The visual processes underlying binocular brightness summation

Abstract

Magnitude estimates of the brightness of targets presented monocularly were combined to predict the binocular brightness resulting from the fusion of monocular targets of various luminances. It was found that binocular brightness was a function of the vector sum of the monocular brightness responses and the spatial cross-correlation of the two monocular test fields taken as wholes. Certain non-linear summation effects, e.g. Fechner's Paradox, found by previous investigators, were controlled in this investigation. An underlying mechanism explaining the non-linearities is proposed.