Interaction between binocular rivalry and depth in plaid patterns

Binocular rivalry was studied using plaids which were the sum of orthogonal diagonal gratings plus identical vertical gratings in the two eyes. The rivalry alternations sped up as the spatial frequency difference between the vertical and diagonal gratings was increased above about one octave, but slowed down for smaller differences. The interaction between depth and rivalry was studied using similar plaids but with depth introduced in the vertical components. Depth and rivalry coexisted when the spatial frequency difference between the vertical and diagonal gratings was greater than about one octave, but rivalry slowed down and depth perception was reduced for smaller differences. Plaids consisting of square wave gratings were used to compare: (1) added gratings; (2) vertical gratings superimposed on (i.e. occluding) diagonal gratings; (3) diagonal gratings superimposed on vertical gratings. Rivalry alternations were fastest in condition (3), indicating that grouping effects played a role. The final experiment indicated that depth and rivalry coexisted within a spatial frequency band if the orientation difference between the vertical and diagonal components was 60–70°. These results place constraints on models of stereopsis and rivalry, indicating that depth and rivalry can coexist in different spatial frequency and orientation bands but that each interferes with the other in the same band.