Parsing the Behavioral and Brain Mechanisms of Third-Party Punishment

Abstract

The evolved capacity for third-party punishment is considered crucial to the emergence and maintenance of elaborate human social organization and is central to the modern provision of fairness and justice within society. Although it is well established that the mental state of the offender and the severity of the harm he caused are the two primary predictors of punishment decisions, the precise cognitive and brain mechanisms by which these distinct components are evaluated and integrated into a punishment decision are poorly understood. Using fMRI, here we implement a novel experimental design to functionally dissociate the mechanisms underlying evaluation, integration, and decision that were conflated in previous studies of third-party punishment. Behaviorally, the punishment decision is primarily defined by a superadditive interaction between harm and mental state, with subjects weighing the interaction factor more than the single factors of harm and mental state. On a neural level, evaluation of harms engaged brain areas associated with affective and somatosensory processing, whereas mental state evaluation primarily recruited circuitry involved in mentalization. Harm and mental state evaluations are integrated in medial prefrontal and posterior cingulate structures, with the amygdala acting as a pivotal hub of the interaction between harm and mental state. This integrated information is used by the right dorsolateral prefrontal cortex at the time of the decision to assign an appropriate punishment through a distributed coding system. Together, these findings provide a blueprint of the brain mechanisms by which neutral third parties render punishment decisions.

Cerebral responses to self-initiated action during social interactions

“…Thus, to the extent that ball tosses are dictated by the behavioral task, these neural processes may not speak directly to self-agency. Furthermore, self-agency may play a role in decision making more broadly in and beyond social interactions; e.g., in determining individual differences in control-averse behavior (Rudorf et al, 2018), in modulating choice behavior when unexpected outcomes arise from errors in action (Parvin, McDougle, Taylor, & Ivry, 2018), and in mentalizing to assign third-party punishment (Ginther et al, 2016). The current findings may add to this literature and facilitate research of the influences of social exclusion on many other decision making processes that involve social interactions.…”

Reasoning supports forgiving accidental harms

“…When it comes to evaluating third-party harmful behavior like this, past work has shown that people rely not only on the assessment of the mental state of the perpetrator, but also on the presence of a harmful consequence for the victim (Buon, Seara-Cardoso, & Viding, 2016;Cushman, 2015;Ginther et al, 2016;Young & Tsoi, 2013). In other words, after witnessing harmful event, third-party moral judge reasons about the intentions of the actors ("What was Blythe thinking when he threw his fan off the stage?!")…”

Neuroanatomical correlates of forgiving unintentional harms

“…For example, the encoding of mental states occurs very early during information processing in the right TPJ7, left TPJ8, and amygdala9. The rTPJ, dmPFC, and PCC are also involved in integrating belief states1011 with other morally relevant pieces of information (e.g., consequences) to construct final moral judgments12131415. On the other hand, the dmPFC is involved in encoding the valence (harmful or neutral) of the beliefs10.…”