Updated - Apr 23rd, 2021
For decades, we’ve thought that dogs can only see in black and white. But if your dog LOVES that yellow tennis ball much more than the red ball, it may be because he can see it better!
Science has proven that yes, dogs see colors, but not as many or with the same visual acuity as humans do. But that doesn’t stop them from having some clear sight advantages we don’t share.
Let’s find out why a dog’s color vision differs from ours.
Cones and Rods Make the Difference
The anatomy of the eyes determines what a species will see. When you’re talking about different colors, it’s the cones and rods in the retina that make the difference between what we humans see compared to our tail-thumping canine companions.
It all starts with the retina in the back of the eye. It converts light into electrical signals that are sent to the brain through the optic nerve. Once there, the brain forms those signals into the images we see, including the color perception.
Colors are wavelengths of light reflected by an object. How we see those colors are determined by the nerve cells, or color receptors, in our retinas called cones and rods.
Cones: Cones work in the bright light spectrum and control the perception of color. Humans have three cones, giving us the full range of colors in the color spectrum of a rainbow or a flower garden. We call this type of vision Trichromatic and it gives us the ability to see red, blue, and green, our primary colors and all those different shades of each. Our full spectrum of colors comes from the blending of these primary colors.
Dogs only have two cones, allowing them to see only two primary colors; blue and yellow. They call this dichromatic vision. It’s a lot like being colorblind, but it really isn’t.
Are Dogs Colorblind?
This is a misconception. In human eyes, colorblindness is an abnormality of the color detecting molecules. Some people that are considered colorblind can’t distinguish colors outside the red-green spectrum, and others can’t distinguish outside the blue-yellow spectrum. A dog’s vision is in the red-green colorblindness spectrum, and they can’t see that green grass or a bright red rose as vividly as we can.
In your dog’s eye, red appears as dark brownish gray, or black. Yellow, orange, and green look yellowish, but blue they see really well and purple looks the same as blue.
Rods – A Dog’s Superpower
Rods: Rod cells are very sensitive and work well in low light (like night vision) and detect the smallest movement. Humans don’t see well in low light because we only have one rod, where dogs have two, giving them the superpower of seeing even the smallest movement in low light.
Humans evolved needing to hunt for plants and animals, needing the ability to distinguish between green leaves and red berries, and distinguish between animals that they can eat and those that may eat them. Seeing a complete full-color spectrum was necessary.
Wolves, the domestic dog’s ancestor, needed to see when hunting, even if it was at nighttime or in dim light. They also needed to focus on movement, no matter how small, to catch their prey. There wasn’t a need to see color as much to survive.
But their vision advantages don’t end there!
Dogs also have pupils that dilate wider, a bigger lens, and a larger corneal surface. A reflective lens behind the retina called tapetum lucidum reflects all the light in the darkness, giving your dog superior night vision. If you’ve ever seen an animal with glowing eyes peering at you in the dark, that glow is the tapetum lucidum reflecting the surrounding light.
Visual Acuity is different too
Dogs are nearsighted, meaning they can’t see far away as clearly as we can. But they have much better peripheral vision! Because their eyes are more toward the side of their heads, they see 250-degree views, where we see 60-degree views.
So while we can clearly see all around us, our dogs cannot. Your dog’s best vision is directly in front of them. The rest of their visual field is more blurry than we see.
That dog toy may be the wrong color
As you can see (pun intended) dogs and humans see things differently, but it’s not all bad. While we can see and appreciate all the different shades of blue in the sky and colorful landscapes, our dogs can see the mouse or squirrel twitching in the field far away, even if it’s dark outside. And they don’t live in just a black and white world as we thought.
So even though your pooch can’t distinguish the subtleties of light blue shades, dogs aren’t color blind; they just have fewer cones or color receptors than we do. This may explain why they eagerly chase that yellow tennis ball and show no interest in the red ball. It may be worth your while to look at the colors of your dog’s toys and see if the blue and yellow ones are more loved because your tail-wagger can clearly see them.
And if you’re wondering why your dog can always find his yellow tennis ball in the sea of tennis balls at the dog park, it’s because of his superior sense of smell!