Can Rats and Mice See Color or Do They Have Limited Vision?

Wild wood mouse in its natural habitat in a green forest

The average person doesn’t have the best view of rodents. However, mice and rats have been an invaluable asset to humanity. Rodents are a long time favorite for intelligence, memory and behavioral testing in laboratory settings. When we want to know how humans will react to something, we typically try it out on rodents first. On noting that, we might wonder what the world, and especially the world of color, looks like to our little friends.

A World Without Color

We often assume that most animals live in a world painted in shades of gray. For example, when we see through a dog’s eyes on TV, the show will often switch to black and white. And there’s some truth to the idea that most mammals aren’t able to see a wide variety of colors. However, it’s not nearly the bleak world of gray that we often assume. But to understand why that’s the case we first need to take a look at how our own eyes operate.

How Humans See Color

Most humans are able to see a vast array of colors. Primates as a whole, with some exceptions, see more colors than most mammals. And humans have better color vision than most of our relatives in the primate family. In short, we’re gifted with an ability to appreciate more of the world’s beauty than the vast majority of warm blooded animals on Earth.

Structure and function of the photoreceptor in the retina of the human eye with rod and cone cells

Our colorful vision is due to a special type of cell in our eyes. These cells, called cone cells, come in three different varieties. Each type allows us to see ranges of red, green and blue. We see these ranges of colors in a similar way to how we’d mix paint. Triggering cone cells in different ways will produce various mixtures of their colors.

How Most Mammals See the World

Most mammals, including mice and rats, only have two of these cone cells. They basically live in a world without red. This presents other mammals with a more washed out view of the world than we have. However, it’s not the black and white world that many assume.

A Closer Look at Rodents

But what about mice and rats? Do they see things any differently than the average mammal? You might imagine that we’d know a lot about how rodents see the world. After all, mice are a mainstay of experimental science.

It’s true that we certainly assumed that we knew everything we needed to know about their eyes. However, a few relatively recent studies are challenging long held beliefs. It may well be that we’ve had some things wrong about the rodent’s view of the world.

Different Ways to See Red

Curious rat peeking out of a red colored woolen bag

We’ve assumed that mice and rats were essentially blind to red light. This has led to the use of red light in rodent studies where we’ve wanted to simulate darkness. A new study suggests that rodents aren’t actually blind to red light. It’s true that they don’t see the color red. But they do appear to perceive red light as white light rather than darkness. However, it’s important to keep in mind that this is a fairly new discovery. There’s still some more work to be done before we can state anything with absolute certainty. But this new study does help shine a little light onto a rodent’s worldview.

Rats and mice appear to see the world in a similar way to what we’ve assumed of most mammals. The main difference is that we’ve assumed rodents are red-light blind. It’s instead better to mentally swap out red with white when we try to imagine what mice and rats see. In the end we can imagine that mice and rats are looking out into a world filled with color. It’s simply that they see less of the colors than we do. And on top of that the colors are a little more washed out.

A New Type of Mouse With a New Way to Look at the World

Genetically modified white mouse with enhanced color vision

Normally this would be the end of the story. We’ve examined the physical cells within the rodent eye and noted a lack of receptors for the color red. And we’ve even performed experiments to help hone in on what they see when exposed to light in that range. There wouldn’t seem to be much more to examine unless a whole new type of mouse came into the world. And that’s exactly what happened in the University of California.

Researchers essentially grafted the DNA needed to generate red cone cells into mice. These genetically modified mice may well be the first rodents to ever directly perceive the color red. This was an amazing accomplishment in and of itself. But the story doesn’t end there. What’s even more astonishing is that the mice were able to properly make use of those cone cells.

Even if the mice had the physical ability to see red, that wouldn’t guarantee that their brains could understand what they saw. The average mammal has an extremely powerful brain. We don’t just take in and instantly react to raw visual data. The mammalian brain instead takes some time to process and integrate visual data into a more subjective view of the world around us. A simple example of this can be demonstrated by simply looking around your environment.

The Brain and Eye Work Together to Perceive the World

Eye and visual cortex nerves

Take a moment to note how you see a singular and unified vision of the world. However, each of your eyes is taking in a slightly different view than the other. Despite this we don’t see the world like two TV screens propped up next to each other.

The two input streams from your eyes are processed by your brain into a singular whole. The mental processing will, among other things, also remove our awareness of any blind spots. We see the world as much through our brain as we do our eyes. And this is true for most mammals. We’ve even found that the visual cortex of mice, while different than primates, often operates in similar ways.

This experiment with red cone cells in mice shows that their brains are capable of using data from new perceptive apparatus. It also highlights that the mice were using their new cone cells in a similar way to how we use ours. In short, these mice didn’t simply have the ability to see red. The mice were noting the color in both a purely physical sense and as a higher level cognitive event.

The rodents weren’t simply looking at the color red. They were seeing, mentally processing, and properly perceiving the color red in the same way they would any other color. This was quite possibly the first time in all of history that a mouse or rat looked at the color red and fully incorporated it into its worldview.

Bringing It All Together to Understand a Rodent’s Worldview

Closeup of white rat on wooden table

In short, we can say that mice and rats do see color. Of course with the exception of the mice from the University of California they’re not able to see red. But we can also say that we now know that they’re capable of relating to that normally invisible color in ways that we hadn’t imagined until quite recently. They’re not totally blind to red light, as we’d often assumed. And given the right genetic upgrades they can even properly perceive it in a similar way to primates.