Transcranial direct current stimulation of the LTPJ shifts the agent's behaviors in repeated hold-up game

The Hold-up problem is very common in transactions with specific investment in incomplete contractual relationships, which is affected by human trusting, cooperative, altruistic behavior. Recent neuroscience studies have shown that TPJ plays an important role in social cognition and prosocial decision-making. However, most of the studies have focused on RTPJ in the right hemisphere, while few studies have focused on LTPJ in the left hemisphere. The purpose of this study is to modulate the excitability of LTPJ through transcranial direct current stimulation (tDCS) and to explore the effects of LTPJ on the investment and offer behavior of participants in the repeated hold-up game. Our results showed that cathodal stimulation significantly improved the investment rate of participants in the repeated hold-up game compared with sham stimulation. One possible explanation is that the change of LTPJ activity caused by cathodal stimulation may reduce the participants' inference ability of the others' intention, thus reducing the participants' betrayal aversion behavior, so that the participants will not reduce their investment behavior in the repeated game.