Domestic dogs respond to 89 words and phrases, on average 鈥� including verbs, nouns and terms of endearment 鈥� suggesting that their human vocabulary skills extend well beyond intentional cues like 鈥渟it鈥� and 鈥渟tay鈥�.
and Catherine Reeve at Dalhousie University in Canada created an initial inventory of 172 words and phrases they suspected pet and working dogs might be most likely to recognise. That list was based on prior studies, dog training courses, items marketed for dogs in pet shops, places dogs often go, their own experiences with dogs and recommendations from a group of dog owners.
Then, the pair collected information from 165 dog owners responding to their online questionnaire, shared mainly via social media. The survey asked owners to rate how well their dogs consistently and clearly responded to the English words and phrases on the list.
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By 鈥渞esponding鈥�, the researchers meant not only performing a trick or obedience behaviour, says Jacques, but any other specific reaction like enthusiastic tail wagging, a directed gaze or searching around. They also asked participants to suggest additional relevant terms not included on the list.
On average, the owners reported that their dogs responded to 78 items on the original list as well as 11 owner-added terms, meaning the average dog responded to 89 words or phrases.
The list of expressions in the current study probably helped trigger owners鈥� memories of words their dogs recognised and inspired them to think of others, says Jacques. In total, owners added around 1000 unique words to the researchers鈥� list based on their own dogs鈥� experiences.
Individually, dogs鈥� vocabulary levels ranged from 15 to 215 words and phrases, three times more than shown in . The repertoire comprises words and expressions the animals probably learned incidentally through living with humans, such as 鈥渙utside鈥�, 鈥渄inner鈥�, 鈥渧et鈥�, 鈥渨ho鈥檚 that?鈥�, 鈥淚 love you鈥�, room names and the names of family members and other pets, says Jacques.
鈥淲e were very careful not to ask if the dogs know, or understand, words, but if they respond to words,鈥� says Jacques. 鈥淚f any owner uses the same words over and over again, in a predictable context, their dogs might start picking up on those words [perhaps without the owner even realising it].鈥�
While the researchers didn鈥檛 investigate differences between individual breeds, they did note trends among seven major breed categories. In particular, herding dogs 鈥� collies and shepherds 鈥� and toy-companion breeds, such as Chihuahuas and poodles, averaged slightly over 112 words. Meanwhile, sporting and gun dogs 鈥� mainly spaniels and retrievers 鈥� responded to an average of about 80 words.
鈥淭he higher numbers of words for herding and shepherd dogs wasn鈥檛 surprising because that鈥檚 what these dogs were bred to do, to interact with humans,鈥� says Jacques. 鈥淎nd toy dogs are bred to be human companions and spend a lot of time close to humans, so that makes sense as well.鈥�
The dogs鈥� working status was also related, she says, with those professionally trained for working with humans, such as service dogs, responding to about 48 per cent more terms than those that aren鈥檛.
Characteristics of the dogs鈥� owners, however, didn鈥檛 influence the results, says Jacques. There was no link between a person鈥檚 level of education, household income or experience as a dog trainer and the total number of terms their dogs responded to.
鈥淭he next step is to see whether or not this predicts anything about the dogs, like cognitive skills, later word knowledge or other capacities,鈥� she says. 鈥淎nd if so, this might become a really important tool for identifying potential service dogs in particular.鈥�
Applied Animal Behaviour Science
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