Temporal aspects of depth contrast.

Depth contrast is a contrasting change in the depth of a feature that results from changes in the disparities of other objects in the field of view, even though the disparity of the original feature remains unchanged. Depth contrast effects decrease during continuous viewing of the stimuli and may disappear altogether after several minutes unless the disparities of the inducing features change with time. This fading occurs whenever the inducing features have constant disparity, whether they are stationary or oscillating laterally. Depth contrast effects occur whenever the inducing features are visible within half a second before or after presentation of the test features. When test features are enclosed by a rectangle which is just inside of a circumscribing outer trapezoid, the inner rectangle "shields" the test features from the depth-inducing effects of the outer trapezoid. Surprisingly, this shielding effect persists if the inner rectangle and outer trapezoid have the same slant direction, but fades with time if the slants are opposite in direction.