In competitive interactions, humans have to flexibly update their beliefs about another person's intentions in order to adjust their own choice strategy, such as when believing that the other may exploit their cooperativeness. Here we investigate both the neural dynamics and the causal neural substrate of belief updating processes in humans. We used an adapted prisoner's dilemma game in which participants explicitly predicted the coplayer's actions, which allowed us to quantify the prediction error between expected and actual behavior. First, in an EEG experiment, we found a stronger medial frontal negativity (MFN) for negative than positive prediction errors, suggesting that this medial frontal ERP component may encode unexpected defection of the coplayer. The MFN also predicted subsequent belief updating after negative prediction errors. In a second experiment, we used transcranial magnetic stimulation (TMS) to investigate whether the dorsomedial prefrontal cortex (dmPFC) causally implements belief updating after unexpected outcomes. Our results show that dmPFC TMS impaired belief updating and strategic behavioral adjustments after negative prediction errors. Taken together, our findings reveal the time course of the use of prediction errors in social decisions and suggest that the dmPFC plays a crucial role in updating mental representations of others' intentions.

在竞争性互动中，人类必须灵活地更新自己对他人意图的信念，以调整自己的选择策略，例如当相信对方可能会利用自己的合作性时。在这里，我们研究人类信念更新过程的神经动力学和因果神经基础。我们使用了一种改编的囚徒困境游戏，其中参与者明确预测了共同玩家的行为，这使我们能够量化预期行为和实际行为之间的预测误差。首先，在脑电图实验中，我们发现负预测错误的内侧额叶负性（MFN）比正预测错误更强，这表明内侧额叶 ERP 成分可能编码了共同玩家的意外背叛。 MFN 还预测了负预测错误后的后续信念更新。在第二个实验中，我们使用经颅磁刺激（TMS）来研究背内侧前额叶皮层（dmPFC）是否在意外结果后因果性地实施信念更新。我们的结果表明，在出现负面预测错误后，dmPFC TMS 会损害信念更新和策略行为调整。总而言之，我们的研究结果揭示了在社会决策中使用预测错误的时间过程，并表明 dmPFC 在更新他人意图的心理表征方面发挥着至关重要的作用。