Abstract
Measured luminance thresholds in 2 Ss for downward moving contours under several conditions of adaptation. Included was 1 condition which desensitized visual mechanisms responsive to downward motion. Another condition exerted equal effects on both up- and down-sensitive mechanisms. Thresholds for moving contours were unaffected by exposure to contours which moved in the opposite direction. Results indicate that the perception of motion does not depend upon the relative activity in oppositely tuned, directionally selective visual mechanisms.