Par intervenant > Chancel Marie

Body ownership—the multisensory perception of limbs and body parts as one's own—has been extensively studied in the contexts of vision, touch, and proprioception. Bayesian causal inference models have recently been employed to explain body ownership illusions, such as the visuotactile rubber hand illusion, suggesting that observers compute the probability that visual and tactile signals originate from a common source. However, it remains unclear whether similar computational processes underlie the perception of ownership over the entire body.

To address this question, we developed a detection task relying on the classic full-body illusion paradigm. Participants reported whether the body they observed (a mannequin's body) felt like their own (yes or no answer). We systematically manipulated the asynchrony between visual and tactile stimuli delivered to the mannequin and the participant's real body, alongside varying levels of visual noise.

Our results revealed that the probability of experiencing the full-body illusion was accurately predicted by a causal inference model, wherein observers estimate the likelihood that visual and tactile signals arise from a common source. This model outperformed a non-Bayesian alternative that did not account for sensory uncertainty, even though the behavioral effects of visual noise were relatively weak. These findings provide evidence that Bayesian causal inference mechanisms extend to whole-body ownership illusions. We discuss the implications of these results for understanding the relationship between part-based and whole-body ownership in multisensory awareness.