Fair Play in the Brain – Cortical Activity in Response to Fair and Unfair Offers of a Fictitious Partner in a Gambling Design

Abstract

The present MEG study explored whether and how fair and unfair offers made by a fictitious teammate modulate cortical responses to decision-related cues.

Electromagnetic activity analyzed in the source space (minimum norm estimate) disclosed larger (bilateral) frontotemporal activity 170 - 250 ms after cue-onset for fair compared to unfair offers, irrespective of the subsequent decision to accept/reject. Bilateral posterior and frontotemporal activity 120-190 ms after feedback-cue onset was larger following ‘reject’- compared to ‘accept’-decisions. Frontotemporal activity 150 - 200 ms tended to be larger following satisfied rejection (1€ gain) compared to ‘loss’ feedback upon rejectdecision. Brain activity patterns did not vary with the emotional expression of the fictitious teammate (first cue). Results suggest that evaluation of a fair or unfair offer in an experimental team-play situation modulates (fronto-)cortical activity related to decision-making, and that cortical responses to feedback reflect evaluation of risky (rejection may be rewarded by gain or punished by loss) decisions.