Which system is primarily engaged in low-light environment vision?

The scotopic system is primarily engaged in low-light vision because it relies on rod photoreceptors, which are highly sensitive to light and enable us to see in dim conditions. Rods are not involved in color discrimination, which is why when lighting conditions are low, our ability to perceive colors diminishes, and we rely more on the shapes and distinctions of objects based on shades of gray. This adaptation allows for enhanced sensitivity and provides night vision, making it crucial for activities in dark environments.

In contrast, the photopic system is responsible for vision under well-lit conditions, utilizing cone photoreceptors that enable color vision and high acuity. The mesopic system serves as a transitional phase between photopic and scotopic vision, operating in intermediate lighting conditions. The diurnal system isn't a recognized term in visual physiology but generally refers to the behavior or processes linked to daytime or light conditions, further highlighting the distinct roles of rod and cone systems in vision across various levels of illumination.