Perception of Body Ownership Is Driven by Bayesian Sensory Inference

Recent studies have shown that human perception of body ownership is highly malleable. A well-known example is the rubber hand illusion (RHI) wherein ownership over a dummy hand is experienced, and is generally believed to require synchronized stroking of real and dummy hands. Our goal was to elucidate the computational principles governing this phenomenon. We adopted the Bayesian causal inference model of multisensory perception and applied it to visual, proprioceptive, and tactile stimuli. The model reproduced the RHI, predicted that it can occur without tactile stimulation, and that synchronous stroking would enhance it. Various measures of ownership across two experiments confirmed the predictions: a large percentage of individuals experienced the illusion in the absence of any tactile stimulation, and synchronous stroking strengthened the illusion. Altogether, these findings suggest that perception of body ownership is governed by Bayesian causal inference—i.e., the same rule that appears to govern the perception of outside world.近年来的研究表明，人类对身体所有权的感知具有高度可塑性。其中一个广为人知的例子便是橡胶手错觉（Rubber Hand Illusion, RHI）：个体能够感知到对一只假手的所有权，而此前普遍认为该错觉需要对真手与假手进行同步轻抚。本研究旨在阐明支配该现象的计算原理。我们采用多感官感知的贝叶斯因果推断模型（Bayesian causal inference model），并将其应用于视觉、本体感觉与触觉刺激的处理中。该模型不仅复现了橡胶手错觉现象，还预测该错觉可在无触觉刺激的情况下发生，且同步轻抚能够强化该错觉。通过两项实验中多种所有权感知评估手段，我们验证了上述预测：在无任何触觉刺激的条件下，仍有大量个体感知到了该错觉，且同步轻抚可进一步增强该错觉的强度。综上，本研究结果表明，人类对身体所有权的感知由贝叶斯因果推断所支配——这一规律同样适用于对外部世界的感知。