Comparative monocular brightness contributions in normal binocular observers

In order to find out whether equal monocular light stimuli result in equal monocular brightness sensations in normal binocular observers, one-half of a bipartite field presented to one eye was matched to the other half seen by the opposite eye while a binocular surrounding field maintained constant adaptation. Ratios of monocular luminances required for brightness matches showed an overall average mismatch of 2% (SD = 2) in 12 subjects. This value is significant at the 0.01 level, and only one subject showed a mismatch greater than 6% (more than 2 SD from the mean). It is concluded that about two-thirds of normal binocular observers would be expected to show monocular contributions to brightness that match each other within 4% or better.