Orientation sensitivity in the peripheral visual field.

Orientation sensitivity in the peripheral visual field has been tested in two tasks: (a) setting horizontal the orientation of a grating at various retinal eccentricities, and (b) matching the orientation of a peripherally viewed grating as close as possible to an oblique reference viewed foveally. Both performances fall off with increasing retinal eccentricity. Magnification of the stimulus optimizes peripheral performance. Peripheral performance, optimized by magnification, varies with retinal eccentricity. It approaches, but does not reach, the foveal value (tested by the same method) at 10 deg of eccentricity, and is much lower at 20 and 30 deg of eccentricity.