Trust me, you are there: the role of verbal manipulation on embodiment and body localization.

Body ownership (the perception of the body as belonging to oneself) and body spatial perception arise from multisensory integration and can be altered by body illusions (e.g., Rubber Hand Illusion, RHI). In the RHI, synchronous visuo-tactile stimulation elicits ownership over a fake hand and shifts the perceived real hand position (Proprioceptive Drift). This study investigated whether altering body spatial predictions through verbal manipulation affects ownership in a virtual RHI (vRHI). In the Misleading Information Condition, participants were told their hand would be moved closer to the virtual hand. In the Correct Information Condition (Control Condition), participants were told their hand would be moved and then put back in its original position. Embodiment and perceived hand position were assessed at baseline (T0), after verbal manipulation (T1), and after vRHI induction (T2). Results showed that verbal manipulation altered spatial predictions: in the Misleading Information Condition, proprioceptive drift at T1 increased. However, after the vRHI, the drift was lower in the Misleading Information Condition than in the Control condition. Embodiment increased only after the vRHI. Thus, manipulating spatial predictions influenced hand position but not embodiment, revealing top-down modulation of body spatial perception. In contrast, multisensory illusion affected perceived position and embodiment, independently of prior verbal manipulations, suggesting a possible distinction between these processes.