Human Colour Vision and Granit's Theory

Abstract

GRANIT'S brilliant experiments on electroretinography¹ have led him to postulate photopic and scoto 'dominator' mechanisms which have all the properties of independent brightness receptors, and 'modulator' mechanisms which may give cues to colour because they are sensitive to relatively narrow bands of the visible spectrum. Many of the animals on which the experiments were done, such as the cat, rat, guinea pig and frog, are totally colour blind to the best of our knowledge ; and Granit points out (a) that most laboratory animals, with the exception of the snake, possess very few modulators relative to their dominator units ; (b) that these proportions in the highly colour-sensitive human fovea are not known ; (c) that the demonstration of modulator units is not in itself a proof of the presence of colour vision.