Multisensory integration across exteroceptive and interoceptive domains modulates self-experience in the rubber-hand illusion

TLDR

Body identification is central to consciousness, and the rubber‑hand illusion shows that body‑ownership can be modulated by exteroceptive feedback, yet how interoceptive signals interact with exteroceptive cues to shape ownership remains unclear. This study aims to show that body‑ownership depends on the online integration of exteroceptive and interoceptive signals using a cardiac‑rubber‑hand illusion. The authors implemented a cardiac‑rubber‑hand illusion that combines computer‑generated augmented reality with synchronous cardiac feedback to integrate visual, tactile, and interoceptive information. Synchronous cardio‑visual feedback increased both subjective and objective ownership, correlated with interoceptive sensitivity, and was further modulated by proprioceptive remapping, supporting interoceptive predictive‑coding models of self‑hood.

Abstract

Identifying with a body is central to being a conscious self. The now classic "rubber hand illusion" demonstrates that the experience of body-ownership can be modulated by manipulating the timing of exteroceptive (visual and tactile) body-related feedback. Moreover, the strength of this modulation is related to individual differences in sensitivity to internal bodily signals (interoception). However the interaction of exteroceptive and interoceptive signals in determining the experience of body-ownership within an individual remains poorly understood. Here, we demonstrate that this depends on the online integration of exteroceptive and interoceptive signals by implementing an innovative "cardiac rubber hand illusion" that combined computer-generated augmented-reality with feedback of interoceptive (cardiac) information. We show that both subjective and objective measures of virtual-hand ownership are enhanced by cardio-visual feedback in-time with the actual heartbeat, as compared to asynchronous feedback. We further show that these measures correlate with individual differences in interoceptive sensitivity, and are also modulated by the integration of proprioceptive signals instantiated using real-time visual remapping of finger movements to the virtual hand. Our results demonstrate that interoceptive signals directly influence the experience of body ownership via multisensory integration, and they lend support to models of conscious selfhood based on interoceptive predictive coding.