It had already been established that dogs respond to human voices better than their wolf brethren, are able to match hundreds of objects to words and learn elements of grammar, and can be directed by human speech. But the new findings mean dogs are more like humans than was previously known: They process language using the same regions of the brain as people, according to the researchers, whose paper was published in Science.
This had already been demonstrated in studies that observed dogs, but no one had seen how it works inside the canine brain. To determine this, Attila Andics and colleagues at Eötvös Loránd University in Budapest recruited 13 family dogs — mostly golden retrievers and border collies — and trained them to sit totally still for seven minutes in an fMRI scanner that measured their brain activity. (The pups were not restrained, and they “could leave the scanner at any time,” the authors assured.)
A female trainer familiar to the dogs then spoke words of praise that all their owners said they used — “that’s it,” “clever,” and “well done” — and neutral, common words such as “yet” and “if,” which the researchers believed were meaningless to the animals. Each dog heard each word in both a neutral tone and a happy, atta-boy tone.
Using the brain activity images, the researchers saw that the dogs processed the familiar words regardless of intonation, and they did so using the left hemisphere, just like humans. Tone, or the emotion behind the word, on the other hand, was analyzed in the auditory regions of the right hemisphere — just as it is in people, the study said.
In an e-mail, co-author Tamás Faragó acknowledged that the left hemisphere’s response to praise words didn’t prove the dogs were comprehending meaning and not simply reacting to familiarity. But, he said, it’s safe to assume the dogs hear the neutral words in daily human conversation as often as they hear the praise words, “so the main difference will be not familiarity, but whether the word is addressed to the dog or not.” In other words, whether it has meaning for the pooch.
Finally, the researchers saw that the dogs’ “rewards center” — which is stimulated by pleasant things such as petting and food and sex — did the brain equivalent of jumping and yelping when positive words were spoken in a positive tone.
“It shows that for dogs, a nice praise can very well work as a reward, but it works best if both words and intonation match,” Andics said in a statement. “So dogs not only tell apart what we say and how we say it, but they can also combine the two, for a correct interpretation of what those words really meant.”
The researchers said it’s unlikely that human selection of dogs during their domestication, which occurred at least 15,000 years ago, could have led to this sort of brain function; Faragó said that it’s more possible it would be a side effect of other dog traits selected by humans, such as attention. But he said he and his co-authors think these neural mechanisms are probably far more ancient, and perhaps “more widespread than we thought before.”
That means we aren’t as special as we like to think, at least when it comes to how our brains deal with language. What makes words uniquely human, Andics said, is that we came up with using them.
Oh, and if you’re a cat person? Faragó said it’s likely they (and other domestic animals) might also be able to understand words and tone. But given that cats were domesticated thousands of years later and have generally lived less closely to humans, they might not be as adept as dogs. They certainly wouldn’t be as cooperative on an fMRI scanner.