Which system has better spatial resolution?

• A. Scotopic
• B. Photopic
• C. Both equally
• D. Neither

Answer: (B)

Spatial resolution is about how well two nearby points can be distinguished as separate. In bright light, vision is mediated mainly by cones. Cones have small receptive fields and, especially in the central retina (the fovea), connect to ganglion cells with little pooling—often one cone per ganglion cell. This keeps signals precise and allows fine detail to be detected, giving high spatial resolution.

In low light, vision relies on rods. Many rods funnel their signals through the same ganglion cells, producing large receptive fields. This pooling increases sensitivity to dim light but comes at the cost of detail, so spatial resolution is reduced.

So, the cone-dominated, photopic system provides better spatial resolution than the rod-dominated, scotopic system.