Experiments by George Wald and others showed that rods are most sensitive to wavelengths of light around 498 nm (green-blue), and insensitive to wavelengths longer than about 640 nm (red).
Os experimentos realizados por George Wald e outros demostraron que os conos son máis sensibles a lonxitudes de onda de arredor de 498 nm (verde azulado), e insensibles a lonxitudes de onda maiores de 640 nm (vermello).