The effect of slant on visuomotor localization

Visuomotor localization in the presence of slant was measured. Five subject s pointed at the center LED of an array of five LEDs viewed monocularly. Po inting was open-loop. The LEDs were separated by 1.5. 3.0, or 4.5 cm. The a rray was rotated about a vertical axis coincident with the center LED to sl ant the array from - 50 degrees to + 50 degrees. LED separation had no effe ct. A small linear relationship was found between errors in localization an d slant (slope = - 0.02). The errors were as expected if the perceived stra ight ahead was in the direction of the normal to the surface, but these err ors were so small as to be functionally insignificant. It is concluded that extraretinal eye position information dominates over slant for visuomotor localization. (C) 1999 Elsevier Science Ltd. All rights reserved.