How do dogs recognise that another animal is also a dog when there is such a vast array of canine shapes and sizes?
Garry Trethewey
Arkaroola Wilderness Sanctuary, South Australia
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The obvious answer might be 鈥渂y smell, not by sight鈥�. But it isn鈥檛 that simple.
Epistemology is a branch of philosophy that asks: 鈥淲hat is knowledge?鈥� So what does 鈥渞ecognise鈥� mean?
Dogs respond to other dogs, as well as people and sometimes goats, sheep and geese, based on a range of stimuli. Sometimes, it is familiarity; sometimes, it is smell.
They might approach other dogs and humans in amorous or aggressive ways.
It can be said they 鈥渞ecognise鈥� the object of their attention, in the sense that they would respond to a block of wood differently. But we have no way of knowing how or if a dog 鈥渞ecognises鈥� another dog as being different from its owner or any other familiar creature.
Robert Stewart
San Francisco, California, US
Do dogs know that other dogs are dogs just by looking at them? That is the question researchers in France wanted to answer in 2013.
They conducted a with nine companion dogs who were trained and had experience with both dogs and people. The researchers wanted to see if they could recognise other dogs based solely on appearance, without relying on their sense of smell.
All the dogs in the study knew their way around both dogs and humans. And let me tell you, they didn鈥檛 all look the same 鈥� there were two pure-bred dogs and the rest were mutts.
So, here鈥檚 how it went down: in each trial, the dogs looked at two screens, one on the right and one on the left, with a divider in between. The screens showed two images at the same time. If the dogs approached the screen with the 鈥渞ight鈥� image, they got a click and a treat.
To see if dogs could identify other dogs just by their looks, the researchers needed to establish some common ground with their furry subjects. They did this by having three training sessions where the dogs only got a treat when they approached the screen with a dog鈥檚 face.
It was important that they used the same picture of a dog throughout the training sessions. The other screen either showed all black, all blue or a picture of a cow鈥檚 face 鈥� approaching those wouldn鈥檛 get the dogs any treats. The researchers wanted to make it clear they would only get rewarded for approaching the 鈥渄og鈥� image, nothing else.
The dogs had to choose the dog image correctly at least 10 out of 12 times in two consecutive sessions. And guess what? All nine dogs nailed it! They seemed to understand the common language that the researchers had set up.
I have done a number of similar experiments myself over the years. Dogs are amazingly perceptive creatures and I have been fascinated with them my whole life.
Peter Scott
Radlett, Hertfordshire, UK
I am pretty sure that dogs recognise other dogs in much the same way as we do: years of visual pattern recognition.
What I really don鈥檛 understand is how my dog Daisy knows that a fox isn鈥檛 a dog. For Daisy, a fox is worthy of hysterical barking and lunging, a behaviour she doesn鈥檛 exhibit with Canis familiaris.
She does this even when upwind of the fox at 30 metres or more.
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The spelling of Robert Stewart鈥檚 name has been corrected in this piece.