Dogs can perceive color, but their spectrum contains a lot fewer hues than what humans see.
Scientific research progresses in small increments with a lot of digressions. But many news organizations would rather have a story of some great big sudden breakthrough, and the news media tends to have a short memory. That is why we get a human interest story every few years that is all about some scientist as “discovering” that dogs are color-blind. Not completely color-blind, mind you, but red-green color-blind. In humans, this is usually described as protanopia.
Most mammals have protanopia, so it is not the red color of the cape that attracts the bull’s attention. Many insects cannot see red but can perceive ultraviolet. Humans, some other primates, fish, and birds have trichromatic vision. Some birds may have one or even two more color receptive cells than us, and so see colors and shades we cannot even imagine.
So dogs can see yellow and blue, but no green or red or colors created by these shades, such as pink, orange or purple. Or, more accurately, the color they see will be a shade of blue or yellow rather than the color that you see. If you look at the rainbows below, you see that for dogs, purple loses its red hue and becomes blue. Red becomes a murky shade of yellow mixed with dark grey.
It is strange to look at the array of dog products in the stores, or the dyed shades of kibble, and realize that very little of this is done for dogs’ benefit. Almost all products designed for dogs seem to really be tailored to the owner, right down to color. In fact, as many as eight percent of men have some form of color-blindness, too, so it surprises me how little it is considered in the design process, from red-green traffic lights to sports team colors.
However, knowing the colors your dog can see can help you create an environment you dog can easily understand and enjoy. There are a few basic rules. If you are using color to create contrast, stop and think about how it will look to the dog.
What looks like yellow and blue to you, looks like yellow and blue to a dog. So if you want to provide color contrast and have an environment that looks similar to you and your dog, this is the color pallet is what you should use. (Even then the exact shades and their meanings are still going to be different for a dog).
If you want to assess how something might look to your dog, there are a range of filters that can give an estimate. There is an iPhone app called the Chromatic Vision Stimulator by Kazunori Asada. If you select “P” mode, you can use the phone’s camera to see a simulated protanopian view of the world. The pictures below show a few of Vera’s favorite things as they look to me and as they might look to her. It is pretty obvious that I was not thinking about dog color vision when I made some of these selections.
When you do this you can see that red and green objects can still present a color contrast. A red bag on a blue blanket can still be clearly seen as a kind of yellow-brown against the blue. If in doubt, it is a good idea to provide other sources of contrast, such as pattern, texture or smell, to ensure your dog can easily find his things.
Recent research showed that while dogs certainly can discriminate objects by color, when they cannot tell the colors apart they fall back on using bright versus dark as a cue. For example, a red toy on green grass might be only slightly different kinds of brownish yellow to a dog; a bright white toy will be much easier to find. There is a reason why tennis balls are bright yellow and golf balls are white. Even to the human eye, brightness makes these balls easier to see against grass, which is generally a medium to dark shade.
If you have a bed you travel with, to give your dog a “home base,” it can be good to make this as easy to find as possible. A strong pattern, plush texture, and even a non-toxic herb sachet sewed inside can make the bed easy to locate no matter where you travel and give any hotel or guest bedroom a reassuring piece of home.
And in case you think we should feel sorry for dogs not seeing all the colors we do, it all probably evens out or perhaps goes somewhat in the dog’s favor. They can hear ultrasound. They can follow a smell map or even diagnose cancer by scent. The richness of their sensory world holds pleasures we cannot even imagine, any more than we can know all of the colors that the honey-bee can see.
by Emily Kane
Diana Ruth Davidson, Chief Pet Officer and Managing Nanny, Westside Dog Nanny
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