Ambiguous Body Ownership Experience Caused by Feeling-judgement Conflict: Evidence from Subjective Measurement in Rubber Hand Illusion using Integrated Information Theory

Human body awareness is malleable and adaptive to changing contexts. The illusory sense of body-ownership has been studied since the publication of the rubber hand illusion, where ambiguous body ownership feeling, expressed as "the dummy hand is my hand even though that is not true", was first defined. Phenomenologically, the ambiguous body ownership is attributed to a conflict between feeling and judgement; in other words, it characterises a discrepancy between first-person (i.e. bottom-up) and third-person (i.e. top-down) processes. Although Bayesian inference can explain this malleability of body image sufficiently, the theory does not provide a good illustration of why we have different experiences to the same stimuli -- the difficulty lies in the uncertainty regarding the concept of judgement in their theory. This study attempts to explain subjective experience during rubber hand illusions using integrated information theory (IIT). The integrated information {Phi} in IIT measures the difference between the entire system and its subsystems. This concept agrees with the phenomenological interpretation -- that is, there is conflict between judgement and feeling. By analysing the seven nodes of a small body--brain system, we demonstrate that the integrity of the entire system during the illusion decreases with increasing integrity of its subsystems. These general tendencies agree well with many brain-image analyses and subjective reports; furthermore, we found that subjective ratings were associated with the {Phi}s. Our result suggests that IIT can explain the general tendency of the sense of ownership illusions and individual differences in subjective experience during the illusions.