Have you ever wondered how do dogs see the world? Why can’t I sometimes see things that are so obvious to us?
For example, it was once thought to be because dogs are color-blind, in other words – color blindness is present here.
It has long been believed that dogs do not recognize colors and that they see the world in black and white or in shadows. After numerous studies and experiments, the scientific world agrees that dogs can also see colors.
However, the range of colors that dogs recognize is far poorer and less vivid than humans but does make up for this shortcoming with other senses.
How dogs see the color spectrum
People practically see the world in three colors. Red, green, and blue. Thanks to certain photoreceptors, people can partially see in the dark.
However, today we know that dogs see colors, just not in the spectrum in which we see them. The eyes of man and the eyes of a dog contain special cells that capture light and are called cones.
The number of cones in the eye depends on how many colors we will see – dogs have fewer cones, but that’s not all – there are more types of cones, we have three.
The same thing is with dogs – a Russian study from 2013 showed that they see a slightly different spectrum.
In dogs, the color scale they see includes shades of cream, white, blue, purple, and gray.
Dogs can recognize blue-purple shades, yellow, and shades of gray, but do not see the difference between green, yellow, orange, and red. It is also very difficult to distinguish green from gray shades.
This would, therefore, be the basic color spectrum of the correct human eye:
And this is roughly the range of canine:
In other words, forget all those red and orange toys and balls we buy them and then swear why they don’t see them when they’re in front of their noses.
The same thing applies to all those red balls you buy according to your own visibility criteria – dogs perceive them as brown.
Canine vision also has some other characteristics, such as the width of the human field of vision, which in humans is 170 degrees on both sides.
The dog’s eyes are set a little higher on the side of the head, which means that dogs have a much wider field of view from 200 to as much as 270 degrees.
Because of that, a dog can notice more things happening around and behind it, but, unlike humans, dogs do not have such a developed sense of depth in their sight.
At one time I had two red Congos and one bright pink, almost white Puppy Kong – and it’s only now clear to me why the latter was the favorite – they simply saw him better.
How sharply the dogs saw
And how sharply do dogs see? It’s not that we can put them in front of Snellen’s table, is it?
But still, scientists have come up with ways to test a dog’s visual acuity – using a table with black and white stripes of different densities – from large to smaller and one gray.
Once we teach the dog to get a reward when he touches the black and white plate with his nose, we replace it with one with thinner and thinner stripes, until the dog is no longer able to distinguish between black and white and gray.
The thickness of the black and white stripes can then be converted to the equivalent of a Snellen table for humans.
Based on one Poodle tested in Hamburg, it was found that the average dog differs from human stripes only if they are 6 times thicker than those seen by the average healthy-eyed man.
It will probably be easier for you to imagine it like this – from 6 meters the dog sees the stripes that a man would see from 23 meters.
Dogs see movement better than humans
But that’s why dogs see movement much better than we do – in fact, so fast that their TV screen is not interesting because the number of frames per second is not enough to see the picture as movement, but see it as a series of photos.
If you want to protect your dog’s eyes from extreme conditions such as UV radiation, snow, rain, wind, dust, see NVTED dog glasses. They will protect your dog’s eyes when walking in the snow in winter, when there is a strong wind outside or when you are in the desert walking with your dog.
Apparently they see a little better if they look at the latest TVs that produce more thumbnails than standard … anyway, my dogs are sure to bark if they hear other dogs, cats, chickens, and sheep on TV (which they have never seen in their lives, btw.).
They know how to look at the screen, but I think it’s more because of the direction from which the sound comes.
In addition to seeing incomparably better movement, dogs also see much better in the dark than we do.
This is thanks to reflective sticks (compared to us humans, dogs have more sticks than cones) that reflect light.
They thus create the so-called tapetum lucidum, due to the reflection of which we can notice a bluish or yellowish reflection when looking directly at the light source in the dark or semi-darkness (eg in the light of a battery or headlights, or street lamps).
If you have a black dog, it can seem quite spooky, considering that – apart from looking like a laser-looking alien in the photos, it can look like a pair of floating eyes in the dark and it’s no wonder that people in the Middle Ages were afraid of black dogs and cats. and considered them the personification of Satan.
But that’s not all – tapetum lucidum, in addition to refusing additional light in the retina, thus increases the ability to see in low light, and also reduces visual acuity in bright light. In other words, dogs don’t need sunglasses!
The third eyelid in dogs
And finally, unlike humans, dogs also have a third eyelid that represents the membrane between the outer eyelid and the eye itself.
The purpose of this membrane is to protect and clean the eyeball, and depending on the type of eye, in some dogs, it is more pronounced and noticeable.
When my dog falls asleep, sometimes her eyes remain half-open, but that pink third eyelid is pulled over half an eye, so it looks a little creepy to the uninitiated …. even though she is almost 11 years old, there is no sign of impaired vision, in fact – there is no chance of falling off the table crumb, already eats it in the air!