As discussed before here on the blog, imaging studies by Josh Greene, Jorge Moll and others have demonstrated that emotional responses play a pivotal role in forming moral judgments. A new study by Sylvie Berthoz adds further information to this growing story.
Berthoz and her colleagues had subjects read short stories describing transgressions of social rules. The stories either described situations where (1) the subject was the agent of transgression, and the violations was accidental, or situations where (2) the protagonist was another person than the subject, and the violations was accidental, or situations where (3) the subject was the agent of transgression, and the violations was intentional, or situations where (4) the protagonist was another person than the subject, and the violation was intentional. Thus, Berthoz et al. were able to contrast intentional moral transgressions performed by one self from transgressions performed by others, or from accidental transgressions.
This contrast showed significant bilateral amygdala activation, and Berthoz et al. speculate that such activation may be related to one’s anticipation of possible punishment as a consequence of one’s own immoral behaviour. This suggestion, of course, squares well with ideas from the emerging field of social neuroscience - especially the hypothesis that social cooperation rests upon a tit-for-tat regime: If I share my ressources with you, I expect something in return. If I don’t get anything back, I will punish you. It is pretty clear, as well, that the back-bone of the success of such social behaviour is the brain’s reward and punishment system: The expectancy of a return is modulated by the reward system, and the anticipation of a punishment - which works to keep you from cheating the other members of your social group - is modulated by the punishment system, including the amygdala.
Now, it would be very interesting to apply a genetic analysis to this result. Maybe we would then find a similar variance as reported by Hariri with regard to serotonin re-uptake and mood? That is, some people may be more afraid of transgressing moral rules than others due to a difference in amygdala activity. It is rather obvious, after all, that some people won’t loose any sleep over sticking it to you!
Berthoz, S. et al. (2006): Affective response to one’s own moral violations. To appear in NeuroImage.