Autonomic Interplay and the Bimodal Classification of Aggression: Baseline and Reactivity Profiles in Urban Adult Males.

Biological theories propose distinct physiological profiles for premeditated aggression (PM) and impulsive aggression (IA), yet prior research has relied on single-system markers that have yielded inconsistent findings, and no study has examined PNS-SNS interplay in relation to these aggression subtypes in adult samples including active offenders. This study investigated whether multisystem autonomic profiles at rest and during a modified Trier Social Stress Task differentially associated with PM and IA in a heterogeneous urban adult sample. Active offenders, demographically matched controls, and college students (N = 130, all male, M age = 28 years) were recruited in Atlanta. Skin conductance and respiratory sinus arrhythmia were recorded at rest and during three mTSST components varying in social confrontation demand and cognitive load. Each aggression subtype was modeled with the other adjusted for (PM and IA correlated at r = 0.54), so all associations pertain to the variance unique to that subtype. Baseline RSA was positively associated with PM only at low to moderate baseline SCL, and both reciprocal PNS and SNS activation profiles during social confrontation were associated with higher PM. Low baseline RSA was associated with more IA regardless of arousal level, with no significant reactivity interactions. All findings are replicated using peak-to-valley RSA. These results indicate that PM and IA are associated with qualitatively distinct multisystem physiological profiles. PM was associated with two divergent patterns under social challenge, physiological disengagement and organized mobilization, whereas IA was associated with a single trait-level marker of low regulatory capacity independent of situational arousal.