Visual Spatial Aftereffect from Prolonged Head-Tilt

Subjects with head upright were required to adjust a lighted bar in a dark room until the bar appeared vertical; the task was performed before and after 2 and 3 minutes of lateral head-tilt with their eyes closed. A visual spatial aftereffect was observed which varied as a function of the angle of head-tilt and which was opposite in direction to head-tilt.