Abstract
Purpose: We investigated the general mechanisms of disparity averaging. Methods: We employed a method of constant stimuli to measure the perceived depths for compound sine-wave gratings with two components placed at different depths. Observers compared perceived depths between two compound gratings: test and reference gratings. In each condition, both compound gratings contained the same spatial frequencies (SFs) and contrasts. Both components in the test grating were fixed at different disparities while the components for the reference grating had the same disparity. The reference disparity varied from trial to trial. The task was to indicate which grating was farther. Across conditions, component SFs and contrasts were varied independently and systematically. Results: At equal component contrast, the perceived depth is biased towards the disparity of the higher-frequency component. When the contrast of one of the components is reduced, the overall perceived depth moves towards the disparity of the other component. The rate of this change in perceived depth with respect to contrast differs for different SFs. The perceived depth as a function of contrast is systematically ordered with respect to ratios between the component SFs, independent of their absolute values. Conclusion: Both SF and contrast are significant factors in disparity averaging and they interact with each other. The general observation is that the greater the SF ratio, the greater the bias in perceived depth towards the higher SF.