Abstract
Relative retinal motion yields depth perception when combined with an observer's head movement to form motion parallax, as well as relative motion perception when the observer's head is stationary. The present study compared detection thresholds of relative motion and depth from identical random dots patterns containing sinusoidally modulated velocity gradients, to explore relation of their processings. In Exp. 1, the detection thresholds were determined as a function of the spatial frequencies (SFs) of the velocity gradient. SF threshold functions of the motion and depth showed U-shapes similar except that the depth threshold was elevated above the motion threshold and increased more considerably in the higher SFs. In Exp. 2, the detection thresholds were determined as a function of viewing distance. The depth threshold decreased with the viewing distance, whereas the motion threshold did not change. These results suggest that the relative motion detector and the depth detector are different in the following respects: (1) the depth detector is located later in the processing path, (2) it has larger receptive field area, and (3) it includes distance information.
