Causal role of right dorsolateral prefrontal cortex for norm-guided social decision making: A meta-analysis of TMS studies

Theoretical accounts ascribe the right dorsolateral prefrontal cortex (rDLPFC) a crucial role in social decision making, but previous studies assessing the rDLPFC's function with transcranial magnetic stimulation (TMS) provided inconsistent evidence. While some studies suggest that the rDLPFC promotes norm-guided behavior, others report the rDLPFC to implement selfish choices. To decide between these conflicting accounts, we con-ducted a meta-analysis of studies that investigated the impact of rDLPFC TMS on social decision making. While we observed no significant effect of rDLPFC TMS across all studies, moderator analyses revealed that the rDLPFC's role in social decision making crucially depends on the social context: in particular, we found that rDLPFC promotes norm-guided behavior predominantly when decision makers have to trade-off their interaction partners' intentions and fairness expectations against their selfish interests (reactive fairness). In contrast, there was no evidence that rDLPFC TMS affects prosocial giving (proactive fairness). Our results thus inform theo-retical accounts by showing that brain stimulation over rDLPFC does not increase or decrease norm-guided behavior per se; instead, contextual factors determine the role of the rDLPFC in social interactions.