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Everything here is gathered from things other people actually researched, thought through, and built: books, papers, historical records, and the people behind them. If something here catches your interest, go look at the original sources listed at the bottom of the page. They carry more depth than a page like this ever can.

Do Dogs and Cats See the World in Black and White?

Category: Living Things

People often say that dogs see the world in black and white. However, a 2013 experiment reported that when given choices with different brightness and colors, 8 dogs chose based on color rather than brightness [4]. So, what colors do dogs and cats actually see? Experiments with a toy poodle and studies on cats reveal a two-color world and eyes that may be good at things other than color.

1. Why a red ball on green grass can be hard for a dog to see

Imagine throwing a red ball onto green grass in a park. You might think a dog would spot it instantly. But it is explained that while dogs can distinguish blue and yellow, they have trouble telling red and green apart, which may make a red ball less noticeable on grass [3]. This explanation suggests that dogs may use movement, shape, and light reflection as clues, not just color [3]. It is more accurate to say they are poor at distinguishing red from green, rather than saying they cannot see red at all. Since we cannot ask a dog "What color do you see?", researchers had to find other ways to test their vision.

2. How a researcher tested a dog's color vision by asking "Which one is different?"

An American researcher named Neitz conducted an experiment. According to his own account, he brought his toy poodle, named Retina, to the laboratory every day of the week for a year [2]. The method involved three glowing discs, where only one was a different color. If the dog pushed the different disc with its nose, it was correct and received a reward [2]. If the dog saw two colors as the same, it would not know which one was different, and its choice would be a guess. Conversely, if the dog consistently pushed the correct disc, it was thought that the two colors appeared different to the dog. This story comes from an article citing Neitz's own words, but the specific numbers were confirmed in the paper discussed in the next section.

3. Why dogs have two types of color cones but still use color clues

A 1989 paper by Neitz and colleagues showed that dogs have two types of color-sensitive cones. The sensitivity peaks are at about 429nm and 555nm [1]. Humans have 3 types, so dogs are considered to have dichromatic color vision. This means they handle light close to blue-violet and light close to yellow-green. Therefore, it is thought that while they are good at distinguishing blue and yellow, they are poor at distinguishing red and green [1][3]. Do dogs use color at all? In a 2013 paper, 8 untrained dogs chose based on color rather than brightness when given options with different brightness and color [4]. The magazine Discover reported that half of the dogs chose by color in all 10 trials [5]. However, this was a choice task under natural light. It does not mean they "always use color" [4].

4. Which colors cats could not tell apart in a 2016 experiment

What about cats? In a 2016 experiment, 2 cats were shown monochromatic light to test if they could distinguish it. Both cats distinguished light between 456–497nm and 510–524nm, but they could not distinguish light at 505nm [6]. A single point where distinction becomes impossible is called a "neutral point." It is thought that dichromatic eyes have this neutral point. From this result, cats were classified as dichromatic, similar to human red-green color blindness [6]. Research on cat brains also offers clues. A 2013 paper states that cats have "blue-on cells" in their brains that receive input from 2 types of cones, and the mechanism for handling blue and yellow contrast is similar to primates [7]. However, the behavioral experiment involved only 2 cats. A commentary by VIN states that cats' ability to see color is "limited," meaning they can only detect it when the stimulus is large and the color difference is significant [8]. "Cats can see color" and "cats see well" are different things.

5. How cats see in the dark and how they sense flicker

Cat eyes are strong in the dark. Cat retinas have many rods, which work in dark places. Cats can sense light at as little as one-seventh the brightness humans need. The reflective layer at the back of the eye (tapetum) returns up to 130 times more light than the human eye [8]. Dogs have a similar mechanism, but it is not as strong as in cats [8]. Note that "one-seventh" refers to the minimum brightness they can detect; it does not mean they can see in total darkness. Regarding sharpness, visual acuity is said to be about 20/75 for dogs and 20/100–20/200 for cats. For dogs, this means they must be about 6 meters (about 20 feet) away to see details that a human can see from about 23 meters (about 75 feet) away [8]. This notation cannot be simply converted to "1/X of human vision." On the other hand, dogs can detect flicker above 70–80Hz, so a 60Hz TV might appear to flash [8]. Even with two-color vision, they may be better than humans at detecting motion and darkness.

6. How you can observe your own pet's vision with toys

If you have a dog or cat, try placing blue and yellow, or red and green, toys on grass or the floor. Watch quietly to see which one they find first. Since dogs also use smell, you cannot draw a conclusion from one dog's behavior alone. Choose toys that are large enough so they are not swallowed. A 2018 review summarizing dog vision states that our understanding of how dogs see is still incomplete, though it is necessary for cognitive research [9]. This is a field where much is still unknown. If you want to read more, look up the paper by Neitz et al. [1] and the paper on the cat's neutral point [6].

Sources

  1. Neitz, Geist & Jacobs (1989) "Color vision in the dog", Visual Neuroscience 3(2) https://www.cambridge.org/core/product/5A30E35A384D10B6A2B46B01C896D3D5 (Supports the fact that dogs have 2 types of cones.)
  2. Laughing Squid "Color Blindness in Dogs" https://laughingsquid.com/color-blindness-in-dogs/ (Introduces Neitz's account of training his poodle (secondary source).)
  3. Scientific American "What Colors Do Dogs See?" https://www.scientificamerican.com/article/what-colors-do-dogs-see (Discusses distinguishing blue/yellow vs red/green and the red ball example (secondary source).)
  4. Kasparson, Badridze & Maximov (2013) "Colour cues proved to be more informative for dogs than brightness", Proceedings of the Royal Society B https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=(TITLE:%22dogs%22%20AND%20AUTH:%22Kasparson%22)&resultType=core&format=json (Supports the experiment where dogs used color cues.)
  5. Discover "Dogs See the World in Living Color" https://discovermagazine.com/planet-earth/dogs-see-the-world-in-living-color (Reports the ratio from the 2013 experiment (secondary source).)
  6. Clark & Clark (2016) "Neutral point testing of color vision in the domestic cat", Experimental Eye Research 153 https://pubmed.ncbi.nlm.nih.gov/27720709/ (Supports the cat's neutral point findings.)
  7. Buzás et al. (2013) J Neurosci 33(4) https://pubmed.ncbi.nlm.nih.gov/23345221/ (Supports the presence of blue-on cells in cat brains.)
  8. Veterinary Information Network "Vision in Animals – What do Dogs and Cats See?" https://www.vin.com/doc/?id=3844144 (Supports figures for dark sensitivity, visual acuity, and flicker (secondary source for vets).)
  9. Byosiere et al. (2018) "What do dogs (Canis familiaris) see?", Psychonomic Bulletin & Review https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=(TITLE:%22Do%20dogs%22%20AND%20AUTH:%22Byosiere%22)&resultType=core&format=json (Supports the summary of dog vision research status.)