The use of different features by the matching process in short-range motion.

The perception of the direction of motion in luminance kinematograms breaks down when the displacement exceeds a few element widths (this limit is called Dmax). When kinematograms whose elements differ only, in hue are used, motion can be seen but performance declines at smaller displacements. The short-range process, once thought to be only a luminance correlator, is thus able to use hue. If the size of Dmax indicates how well a feature stimulates the motion sensors, hue might be said to have an especially weak input to motion sensors. In order to find the relative potency of luminance and hue as bases of the short-range matching process, Dmax for these features was compared to those obtained for kinematograms whose elements differed in phase (T-phase or L-phase) or orientation (/or/). The matching process could use all the features tested. Luminance seems to be the preferred basis for motion matching, with hue and phase (a tie) yielding smaller Dmax and orientation the smallest.