title: Subadditivity and superadditivity in heterochromatic brightness matching.
abstract: Heterochromatic brightness matches were carried out between bichromatic mixtures of lambda 1 and lambda 2, and a 100 td white reference light of 2 degrees arc. Two characteristic properties of additivity failure were observed. One is the asymmetrical property of additivity failure, that is a remarkable brightness reduction at the luminance ratio where the hue cancellation occurred. The other is the superadditivity for a mixture of a violet and a white or a middle-wave light. These properties were accounted for by a nonlinear vector model on the assumption that the opponent-color channels outputs were nonlinearly transferred to the brightness perception.
mesh_terms: D000328:Adult; D003118:Color Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008959:Models, Neurological; D013053:Spectrophotometry