By Jennifer Lueck
It is a common misconception that dogs see in blackand white, but dogs do see in color, just not the samerange of colors humans with normal vision see.
How do they know?
Scientists have been trying to test the color vision ofanimals since the early 1900’s with mixed results. Anexperiment was conducted in 1989 at the University ofCalifornia, Santa Barbara, by Jay Neitz and his colleagues. The test subjects were two Italian Greyhounds, Flip and Gypsy, and Neitz’ own dog a toy poodle named Retina. For the trials, the dogs were placed in a box facing a display of three round light panels. A computer randomly selected color combinations. Two of the three lights werealways the same color. The dogs were taught to findthe unique color and touch it with their noses. Everycorrect choice was rewarded with a dog treat droppedin the cup beneath the light they chose. Wrongchoices meant they didn’t get a treat. Neitz performedapproximately 4,000 trials with the dogs and chartedthe results. The experiment proved that dogs do see color, but they see a more limited range than humanswith normal color vision. Neitz’ results wereconfirmed in 1993 by a researcher using asophisticated optometric instrument that measures theindividual absorption rates of the cones in dogs’retinas
Normal human retinas have three types of colorreceptors, called cones. Each cone is sensitive to aparticular wavelength of light. The combined activity ofthe three different kinds of cones gives normalhuman their full range of color. Dogs and most colorblindhumans have only two kinds of cones, making theircolor vision more limited than normal human color vision.
It seems that most dog toy companies choose colors that appeal to the owner, rather than the dog! Knowing whatcolors your dog can see will help you choose toys andtraining equipment that will be the most visible to yourdog. To give you an example of how toys look to dogs, Itook pictures of some of Casey’s toys on our carpet and in grass. I filtered the pictures using www.vischeck.com,which is an application web developers use to make suretheir sites are visible to color blind humans. The pictureson the left are normal human vision; the pictures on the right are close approximations of what dogs see.
I’ve known for years that dogs were red-green color blind but I was still amazed by the results. It’s easy tothink that red and green are the only colors dogs don’tsee, but red and green are actually components of a many other colors. Without red, purple just looks blueand pink looks light gray. My experiment shows thatlight pink toys show up fine in grass, but are almostcompletely invisible on the carpet! Green and red arevisible on the carpet, but are lost in the grass. On both carpet and grass, blue and yellow toys are the most visible, making them the best color choices for toys.
Before you start to feel bad for your dog because his color vision isn’t as good as yours, check out Amy’s article on scent to see how much we’re missing by having human noses!
“Color Vision: Almost Reason Enough for Having Eyes.” Jay Neitz, Joseph Carroll and Maureen Neitz. Optics and Photonics News, January 2001