The Respiratory Cycle and the Rubber Hand Illusion : A Novel Exploration

The Rubber Hand Illusion (RHI) offers an effective paradigm for investigating body ownership. Prior research suggests that interoceptive awareness, the ability to accurately perceive internal bodily signals, plays a crucial role in modulating susceptibility to the illusion. Additionally, an increasing number of studies show that this ability is influenced by physiological processes such as breathing. This study explored a novel dimension: how respiration phases modulate the perceptual experience of body ownership in the RHI. A total of 26 participants underwent standard RHI procedures, consisting of synchronous and asynchronous stimulation trials. Illusion responders underwent an additional breathing-monitored trial in which they marked the time of the onset of the illusion (i.e., the experience of owning the rubber hand) by pressing a foot pedal. Our results showed that 80% of illusion onsets occurred during exhalation, suggesting a potential link between this phase of the respiratory cycle and multisensory integration. Another interpretation considers the tendency for self-initiated action during exhalation as a possible explanation. This study contributes to the increasing body of knowledge that helps to understand the link between physiological processes and the sense of body ownership.