Date of Award

Spring 2008

Project Type


Program or Major


Degree Name

Master of Arts

First Advisor

William Wren Stine


When square wave gratings are viewed binocularly with lower luminance or contrast in one eye, the individual bars of the grating appear to rotate around a vertical axis. Studies of motion-and-depth using geometric disparities have shown that perceived depth vanishes at frequencies near 5 Hz. By changing contrast disparity over time, this study measured the frequency at which both the perception of motion-and-depth and the perception of depth are no longer visible. For experienced observers, the perception of motion-and-depth decreased at 1 Hz (Experiment 1) and the perception of depth decreased at 1.4 Hz (Experiments 1 and 3); both of which are lower than the frequency where depth from a geometric disparity diminishes (above 5 Hz in experiment 2). These results were replicated with a naive observer (experiments 4 and 5). The differences between the dynamics of depth from geometric and contrast disparities suggest that the perception arises from separate neural mechanisms.