ROLE OF OPTICAL-FLOW FIELD ASYMMETRY IN THE PERCEPTION OF HEADING DURING LINEAR MOTION

During linear translation through a stationary environment, the patter n of optical flow generated on each retina is symmetrical when the hea d is aligned with the heading, but during lateral gaze the optical flo w is asymmetric. We assessed whether human subjects could use the magn itude of this asymmetry to determine the direction of heading during p assive translation through a 3-D environment. When allowed to move the ir heads in order to look in the direction of self-motion, subjects in dicated their heading precisely and accurately. When the head was lock ed in alignment with the misaligned body, and gaze adjustments were no t allowed, responses were quite precise, but showed a large bias which increased with increasing heading angle.