Calibration of Distance and Size Does Not Calibrate Shape Information: Comparison of Dynamic Monocular and Static and Dynamic Binocular Vision

This study investigated the coupling of distance and size perception as well as the coupling of distance and shape perception. Each was tested in 2 ways using a targeted reaching task that simultaneously yielded measures of distance, size, and shape perception. First, feed-forward reaches were tested without feedback. Errors in size did not covary with errors in distance, but errors in shape did. Second, reaches were tested with visual feedback. Estimated distance and size became more accurate, but shape did not. The evidence indicated that distance and size perception and distance and shape perception are not coupled. These results were replicated 3 times, as we also compared performance using dynamic monocular, static binocular, and dynamic binocular vision. Performance was better with binocular than monocular vision both without and with feedback. The presence of a size gradient did not improve monocular distance perception, yielding additional evidence that distance and size perception are not coupled.