Vision Fine-Tunes Predictions of Bimanual Self-Touch.

Self-touch is attenuated compared to external touch due to internal forward models predicting the somatosensory consequences of our movements. These self-touch predictions are continuously updated during the movement using the available sensory input, resulting in a precise temporal tuning of somatosensory perception. However, the contributions of different sensory inputs, such as vision, to the predictions of the forward models and thus the resulting modulation of somatosensory perception remain unknown. In this pre-registered study, participants discriminated forces applied to their left index or ring finger during a reaching movement of the right hand towards the left hand, performed both with and without visual input. When vision was available, somatosensory perception was gradually attenuated during the movement and peaked at the time of self-touch, replicating our previous findings. Without visual input, this temporal tuning was reduced, as somatosensory perception was more uniformly, rather than gradually, attenuated throughout the movement. Our findings thus indicate that vision increases the precision of self-touch predictions, thereby fine-tuning the temporal modulation of somatosensory perception during movements to self-touch.