Touch used to guide action is partially coded in a visual reference frame

Abstract

The perceived location of touch on the skin is affected by the position of the eyes in the head, suggesting that it is at least partially coded in a visual reference frame. This observation was made by comparing the perceived location of a touch to a visual reference. Here, we ask whether the location of a touch is coded differently when it guides an action. We tested the perceived position of four touches on the arm (approximately 5 cm apart) while participants adopted one of four eccentric fixations. A touch-sensitive screen was positioned over the stimulated left arm and subjects pointed, using their right arm, to the perceived touch location. The location that subjects pointed to varied with eye position, shifting by 0.016 cm/deg in the direction of eye eccentricity. The dependence on eye position suggests that tactile coding for action is also at least partially coded in a visual reference frame, as it is for perception.