Figure 11.

Depth from horizontal disparity versus RDA. (A) Monocular example of center-surround plaids, with exaggerated contrast. In the experiment the disparity of the annulus was fixed while the disparity of the center plaid was varied in order to determine the point of subjective equality (PSE) for depth. Component orientations of the plaids were 45°/75°, 75°/105°, and 105°/135° in various center-surround combinations. Disparity directions were 0° and ±30°. Stimuli were presented briefly (180 ms) after horizontal and vertical nonius alignment of the eyes and in the absence of irrelevant binocular stimuli (Farell & Ng, 2018). (B) Means and standard errors of depth-match disparity ratios for four observers. Ratios are between target and reference disparity magnitudes at the depth match. Also shown are the ratios predicted by horizontal disparity and RDA metrics. Fit of RDA predictions to the data exceeds that of horizontal predictions (r² = 0.83, t₍₂₎ = 3.08, p < 0.05 and r² = 0.20, not significant, respectively). Stimulus conditions, defined by plaid orientations and disparity directions, are sketched along the x-axis. Each condition contained two symmetrical stimulus arrangements (sets 1 and 2). The stimulus appearing in panel A is an example of the two left-most stimulus pairs in set 2.