Displacement limits for spatial frequency filtered random-dot cinematograms in apparent motion

Two-dimensional band-pass filtered random-dot cinematograms were used to study apparent movement mediated by the short-range process. In the first experiment maximum displacement (dmax) for correct direction of movement was measured for symmetrically filtered low-pass, medium-pass, and high-pass images. dmax was found to be limited by the grain size in the image and increased with the target area. Since eccentric presentation had no effect on dmax, the increase of dmax with target area suggests that apparent movement perception is a global process. In the second experiment the stimulus was filtered differentially in the two orthogonal directions using cone filtering. dmax was found to be commensurate with the length of the clusters in the direction of the movement.