Spatial-Frequency Masking in Vision: Critical Bands and Spread of Masking*

Vertical sinusoidal gratings were viewed in masking noise consisting of vertical stripes spread along the horizontal direction. Masking functions were obtained while varying the grating frequency relative to various one-octave-wide bands of noise. These functions closely resemble curves derived from previous experiments on adaptation to gratings. Masking was also measured as a function of the width of a band of noise centered on the grating frequency. Masking increased as the band was widened up to approximately ±1 octave; masking did not increase further when the band was widened beyond this range. The results demonstrate that a grating is masked only by noise whose spatial frequencies are similar to the grating frequency. The experiments provide further indication of the existence of channels in the visual system that are selectively tuned to different spatial frequencies.