Rat Vision

What is in a rat's vision?

Seeing a rat's behavior each time they are found in human territories, it begs us the question, "What exactly do they see around them?". For some time scientists have been studying how rats perceive the world through their eyes, and they now somehow have a pretty clear idea on what's on the scene. Generally, rats are actually dichromats. They perceive the world through their eyes pretty much of human beings do, but with slight red-green color blindness. However, the color saturation in their vision is severely faint, and surprisingly, the color found in their environment is of less importance compared to the value of brightness in their vision. Actually, the vision of rats is very blurry; that's the case in most rats. But in cases of albino rats, they are more than half the time blind or extremely visually degraded. The rating of their vision would be around 20/1200.

Vision in Pigmented Rats

Surprisingly, despite the difference in visual projections humans and rats have something in common in the optical structure. Both species have two light receptors: cones and rods. Cones are the ones responsible to receiving the brightness or lightness of the color being perceived, while rods are the ones responsible sensing the dimness of the light and couldn't not detect the color. However, the retinas of humans differ from rats. The density and types of the retinal cones differ, and are the source of visual implication.

Colors in the Retina

In humans, we have three types of colors seen through our retinas. Hence, we have trichromatic sense of vision. The trichromatic color perception of is comprised of shortwaved cones colored blue, mid-wavelength green and longer wavelength cones colored red.

However, since rats are dichromatic, they only have two cone types in their retinas: a short-blue wave and the middle red wave cones. The peak sensitivity of the green ones is somewhere around 510 nm. The blue cones are then shifted to shorter wavelengths and would only reach a peak of 359 nm. This would imply that rats could actually see through ultraviolet, therefore making them see certain colors invisible to a human's naked eye.

There is about 88% percent of the rat population all over the globe whose color cones are middle green type while there are only a 12% of them that are with long blue UV receptive cones. The UV receptors are seen below or bottom of the rat's retina.

Color Perception in Rats

Now that we know that a rat's retina is super sensitive to green and blue-colored ultraviolet, the question now would be are they able to discern and perceive the colors that they see and distinguish the difference between all of them?

For a very long time, rats were believed to be color-blind (unable to distinguish the difference between color types). However recent studies indicate that rats are actually able to distinguish the difference between colors through the fact that they do perceive ultraviolet colors. They have further deduced that with proper training, they will be able to distinguish the difference between ultraviolet light and visible light as well as the disparity between the ranges of blue and green.

Having that sort of visual perception, we wonder, what would that vision look like in animals that could only distinguish between green and blue, red colors would look dark to them. They would also happen to have a neutral point in perceiving the blue and green colors. If there are grey shades, they would still find difficultly in identifying them. However, they are keen in identifying colors that can only be visible through ultraviolet.