The role of vision in body representation: a study on hand distortions in blind and sighted individuals

Several studies have shown that healthy individuals present large distortions across different body parts, as assessed through tactile distance estimation. Interestingly, studies have revealed that by temporarily altering visual experience of the body, the perception of tactile distances varies, suggesting that vision might play a crucial role in bodily distortions and more generally in the perception of body. This might be due to the system that tends to preserve tactile size constancy by rescaling the distorted body representation into an object-centred space. This rescaling requires that the brain possesses a representation of the physical size of the stimulated body part. However, it is unclear what role vision plays in tactile size constancy. Here, we investigated the role of vision in body representation by asking blind and sighted individuals to estimate tactile distances between pairs of points on the dorsum of their hand and on their fingers. The results showed that, regardless of visual experience, both groups showed typical hand/fingers distortions, suggesting that visual information does not seem to influence body representation tested using a tactile task. Therefore, rescaling of distorted body representations induced by touch seems not to be visually-driven.