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Whether it is a piece of food or a four-letter expletive, words can be learned by young children overhearing adults – but now researchers have found certain dogs can do something similar.
Scientists have discovered canines with the unusual ability to learn the names of myriad objects can pick up such labels by eavesdropping on conversations.
The team say such abilities are thought to rely on a host of social cognitive skills, from identifying the relevant word within a conversation to using cues from people’s gaze, gestures, and voices to understand what the word refers to.
“There is a lot of complex social things that are happening here and we don’t know if the dogs are doing it the same way as the kids,” said Dr Shany Dror, first author of the research from the University for Veterinary Medicine in Vienna. “But on the surface level, we see that the outcome seems to be the same.”
Writing in the journal Science the team report how they made their discovery by working with “gifted word learner” dogs.
In the first experiment, 10 such dogs – among them border collies, a border collie-mix rescue and a labrador – were each introduced to two new toys.
Each toy was presented to a dog over a one-minute period, with the name of the toy repeated, before the dog was allowed to play with it. This process was carried out many times over a series of days.
A second experiment was similar but instead of introducing a new toy directly to the dog, family members passed it between each other while using its name, ensuring they did not interact with their canine in the process.
For each experiment the team tested whether a dog had learned the names of its new toys by placing the objects in a room alongside nine familiar toys. Its owner then asked the dog to retrieve a particular toy by name, completing 12 trials for the new toys and 12 for the old toys.
Taken as a group, the dogs picked the correct new toy when asked about 90% of the time if they had previously been told its name directly, compared with about 80% of the time if they had previously only overheard its name – a difference that is statistically negligible. What’s more, in both scenarios the dogs did better than chance at picking the correct new toy of the two.
“I think the exciting bit is what it tells us about these dogs’ ability to interpret our communication,” said Dror.
A further experiment suggested “gifted word learner” dogs could learn the name of a new toy even if it was not mentioned until after the object was out of sight – a skill children also show.
The team note the ability to learn labels from overheard speech has previously been found in bonobos raised in a language-enriched environment, with some evidence for the skill in an African grey parrot. However, the new study revealed typical family dogs do not have the skill.
Even so, the researchers say their results suggest it is not only humans that have the necessary social abilities.
“The fact that this skill also exists in a species that does not have language suggests that the skill itself predates language,” said Dror. “So humans first evolved an ability to understand complex social interactions and only later used this complex understanding to develop language.”
Prof Marilyn Vihman of the University of California, Berkeley, who was not involved in the work, said it remained unclear why some dogs were “gifted word learners”. But she said the ability of such dogs to pick up word forms from overhearing them was quite striking, and seemed to correspond to what 18-month-olds were often able to do.
“As dogs are, as the authors note, highly attuned to the humans on whom they depend for survival, this does not seem surprising,” she said. But Vihman added it is also possible researchers may previously have made too many assumptions about the social skills infants need to pick up word forms and meanings from overheard speech. “Perhaps merely hearing a word repeatedly is sufficient for the word to be retained, in some cases,” she said.
