Event Related Potentials Reveal Fairness in Willingness-to-share

Abstract

Willingness-to-share is tested in an Ultimatum Game where the participants iteratively play a role of Proposer and Responder sharing a virtual amount of money. We test the hypothesis that brain activity associated with small vs. large share offered by the Proposer can be detected by event related potentials (ERPs). We observed that differences between wretched and prodigal offers in ERPs latencies, amplitudes and locations appeared along the antero-posterior midline at the time of Proposer’s invite to make the offer, that is before the actual offer was made. Differences in ERPs associated with the offered amount of the share were localized at parietal areas when the offer was accepted. We discuss the outcome of these results for reward learning processes.