Going back to the discussion of the retina, recall that there are two different kinds of receptor cells in your eyes—rods and cones. As we reminded you, the rods are responsible for achromatic vision, or colorless vision. The cones, on the other hand, are the receptors that enable you to see colors. Without them, you are color blind, whereas a problem with one or two types of cones leads to a color deficiency.
Observations about additive color mixtures—e. g. , that the combination of just three primary colors (Young suggested red, green, and blue) produces all the colors of the visual spectrum—led to the first major theory of color vision. This is the Young-Helmholtz, or trichromatic, theory. (Trichromatic means three colors. )
Thomas Young |
In 1802, English physician and physicist Thomas Young theorized that the perception of colors is caused by a pattern of stimulation of three different receptor types (cones) in the eye. For example, light reflected from a ripe banana would cause little activation of “blue” receptors and approximately equal stimulation of “red” and “green” receptors, causing us to perceive the banana as yellow. |
