When Maureen and Jay Neitz adopted an adorable, fluffy black puppy in the late 1980s, they had no idea how important she would be in making new discoveries about vision.
They were just looking for a dog who was size-appropriate for the small apartment they lived in as UC Santa Barbara PhD candidates. Eventually, the teacup Poodle they named “Retina” helped the couple prove that dogs see much more than just black and white, and that dogs’ color vision is similar to that of the 8 percent of the human population who are red-green colorblind.
Ten million Americans, most of them male, are affected with red-green colorblindness, a genetic trait carried on the X chromosome. People with this condition can’t clearly see the difference between red and green. They often mistake green for white and red for brown or dark gray.
Colorblindness might not seem like a serious disability, but it causes unexpected, and sometimes tragic, problems for humans. For example, airline pilots must be able to differentiate between colors, which someone with red-green colorblindness can’t reliably do. Color vision is, of course, crucial in being able to discern if a traffic light is red or green. According to Don Peters, a consultant to the biotech industry who has red/green colorblindness, “Sodium vapor lights look a lot like red stoplights to me. It’s confusing to drive in an area with these lights, especially at night.” As a child, he had difficulties with color-related tasks: “I can still hear my teacher asking me why I colored the tree red. I couldn’t tell the difference.”
Colorblind people miss a lot of detail that people with normal color vision take for granted: they might not see the lines on a map, or lettering printed in colors that seem bright to those with normal vision but blend in for them. This can be dangerous when reading traffic signs or medication labels. Jay Neitz pointed out that children who are colorblind often have trouble in school, and can be mistakenly diagnosed with learning disabilities or ADHD; in spite of these potential problems, schools do not test students’ color vision.
The Neitzes established that dogs see shades of yellow, blue and gray. Other colors, such as red and green, appear faded or indistinct. Jay Neitz had an “aha” moment when Retina could not find her orange ball in a green lawn. “Sometimes the ball was right in front of her, but she would sniff around in the grass, trying to find it by smell. We realized that she simply couldn’t see it, even though it was obvious to us,” he said.
As UC Santa Barbara post-docs with degrees in biochemistry, molecular biology and biopsychology, the couple had access to a lab in which they could set up a testing area. “I realized that I had the opportunity to find out, once and for all, what kind of color vision dogs really have.” Jay built an apparatus that placed dogs in front of a screen with three lit panels. He trained the dogs to touch the screen with their noses when they saw a different shade. If the dog got it right, she would receive a cheese-flavored dog treat. In order to get the dog to touch the screen, Jay used peanut butter as an incentive. Once the dog mastered that part of the test, Jay no longer used the peanut butter.
Right away, Maureen and Jay discovered that, like people, dogs were good at figuring out shortcuts to getting a treat. In addition, “About 30 percent of the time, the dog made a lucky guess,” according to Maureen. The dogs’ attention spans were short, and on more than a few days, they just didn’t feel like doing the tests. “It took six months per dog to train them,” Maureen said. In addition to Retina, the Neitzes used two Italian Greyhounds; like Poodles, they are small, intelligent, easily trained dogs. “The dogs were treated very well,” Maureen said. “We had the utmost concern for their welfare.”
In 1989, Jay Neitz co-authored “Color vision in the dog,” which was published in the journal Visual Neuroscience; the research paper confirmed that dogs do, indeed see more than black and white. That led to a years-long search for a cure for colorblindness in humans.