Bodily Self-Consciousness

This study examines how voluntary fast, deep breathing (hyperventilation) affects the way healthy adults perceive their own body. Participants wear a virtual-reality (VR) headset and see a virtual body; a glowing halo around it either pulses exactly in time with their own breathing or is time-shifted. During the study, breathing, heart activity, blood-oxygen level, the carbon-dioxide content of exhaled air, and brain activity (EEG, measured non-invasively from the scalp) are recorded continuously, and participants complete questionnaires about their experience. The aim is to understand whether and how altered breathing changes the interplay between what people see and what they feel inside their body, and thereby the sense of being located within one's own body. The study uses a 2×2 within-subjects design crossing Breathing (normal vs. hyperventilation) with Visual synchrony (synchronous vs. asynchronous), with the asynchronous and normal-breathing conditions serving as within-subject controls. No medication is administered and no medical device is being tested; the instruments used serve only for monitoring and measurement. Participation involves a screening visit (including a short, \~5-minute guided-hyperventilation tolerance test) and an experimental visit.