The psychologists wanted to know if there is something inherently rewarding about being treated decently. So, they scanned several parts of the participants' brains while they were in the act of weighing both fair and miserly offers. Consistent with previous results, the researchers found that a region previously associated with negative emotions such as moral disgust (the anterior insula) was activated during unfair treatment. However, interestingly, they also found that regions associated with reward (including the ventral striatum) were activated during fair treatment even though there was no additional money to be gained.

As reported in the April issue of the journal Psychological Science, a journal of the Association for Psychological Science, the brain finds self-serving behavior emotionally unpleasant, but a different bundle of neurons also finds genuine fairness uplifting. What's more, these emotional firings occur in brain structures that are fast and automatic, so it appears that the emotional brain is overruling the more deliberate, rational mind. Faced with a conflict, the brain's default position is to demand a fair deal.

Furthermore, when the scientists scanned the brains of those who were "swallowing their pride" for the sake of cash, the brain showed a distinctive pattern of neuronal activity. It appears that the unconscious mind can temporarily damp down the brain's contempt response, in effect allowing the rational, utilitarian brain to rule, at least momentarily.

(Also from Science Daily)