Rapid rTPJ-driven signals encode malicious intentions during implicit moral evaluation: a TMS-EEG study

Understanding how we attribute blame when witnessing one person harming another provides key insights into moral cognition. People typically judge an agent more severely when harm is intentional rather than accidental, prioritizing intentions over outcomes. Yet, the precise neural mechanisms underlying this tendency remain debated. The right temporo-parietal junction (rTPJ), a key region for mentalizing, is frequently implicated in integrating beliefs about others’ intentions with observed outcomes in moral judgment. However, its causal interactions with other brain regions during moral evaluation remain unclear. We combined transcranial magnetic stimulation and electroencephalography (TMS-EEG co-registration) to investigate how rTPJ influences the moral cognition network during implicit moral evaluation. Sixty-six right-handed adults viewed videoclips depicting one person interacting with another in scenarios involving either physical harm—deliberately inflicted (Intentional Harm, IHS) or accidental (Accidental Harm, AHS)—or neutral actions without harm (Neutral Actions, NAS), all while performing an unrelated attentional task. During this task, single-pulse TMS targeted either the rTPJ, left TPJ (lTPJ), or right primary somatosensory cortex (rS1, control) while TMS-evoked potentials (TEPs) were recorded. rTPJ stimulation selectively enhanced early frontal TEPs for IHS compared to AHS (~20–65 ms post-TMS pulse), indicating rapid differentiation of intentional versus accidental harm. Source analyses linked this effect to early medial prefrontal cortex (mPFC) activation, suggesting a feedforward rTPJ-to-mPFC communication pathway for processing harmful intents. Neither lTPJ nor rS1 stimulation yielded similar differences, highlighting both functional and anatomical specificity. Stronger rTPJ TEPs under IHS correlated with greater moral condemnation (i.e., lower permissibility ratings), highlighting the behavioral relevance of rTPJ-mPFC communication. Our findings suggest that the rTPJ quickly processes and relays information about malicious intentions, shaping downstream evaluation in prefrontal circuits. Using TMS-EEG, we provide direct evidence that early rTPJ-driven signals are pivotal for intent-based moral judgments, shedding new light on how mentalizing mechanisms shape moral cognition.