This study explored autonomic arousal in adults with Autism Spectrum Condition (ASC; n=29) compared to non-ASC adults (n=33), aged 20–30, during rest and passive social engagement involving watching reality TV. Grounded in the Polyvagal Theory, which proposes that chronic mobilization may disrupt the Social Engagement System in ASC by reducing parasympathetic tone, respiratory sinus arrhythmia (RSA) was measured via photoplethysmography during three MRI sessions to assess static RSA levels during rest and social engagement, as well as RSA-reactivity (RSA-R) during context-switching. Statistical analyses revealed no significant group differences in baseline RSA or RSA-R. A preliminary analysis suggested lower RSA in the ASC group during social engagement (p < 0.05), hinting at possible context-dependent hyperarousal, but this finding’s robustness was limited by inconsistent statistical support. These results provide tentative evidence for state-dependent, rather than trait-level, autonomic dysregulation in ASC. Interpretations are constrained by small sample size and missing respiratory corrections due to equipment issues. Future research should use larger, more diverse samples and improved physiological measures to clarify RSA’s utility as a biomarker for social processing in ASC.