Which visual system has better temporal summation?

The scotopic visual system is responsible for vision under low-light conditions and relies primarily on rod photoreceptors, which are more sensitive to light than cone photoreceptors that operate under photopic conditions (bright light). Since rods can respond to lower levels of illumination, they also have a higher degree of temporal summation, which is the ability to accumulate light information over time.

Temporal summation refers to the process by which visual receptors can integrate light signals over a period of time to form a perception of a stable image, especially in dim lighting situations where quick changes in illumination are not as easily detected. Rods, due to their greater sensitivity and the fact that they can capture and process visual information at lower light levels, can effectively sum signals over a longer duration, making them more adept at detecting motion and changes in low-light environments. This characteristic enables the scotopic system to excel in detecting visual stimuli in circumstances where the photopic system might struggle due to inadequate lighting.

In contrast, the photopic visual system, which is based on cone photoreceptors, is optimized for bright lighting and color discrimination, functioning at a higher temporal resolution that allows it to detect rapid changes in visual stimuli more effectively but with lower sensitivity in low-light conditions