New phenomena show effects of luminance motion on stereoscopic motion and on color motion

Abstract

Stereoscopic motion involves binocular disparity and luminance. In general, binocular and luminance contours of objects move in synchrony, thus sending identical direction signals to binocular disparity and luminance channels. It is possible, using random-dot stereograms, to generate independent directions of motion for luminance dots and cyclopean surfaces. To help illustrate our point, we refer to Ramachandran and Anstis (1986), who raised the question of what would happen if the leopard and the spots on the leopard’s body were to move in opposite directions. Would we still be able to see where the leopard is going? The phenomena we have observed showed that smooth coherent cyclopean movement, in both the frontoparallel and the toward-away direction, can be seen only if luminance motion exists. This suggests that stereoscopic motion is processed by separate binocular disparity and luminance motion units. In the case of color motion, we investigated if motion direction, that is defined solely by color, can be seen under equi-luminant conditions. Instead of using the isoluminant values for different colored dots, we randomized the luminance of the red and green dots in a random-dot cinnematograms to achieve equiluminance. Under these conditions, motion direction which is based solely on color correspondence cannot be perceived. Therefore, like stereoscopic motion, color motion is processed by separate color and luminance motion channels.