Third-party punishment and its neural mechanisms in the digital age: An fNIRS investigation of subjective social class and moral orientation

Third-party punishment (TPP) plays a crucial role in maintaining social justice, and its occurrence is increasingly common in online environments. However, research on TPP in these digital settings, particularly regarding individuals from different subjective social classes (SSC), is still limited. This study investigates the TPP and associated neural activation patterns of individuals with high and low SSC when faced with moral violations of different orientations (justice vs. care) online. Using behavioral experiments and fNIRS, participants observed moral violations online—such as breaches of fairness or harm to others—and decided whether to punish the offenders while their brain activity was recorded. Behavioral findings indicated that high SSC individuals exhibited consistent TPP across both moral orientations, whereas low SSC individuals showed increased TPP in care-oriented violations. The fNIRS results revealed significant activation in the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC) during justice violations. In contrast, reduced activation was observed in these regions during care violations, particularly among low SSC individuals. These findings suggest that TPP in online care-related moral violations is more emotionally driven, with less cognitive control, and demonstrate how social class differentially impacts punishment behavior and its underlying neural mechanisms in digital environments. This study provides novel insights into the interplay of emotion and cognition in online TPP decision-making.