Which photoreceptors are responsible for color vision?

• A. Rods
• B. Cones
• C. Ganglion cells
• D. Bipolar cells

Answer: (B)

Color vision comes from cones, a type of photoreceptor in the retina. Cones are present in three main types, each tuned to different parts of the spectrum—short (blue), medium (green), and long (red) wavelengths. The brain interprets color by comparing the relative activity of these three cone types. In bright light, cones are active and you can see a wide range of colors with good detail. In dim light, rods take over but they do not detect color, so color perception is greatly reduced or absent. The other retinal cells, like bipolar and ganglion cells, are part of the signaling pathway but do not provide color detection themselves—the color information starts with the cones.