Have you ever made eye contact with your pet rat and wondered if they see the world as you do? Can your rats see you? Is their world black and white?
While they have a very different type of eyesight than humans, rats still see most of what we do – just differently. They can differentiate between certain colors, and they can definitely see you looking back at them.
To find out exactly how your rat sees the world, keep on reading!
How do Rats See the World?
Can Rats See Humans?
Of course, your pet rat can see you. But your rat’s vision is very different from yours.
For starters, your rat’s world is rather blurry. A pet rat has a visual acuity (measure of the ability to distinguish the details of objects) of about 1 cycle per degree (cpg), compared to humans’ 30 cpg1!
While they can recognize the outlines of objects, the details are hazy to them.
Additionally, rats have poor binocular vision, as their eyes are on the sides of their heads, so the fields of vision from both eyes don’t overlap very much2.
Due to this, rats have a much larger field of vision than humans do – a feature that is very important for a prey animal, as it enables them to spot the danger coming from behind, so to speak.
On the other hand, poor binocular vision means that rats will have trouble perceiving depth. To make up for this, they use a technique called “relative motion parallax” to calculate the distance between objects3.
If you’ve ever seen your rat pause before an obstacle and sway their head from side to side, then you’ve observed motion parallax in action.
So, you can see that a pet rat’s vision is, in many ways, poorer than yours.
This doesn’t hinder them from exploring the world, though. Rats will use their other senses to make up for their poor vision: Sounds, smells, tastes, and tactile sensations carry a lot of information for them.
Rats can use their whiskers to navigate the world4 – except for Rex rats with their curly whiskers, who may have trouble doing so.
How Do Rats See Colors?
Can Rats See Green?
For a long time, rats were thought to be colorblind, but research has shown this to be untrue.
To understand what colors rats can see, we must first talk about the way colors are perceived in the eye.
Humans have trichromatic vision, meaning that we have three types of color cones in our retina: blue, green and red cones5. The cones will pick up different wavelengths of light, thus translating into the various colors.
Rats, on the other hand, have dichromatic vision: They only have blue and green cones, so these are the colors that they can perceive most clearly6.
The presence of green cones in their retina means that rats perceive shades of green.
Their blue cones are attuned to even shorter wavelengths than ours, meaning that they can also see into the ultraviolet light spectrum (whereas humans can’t)7.
Can Rats See Red?
According to what you just learned about the cones in the rat’s retina, rats should not be able to see the color red.
Surprisingly, an experiment performed in the 1930s showed that rats can be trained to distinguish between the colors blue, green, red, and yellow8.
It’s not quite clear, however, how this can be reconciled with today’s knowledge about the rat’s retinal physiology.
Researchers have actually used red night lights in their animal facilities for years, assuming that rats will not be able to see the light and will thus not be disturbed by it. But this assumption is being challenged by newer studies9, and there will probably be more knowledge available on this subject in a few years’ time.
What Colors Do Rats Hate?
The truth is that rats are probably rather indifferent to colors. Cones only make up 1% of their retina (as opposed to 5% in humans)10.
The rest of the rat’s retina is made up of rods, which detect light and darkness.
This could indicate that rats do not perceive colors as clearly as we do, and that colors don’t play a major role in how they navigate the world.
It is in fact substantially easier to train rats to differentiate between brightness and darkness than between colors7.
Are Rats Blind at Night?
Rats do not have any adaptations that would grant them good night vision. They can’t really see in low-light situations, but they can use their other senses – such as touch, smell and hearing – to make up for it.
In the twilight hours, rats may be able to see better due to their ability to perceive ultraviolet light, which is more abundant at dusk and dawn11.
Another theory for the function of ultraviolet vision is that that it enables them to see urine marks in the dark12.
What Do Albino Rats See?
The reason why albino rats have red eyes is that they lack the pigment (melanin) that colors the iris.
This isn’t just an aesthetic problem – it also means that the light which arrives in the eye is not absorbed by the pigment and floods the retina directly. This causes retinal degeneration over time1, thus further weakening their already poor eyesight.
Additionally, albino rats show abnormalities in their optic nerve, which connects the eye to the brain13.
These facts taken together mean that albino rats have even poorer vision than pigmented rats.
Understanding Your Pet Rats Vision
You may now have a better understanding of the way your pet rats perceive the world. As they don’t see colors very strongly, you shouldn’t really bother picking out a color theme for their cage.
And the idea that rats can’t perceive red light might just be a myth after all, so there’s no need to buy a fancy red night lamp.
You can help your rats see better by providing a good source of light during the day, while avoiding lights that are too bright and that shine directly in their eyes.
And rest assured that when you look at them, they can absolutely see you, recognize you and reciprocate your gaze with interest!
Resources:
1. Prusky GT, Harker KT, Douglas RM, et al. Variation in visual acuity within pigmented, and between pigmented and albino rat strains. Behav Brain Res 2002;136:339-348. https://pubmed.ncbi.nlm.nih.gov/12429395/.
2. Block MT. A note on the refraction and image formation of the rat’s eye. Vision Res 1969;9:705-711. https://pubmed.ncbi.nlm.nih.gov/5822786/.
3. Schiffman HR, Lore R. Depth perception in the rat (Rattus Norvegicus): prepotency of three-dimensional over two-dimensional surfaces. Perception 1975;4:73-77. https://pubmed.ncbi.nlm.nih.gov/1167187/.
4. Gugig E, Sharma H, Azouz R. Gradient of tactile properties in the rat whisker pad. PLoS Biol 2020;18:e3000699. https://pubmed.ncbi.nlm.nih.gov/33090990/.
5. Hubel DH. Eye, brain, and vision / David H. Hubel. New York: Scientific American Library : Distributed by W.H. Freeman, 1988. https://catalogue.nla.gov.au/Record/2583254
6. Szél A, Röhlich P. Two cone types of rat retina detected by anti-visual pigment antibodies. Exp Eye Res 1992;55:47-52. https://pubmed.ncbi.nlm.nih.gov/1397129/.
7. Jacobs GH, Neitz J, Deegan JF, 2nd. Retinal receptors in rodents maximally sensitive to ultraviolet light. Nature 1991;353:655-656. https://pubmed.ncbi.nlm.nih.gov/1922382/.
8. Walton WE. Color vision and color preference in the albino rat. II. The experiments and results. Journal of Comparative Psychology 1933;15:373-394. https://psycnet.apa.org/record/1933-05175-001.
9. Niklaus S, Albertini S, Schnitzer TK, et al. Challenging a Myth and Misconception: Red-Light Vision in Rats. Animals (Basel) 2020;10. https://pubmed.ncbi.nlm.nih.gov/32138167/.
10. LaVail MM. Rod outer segment disk shedding in rat retina: relationship to cyclic lighting. Science 1976;194:1071-1074. https://pubmed.ncbi.nlm.nih.gov/982063/.
11. Hut RA, Scheper A, Daan S. Can the circadian system of a diurnal and a nocturnal rodent entrain to ultraviolet light? J Comp Physiol A 2000;186:707-715. https://pubmed.ncbi.nlm.nih.gov/11016786/.
12. Desjardins C, Maruniak JA, Bronson FH. Social rank in house mice: differentiation revealed by ultraviolet visualization of urinary marking patterns. Science 1973;182:939-941. https://pubmed.ncbi.nlm.nih.gov/4745598/.
13. Silver J, Sapiro J. Axonal guidance during development of the optic nerve: the role of pigmented epithelia and other extrinsic factors. J Comp Neurol 1981;202:521-538. https://pubmed.ncbi.nlm.nih.gov/7298913/.
Featured Image Credit: Image by Erik Smit from Pixabay
Nina has a degree from the Veterinary School in Zurich, with a special focus on microbiological research. Nina has a passion for sports, nutrition and the outdoors and she loves all pets, but rats have a special place in her heart. When she’s not working or reading and writing about all things related to pet health, she loves to travel and surf.
As a small animal veterinarian, Nina is your go-to expert on pet health and nutrition.
