Disparity averaging across spatial scales.

To determine whether disparity averaging occurs across spatial scales, a series of depth matching experiments was performed using stimuli composed of the sum of two cosine gratings of different spatial frequency and retinal disparity. Although there were large individual differences in the data, averaging was observed when the relative frequency of the cosines were separated by 3.5 octaves or less and when the relative orientation was less than 30 deg. Beyond these limits, averaging never occurred and the stimulus components were perceived transparently in depth. Furthermore, as the relative contrast of the gratings was varied, perceived depth varied smoothly in the direction of the higher contrast component. This dependence on contrast can be accounted for by a multi-channel model in which separate disparity estimates are generated on each spatial scale and then combined to determine the overall perceived depth of the stimulus.