How does one dog recognize another animal as a dog?
Q: How does one dog instantly recognize another as a dog, not some other animal?
A: Studies of dogs’ ability to discriminate their kind from other animals show that they can do so based on purely visual evidence, even in images.
This is even more remarkable in view of the fact that “domestic dogs, Canis familiaris, present the largest phenotypic diversity among domestic mammals,” in the words of one study, which was conducted in France and published in 2013 in the journal Animal Cognition.
Ranging in size from a tiny Maltese to a giant St. Bernard, and showing myriad differences in coats, snouts, ears, tails and bone structure, dogs might not always appear to belong to one species.
Yet other dogs recog- nize them easily, even in the absence of clues like odor, movement and vocalizations.
The French study trained nine dogs to expect a food reward when they picked the dog from side-by-side computer displays of a dog’s face and that of another creature, including domestic and wild cats, sheep, goats, cows, birds, reptiles and humans.
They were presented with random selections from 3,000 pairs of uniformly scaled images, none of them repeated.
Each dog saw 144 such pairs. Earlier discrimination studies had used far fewer images.
What facial features enabled the dogs to pick out other dogs was not studied, a Scientific American blogger said in a review article.
Another possible weakness of the research was that it did not include images of closely related species, like foxes and wolves.