It’s a common misconception that dogs are entirely colorblind. This myth, perpetuated by TV, movies, and outdated research conclusions, leads people to believe that dogs can only see in black and white. However, contrary to popular belief, canines can perceive color — just not as vividly as humans do.
Like most myths, the notion of the colorblind dog has some basis in truth. Dogs are indeed red-green colorblind, which means they can’t distinguish between these two colors. From a dog’s perspective, a red apple and a green apple may appear to be the same yellowish-brown hue. However, dogs possess dichromatic color vision, meaning they can differentiate between blues, yellows, and various shades of these colors. Complete color blindness, known as monochromatic vision, is more akin to the black-and-white vision that people mistakenly believe dogs have.
The ability to see and differentiate colors depends on the number of cone subtypes present in an animal’s eye. Cones are photoreceptor cells within the retina that detect the wavelength of visible light and interpret it as specific colors. Humans have three types of cones, corresponding to long, medium, and short wavelengths of light. Dogs, however, lack the long wavelength receptor, making “warmer” colors more challenging to distinguish.
What the world of colors looks like to a dog
Unfortunately, imagining what dogs see isn’t as straightforward as adding or removing colors from the color wheel and replacing them with shades of grey. Although dogs lack a third cone subtype in their eyes, there is considerable overlap in the spectrum of light that two different cone subtypes can detect. Moreover, scientists can’t simply ask dogs to describe their vision.
Researchers must instead compare dog color vision to human vision to infer how dogs perceive the world. Since dogs lack the long-wavelength “red” cone, their color perception is likely similar to that of humans with red-green color blindness. Such individuals often describe green colors as washed-out shades of blue or yellow, but never both simultaneously (since combining blue and yellow creates green). Different shades of orange and red are also indistinguishable to people with red-green color blindness, appearing as a single brownish-gray color.
Canine behavior provides further clues. Dogs prefer yellow and blue toys over red, orange, and green ones. Ironically, dog owners frequently purchase red and orange toys. The reason dogs favor yellow and blue toys is likely because these colors appear more vibrant and stand out from the surroundings, capturing a dog’s attention. This may explain why dogs have a fondness for tennis balls; the bright yellow color starkly contrasts with the green grass, allowing dogs to easily track the ball during a game of fetch.
Other ways dogs see differently than we do
Color isn’t the only aspect in which canine vision differs from our own. Dogs have significantly weaker visual acuity compared to humans, making their world appear quite blurry. In a study summarized in Psychology Today, researchers analyzed canine visual acuity by comparing responses to increasingly closer rows of printed lines, similar to how human vision is tested using eye charts. The results suggest that dogs have 20/75 vision (normal human vision is 20/20). Thus, dogs likely view the world as if looking through “a light coat of petroleum jelly.”
While dogs may have deficiencies in color perception and visual acuity, they excel in other areas. For instance, dogs have more rods in their eyes than humans do. Like cones, rods are photoreceptor cells in the retina that detect light. Unlike cones, rods convey information about light intensity, helping to discern movement. As a result, dogs can detect movement better than humans. This may be an adaptation from their ancestors’ hunting days, and it explains why dogs can easily track a zig-zagging fly as it buzzes around the room.
Moreover, dogs have superior night vision compared to humans. The abundance of rods increases their sensitivity to light, and canine eyes possess another tool for seeing in the dark: the tapetum. Many animals have a tapetum lucidum membrane, which is a layer of reflective cells located behind the retina. When light passes through the retina, these cells reflect the light back, essentially duplicating light information for the retina. If your dog ever lunged after a critter you couldn’t see during a night walk, you can attribute their tapetum for enhancing their night vision.
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