This study investigates how mechanisms for amplifying 2-D motion contrast influence the assignment of 3-D depth values. The authors found that the direction of movement of a random-dot conveyor belt strongly inclined observers to report that the front surface of a superimposed, transparent, rotating, random-dot sphere moved in a direction opposite to the belt. This motion-contrast effect was direction selective and demonstrated substantial spatial integration. Varying the stereo depth of the belt did not compromise the main effect, precluding a mechanical interpretation (sphere rolling on belt). Varying the speed of the surfaces of the sphere also did not greatly affect the interpretation of rotation direction. These results suggest that 2-D center-surround interactions influence 3-D depth assignment by differentially modulating the strength of response to the moving surfaces of an object (their prominence) without affecting featural specificity.