could differentiate subjects who will keep their promise and who will break it by brain activity during the promise stage, when the deceitful act is already planned.
This study found that all stages of the paradigm revealed different, highly specific activation patterns in the brain. The promise stage is where the dishonest act may be already planned but not yet implemented and researchers hypothesize if the subject already plans to break a promise, this misleading gesture will induce an emotional conflict. This emotional clash shows activity in parts of brain involved in conflict and negative emotional process such as the anterior cingulated cortex or amygdala. The anticipation stage showed parallels in brain activity to personality traits such as depression and neuroticism, both of which are associated with negative expectations of the future. When the subject had to decide to keep or break the promise, breaking the promise showed similar brain activity to the emotional process of telling a lie and the guilt that that involves. This study showed plausible evidence tying nonbinding agreements to emotional and logical processes of the brain. This evidence is critical in explaining why humans value and venerate the simple idea of a promise.
Baumgartner, Thomas, Urs Fischbacher, Anja Feierabend, Kai Lutz, and Ernsty Fehr. "Broken Promises." Neuron 64.5 (2009): 756+. Science Direct. Elsevier Inc, 10 Dec. 2009. Web. 5 Dec. 2011.