Which photoreceptors are responsible for color discrimination?

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

Answer: (A)

Cones are the photoreceptors that enable color discrimination. They come in three types, each with sensitivity to different wavelengths (roughly corresponding to short, medium, and long wavelengths). The brain compares the signals from these different cone types to determine which colors are present. In dim lighting, rods take over, but they are not color-sensitive and provide grayscale vision, which is why color discrimination diminishes in low light. The other retinal cells mentioned—bipolar and ganglion cells—are not photoreceptors; they transmit and process signals from photoreceptors, but the actual color detection comes from the cones.