MySpace Lab, Department of Clinical Neurosciences, University Hospital of Lausanne, University of Lausanne, Lausanne, Switzerland.
School of Medicine, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
Cortex. 2023 Oct;167:247-272. doi: 10.1016/j.cortex.2023.06.019. Epub 2023 Jul 25.
Simple multisensory manipulations can induce the illusory misattribution of external objects to one's own body, allowing to experimentally investigate body ownership. In this context, body ownership has been conceptualized as the result of the online Bayesian optimal estimation of the probability that one object belongs to the body from the congruence of multisensory inputs. This idea has been highly influential, as it provided a quantitative basis to bottom-up accounts of self-consciousness. However, empirical evidence fully supporting this view is scarce, as the optimality of the putative inference process has not been assessed rigorously. This pre-registered study aimed at filling this gap by testing a Bayesian model of hand ownership based on spatial and temporal visuo-proprioceptive congruences. Model predictions were compared to data from a virtual-reality reaching task, whereby reaching errors induced by a spatio-temporally mismatching virtual hand have been used as an implicit proxy of hand ownership. To rigorously test optimality, we compared the Bayesian model versus alternative non-Bayesian models of multisensory integration, and independently assess unisensory components and compare them to model estimates. We found that individually measured values of proprioceptive precision correlated with those fitted from our reaching task, providing compelling evidence that the underlying visuo-proprioceptive integration process approximates Bayesian optimality. Furthermore, reaching errors correlated with explicit ownership ratings at the single individual and trial level. Taken together, these results provide novel evidence that body ownership, a key component of self-consciousness, can be truly described as the bottom-up, behaviourally optimal processing of multisensory inputs.
简单的多感官操作可以诱使人们将外部物体错误地归因于自己的身体，从而可以对身体所有权进行实验研究。在这种情况下，身体所有权被概念化为在线贝叶斯最优估计一个物体属于身体的概率的结果，这种概率来自多感官输入的一致性。这个想法非常有影响力，因为它为自我意识的自下而上的解释提供了定量基础。然而，完全支持这种观点的经验证据很少，因为没有严格评估假设推断过程的最优性。这项预先注册的研究旨在通过测试基于空间和时间视动本体感觉一致性的手部所有权的贝叶斯模型来填补这一空白。将模型预测与虚拟现实伸手任务中的数据进行比较，通过该任务，通过时空不匹配的虚拟手引起的伸手误差被用作手部所有权的隐含代理。为了严格测试最优性，我们将贝叶斯模型与多感觉整合的替代非贝叶斯模型进行了比较，并独立评估了单感觉组件，并将其与模型估计进行了比较。我们发现，本体感觉精度的个体测量值与从伸手任务中拟合的值相关，这提供了令人信服的证据，表明潜在的视动本体感觉整合过程接近贝叶斯最优性。此外，伸手误差与个体和试验水平的明确所有权评分相关。总之，这些结果提供了新的证据，表明身体所有权是自我意识的一个关键组成部分，可以真正被描述为多感官输入的自下而上、行为最优的处理。
