Abstract: The relation between stimulus size of sine gratings and the low spatialfrequency channels has been systematically investigated by television technique. Experimental data suggest that the human visual system contains thelow spatial frequency channels. Variation of stimulus area of gratings is asignigicant condition for the display of the low spatial frequency channels. Itwas found that with the area of sine gratings increasing (from, 1°, 2°to 5°,10°field), human eyes become more sensitive to the low spatial frequency,to which the position of the lowest spatial frequency channels is leading, andadaptable range of the low spatial frequency is extended (from 3 c/d to 0.2c/d). At 10°visual field position of the lowest spatial frequency channelsstays at 0.3 c/d. The asymmetry of the bandwidth of the low spatial frequencychannels has also been observed.

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