Perceived touch location is coded using a gaze signal

The location of a touch to the skin, first coded in body coordinates, may be transformed into retinotopic coordinates to facilitate visual-tactile integration. In order for the touch location to be transformed into a retinotopic reference frame, the location of the eyes and head must be taken into account. Previous studies have found eye position–related errors (Harrar and Harris in Exp Brain Res 203:615–620, 2009) and head position–related errors (Ho and Spence Brain Res 1144:136–141, 2007) in tactile localization, indicating that imperfect versions of eye and head signals may be used in the body-to-visual coordinate transformation. Here, we investigated the combined effects of head and eye position on the perceived location of a mechanical touch to the arm. Subjects reported the perceived position of a touch that was presented while their head was positioned to the left, right, or center of the body and their eyes were positioned to the left, right, or center in their orbits. The perceived location of a touch shifted in the direction of both head and the eyes by approximately the same amount. We interpret these shifts as being consistent with touch location being coded in a visual reference frame with a gaze signal used to compute the transformation.