Final answer:
In darkness, cones cannot react well to low-intensity light, so the brain relies on rods which lead to grayscale vision as cones are responsible for color detection.
Step-by-step explanation:
The brain activates retinal cones by comparing the activity of the different cones which are sensitive to various wavelengths of light, allowing us to perceive color. However, in darkness, cones cannot react to low-intensity light, and vision is primarily dependent on rods, which do not sense color.
Hence, in darkness, our vision is essentially in grayscale, as cones are not activated and rods take over. Any perception of color in low light conditions is likely due to the brain's memory of the object's color in normal lighting. In conditions where there is very little light, such as a dark room, cones are not sufficiently stimulated to send visual signals based on color.
Rods, on the other hand, can be activated by even a single photon. The continuous tonic activity of photoreceptors in the retina ensures a baseline firing rate that adjusts with changes in light exposure, allowing for the perception of light and dark contrasts despite the absence of colored vision in dim environments.