Asymmetries in visual acuity around the visual field

Human vision is heterogeneous around the visual field. At a fixed eccentricity, performance better along horizontal than vertical meridian and lower upper meridian. These asymmetric patterns, termed fields, have been found in numerous tasks, including those mediated by contrast sensitivity spatial resolution. However, it unknown whether resolution asymmetries are confined to cardinal meridians or how far they extend into hemifields. Here, we measured acuity at isoeccentric peripheral locations (10 deg eccentricity), every 15° of polar angle. On each trial, observers judged orientation (± 45°) one four equidistant, suprathreshold grating stimuli varying frequency (SF). block, as function stimulus SF 4 24 locations. We estimated 75%-correct threshold, cutoff point (i.e., chance-level), slope psychometric for location. higher estimates acuity) were most pronounced decreased gradually angular distance from increased. This gradual change with angle reflected shift without changes slope. The same pattern was under binocular monocular viewing conditions. findings advance our understanding processing field help constrain models perception.