What dogs and cats really see
Dogs and cats do not see in black and white, but they do not see the world the way we do either. Their eyes are built for movement and dim light, and they trade away some of the color and fine detail that human eyes are good at. The camera above turns those differences into a picture you can hold up against your own view.
Dogs see blue and yellow best
A dog’s eye has two kinds of color-sensing cones instead of the three that most people have. In a well-known study, Jay Neitz and colleagues measured them and found sensitivity peaks at about 429 and 555 nanometers, which makes dogs dichromats. In everyday terms, the American College of Veterinary Ophthalmologists explains that dogs see blues and yellows best and have difficulty telling red from green.
That is why a red ball that seems bright to you can disappear into green grass for your dog. To the dog, both are similar dull, yellowish shades, and the ball has to be found by movement and smell instead. A blue or yellow toy stands out far better on a lawn, which the camera shows nicely if you point it at a few toys on the floor.
Sharpness: a dog sees less detail, a cat even less
Veterinary ophthalmologists put a typical dog’s visual acuity at about 20/75. A dog has to be at 20 feet to see the detail that a person with normal sight can make out from 75 feet. A cat’s acuity is lower still, about 20/150, so a cat needs to be more than seven times closer than we do to see an object as sharply.
The camera blurs the picture by those amounts. Small print, the texture of a carpet and a face across the room soften first, while large shapes and anything that moves stay easy to follow. Dogs are more sensitive to moving objects than stationary ones, so a still toy may be ignored until it twitches.
Cats and the dark
Cats see remarkably well in dim light. Their retinas are packed with rods, the cells that work in low light, and behind the retina a reflective layer called the tapetum sends light back through it for a second chance to be caught. According to a review by veterinary ophthalmologist Ron Ofri, a person needs about six times as much light as a cat to see at all. The price is daytime detail: the same features that help at night make the picture less sharp in bright light.
Turn on night vision for the cat in a dim room to see a rough version of this: dark corners lift, colors fade, and the picture becomes grainy but readable. Cats do have three types of cones, yet behavioral studies have not found rich color vision in them, so the camera mutes their colors too.
How the simulation works, and its limits
The color filter uses a model that scientists use to simulate red-green color blindness in people, which matches the two-cone vision of dogs. The blur is scaled to the acuity figures above, assuming you look at the screen from a normal reading distance. It is an illustration, not an exact copy of what any one animal sees. Breeds, age and eye health all make a difference, and dogs and cats also see a wider field around them than this picture can show.
Everything happens in your browser. The camera picture and any photo you choose are not uploaded or saved.
Frequently asked questions
Are dogs color blind?
Not completely. Dogs have two kinds of cones, so they see a narrower range of colors than most people. They see blues and yellows best but find it hard to tell red from green, much like a person with red-green color blindness.
What color toy is easiest for a dog to see?
Blue and yellow toys are easiest for dogs to pick out, especially on grass. Red and orange toys look dull and brownish to a dog and blend into green lawns.
Can cats see in the dark?
Not in total darkness, but cats see in far dimmer light than people can. Their retinas have many more rods than ours, and the reflective tapetum behind the retina gives each bit of light a second chance to be detected.
Sources
- Neitz J, Geist T, Jacobs GH – Color vision in the dog. Visual Neuroscience, 1989
- American College of Veterinary Ophthalmologists – Vision in Pets
- Ofri R – Vision in the Animal Kingdom. World Small Animal Veterinary Association World Congress Proceedings, 2014
- Miller PE, Murphy CJ – Vision in dogs. Journal of the American Veterinary Medical Association, 1995
- Machado GM, Oliveira MM, Fernandes LAF – A physiologically-based model for simulation of color vision deficiency. IEEE Transactions on Visualization and Computer Graphics, 2009