RELATIVE EFFICIENCY FOR THE DETECTION OF APPARENT MOTION

We measured the relative efficiency for motion and position discrimina tions of brief, localized spot stimuli with a technique that makes no assumptions about sites of noise or information loss in the visual sys tem. In one task, the observer had to discriminate whether an incremen t was located at one (left) or another (right) closely spaced spots. I n the other task, the observer had to discriminate two successive brie f increments of the left spot from a left spot increment followed by a right spot increment. Ideal observer theory predicts identical perfor mance on the two tasks. Observers' thresholds, however, were significa ntly lower in the motion task at all intervals between Bashes (ISIs) l ess than 60 msec in one observer and all ISIs less than 150 msec in tw o other observers (P < 0.01, t-test). We conclude that this apparent m otion stimulus is seen more efficiently than a non-moving stimulus, an d that the higher efficiency may be due to use of a motion sensitive c hannel in addition to independent position sensitive channels. Copyrig ht (C) 1996 Published by Elsevier Science Ltd.