This 2014 Japanese human study showed which brain areas were involved in indirect reciprocity. The researchers found that it was mainly cerebral areas that were active in:
“Reputation-based reciprocity, in which they help others with good reputations to gain good reputations themselves.”
Previous studies found much the same with direct reciprocity, where an individual was reimbursed by someone who directly owed them a debt of cooperation.
The researchers found it was mainly limbic system areas that were active in:
“Pay-it-forward reciprocity, in which, independently of reputations, they help others after being helped by someone else.”
The researchers thus compared and contrasted the subjects’ self-interested behaviors of:
- direct reciprocity and
- reputation-based reciprocity,
both of which sought rewards in the cerebrum, with the subjects’ empathetic behaviors of:
- pay-it-forward reciprocity,
where the subjects sought emotional rewards in the limbic system.
http://www.pnas.org/content/111/11/3990.full “Two distinct neural mechanisms underlying indirect reciprocity”