Comparison of perceived spatial frequency between the fovea and the periphery.

A grating viewed in the periphery usually appears to be of higher frequency than the same grating viewed at the fovea, for frequencies below the Nyquist frequency of the periphery. Systematic shifts in perceived frequency between fovea and periphery were found under several experimental conditions: spatially localized or extended sine-wave patterns, test stimuli presented in the superior or the inferior visual field, and stimuli of high or low mean luminance at several different contrasts. A multiple-spatial-frequency channels model can qualitatively account for our results, if it is assumed that each channel has a receptive-field size that increases as a function of eccentricity but has a perceived frequency label that does not change as a function of eccentricity.