Kinematogram

A kinematogram, often referred to as a random-dot kinematogram (RDK), is a visual stimulus used in vision science to study motion perception. It consists of a field of small dots displayed against a uniform background. A portion of the dots moves in a common direction (coherent motion) while the remaining dots move in random directions (noise). By adjusting the proportion of coherently moving dots, researchers can control the strength of the motion signal.

Several parameters shape a kinematogram. Coherence is the percentage of dots moving together, and it governs the ease with which observers can perceive the overall motion direction. Other variables include dot speed, dot density, and whether dots have a finite lifetime (disappearing and reappearing at new locations) or persist throughout the trial. Kinematograms can also vary in the field size, duration of presentation, and the angular dispersion of the coherent motion.

Kinematograms are used to measure motion perception thresholds and to probe the neural mechanisms underlying motion processing. In psychophysics, observers report the direction of motion, allowing researchers to derive psychometric functions that reflect sensitivity to coherent motion. In neuroscience, the method helped establish the role of area MT/V5 in motion perception and the tuning of neurons to direction and speed.

History and variants: random-dot stimuli were developed to isolate motion cues from form cues and have become standard in studies of visual motion. While primarily used for motion, related stimulus types exist for depth and binocular processing as well.