Are Dogs Really Colour Blind?
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 colours 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 Colour 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 colour spectrum similar to that of humans with red-green colourblindness, says the American Kennel Club (AKC). Whereas the eyes of humans with normal vision contain three colour receptors, called cones, that perceive the full range of the visible light spectrum, people with red-green colourblindness 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 colours, such as pink, purple, and orange. Dogs are also unable to perceive subtle changes in a colour's brightness or shade.
What Colours 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 colours, 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 colour. This belief persisted about dogs until fairly recently when, in 2013, Russian researchers challenged the question, "Are dogs colour 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 colours 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 colour. But the majority of dogs went straight for the yellow paper the majority of the time, demonstrating that it was the colour, not the brightness, that they had learned to associate with the food.
Missing colour 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.
Your Dog's Other Senses
Before you feel too bad about your dog's muted-coluor world, keep in mind that what he lacks in vision, he more than makes up for with his other senses. For one thing, dogs can hear a much wider range of frequencies than humans can, says DogHealth.com, including sounds that are so high-pitched they can't be heard by human ears.
But a dog's hearing is only second to his sense of smell. A dog's olfactory sense is at least 10,000 times more powerful than that of humans, if not more so, says NOVA PBS. A dog's nose has 300 million olfactory receptors, whereas humans have a mere six million or so.
What's more, the part of a dog's brain that analyzes smell is forty times greater than in humans. All of this means that your dog can "see" more vivid pictures with his nose than we can even begin to imagine. What he lacks in poor eyesight and color perception is more than made up for by the knowledge he gains through smell alone.
See What Your Dog Sees
While there's no way to experience scent the way your dog can, you can get an idea of how the world appears visually to your dog thanks to an online app. Dog Vision lets you upload a photo and then adjust the colours and focus to show you how it would look to your dog. This is an insightful tool for anyone who has ever wondered how they look to their dog, or simply how dogs see the world in general.
The next time you gaze into your pup's expressive eyes, don't feel bad that he doesn't see you as clearly as you might see him. Your unique scent tells your dog more about you than simply looking at you ever could, and he would know your smell anywhere, whether he can see you or not.
Jean Marie Bauhaus
Jean Marie Bauhaus is a pet parent, pet blogger and novelist from Tulsa, Oklahoma, where she usually writes under the supervision of a lapful of furbabies.