Bridging subjective and neural state transitions in the rubber hand illusion: a neurophenomenological study

The rubber hand illusion (RHI) provides a powerful paradigm for probing the malleability of bodily self-consciousness. While conventional studies rely on proprioceptive drift, questionnaires, or averaged neural measures, phenomenological research suggests that the RHI unfolds through multiple subjective state transitions rather than as a simple binary phenomenon. Participants often describe ambiguous coexistence of real and artificial hands, partial incorporation, and eventual ownership, indicating meaningful dynamics of selfhood. Here, we adopt a neurophenomenological approach that integrates first-person interviews with electroencephalographic (EEG) functional connectivity network analysis. Subjective trajectories during the RHI were characterized through phenomenological interviews and modeled as successive states. EEG connectivity was analyzed using graph neural networks, enabling data-driven clustering of neural states aligned with subjective transitions. To establish a correspondence between the phenomenological and neural domains, we employed Gromov-Wasserstein (GW) optimal transport, which maps structural correspondences between subjective and EEG-derived state spaces despite their differing metrics. The results show that specific subjective transitions correspond to distinct changes in network topology. Major subjective states were associated with reconfigurations of connectivity patterns and shifts in degree centrality across several regions, including the premotor cortex and insula, which are known to contribute to body ownership. GW optimal transport further revealed a principled correspondence between the geometry of subjective and neural state spaces. Together, these findings demonstrate that subjective transitions in the RHI are mirrored by dynamic reorganization of brain networks, illustrating how neurophenomenology combined with computational modeling can advance the study of embodied selfhood.