Towards a Technology-Based Assessment of Sensory-Motor Pathological States Through Tactile Illusions

Touch provides important information on the physical properties of external objects, and contributes to the sense of our hand position and displacement in perceptual tasks. Recent studies showed that the texture of the touched surface produced a bias on the perceived tactile motion, ultimately affecting the direction of hand motion in reaching tasks. Specifically, moving on a plate with parallel ridges, the hand motion deviates towards a direction opposite with respect to the one predicted by tactile flow mathematical model, i.e. perpendicular to the ridges. Here, we used this phenomenon to quantitatively assess an impairment in tactile channel. We asked healthy participants slide the hand on a plate with parallel ridges, either with bare fingertip or by wearing a glove. The glove condition simulated a dysfunction in tactile channel, as may occur in pathological conditions, for e.g. due to a neurological disease. Our hypothesis is that, wearing a glove, the systematic error induced by the texture orientation will be smaller because the information provided by the tactile channel is noisier. Results are in agreement with our hypothesis, and could open interesting perspectives towards a quantitative technology-based tool for the assessment of tactile impairment in pathological conditions.