Why dog trainers should not wear red..
Dogs are color blind, and can not distinguish between red and green. In other words, if you throw a red ball in a green field, dogs have trouble finding them. This is evident from today's published research.
The fact that dogs are less well-sighted, especially when distinguishing details, has been known for a long time. Although they smell much better than humans, their vision is up to eight times less than human vision. So far little was known about why they see worse. By developing a special test, scientists from the University of Bari (Italy) found that dogs have a lot of problems in distinguishing between red and green. It corresponds to a color blindness, deuteranopia, which also occurs in humans.
When dogs were still "wolves", that color blindness was of little importance, after all, the hunt was usually during dusk, and then there are far fewer colors to see. But since the dog has become a daytimepet of us, this facial power adds more problems.
At the same time, says researcher Marcello Siniscalchi, we can help the dogs now. For outdoor training, for example, we should not wear red clothes or shoes, as the movement of red things in green grass is badly observed. And with the daily training outside (unless someone has a green interior), we can keep this in mind. A blue frisbee or ball is seen much better than a red after all.
The researchers discovered this by adapting an existing human test, the Ishihara test, for dogs. In humans, numbers are hidden in a number of colored dots. Anyone (see figure above) that sees no number here is red-green color blind. Because numbers are not known to dogs, the dog test was done with the image of a cat.
And from that the red-green blindness became apparent. Presumably, scientists believe dogs also see little difference between brown and orange, but that test has not yet been done.
In the study, 16 dogs, all domestic dogs, were used. Three Australian Shepherds, an Epagneul Breton, a Weimaraner, a Labrador and ten muts.
foto's: University of Bari