p329fig08.50 The common motion direction of the two dots builds upon illusory contours that connect the dots as they move through time.  The common motion directin signal can flow along these boundaries.<BR>||  How is common motion direction computed?  retinal motion.  Bipole grouping in the form stream creates illusory contours between the dots.  V2-MT formotion interaction injects the completed boundaries into the motion stream where they capture consistent motion signals.  Motion of illusory contours is computed in the motion stream: cf. Ramanchandran