Abstract

Normal human observers have been shown to be acutely sensitive to the relative spatial position of visual features. The angular extent of just noticeable differences in position are much smaller than spatial resolution thresholds, and these very fine thresholds are called the hyperacuities (Westheimer, 1975). Examples of visual tasks that yield hyperacute thresholds are vernier alignment, bisection, stereoscopic depth, and relative motion detection.

© 1991 Optical Society of America