Perception of coherent motion, biological motion and form-from-motion under dim-light conditions

Three experiments investigated several aspects of motion perception at high and low luminance levels. Detection of weak coherent motion in random dot cinematograms was unaffected by light level over a range of dot speeds. The ability to judge form from motion was, however, impaired at low light leve ls, as was the ability to discriminate normal from phase-scrambled biologic al motion sequences. The difficulty distinguishing differential motions may be explained by increased spatial pooling at low light levels. (C) 1999 El sevier Science Ltd. All rights reserved.