The principle stating that any single cone system is colorblind is called what?

• A. Color constancy
• B. Univariance
• C. Opponent-process
• D. Phototransduction

Answer: (B)

Univariance is the idea that a single cone type cannot signal wavelength on its own. A cone’s response reflects the total amount of light it absorbs, not the exact color. Different wavelengths can produce the same neural response if their intensities differ, so with only one cone type the color information is indistinguishable—hence colorblindness. Color vision comes from comparing signals across multiple cone types that have different spectral sensitivities, which is why humans rely on more than one cone to discern colors.

Color constancy is about keeping our perception of an object's color stable under changing lighting. Opponent-process refers to the post-receptoral coding of color in opposing channels (like red-green and blue-yellow). Phototransduction is the process by which photoreceptors convert light into an electrical signal.