Normal visual acuity, that is, the minimum separation required to resolve two features (about 1 min of arc), is fairly well understood. Another class of tasks involves spatial localization of features, the so-called hyperacuities, with thresholds of 1 to 10 seconds of arc. Several models have recently shown how the visual system can achieve this astonishing performance. The demonstration that visual acuity and hyperacuity are relatively unaffected by retinal image motion at velocities ranging up to 3 deg/sec causes problems for many of these models. The importance of achieving good acuity in the presence of image motion should not be underestimated. The task of compensating for retinal motion is likely to be one of the main problems to be solved by the mechanisms of early vision. The eyes are constantly moving, so in order to preserve image quality there must have been strong evolutionary pressures to solve this problem. Dr. Stanley Klein is a leading investigator in the area of spatial vision. Dr. Klein's research has two goals. The first is to understand how high levels of acuity are maintained during image motion. The second goal is to use image motion to isolate distinct localization cues for a variety of hyperacuity tasks. The experiments will test predictions from several models of acuity and hyperacuity. The results of the proposed experiments will also provide additional constraints on a model of human spatial localization for stationary stimuli being developed by Dr. Klein.
