Solving the Aperture Problem: Perception of Coherent Motion

The aperture problem describes an effect by which a contoured stimulus, moving behind an aperture with both ends occluded, appears to move in a direction perpendicular to its own orientation. Mechanisms within the human visual system allow us to overcome this problem and integrate many of these locally ambiguous signals into the perception of globally coherent motion. In the current experiment, observers viewed displays composed of many straight contours, arranged in varying orientations and moving behind apertures. The total pattern of movement was consistent with a globally coherent trajectory. Observers were asked to estimate direction of global motion over a range of 0 to 360 degrees. Given a greater number of motion signals (i.e., 64 motions within apertures), younger adults can reliably and accurately judge coherent motion direction with an average error below 10 degrees. For fewer motion signals (i.e., 9 motions within apertures), younger adults exhibit greater error in their direction judgments