Is the Bystander Truly Objective? The Moderation of Third-Party Moral Judgment by Perspective Taking in Moral Scenarios

In moral scenarios, individuals often exhibit divergent interpretations and judgments of the same moral event due to varying prior experiences, making true "bystander objectivity" challenging. This study investigates how prior experiences influence perspective selection and subsequently moderate moral judgment and its neural underpinnings by activating different moral role perspectives (decision-maker vs. receiver) using Event-Related Potentials (ERPs). Results reveal that activating the receiver's perspective leads to stricter moral judgments, whereas activating the decision-maker's perspective results in more lenient judgments. Furthermore, the moderating effect of perspective on moral judgment weakens as the decision-maker's gains from immoral choices decrease. At the neural level, activating different moral role perspectives affects early processing and emotional arousal during moral judgment, manifesting as larger N1 and P2 components for the decision-maker perspective, and larger FRN components related to expectation violation for the receiver perspective. These findings indicate that prior moral experiences significantly shape an individual's moral judgment preferences as a bystander, primarily by modulating early processing of others' moral decisions.