The aim of this work was to measure narrow-band frequency response curves for two radial frequency filters, spatial stimuli modulated by cylindrical Bessel profiles, J0, whose test frequencies were 1 and 4 cpd. Five humans observers with normal or corrected visual acuity measured 15 curves for each filter with a supra-threshold response summation psychophysics method allied within a forced-choice paradigm. The results showed maximum summation effects at test frequency for filters 1 and 4 cpd surrounded on both sides by strong inhibition. These results are consistent with the existence of narrow-band radial frequency filters operating in human visual system either through summation or inhibition of specific frequency ranges.
Visual processing of form; radial frequency filter; radial frequency; supra-threshold summation method
