Anodal tDCS over TPJ reduces bidding in Tullock contest: Implications for social decision-making

Contests, as economic, political, and social interactions, can stimulate high levels of effort, but they can also lead to inefficient expenditure of effort (overbidding), resulting in the wastage of social resources. Prior studies have indicated that the temporoparietal junction (TPJ) is associated with overbidding and speculating on the intentions of others during contests. This study aimed to investigate the neural mechanisms of the TPJ in overbidding and to examine changes in bidding behavior after modulating TPJ activity using transcranial direct current stimulation (tDCS). The experiment randomly allocated participants into three groups, each receiving either anodal stimulation of the LTPJ/RTPJ or sham stimulation. Following the stimulation, the participants engaged in the Tullock rent-seeking game. Our results revealed that participants who received anodal stimulation of the LTPJ and RTPJ significantly reduced their bids compared to the sham group, possibly due to enhanced accuracy in guessing others' strategies or enhanced altruistic preferences. Moreover, our findings suggest that while both the LTPJ and RTPJ are associated with overbidding behavior, anodal tDCS targeting the RTPJ is more effective than stimulation of the LTPJ in decreasing overbidding. The aforementioned revelations offer proof of the neural mechanisms of the TPJ in overbidding and provide fresh substantiation for the neural mechanisms of social behavior.