What colors can dogs see

What Colors Do Dogs See?

Have you ever wondered whether your dog could see (and appreciate) the striking pink or nuanced teal color of a new toy? Humans on TikTok are using a dog vision filter to help answer this question. With the filter on, youll see the world in shades of blue, yellow and graythe only colors your pup can perceive.

But is this really how our furry friends see the world? Not exactly, experts saytheres way more to your pets vision than color perception.

Scientists once thought dogs saw only in black and white. The idea took off in the public imagination in the 1940s, when optometrist Gordon Walls published his influential book The Vertebrate Eye and Its Adaptive Radiation, in which he claimed that dogs could only weakly see color, if at all. The myth was finally debunked in 1989 when ophthalmologist Jay Neitz, then at the University of California, Santa Barbara, and his colleagues discovered that canines could see blues and yellows but not reds and greens. Some humans, about 8 percent of men and 0.5 percent of women, are similarly red-green color-blind.

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It turns out that dogs possess two types of color-sensing receptors, called cones, in their retinas. This makes them similar to most mammalsincluding cats, cattle and pigsand unlike humans, who have three cones.

Our work has had a big influence, and lots of people now understand what color vision in dogs really is, says Neitz, who is now an ophthalmology professor at the University of Washington.

But to really understand how dogs see the world, we need to move beyond color, says Sarah-Elizabeth Byosiere, an animal behaviorist and former director of the Thinking Dog Center at Hunter College. While a green or red ball lying on grass would not stand out easily to your pet, it might challenge them to identify it by its other featuressuch as its movement, shape and the way it reflects light, Byosiere says. That challenge could either be enriching or frustrating. It all depends on an individual dogs behavior, she says.

If youre really trying to imagine the world through the eyes of your dog, you should picture everything a lot blurrier. Most dogs have 20/75 vision, meaning that they must be 20 feet away from an object to see it as well as a human with clear vision who is standing 75 feet away.

Everything looks clear and detailed in those [TikTok] videos, but it wouldnt look quite as clear to dogs, Neitz mentions.

But unlike humans, who see very poorly in low light, canines have evolved to see well in both daytime and nighttime conditions, explains Paul Miller, a veterinary ophthalmologist at the University of WisconsinMadison. Though dogs have fewer color-sensing cones than humans, they have more rods, the cells that help with night vision. They even have a unique structure in their eyes called the tapetum lucidum, a mirrorlike membrane that allows them to see in six times less light than humans can. The tapetum, which some other animals, such as cats and cattle, also possess, sits behind the retina and reflects light back onto it, giving the receptors a second chance to gather more visual detail. Its also the reason your pets eyes glow in photos and in the dark.

Also important for dogs perception is their sense of smell, which is 10,000 to 100,000 times more powerful than that of an average human. This is as true for chihuahuas and pugs as it is for bloodhounds. While humans have about five million smell receptors, dogs possess up to a billion and can communicate with one another with chemical signals. They can pick up odors as far as 12 miles away.

And canines mighty sense of smell is inextricably linked to how they see the world. A study published last year in the Journal of Neuroscience revealed that canines brain has a direct connection between their olfactory bulb, which processes smell, and their occipital lobe, which processes vision. This integration of sight and smell had not been observed before in any animal species, the authors stated.

The results raise the question of whether dogs sense of smell is orienting their sight, Miller says. Its pretty wild, adds Miller, who was not involved in the study. They [may be able to] smell in 3-D.

So while humans may be attuned to the aesthetics of color, dogs simply arent, Neitz says. Ive had dogs all my life. And I never really felt like, Oh, my God, my poor dogs world is limited from a color vision standpoint, he says. They live in a very rich olfactory world that humans cant appreciate, Neitz adds.

When it comes to buying toys for our canine companions, we dont always have to select the two colors they can see: yellow and blue. Byosiere recommends getting one red and one blue toy to enrich your pets play. You may want to throw the red one on the green grass so that your pup uses its nose and then throw a blue one so that it uses its eyes.

These animals are not deprived in any way, Byosiere says. Its just that they just see the world in a different way.

Dog vision: What colors can dogs see?

Dog vision is very different from human vision. Dogs see the world in fewer hues than we do, but this doesn't mean our canine companions are completely colorblind. But even if dogs' visual worlds are not as clear or as colorful as ours, their ability to see motion is superior.

What colors can dogs see?

The human eye works thanks to three kinds of color-detecting cells called cones. By comparing the way each of these cones is stimulated by incoming visible light, our brains distinguish red wavelengths from green wavelengths and blue wavelengths from yellow wavelengths. Dogs' eyes, like those of most other mammals, contain just two kinds of cones. These enable their brains to distinguish blue from yellow, but not red from green.

Dogs are not completely colorblind, but their eyes are structured in a similar way to those of people with red-green color blindness, whose eyes also lack the third kind of cone normally present in humans, Jay Neitz, a color vision scientist at the University of Washington who conducted many of the modern experiments on color perception in dogs, told Live Science.

We can get an idea of what dogs see, Neitz said, if we assume their brains interpret signals from their cone cells much like the brains of people with colorblindness do.

Related: Red-green and blue-yellow: The stunning colors you can't see

To see blue and yellow, dogs and humans rely on neurons inside a part of the eye called the retina. These neurons are excited in response to yellow light detected in the cone cells (which are also inside the retina), but the neurons' activity gets suppressed when blue light hits the cones. A dog's brain interprets the excitation or suppression of these neurons as the sensation of yellow or blue, respectively. However, in dogs and in people who are colorblind, both red light and green light have a neutral effect on the neurons. With no signal to interpret these colors, the dogs' brains don't perceive any color. Where you see red or green, they see shades of gray.

"A human would be missing the sensations of red and green," Neitz said. "But whether or not the dog's sensations are missing red and green, or if their brains assign colors differently, is unclear."

Furthermore, like people with colorblindness, dogs may use other cues to distinguish the color we call "red" from the color we call "green."

Related: See 15 crazy animal eyes

"A lot of the time, there are good cues to help them figure it out; for example, red objects tend to be darker than green objects," Neitz said. "So, if it's a dark apple, a red-green colorblind person would know that it's probably a red one, and if it's a lighter apple, it may be a Granny Smith."

There is some evidence that dogs may be able to see colors humans cannot. A 2014 study published in the journal Proceedings of the Royal Society B found that the lenses in the eyes of a dog transmit significant amounts of ultraviolet light, whereas these wavelengths are blocked by human lenses. This suggests that dogs might see more blue light than we do.

How sharp is dog vision?

In addition to missing some of the hues perceived by human eyes, dog vision lacks some of the sharpness of human vision. In a 2017 study, published in the journal PLOS One and conducted at Linkping University in Sweden, researchers designed a canine visual acuity test similar to the tests ophthalmologists give to people. Instead of having to discern letters of decreasing size, the dogs were rewarded with treats for correctly identifying images containing vertical or horizontal lines with ever-decreasing amounts of space between them.

The researchers discovered that dogs or at least the whippets, pugs and the single Shetland sheepdog that participated in the experiments were very nearsighted. The results of the experiment suggest that dogs, in well-lit conditions, have roughly 20/50 vision. This means that they have to be 20 feet (6 meters) away from something to see it as well as a human who is 50 feet (15 m) away from that same object.

Do dogs have night vision?

While dogs' night vision is fairly blurry, at roughly 20/250, according to the 2017 study, it is also much more sensitive than humans' night vision. Dogs are crepuscular, meaning they tend to be most active at dawn and twilight, according to the American Kennel Club. While human eyes are chock-full of cones, which help detect colors and work best in bright daylight, dogs' eyes contain more of the light-detecting cells known as rods, which distinguish between dark and light and thus are at their best in low-light conditions, according to the Merck Veterinary Manual.

Related: See the world from a cat's eyes

Many dog breeds (though not some of the toy dog breeds) also have a special eye layer, known as the tapetum lucidum, that bounces light back toward their retinas, essentially magnifying the light that does reach the rods there, according to a 2014 study in The Journal of Veterinary Medical Science. The tapetum lucidum is what causes dogs' eyes to glow a bluish green when light shines on them at night, according to the Merck Veterinary Manual.

The takeaway? Dogs have better night vision than humans do.

Canine motion detection

While you might think dogs live in a dull, blurry visual world compared with ours, there is one area where their vision beats ours: They are much better at detecting motion. This is due to something called the critical flicker fusion rate. Imagine a light that flickers faster and faster. By the time the light is flickering 60 times per second, humans will believe the light is shining steadily. According to a 1989 study published in the journal Physiology and Behavior, that same light has to flicker roughly 75 times per second to fool a dog.

This ability likely enables dogs to spot moving objects, such as prey, much more quickly and accurately than humans can.

Additional resources

Bibliography

Byosiere, S. E., Chouinard, P. A., Howell, T. J., & Bennett, P. C. (2017). What do dogs (Canis familiaris) see? A review of vision in dogs and implications for cognition Research. Psychonomic Bulletin & Review, 25(5), 17981813.

Coile, D. C., Pollitz, C. H., & Smith, J. C. (1989). Behavioral determination of critical flicker fusion in dogs Physiology & Behavior, 45(6) 10871092.

Douglas, R. H. & G. Jeffery. (2014). The spectral transmission of ocular media suggests ultraviolet sensitivity is widespread among mammals. Proceedings of the Royal Society B: Biological Sciences, 281, (1780).

Hirskyj-Douglas, I. (2016, September 8). Here's what dogs see when they watch television. The Conversation.

Miller, P. E., & C. J. Murphy. Vision in dogs. (1995). Journal of the American Veterinary Medical Association, 207(12), 16231634.