Final answer:
The trichromatic theory posits that the retina contains three types of color receptors or cones that are sensitive to red, green, and blue light, enabling the perception of the full color spectrum through combinations of these primary colors.
Step-by-step explanation:
The Young-Helmholtz (trichromatic) theory of color vision proposes that there are three types of color receptors in the retina. This theory states that color vision is possible through the activation of these receptors for the primary colors: red, green, and blue. The receptors, which are types of cones, each respond to different wavelengths of light. When these cones work in combination, they can produce the perception of the full color spectrum.
In accordance with this theory, the perception of various colors arises from the mixing of the three primary colors at different intensities. This doctrine is an essential element of understanding how our visual system interprets color and translates light into the vivid imagery we perceive.