Selectivity of cyclopean masking for the spatial frequency of binocular disparity modulation.

Previous studies have presented evidence for the existence of channels tuned to the spatial frequency (SF) of binocular disparity modulation. Bandwidths reported for masking curves were extremely narrow, possibly because of off-frequency viewing, whereby observers can best detect a signal with a channel tuned to an SF on the opposite side of the signal from the masker's SF, rather than with a channel tuned directly to the signal's SF. Herein are reported the results of four detection experiments. Experiment 1 measures unmasked threshold for detection of a cyclopean grating. Experiments 2-4 are masking experiments. Experiment 2 demonstrates that threshold for detection of a cyclopean grating is proportional to the intensity of masking noise, which is consistent with the operation of linear channels. Experiments 3 and 4 demonstrate that masking curves are narrower when obtained with narrowband-noise maskers than when obtained with notched-noise maskers, which render the off-frequency viewing ineffective. Implications for understanding the processing of cyclopean images are discussed.