What Can Dogs See?
by Jennie K. Willis PhD, as printed in the Coloradoan in March 2013
Can dogs see color? We have all been told at some point that dogs only see in black and white. What is interesting about this perpetuating piece of information is that it did originally come from research- but over 100 years ago. Science is always moving on and finding new information. Later experiments which looked at the actual cells in their eyes were able to find out the wavelengths of light that dogs can detect. It turns out dogs can see color, but not in the same way that we do. Dogs share much in common with the way the average color-blind person views the world. Differentiating red and green are a real problem for them, both of those colors washing out to look the same. Next time you are in the pet supply store, take note of how many toys are marketed with a combination of red and green. They are really marketed to us, not our dogs.
Why are dogs so motivated to chase small moving things? It starts with their vision. Dogs can see movement better than we can because they have more of a particular type of cell called a rod. Rod cells react only to movement, sacrificing color and detail. If you notice, prey animals like rabbits use a strategy of sitting still until the last possible moment because predator vision won’t find them until they move. Watching and chasing moving creatures are highly pleasurable activities for our pet dogs, even if they never catch the animal they are interested in. Just watching releases a pleasurable feeling.
Can dogs see in the dark? At night, dogs can detect individuals moving better than we can through several strategies. Their pupil dilates, letting in more light. If we turn on a porch light at night we can see their eyes shine. That shiny part is called the tapetum and acts like a mirror, reflecting any light that enters the eye back out. This allows the dog to use the available light twice, making night vision easier for them. Rod cells work better in low light but don’t detect detail as well, however, so dogs get a grainy picture like an old computer screen.
Why do dogs react badly to strange shapes of people? If your dog hasn’t been well socialized to people they may become afraid seeing a person with an umbrella or a man with sunglasses and a baseball cap. The outline obscures the shape your dog may be expecting a person to be. Dogs have blurry vision compared to people. If a letter in this article were to be clear to a dog it would need to be several inches tall. Cones are the cells responsible for sharp contrast in details, and they only have a small number of the cones that people have.
Appreciating our pet’s amazing senses helps us understand their behavior better.
Dr. Jennie Willis is an instructor of animal behavior at Colorado State University and owns a private consulting business, which provides counseling for problem pets and their people. For more information about consultation, seminars and classes please visit www.AnimalBehaviorInsights.com