How Dogs See The World
Dogs have been credited with being man's best friend. And, even though we're not all dog people, and women can have dogs as best friends too, scientifically, dogs are quite interesting when it comes to the vision. People have the misconception that dogs can only see in black and white. And other than that most people are left in the dark about what kind of vision dogs actually have. Now, vision in most organisms is made possible through the teamwork of Cones, Rods, and Ganglion cells. Rods themselves are in charge of being able to register light and dark, while Cones are able to register color. And being able to perceive it. Now, for comparative purposes, the human eye has about 6 million Cone receptors, concentrated in a little indent known as the Fovea. Around the Fovea, the human eye has about 120 million Rod receptors. And if you know numbers, that's quite a difference.
On the other hand, dogs have only 1,200,000 Cone receptors in the back of their eye that is about 20% that of what humans have. And they also lack a Fovea. But dogs do have more Rods within their eyes than humans do. And even though it's hard getting an exact number on how many they have exactly, we do know that their eyes are 5 times more sensitive to light than that of humans. When it comes to color vision, the average human has Trichromacy, unless they're color blind. This means we have Cone receptors within our eyes that are able to perceive one of three colors red, green, or blue. Trichromacy gives us the ability to see about 1 million different shades of colors, in contrast to a dog's color vision. Dogs have Dichromacy, meaning they only have Cone receptors that are able to pick up two different colors, blue and yellow. This means that dogs and any other animal that has Dichromacy can only perceive about 10 thousands different colors. This is why, when you go to competitions that involve dogs, the obstacles tend to be blue and yellow colors. Interestingly enough, though dogs cannot perceive the color red at all. But the most popular color for dog toys is red. So, it's actually a better idea to buy dogs blue and yellow toys, because they have a hard time being able to identify red objects anywhere near green things. Like grass for instance. But even though that's a bit of a disadvantage, dogs do have some advantages over humans, such as their field of vision. Most dog breeds have about 250 degrees of vision. In contrast to humans, who only have about 190 degrees of vision. And not only do they have the capability to see more, but they also have better night vision. This is due to a combination of having more Rods than humans, having larger pupils than us, as well as having a Tapetum. The Tapetum acts like a mirror within the dog's eye, so once light enters the eye, it reflects back and forth and back and forth, giving the eye more of an ability to absorb Photons, and in turn, being able to see things in the dark. This also gives them shiny eyes when you take pictures of them. And the increased amount of Rods also gives them better motion detection than humans. But probably the best thing going for humans is that we, on average, can see further than dogs. The average human has 20/20 vision, and the average dog has 20/80 vision. This means that a dog would have to be 20ft away from something to see it just as clearly as we could 80ft away.