Are Dogs Color Blind?
A common perception among people is that dogs are color blind and can see a world that is purely black and white. Well, they are color blind, but in a completely different way. While their vision sensitivity and chromatic acuity is significantly less than humans, your canine friends can see color. The only thing is that dogs see something like a human deuteranope, that is, they are red-green color blind. This is because of the presence of 2 cone types or light sensitive cells rather than 3 that a human eye contains. So basically dogs have a blue-violent receptor range and the yellow-green receptor range. Why are Dogs Color blind?
Like the human eyes, the eyes of dogs contain light sensitive cells known as rods and cones. These are the parts that enable a human, as well as a dog to distinguish colors and ascertain the details of a vision. Due to the presence of fewer cone cells in the retina and a higher density of rod cells, dogs cannot distinguish between red, orange and green. They can only see various shades of blue and yellow and can possibly differentiate between closely related shades of gray that are not distinguishable to people. Moreover, they cannot understand the finer details of a scene. So while we see 20/20 or a little better, the dogs see about 20/80. This would make the scene around three to four times blurrier!
So how does your dog identify and chase the orange ball that you threw on the green grass? Well, dogs have a higher concentration of rods that help it discern the visual information in dim light and are sensitive motion detectors as well. So while an orange ball on the green grass may appear as yellow against yellow to your dog, the motion of the ball helps it catch it anyway.
Do you know why dogs are able to detect motion better than humans? The answer to this question lies in the evolution of the species. The perception of depth and accuracy of the vision was an evolutionary essential for a primate from which we humans have evolved. This allowed the primates to jump from one tree to the other and choose the best fruits based on its color. On the other hand, dogs have evolved from species that need to hunt its prey especially ones which are camouflaged at night. Therefore, the night vision of the dogs is enhanced by the presence of not only more rods but also a structure called the Tapetum Lucidum
that reflects the light falling on the retina and gives the eerie shining look at night. Also they can survey a large field of view to scan for their prey, have maximal contrast and can detect even the slightest of motion.
In 1989, researchers Neitz, Geist and Jacobs concluded that although the dogs are color blind, they can see certain colors. This along with a sense of motion, ability to detect contrast, view things at night and a wilder field of view enable dogs to hunt their prey at night.
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