Dogs come in a wide assortment of shapes and sizes. If you recently watched the Westminster Dog Show, you saw the Best In Show winning monkey-faced affenpinscher and the lion-like Tibetan mastiff. Who would imagine that the sleek, 10-pound, hairless Chinese crested and the 80-pound Bergamasco covered with felt-like mats could possibly be the same species. People often tell me how their dogs are glued to the television when a program with dogs is being shown, while ignoring programs showing cats, horses, and other animals. On our daily walks and romps, my dogs easily recognize tiny and big, long-haired and short-haired dogs as being potential playmates and clearly different from cats, cows, and horses. How do they do it?
Researchers from the National Veterinary School in Lyon France recently developed experiments to answer that question and their results have been published in the journal Animal Cognition. In their experiments, pet dogs sat between two computer screens that showed the faces of dogs and other animals, like cows, cats, rabbits, birds, reptiles, and humans. First, one computer screen was blank and the other showed a picture. The dogs were trained using clicker training to sit between the two screens until hearing the command “image.” On receiving the command, they first learned to go to the computer screen with the picture and put their paw on a tablet in front of the picture. After this basic training was completed, the dogs were shown pictures on both computers — one picture was a dog and one was something other than a dog. For the first set of experiments, the dogs received a reward when they selected the dog and not when they chose the non-dog. After a few times, the dogs quickly learned to go to the dog screen, put their paw on that tablet, and then return to the tester for a treat. After completing the first set of experiments, the experimenter switched the treat, giving the treat only when the dog went to the non-dog image. Again, the dogs quickly learned to go to the non-dog image, put their paw on that tablet, and return to get a treat. These experiments showed that the dogs were able to categorize the images as dog or not a dog. The dogs were able to show the experimenter this organization by learning to go to the dog or the non-dog to get a treat, depending on what the experimenter was offering treats for during that set of experiments.
Each of the tested dogs was successfully able to group the images into dog or non-dog, quickly learning that receiving a treat was linked with choosing either the dog in the first set of experiments or the non-dog in the second set. These experiments helped researchers understand that dogs can recognize other dogs and distinguish them from other types of animals and birds by simply looking at their faces. While dogs are likely also picking up important clues from their other senses when out on walks, visual clues are enough for a dog to understand, “Hey — that’s another dog. Wanna play?”