Abstract

Vernier acuity is a hyperacuity task which involves the ability to perceive a disparity in the relative location of two elements of a target. The term hyperacuity was coined by Gerald Westheimer because thresholds to these targets are substantially lower than thresholds to Snellen type targets (minimum resolvable acuity). Prac­ticed normal observers can detect vernier offsets of 2 to 10 seconds of arc, compared with normal Snellen thresholds of 30 to 60 seconds of arc. (Westheimer, 1981). Vernier acuity determinations require striatal integration of information from adjacent or overlapping receptive fields (Braddick, 1984; McKee and Levi, 1987; Westheimer and McKee, 1977).

© 1991 Optical Society of America