How far can rats see? - briefly
Rats can detect objects at distances of roughly one to two metres when lighting is sufficient. Their visual system prioritizes motion detection over sharp, long‑range detail.
How far can rats see? - in detail
Rats possess a visual system adapted to their nocturnal and crepuscular habits. Visual acuity is low; the best‑measured resolution is approximately 1 cycle per degree, comparable to 20/400 in human terms. Consequently, objects must be relatively close to be distinguished as distinct shapes. Experiments using grating patterns indicate that rats can resolve details only within a range of 10–30 cm under moderate illumination.
Field of view is wide, extending roughly 300° horizontally due to laterally positioned eyes. This panoramic perception aids in detecting motion at the periphery rather than focusing on distant stationary targets. Depth perception relies heavily on motion cues and whisker input, compensating for limited stereoscopic vision.
Low‑light performance is enhanced by a high proportion of rod photoreceptors and a reflective tapetum lucidum. Under scotopic conditions, rats can detect light sources from several meters away, but identification of form remains restricted to the near field. Behavioral studies show avoidance responses to looming shadows presented at distances of 0.5–1 m, suggesting sensitivity to distant movement without detailed visual discrimination.
Color vision is dichromatic, with peak sensitivity in the ultraviolet and green regions. This spectral range does not extend visual distance; it primarily influences foraging and mate selection.
In summary, rats can detect the presence of light and motion at distances up to a few meters, yet the ability to resolve shapes and patterns is limited to a few tens of centimeters. Their visual strategy emphasizes broad coverage and motion detection, supplemented by tactile and olfactory systems to navigate and locate objects beyond the immediate visual range.