For decades, scientists thought that dogs view the world in plain black and white. However, relatively recent research into canine anatomy and behavior shows that man’s best friend actually sees things in color, albeit not as well as humans.
Dogs can only see shades of blue and yellow, as well as some shades of gray. This means that they can distinguish between blue and green, but they may have difficulty telling the difference between red and green. So while humans are trichromatic, dogs are dichromatic, or “two-colored”.
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A Dog’s Eye View: Understanding Canine Vision
The human eye perceives color when certain wavelengths of light are reflected off objects and into the lens. The refracted light is then focused on the retina where photoreceptors called cones and rods interpret the message in order to be processed by the visual cortex in the brain. There are millions of these photoreceptors throughout the human retina.
Rods are responsible for our ability to see in low light levels, or scotopic vision, allowing us to perceive shapes and motion even in dim light or almost no light at all. Cones are made up of three different types of receptors (short, medium, and long-wavelength cones) that allow us to perceive color.
The most important difference between the cone and the rod is that the cone is more light-sensitive than the rod and requires much more light to enter it in order to send signals to the brain. This explains why we can’t see colors in the dark.
Initially, it was thought that dogs lack cones, which led to the conclusion that they can’t see color. Anatomical dissections, however, showed that dogs also have cones, but much fewer compared to humans. Additionally, humans and other primates are trichromatic, meaning they have three kinds of cones, whereas dogs are dichromatic, only having two types of cones. Dogs are missing red-green cones, so they can’t see these colors.
On the upside, dogs have more rods than humans, allowing them to see much better in the dark than us. Dogs are essentially domesticated wolves, nocturnal predators that need to have good eyesight in the dark to track and catch prey.
The canine eye also has a larger lens and corneal surface, as well as a reflective membrane behind the retina, called the tapetum lucidum, which further enhances night vision. The tapetum reflects back the light that has already entered the eye, giving the dog’s eyes a boost. It’s also the reason why your pet’s eyes may sometimes appear to glow at night.
Although dogs aren’t as good as humans in the vision department, they more than make up for it with their noses and ears. Canines’ hearing is keener than ours and their sense of smell is about 1,000 times more sensitive than the human nose.
Why do people think that dogs are color blind?
The notion that dogs have poor vision and can only see in shades of gray can be attributed to Will Judy, the former publisher of Dog Week magazine in the 1930s.
“It’s likely that all the external world appears to them as varying highlights of black and gray,” Judy wrote in a highly popular 1937 manual called “Training the Dog.”
This myth is surprisingly persistent even though there’s research dating back from the 1960s showing that the structure of the canine eye allows for seeing colors. The reason why it’s so enduring may be due to the fact that dogs do not rely on color vision as much as humans do.
Dogs have evolved to rely more on their sense of smell and hearing than their vision. In fact, many breeds of dogs have a better sense of smell than any other animal. For dogs, the ability to detect scents and sounds is much more important than the ability to see colors.
However, just because dogs don’t rely on color vision as much as humans do doesn’t mean that they can’t see colors at all. While dogs may not see the same range of colors as we do, they are still able to perceive some colors and shades.
What colors do dogs see?
All of this is to say that dogs aren’t fully color blind. In fact, in many ways, dogs probably perceive color similarly to humans with various forms of red-green color blindness. Certain colors aren’t vivid and different hues of the same color are difficult to differentiate between. There are a lot of people who are red-green color blind, such as those who have protanopia and deuteranopia.
Dogs only have two types of cones: one for blue and the other absorbs wavelengths between a human’s version of red and green.
But how exactly do dogs see color? That’s impossible to tell without swapping eyes with them, but judging from their anatomy it’s likely they see best in shades of yellow, blue, and green.
When these colors are combined, a dog’s brain will likely process these wavelengths in dark and light yellow, grayish yellows and browns, and dark blue and light blue. This may explain why dogs go nuts over chasing yellow tennis balls. They probably can see the tennis ball light up, especially against a green grass background which, to them, comes across as rather dull.
The people at Dog Vision took this information about the canine eye and used image processing to offer a momentary glimpse into how dogs see the world. The blurry images below are not a perfect reflection of how a dog truly perceives shapes and colors, but they do a good job of illustrating how different their eyes are from ours.
The reason why these images are blurry is that dogs tend to be nearsighted. A poodle, for example, is estimated to have 20/75 vision. However, dogs are much more sensitive to motion at a distance — anywhere from 10 to 20 times more sensitive than humans.
If you’d like to learn more about how these images are processed, you can read András Péter’s technical explanation, who programmed the app. You may also use the tool to upload images and create your very own dog vision pics.
The Bottom Line: Dogs Can See Some Colors
In conclusion, dogs are not completely colorblind. While they may not see the same range of colors as humans, they are still able to perceive some colors and shades. The myth that dogs are completely colorblind is a common misconception.
As dog owners, it’s important to understand our pets’ vision and how it differs from our own. While color vision may not be as important to dogs as it is to us, it’s still an important part of their perception of the world around them. Now that you know dogs are more sensitive to blue and yellow, you may select toys or activities that emphasize these colors.