Isolation of Binocular Cues for Motion in Depth

There are two binocular cues of motion in depth: the interocular velocity difference (IOVD) and changing disparity over time (CDOT). Psychophysical evidence for the contribution to perceiving motion in depth has been accumulated for both of the two cues, using techniques to isolate each cue. However, no study estimated seriously how reliably each cue is isolated in the techniques. In this study, we apply a model of motion in depth to estimate how each type of stimuli isolates each of IOVD and CDOT cues. The model consists of the motion energy and the disparity energy detectors as subunits and adds their outputs to built the IOVD and CDOT detectors. Simulations show that some, but not all of stimuli used in the literature are appropriate for isolating cues. The temporally uncorrelated randomdot stereogram isolates CDOT cue and the binocularly uncorrelated randomdot kinematogram isolates IOVD cues. However, temporally anticorreated version of randomdot stereogram has influence of reverse motion components of IOVD and binocularly anticorreated version of randomdot kinematogram has influence of reverse motion components of CDOT. Gratings with opposite orientation between the eyes are also good for isolation of IOVD. We performed psychophysical experiments to examine the plausibility of the model prediction