SPATIOTEMPORAL REQUIREMENTS FOR BINOCULAR CORRELATION IN STEREOPSIS

We measured sensitivity to binocular correlation in dynamic random-dot stereograms that defined moving sinusoidal gratings-in-depth. At a ra nge of spatial frequencies and drift rates we established sensitivity by adding Gaussian distributed disparity noise to the modulation of di sparity that defined a cyclopean grating, and finding the noise amplit ude that rendered the grating just detectable, This permitted correlat ion thresholds to be measured at a range of suprathreshold disparity a mplitudes. Spatial requirements for binocular correlation depend littl e on temporal frequency, and vice versa, This suggests that binocular correlation mechanisms can be characterized by independent spatial and temporal sensitivity functions. The temporal frequency function has a low pass characteristic, Sensitivity declines above about 1 c/sec, re aching its limit at 4-8 c/sec. The spatial characteristic depends grea tly on the amplitude of disparity modulation, changing from band pass at low amplitude to low pass at high amplitude, The maximum resolvable spatial frequency is 46 c/deg, but declines sharply for relatively hi gh amplitudes, The interaction between amplitude and spatial frequency cannot be explained by fixed high or low limits on detectable dispari ty gradients.