The ability to distinguish various colors is tested by the use of the pseudoisochromatic plates is made possible by the presence of proper functioning of the cones located in the retina of the eye color blindness.
The ability to perceive colors. Specialized cells called cones in the light-sensitive layer (retina) at the back of the eye contain chemicals that are maximally sensitive to red, green, and blue wavelengths. When stimulated by light, the cone cells transmit impulses to the brain. These impulses are then blended in the brain to produce the many hues the human eye can perceive. A defect in color perception is known as color blindness.