The effects of luminance on affinity of apparent motion

When a single rectangle is replaced by two flanking ones, or vice versa, one sees split or fusion motion. The motion correspondence in these displays is supposed to reflect the affinity between elements. We examined the effects of the element luminance on the affinity. The results indicated that the affinity did not reflect the luminance similarity; it monotonically increased with increasing the luminance of either element of the matching pair. It was also found that the effects of luminance was symmetric in the time axis. These results were obtained for both long-range and short-range apparent motion. Our findings suggest that the affinity directly reflects the response of the simple motion detectors regardless of the displacement size.