If the perceived depth separation between two the stimuli depended only on the relative disparity of components that had the same orientation in both stimuli, the perceived depth functions of
Figures 2 and
3 should be flat. To a first approximation, they are flat. In addition, PSE values should be proportional to the disparity of the plaid component parallel to the test grating; that is, 0° in R
0 conditions and 5°, 15°, or 30° in R
+ conditions.
Figures 2 and
3 show this, too, to be the case. However, both R
0 and R
+ conditions also show minor effects of plaid angle; as discussed below, either component disparities or pattern disparities might be the source of these influences. These effects, evident in
Figures 2 and
3, contributed to statistically significant interactions between reference grating type, R
+ or R
0, with component disparity (
F(2, 16) = 107.7), plaid angle (
F(4, 32) = 8.1), and both component disparity and plaid angle (
F(8, 64) = 2.8), as determined by ANOVA, with all
ps < 0.01, except the last (
p = 0.011). The main effect of test grating type, R
+ vs. R
0, (
F(1, 8) = 76.7), was also significant (
p < 0.01).