Final answer:
The trichromatic theory of color vision is based on the combination of colors in an additive fashion, where different colors of light merge to create various hues.
Step-by-step explanation:
The trichromatic theory of color vision is based on the combination of colors in an additive fashion. This theory posits that the human eye has three types of cones sensitive to red, green, and blue light, and different combinations of these primary colors produce all the hues we perceive. Additive color mixing occurs when different colors of light are projected onto a surface and combine; for example, when red, green, and blue light mix, the result is white light. This contrasts with subtractive color mixing, where pigments absorb certain wavelengths and reflect others, which commonly applies to physical media like paints.