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Friday, March 1, 2013

Dogs categorize each other by sight

If you have a dog, then you’ll have noticed that your dog always shows great interest in any other dog he meets regardless of how physically different the second dog might be. A person who had never seen a dog before would hardly lump an English Mastiff and a Chinese crested into the same species, yet dogs seem to know one another. While it’s likely that much of that recognition is due to scent, that’s not all there is to it. Dominique Autier-Dérian of the University of Paris and her colleagues showed that dogs can categorize other dogs by sight alone.

Dogs recognise other dogs
The participants. Don’t they look happy to be volunteers?
Animal cognition PMID: 23404258.

The scientists chose nine adult dogs as their test subjects: seven crossbreeds, a purebred border collie and a purebred Labrador retriever. After being trained to select the image of a dog over that of a cow or of a food dish, the real tests began. The dogs were presented with two computer screens, one showing a dog and the other a non-dog from one of forty species, including cats, rabbits, birds and humans. 3,000 images were used for each category (dog and non-dog), only twelve of which had been used in the training sessions. Thus, the vast majority of the images were unfamiliar to the dogs. The dogs’ task was to pick out the dog’s faces, if they could.
Three discrimination tests using a dog and a non-dog.
Animal cognition PMID: 23404258.

All the dogs were able to put all kinds of dogs into the category ‘dog’. I should point out that not only were there no non-visual cues, but all the images were headshots that were manipulated to be the same size on the screen. Yet, with that limited amount of information, the nine test dogs were able to generalize about what it means to be a dog. Despite the extensive physical modifications dogs have undergone over the years, they know each other when they see each other.

Autier-Dérian D, Deputte BL, Chalvet-Monfray K, Coulon M, & Mounier L (2013). Visual discrimination of species in dogs (Canis familiaris). Animal cognition PMID: 23404258.

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