Which visual system has greater sensitivity overall?

The scotopic system, which operates in low light conditions, has a greater overall sensitivity compared to the photopic system, which functions under well-lit conditions. This greater sensitivity in the scotopic system is primarily due to the presence of rod photoreceptors in the retina. Rods are highly sensitive to light and can respond to a single photon, making them crucial for vision in dim environments.

In contrast, the photopic system, dominated by cone photoreceptors, is responsible for color vision and fine detail detection in brighter light. Although the cone system provides higher visual acuity and allows for color discrimination, it is less sensitive to light intensity than the rod system. Therefore, in situations with low illumination, the scotopic system excels in detecting faint stimuli, demonstrating its greater sensitivity overall.

This distinction enhances our understanding of how the human visual system adapts to different lighting conditions and the roles played by different types of photoreceptors.