night vision

Dogs see colors differently

The key difference in color perception between dogs and humans lay in their retinas. Those are composed of two types of cells. The rods, that are sensitive to movement and catch the light in dark environments; and the cones, that control color perception et manage bright light. Turns out, dogs have more rods than cones in their retina, when people have the opposite. Therefore, dogs see the world like a color-blind person would because they are missing the green-red cone. For this reason, blue and yellow are the main “bright” colors a dog sees almost like a human does.

Red, green, orange, purple, or pink will look more like a brown or a khaki. Something to keep in mind when choosing a dog’s toys – remember that obsession for tennis balls? It is also the reason why those potty training pads are lined with a blue border: to help the dog localize them more easily.

Dogs see better in the dark

If dogs are not the best at seeing colors like their humans, they compensate with an impressive night vision thanks to three key elements. The extra rods in their retina allow them to distinguish light from shadow and lets more light in; they have larger pupils to catch any ounce of light; and they have an extra mirror-like membrane (scientific name: tapetum) at the rear of their eye that allows the light not absorbed by the rods to rebound to the retina. This is this “mirroring” feature that makes your dog’s eyes shine in the dark. The phenomenon is known as eyeshine. As a result, a dog can see in the dark with 5 times less light than a human would need. A pure product of the evolution, when dogs were nocturnal hunters because it was safer for them to catch their food at night.

Dogs have a larger field of view

Because their eyes are on the side of their head, dogs can see at a 240° angle when humans are limited to 200. But this comes at a price, as their “binocular vision”, the zone in the center where both eyes can see, is smaller than it is for people. Unfortunately, this binocular vision plays a key role in seeing depth and distance, so dogs are at a disadvantage in this area. Their nose is also often in the way which makes this center view area a challenge.

Dogs detect movements more easily… maybe

The rods in the retina are sensitive to motion, and dogs happen to have more of them than humans. Therefore, in theory, they would detect much smaller movements and would sense someone coming before we do. However, a study published in 2017 by the Scientific Reports on Nature Research noted that those findings were not proven in practice. “To the best of our knowledge, studies about the sensitivity of detecting coherent motion in dogs are lacking”, explains a group of five scientists from the Psychology department of the University of Padova, in Italy. So they conducted their own research. Their conclusion: “Dogs are not better than humans at detecting coherent motion”. They think that “canine domestication” might be to blame, because it has “relaxed pressure on the need for a visual system highly specialized in motion detection”.

Dogs can’t see too far

Dog’s vision is roughly estimated to be 20/75. It means that he would need to be 20 feet away from an object to see it as clearly as a human would from 20 feet away. This is due to the lower concentration of cones in their retina, which gives them a visual acuity of 4 to 7 times lower than people, depending on breeds. Labradors are known to have the best eyesight of all breeds, sometimes close to 20/20, which is the reason why they are often used as seeing-eye dogs for people with a vision disability. But for most breeds, they see the world with a slightly blurry lens compared to humans.