A comparison of stereo and vernier acuity within spatial channels as a function of distance from fixation.

We have used DOG stimuli to selectively stimulate size tuned channels within the visual system in order to investigate the relationship between stereo and vernier acuity. We measured these acuities as a function of spatial frequency, retinal eccentricity and distance from the fixation point in depth. Both hyperacuities are poorer with low spatial frequencies but vernier was effected to a smaller extent. Vernier acuity deteriorated to a much greater degree than stereo acuity as retinal eccentricity increased up to 40 arc min. Stereo acuity was more dependent upon distance from the fixation point in depth than would be expected from the dependence of vernier acuity on retinal eccentricity. We conclude that there must be different limiting factors for the two hyperacuity tasks.