Fig. 30. Random Dot Cinematograms. Testing motion perception demands stimuli that minimize inferences of movement from noticeable changes in the visual scene, the way we “see” movement of moon or stars. Suitable stimuli are computer generated animation sequences known as random dot cinematograms (RDC). RDC present a motion signal (open circles) moving in a consistent direction (e.g., up, down, right, left) amid spatially random background noise (closed circles). By varying the ration of signal to noise it is possible to quantify motion perception in patients with cerebral or retinal disorders.