Lateral prefrontal/orbitofrontal cortex has different roles in norm compliance in gain and loss domains: a transcranial current stimulation (tDCS) study

Abstract

Sanction is used by almost all known human societies to enforce fairness norm in resource distribution. Previous studies have consistently shown that the lateral prefrontal cortex (lPFC) and the adjacent orbitofrontal cortex (lOFC) play a causal role in mediating the effect of sanction threat on norm compliance. However, most of these studies were conducted in the gain domain in which resources are distributed among members. Little is known about the mechanisms underlying norm compliance in the loss domain in which individual sacrifices are needed. Here we employed a modified version of Dictator Game (DG) and high-definition transcranial direct current stimulation (HD-tDCS) to investigate to what extent lPFC/lOFC is involved in norm compliance (with and without sanction-threat) in both gain and loss sharing contexts. Participants allocated a fixed total amount of monetary gain or loss between themselves and an anonymous partner in multiple rounds of the game. A computer program randomly decided whether a given round involved sanction threat for the participants. Results showed that disruption of the right lPFC/lOFC by tDCS increased the voluntary norm compliance in the gain domain, but not in the loss domain; tDCS on lPFC/lOFC had no effect on compliance under sanction-threat in either the gain or loss domain. Our findings reveal a complex context-dependent nature of norm compliance and differential roles of lPFC/lOFC in norm compliance in the gain and loss domains.

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