Acute stress reshapes third-party punishment and help decisions: Behavioral evidence and neurocomputational mechanisms

People tend to intervene in others’ injustices by either punishing the transgressor or helping the victim. Injustice events often occur under stressful circumstances. However, how acute stress affects a third party’s intervention in injustice events remains open. Here, we show a stress-induced shift in third parties’ willingness to engage in help instead of punishment by acting on emotional salience and central-executive and theory-of-mind networks. Acute stress decreased the third party’s willingness to punish the violator and the severity of the punishment and increased their willingness to help the victim. Computational modeling revealed a shift in intervention severity bias from punishment toward help under stress. This finding is consistent with the increased dorsolateral prefrontal engagement observed with higher amygdala activity and greater connectivity with the ventromedial prefrontal cortex. A brain connectivity theory-of-mind network predicted stress-induced severity bias in punishment. Our findings suggest a neurocomputational mechanism of how acute stress reshapes third parties’ decisions by reallocating neural resources in emotional, executive and mentalizing networks to inhibit punishment bias and decrease punishment severity. ### Competing Interest Statement The authors have declared no competing interest.