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there is No doubt that the dogs they see the world differently than we do, but is an urban legend that your view will only be able to distinguish the white, the black and mild shadows gray.
While most of the people we are able to appreciate a full spectrum of colors that goes from red to violet, the eyes of the dogs lack some of the receptors of light which to us allow us to distinguish certain colors , especially the red and green . But yes they are able to distinguish the yellow and blue .
The different wavelengths of light result in different colors in the visual system of an animal. The above corresponds to the human eye, and the bottom of a dog – Up: iStock/ Plus via . Below: the same image processed by the Dog Vision Image Processing Tool, of András Péter.
What we see as red or orange, for a dog can be a shade of light brown tone. For my dog Sparky, a ball with an intense orange colour on the green lawn could be a ball with the light brown placed on a lawn of shade also brownish. However, it is likely that your ball intense blue color itself that the appreciation in a similar way. There is an online tool that allows us to see how you would see our dog in a given image.
The animals cannot speak to explain how they see, but to measure their vision, the researchers did not have much difficulty in training dogs for play with the muzzle of colored discs that is lit. Subsequently they trained the dogs to play the disc that was of a different colour than the rest. When these dogs, well trained, stopped to know what the discs had to press, the scientists deduced that at that point they were no longer able to distinguish the differences between colors. These experiments, moreover, demonstrated that dogs could only distinguish yellow and blue.
The retinas of humans, located in the back of our eyeballs, possess three distinct types of cells with the shape of a cone that are responsible for that we can distinguish the different colors we see. But when scientists used a technique called electroretinography to determine how it reacted to the light the eyes of the dogs, they discovered that they have a lower number of these receptors conical.
The light reaches the back of the eyeball, that the perceived thanks to the rods and cones. They send visual signals to the brain – iStock/ Plus via
But it is not just that dogs see fewer colors than we do; probably also see less sharpness. The analysis shows that both the structure and the functioning of your eye to make it look more blurry the objects located at a certain distance. While for a person with perfect vision has a value of 20/20, the typical view of dogs is about 20/75. That means that what a person with normal vision you can see clearly from 75 feet , to see it as the dog must be 20 . However, as the dogs don’t read the newspaper, this lower visual acuity does not affect your life.
Probably there is a great difference between races in terms of the visual capabilities of dogs. In regards to hunting, for example, the breeders have selected over the years to dogs such as greyhounds for having better eyesight than other breeds such as bulldogs.
But the issue is complicated even more. While people, we struggle to see clearly when there is little light, the researchers believe that dogs can see just as well during the dusk or the dawn that during a sunlit morning. This is because, compared with human, the retinas of dogs have a higher percentage and a greater variety of other types of visual receptor. It is the rods, so called because of its shape, and that in conditions of low light work the best cells to conical.
on the other hand, dogs have a layer of tissue reflective in the back of their eyes that helps them see better when the light is low. This is the tapetum lucidum , which works as if it were a mirror, and collects and concentrates the available light to help you see when it is dark. It is this tapetum lucidum that makes dogs and other mammals have that bright reflection in the eyes when at night I aim to the face with a flashlight, or try to take a photo with flash.
dogs have the same kind of vision than many other animals, including the cats and foxes . The researchers believe that for this type of predators it is important to detect the movements of their prey during the night, and for this reason his vision evolved from this mode. Like many other mammals, dogs developed the ability to find food and hunt during the twilight or in low light conditions, which was to the detriment of their ability to distinguish a greater variety of colors. This is something that the majority of birds, reptiles, and primates can do. Humans, in contrast, we evolved to be active during the night, so that we retain our ability to distinguish many colors as well as our vision clear.
Before you feel sorry for the dogs because they are not able to distinguish all colors of the rainbow, consider that some of their other senses are much more developed than ours. You are able to perceive high pitched sounds from much farther away than us, and their sense of smell is much more powerful.
even Though Sparky may not be able to easily distinguish a toy orange on the lawn, you can certainly smell it and find it easily when you want to.
Nancy Dreschel is Associate Teaching Professor of Small Animal Science, Pennsylvania State University
This article was originally published on The Conversation
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