How many color does human see

How many color does human see

The old wives’ tale that dogs can only see in black and white is still true today. This is definitely not true! They can see color, see much better than we do in the twilight, but are short-sighted. Now you probably ask yourself: "Huh, how should one know what and how well dogs see?? You can not tell us!"

Correct! Therefore, there are a lot of behavioral studies and experiments by researchers from all kinds of countries who – just as curious as we are – have studied this topic.
The best known study, which is also cited again and again, is that of Jay Neitz, Timothy Geist and Gerald H. Jacobs in California from 1989. Here you can find the study.And here is an article that explains the study again in more detail. It’s a bit "heavy fare" because it’s very scientifically and pompously formulated, but totally exciting! But here I tell you of course the most important thing you should know from the study.

Our dogs see colorful!

The three researchers, Neitz, Geist and Jacobs, found that dogs actually see colors in much the same way as a red-green color-blind human does. Now that’s something to think about!
Dogs and their relatives see in the spectral range from yellow to green and blue. That is, they see red things as yellow. And other colors that are not in their spectral range, they see as gray.

In addition, they perceive things that move much better than things that are still. Of course, as a hunter and prey predator this is super important! But we will explain this in more detail in a moment.

How many color does human see

On the subject of seeing colors, researcher Neitz says:
"In fact, dogs can poorly distinguish the colors red and green." Red looks yellow to them, green likewise. So if you throw your dog a red ball on a green grass, he sees a yellow ball in the middle of yellow grass. & Therefore it would make more sense to throw a blue toy, because blue is better distinguished and seen by dogs. Dogs have a very strong sense for shades of blue. And the reason for this, as is often the case, lies in their past: for a hunter who is out stalking between dusk and night, and just before sunrise, it is important that they can distinguish shades of blue. This is because the light reflected from the sky has a much higher blue content due to the lack of sunlight. And only if dogs can distinguish blue tones well, the outlines of prey animals stand out for them and they can see their movement immediately.

How many color does human see

How is this possible? For this, nature has invented something really great: Our dogs have a light-reflecting layer on the back of their eyes. This is called "Tapetum lucidum" in Latin – meaning a "luminous carpet".

This is responsible for the fact that the eyes of dogs – but also cats and many other animals – glow in the dark when you shine on them. This is because the "luminous carpet" reflects the light entering through the retina directly back and can use it twice in this way!

How is the dog eye built?

If you take a closer look at the structure of the dog’s eye, it actually resembles ours. The eye is enclosed by the upper and lower eyelid as well as the nictitating membrane, which lies in the lower eyelid and covers the cornea like a pair of goggles when sleeping. The nictitating membrane is atrophied in us humans but surprisingly really present:

Humans also have the nictitating membrane, but only as a small remnant of connective tissue that can be seen in the corner of the nose when looking in the mirror.
"The nictitating membrane is a rudimentary structure in humans and most other primates," knows philosopher and biologist Franz M. Wuketits. "In birds and water-bound mammals, it serves as a protective shield from the cornea"; furthermore, comparable to a windshield wiper, the removal of foreign bodies in the eye. (source)

How many color does human see

And really: when you look in the mirror, you really see a nictitating membrane. Never noticed before that this part of my eye should be exactly the same as Pixie’s nictitating membrane!

The dog’s organ of sight is surrounded by the white sclera. At the front, this sclera merges with the transparent cornea (Latin: cornea). Behind them lies the iris with the pupil. The retina contains the visual cells that are sensitive to light. Somewhat higher is the yellow spot (macula lutea), the place of the sharpest vision of our dog.
The differences to the human eye begin in the back of the eye: The retina, which consists of ten layers, not only contains a very fine network of nerve tissue, but also two different types of light receptors: cones and rods.
Rods convey light-dark impressions and are very sensitive to light. The cones are there for seeing in medium to bright light conditions as well as color vision. And different cones are receptive to the primary colors red, green and blue. From this variety of cones the eye and brain calculate our rich spectrum of colors. We can see thanks to these cones ca. Distinguish 200 shades of color. The retina of our dogs in turn has a particularly large number of rods. Why that is exactly so, I tell you now more exactly:

How many color does human see

Dogs are short sighted

There is a good reason why a prey animal like the deer stops rooted to the spot at the sight of a dog/wolf. They have learned that this behavior can save them. Because it really is their very best chance of not being seen by the dog/wolf. Because they see moving things much much much better than still standing things. One can even push it so far that dogs do not recognize standing still almost at all.
If we hide from our dog and do not move, it is very possible that he will not find us visually. But he can turn on his nose and then again it’s very likely that the nose "sees us". &

What is the reason for this good "motion vision"?? Our dogs are indeed short-sighted. If an object is standing still, he can’t see it at a distance of more than six meters. We however can ca. 20 meters far sharply see.
But if the object moves just a little bit, things are completely different and the dog reacts directly. This is also very important for a hunter. The wolf as the ancestor of the dog, had to be able to recognize and follow its prey animal in the twilight on the run. If the deer runs from its instinct, the hunt begins directly. Our dog can’t really see sharply, but he doesn’t need to if he just has to follow the moving object.

Why do our dogs see so differently than we do?? Here we come back again to the cones and rods! With us humans it is more important that we can see sharply. And as we have just learned, the cones, of which we have an infinite number, are responsible for sharp vision. The point of our sharpest vision is located in the so-called optic pit. It’s a nerve-rich, well-perfused depression that’s only about 1.5 millimeters deep and contains about 140,000 cones per square millimeter.
Our dogs also have a nerve-rich area, but it contains only rods, which enable the dogs to see in low light. This is his priority! Therefore we see about six times sharper than our dogs. But at dusk we totally succumb to his eyesight.

Our dog’s field of vision is larger than ours

Another development of the hunter-being of our dogs is the large field of view. With 240° it is very large – especially compared to the field of view of humans which only covers an area of 180. But this difference is again absolutely logical if you look at it more closely: Dogs, as hunters, have to scan their surroundings for prey in order to react to their movement. The more area they can see and scan at once the better!

But the dogs have for this advantage naturally also again a disadvantage. The spatial depth perception – the stereo or better 3D vision – of dogs is not as good as ours. This depth perception is made possible by the binocular overlap – the area of the visual field seen by both eyes. This range is with the dog with 30 – 60 ° clearly smaller than that of humans with 120 °.

How many color does human see

Can dogs watch television?

Since you can’t watch animal documentaries, much less dog shows, with Pixie in the same room, I’m pretty sure dogs watch TV. But now that I have read up on the topic "How do dogs see", I wanted to investigate the "TV topic" in more detail.
And I found Stanley Coren, who has not only written a lot of dog books, but is also a professor as well as a dog researcher at the University of British Columbia.

He took a closer look at the topic "Can dogs watch TV" (you can find an article about it here) and I learned a lot from him: the development of the HD TV actually makes it possible for our dogs to recognize moving images on the TV set! Older TVs have too low a frame rate, so dogs can only perceive a series of flickering images.
This is certainly neither interesting nor pleasant for them to see. But the new HD-TVs have a frame rate from 75 Hertz up to 120 or 240 Hz. That means: every second 75 (or more) pictures appear, so that there is a fluid picture for us and also for the dogs eyes.
In addition, there is a study – which was published in 2013 in the "Animal Cognition" journal – which proves that dogs can very well recognize images of dogs, humans and other animals.

We have also learned that our dogs naturally cannot see the bright colors of the HD-TV. They don’t have to, because they surely follow especially the movements and yes they recognize and distinguish some colors of the TV set.
Nevertheless, I now know for sure that Pixie is barking at other dogs and animals on the TV because she really recognizes and perceives them. However, I also know of other dogs that have zero interest in television images. This is just different for everyone. &

There is also this crazy dog channel especially for dogs called DogTV (which most people in Germany can receive via cable TV) which broadcasts "dog content" all day long.
I have once reingelinst there, but I could not really let him run for a long time, because Pixie sat directly barking next to me. Because here are not sent relaxing films of forest and meadow moods. I would have expected that now. But you could see other dogs playing and running around. Cute little puppies squabbling over a toy. For me of course totally "making happy" but this mass of dogs went for Pixie of course not at all!
"WaWaWa! How do the strange dogs come into our apartment? WaWaWa! Who let them in? Waaah!"

She even looked behind the TV to see if these dogs were "in there" and if she could catch them. She is really crazy. &
But the transmitter was developed together with dog behaviorists and veterinarians. So somehow it works for some dogs who are alone at home and have to "occupy" themselves in this way. In the USA it is more common than here that dogs are alone most of the day. That’s why the channel comes from the USA, of course. You can think what you want about it, but DogTV is definitely not for my "stimulus open" terrier. &

How many color does human see

Can we "help" our dogs with this new knowledge??

Now that we know that our dogs distinguish blue very well, react primarily to movement, red is yellow for them and green just as well, we certainly can’t just take it into consideration. But also perhaps change our buying behavior.
If you do agility with your dog, you can now realize that your dog definitely does not see the red marked contact zones as red, but rather as yellow markings on a yellow background on a meadow. Exactly the same applies to a red tunnel. If this should stand on a meadow more than six meters far away from them still and rigidly – and tunnels do not move now once& – then it can be well that your dog recognizes this only correctly, if he stands directly before it.
Yes, and the next time you go shopping, you will of course be doing your dog a big favor if you go for blue toys. clearly, a red ball on a green field is easier for us to spot before it gets lost. But your dog can distinguish a blue dummy or ball much better visually.

Now, as always, I am looking forward to your feedback!
Did I forget anything else? What kind of topic would interest you next? Does your dog watch TV or have you observed anything that supports this scientific information??
Feel free to write all this in the comments!

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