Which photoreceptors are responsible for color vision and high acuity in bright light?

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

Answer: (B)

Cones are the photoreceptors responsible for color vision and high acuity in bright light. They come in multiple photopigment types, enabling detection of different wavelengths and thus color. Cones also have small receptive fields and relatively little convergence onto bipolar and ganglion cells, especially in the fovea, so each cone’s input can be resolved into separate signals that the brain uses to form sharp detail. In daylight, this photopic system dominates, giving both color perception and high spatial resolution. By contrast, rods are highly sensitive in dim light and contribute to motion and brightness perception but not color, and their signals converge more, which lowers acuity. Ganglion and amacrine cells are processing neurons downstream of photoreceptors, not photoreceptors themselves.