Abstract: The American Psychological Association's (APA) 2019 report on Ten Trends in Contemporary Psychological Science identifies “Shining a spotlight on equity” as a central research imperative in modern psychology. Current investigations into third-party punishment (TPP), a crucial mechanism for enforcing social norms, including fairness, have largely overlooked the pervasive characteristic of uncertainty in real social contexts. Emerging evidence suggests that uncertainty often induces negative emotions, including anxiety and worry, which subsequently undermines prosocial behaviors such as cooperation and reciprocity. As a specialized form of prosocial conduct and linchpin of norm enforcement, TPP represents a critical societal safeguard. Its impairment could precipitate hierarchical breakdowns in normative constraints: from individual transgressions to collective norm erosion, ultimately threatening systemic social cooperation equilibrium. This necessitates empirical examination of whether and how uncertainty undermines TPP.
Two dimensions of fairness norm violations—outcome unfairness (i.e., observable unfair behaviors) and intentional unfairness (i.e., deliberate motives underlying unfair behaviors)—have been identified as pivotal drivers of TPP. Correspondingly, both outcome uncertainty and intent uncertainty may serve as critical factors influencing TPP. Recent behavioral studies have examined the impact of outcome uncertainty on TPP, yet the role of intent uncertainty remains underexplored. Furthermore, the specific emotional and cognitive processes underlying TPP under these two conditions of uncertainty remain unclear. This investigation aims to systematically examine the effects of outcome and intent uncertainty of norm violations on TPP decisions and its underlying brain network mechanisms. Further, we also explore the motives responsible for the changes in TPP behavior under uncertain contexts. By dissecting the neurocognitive interface between uncertainty appraisal and normative enforcement, this research can advance a mechanistic understanding of the architecture of normative decision-making and the psychological foundations of social norm maintenance. The research findings to be obtained may hold translational potential in terms of developing targeted interventions that nudge third-party norm enforcement behaviors in real-world contexts.
This study aims to elucidate the neural network representations of TPP under uncertainty during emotional processing and intention inference by integrating interdisciplinary techniques from psychology and cognitive neuroscience, particularly employing graph-theoretical analysis of complex brain networks. These methods have revolutionized traditional approaches by redefining the brain not as a collection of discrete anatomical units, but as an interconnected system of neurons, then focusing on and emphasizing how cognitive systems operate in an organized manner. Studying TPP from an integrated perspective of large-scale brain networks represents a significant breakthrough compared to traditional emphases on brain activation patterns and unidirectional mappings between behavior and neural activity. It helps to reveal critical mechanisms that were previously overlooked or undetectable through conventional approaches. In addition, uncertainty typically leads to a reduction in TPP engagement, with behavioral attenuation potentially attributable to motivational heterogeneity among individuals. For example, in situations of uncertainty, concerns about committing a Type I error (misinflicting harm) and cost avoidance both diminish TPP behavior. However, individuals motivated by these two factors may behave differently regarding fairness maintenance. While such behavioral attenuation is not easily observable through external behavioral measures, recent advances in neuroimaging and graph-based network techniques offer promising avenues to disentangle the specific motivational subgroups influenced by uncertainty. This framework could ultimately guide targeted neural interventions aimed at enhancing fairness-maintenance efforts in cost-avoidance motivated individuals. Thus, this study has the potential to expand theoretical boundaries and methodological approaches in TPP research, thereby enabling novel developments.

Key words: third-party punishment, uncertainty, fairness, norm enforcement, brain network