Abstract
Purpose: Gabor patches have ambiguous binocular matching solutions that can either minimize their absolute disparity (nearest neighbor match-NN) or the relative disparity between adjacent patches (minimum relative disparity match-MRD) (Zhang, Edwards, Schor. VIS RES 41(23)). Minimum relative disparity matching solutions follow the smoothness constraint for binocular matches. Using time delays between adjacent stimuli, we have investigated the temporal interval over which binocular matches that follow the smoothness constraint can occur.
Stimulus conditions: A Gabor patch with a 1 cpd carrier was flanked vertically between two separated Gaussian windowed RDS, with a 0.5 edge-to-edge separation. The RDS and Gabor were each presented for 200 ms. The RDS preceded the Gabor patch with temporal delays (inter-stimulus intervals) varying from 0 to 400 ms. The RDS phase disparity was fixed at 135 and Gabor disparity was varied. Subjects reported the depth ordering of the RDS and Gabor patches to indicate the matching solution (NN or MRD).
Analysis: Percent nearest neighbor match was plotted as a function of phase disparity of the center Gabor patch. These psychometric functions were used to estimate PSE that indicates the Gabor phase disparity value for which minimum-absolute-disparity and minimum-relative-disparity matching solutions had equal probability.
Results and Conclusions: PSE increased with temporal delay between the RDS and Gabor patch. As PSE increases, the minimum relative disparity between the RDS and Gabor decreases and the nearest neighbor matches increase. An exponential decay function described the plot of PSE as a function of temporal delay. Decay time constants ranged from 63 to 95 msec. The time constant estimates the temporal range of interactions between adjacent stimuli over which the smoothness constraint for binocular matches is applied.