The human retina contains some 100 million photoreceptor cells. When these are stimulated with light, they communicate that information to the brain and we perceive light. Researchers have now discovered that when light impinges on the photoreceptor-free blind spot alone the pupillary reflex does not occur, but the pupillary reflex is enhanced in response to bright illumination in a normal part of the retina when blue or white light containing shorter wavelengths is simultaneously delivered inside the blind spot.