Disentangling visually driven tactile predictions from multisensory integration in body ownership

The sense of owning one's body is essential for distinguishing internal from external sensations. Research using bodily illusions shows that this sense depends on integrating visual, tactile and proprioceptive signals, yet the role of multisensory predictions remains unclear. We addressed this using a modified rubber hand illusion. Two robotic arms tapped the two visible rubber hands, while a third arm simultaneously tapped the participant's hidden real hand. One rubber hand received synchronous stimulation, while the other was stimulated with varying temporal delays. Visual feedback was manipulated across three conditions: full view of the approaching probe and touch, occlusion of the approaching probe or occlusion of the touch event. Participants reported which rubber hand felt more like their own hand. Using signal detection analysis, we examined whether occluding predictive visual feedback influenced sensitivity to visuotactile synchrony, perceptual bias or both. Results showed that occluding the approaching probe did not reduce sensitivity to visuotactile signals; as long as the touch or its timing was visible or inferable, sensitivity remained stable. However, perceptual bias was reduced when predictive visual information was removed. These findings reveal how visually driven tactile predictions shape body ownership and highlight signal detection analysis as a useful tool to dissociate sensitivity and bias in self-perception.