Terrence Deacon, a professor of biological anthropology at University of California, Berkeley, agrees: “The fact that a dog hears a sound and responds to it preferentially with left hemisphere activation is not a surprise to me,” he says. “But our brains are handling language in a way that is radically different than this dog is handling the sound of words. Dogs don’t have an elaborate semantic network in their heads—interpreting a word as being in relation to a whole system of other words—like we do. That we can understand a complex sentence or any number of sentences is a uniquely human trait that is not being demonstrated here.”
And even if the hemispheric bias is a real phenomenon, Berns says its impossible to determine whether it is a consequence of generalized word processing or because the words that they used to test the dogs were praise words. “Human imaging studies have long shown that the left hemisphere tends to be more active to positive emotions. This could explain the Hungarian results, without invoking lexical processing,” he says.
The combination of praising words and tones, however, activated very different parts of the brain. Andics and his team found that regions typically associated with reward in humans showed significant increases in activity only when praising words were delivered in a praising tone. This means that the dogs exhibited an ability to isolate and separately process word meaning, but they were then able to integrate both in the reward centers of their brain.
In the study, Andics and his team brought 13 pet dogs to their laboratory, and trained them to remain still in an fMRI scanner—a claustrophobic space for even the most well-behaved canine. While their brain activity was monitored, the dogs listened to an audio recording with a variety of familiar praises (e.g. “well done,” “clever,” and “thats it”) as well as neutral conjunctions that are commonly used in everyday speech but had no relevant implications for the dogs (e.g. “as if,” “such,” “yet”). To determine whether the dogs could discriminate between the “what” of the word versus how we say it, each word was spoken in either a praising intonation—characterized by a higher, more varying pitch (i.e. how you might talk to a cute toddler)—or a neutral intonation.
Moving forward, Andics and his team will continue to explore various aspects of speech processing in dogs: how they differentiate between speakers, how they learn new words, and even how they might process a combination of words in syntax.
In the study, Attila Andics, a neuroscientist at Eötvös Loránd University in Budapest, and his colleagues scanned the brains of 13 family dogs of 4 different breeds while the canines listened to a series of praising or neutral words. Different areas of the animals’ brains lit up depending on the tone and meaning of the words.
But David Reby, a psychologist at the University of Sussex, UK, calls the work “an elegant study”, noting that it corroborates his own behavioural findings in dogs3.
But Terrence Deacon, an evolutionary anthropologist at the University of California, Berkeley, notes that although the hemispheric differences in the study were convincing, the results in the reward centres were less so. “It’s such a small area and overlaps with so many different areas that I’m a little suspicious that it’s probably not a strong finding,” he says.
He cautions that dogs probably don’t fully understand language as humans do. Still, the study results suggest that dogs can derive some semblance of meaning from different words.
Over several months, the team had trained the dogs to lie in a functional magnetic resonance imaging (fMRI) scanner and remain completely still for two 7-minute brain-scanning sessions. The dogs were not restrained and could leave the scanner whenever they chose.
For decades, scientists have believed that a big shift occurred in human evolution that made our brains left hemisphere dominant in processing communication, and that this is what led to the evolution of our unique language abilities, says Brian Hare, a cognitive neuroscientist at the Duke Institute for Brain Sciences in Durham, N.C.
All the dogs in the study were willing volunteers and were trained to lie still in the scanner using a training method developed by Marta Gacsi. The dogs could get up and leave the machine whenever they wanted. But it was clear to the dogs that their human companions loved it when they did this very easy task.
Whats more, he says, this study is important because he thinks its the first major finding using noninvasive neuroscience with awake animals — usually they have to be drugged or restrained. “That just changes everything,” he says. “You literally can see whats going on in their brains just like you would with people. And its really the first time that this has led to a big discovery and I think were going to see a lot more of this.”
He says people have been studying great apes and fossils to try to figure out exactly when that left hemispheric shift occurred. “It seems the story is really that there is a general mammalian bias to process words or meaning in communication in the left hemisphere and it became exaggerated in humans,” says Hare. “Its not something completely new to our species.”
He says most dog owners have experimented with trying to “trick” their dogs by saying nonsense words in a cheerful, happy tone of voice. “I think the big difference here is that they only heard us, they didnt see us,” says Andics, because the dogs were inside the machine. “Here, the only information they had was the speech signal. What we saw is that for praise to be processed as a reward, when there is no other supporting information, both word meaning and intonation have to fit.”
Dogs actually understand what you’re saying, study shows
No, really — he actually does. So say scientists in Hungary, who have published a groundbreaking study that found dogs understand both the meaning of words and the intonation used to speak them. Put simply: Even if you use a very excited tone of voice to tell the dog he’s going to the vet, he’ll probably see through you and be bummed about going.
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.)Advertisement
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.This is what dog brain activity hearing human speech looks like. The yellow and red areas are a dog’s auditory regions responding to words. The green area is the dog’s “reward center” which is activated when listening to praise words spoken in a praising tone. (Video: Anna Gabor, MRIcron)
Using the brain activity s, 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.The first study to investigate how dog brains process speech shows that dogs care about both what humans say and how we say it. (Video: Family Dog Project)
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.Advertisement
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.”Advertisement
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.Do dogs really love you for you, or just because you feed them? (Video: Gillian Brockell/The Washington Post)