CONFIGURATION COHERENCE DETERMINES FULL-BODY OWNERSHIP AND ASSOCIATED THREAT-EVOKED AUTONOMIC RESPONSES

Background: Body ownership depends on multisensory integration of bodily inputs, yet it remains unclear whether full-body ownership requires a spatially coherent configuration of body parts. Here, we test whether configuration coherence determines full-body ownership and associated autonomic threat-evoked responses as a physiological marker of body ownership.
Methods: In Experiment 1 (N=42), we manipulated configuration coherence (Humanoid vs scrambled body-part configuration) and synchrony (fully synchronous, fully asynchronous, or partially synchronous; SSS/AAA/SAA) during a multi-part body illusion, quantifying full-body and body-part ownership with mixed-effects models. In Experiment 2 (N=30), we measured threat-evoked EDA during knife threat under SSS vs AAA for coherent vs scrambled configurations and assessed questionnaire–EDA correlations.
Results: Experiment 1 showed a Configuration × Synchrony interaction for full-body ownership (F_(4,328) =5.10, p=5.3×10⁻⁴), with synchrony selectively enhancing ownership in the Humanoid configuration (Humanoid(SSS–AAA) > Scrambled(SSS–AAA), B=1.37, p < 0.001; similarly for SSS–SAA). No interaction was observed for body-part ownership (F_(4,328)=0.92, p=0.45). Experiment 2 revealed threat EDA depended on embodiment (Config × Sync: F_(1,116)=12.67, p=5.4×10⁻⁴): synchrony increased responses for Humanoid (p=5.9×10⁻⁴) but not Scrambled (p=0.72). Critically, configuration-dependent EDA gain (Humanoid SSS – Scrambled SSS) correlated with full-body ownership (ρ=0.48, p=0.009), but not body-part ownership (ρ=−0.12, p=0.55); hierarchical regression confirmed a unique full-body ownership contribution beyond baseline arousal (p=0.036).
Conclusion: Coherence of the spatial configuration of body parts is a critical determinant of full-body ownership, as indexed by both subjective reports and threat-evoked autonomic responses, beyond multisensory integration at the level of individual body parts.