The effect of spatial frequency on binocular contrast inhibition

Previous work has shown that binocular contrast summation, obtained with equal monocular sensitivities, remains constant over a range of spatial frequencies. We measured binocular contrast detection with a log 1.00 ND filter placed in front of one eye. For all eight subjects, the binocular contrast detection decreased to a level below that of the monocular detection, demonstrating a contrast analogy to Fechner's paradox. The degree of binocular inhibition, like summation, remained constant across the range of spatial frequencies.