VISUAL-PERCEPTION OF MOTION - A NORMATIVE STUDY

Background A battery of tests has been developed to better define the variety of defects which can occur in the process of visual perception of motion. Methods The tests assessed the perception of 1) coherent m otion, in each of the four cardinal directions; (2) form from motion; (3) flow in depth; and (4) motion of a target moving in depth, within or without an optic flow surround. A normative study was conducted wit h 34 subjects, 21 to 69 years of age. Results Recognition of form from motion was better with upwards than with downwards motion. Perception of motion in depth was better with backward than forwards motion. The presence of an optic flow altered the perception of a motion in depth . Conclusion The recognition of form from motion demonstrated an asymm etry in threshold between the upward and downward movements. This asym metry did not occur with global coherent motion, thus reflecting the v ariety of mechanisms involved in the visual process of motion. Moreove r, alteration of perception of motion in depth within an optic flow re flected background effect.