While for a long time it was accepted as fact that dogs could only see in black and white, science has proven that's not the case. But what colors can dogs see, and why don't they see the way we do? Read on to learn all about dog vision and how your dog perceives their world.

Are Dogs Color Blind?

While the once widely believed theory that dogs see everything in black and white has been proven false, the truth is that dogs see a color spectrum similar to that of humans with red-green colorblindness, says the American Kennel Club (AKC). Whereas the eyes of humans with normal vision contain three color receptors, called cones, that perceive the full range of the visible light spectrum, people with red-green colorblindness only have two cones, which makes them unable to perceive reds and greens.

Dogs' eyes only have two cones. This means that not only can they not perceive the colors red or green, but they can't perceive shades containing either of those colors, such as pink, purple, and orange. Dogs are also unable to perceive subtle changes in a color's brightness or shade.

What Colors Can Dogs See?

Dogs can see shades of yellow, blue and brown, as well as various hues of gray, black and white. This means that if your dog has a red toy, it will appear brown to him, whereas an orange toy, which is a mix of red and yellow, will appear a brownish yellow. It also means that if you want to fully engage all of your dog's senses during playtime, you should look for toys that are either blue or yellow so that they'll stand out from the duller shades of brown and gray in your dog's field of vision. This could help explain why dogs love those bright yellow tennis balls so much.

The Black and White Vision Theory

If dogs can see certain colors, then where did the idea that they only see in black and white come from? That belief, says the AKC, can be attributed to National Dog Week founder Will Judy, who wrote in a 1937 training manual that it was likely that dogs could only see in shades of black and gray. Researchers in the 1960s perpetuated the myth by hypothesizing incorrectly that primates were the only animals capable of perceiving color. This belief persisted about dogs until fairly recently when, in 2013, Russian researchers challenged the question, "Are dogs color blind?" They proved that dogs can see and distinguish between yellow and blue, reports the Smithsonian.

The researchers conducted an experiment to see whether dogs could distinguish between the two colors or between contrasting degrees of brightness. They did so by placing four pieces of paper — one light yellow, one dark yellow, one light blue and one dark blue — on feed boxes, with only the box with the dark yellow paper containing a piece of meat. Once the dogs learned to associate the dark yellow paper with their treat, the scientists placed only dark blue and light yellow papers on the box, surmising that if the dogs tried to open the box with the blue paper, it would be because they associated the dark shade with food rather than the color. But the majority of dogs went straight for the yellow paper the majority of the time, demonstrating that it was the color, not the brightness, that they had learned to associate with the food.

Missing color receptors aren't the only things differentiating dog vision from that of humans. Dogs are very nearsighted, with their vision estimated to be about 20/75, says Business Insider. This means that when a dog looks at something 20 feet away, it will appear to be 75 feet away.

While this might make it seem like your poor dog has terrible vision, the AKC points out that, thanks to their wide-set eyes, dogs not only have a wider field of vision than humans, but are also better at seeing fast movement, which makes them good at spotting fast-moving prey.