Dog Brains Can Distinguish Between Different Human Languages

You talk to your dog, and of course, you’re convinced your pup understands you. But what if a dog is plopped down in a place where suddenly everyone is speaking a different language?

In a new study, researchers have used brain imaging techniques to find that dogs can differentiate between familiar and unfamiliar languages. Researchers say the findings, from the Department of Ethology at Eötvös Loránd University in Hungary, are the first evidence that shows a non-human brain can distinguish between languages.

A few years ago, first author Laura V. Cuaya moved from Mexico to Hungary for her postdoctoral research. Before the move, Cuaya’s border collie Kun-kun had only heard Spanish. She was curious whether he would notice that people in Budapest spoke a different language, Hungarian.

“Like many dogs, Kun-kun tends to pay attention to humans, trying to predict their social environment,” Cuaya tells Treehugger.

“When we moved to Hungary, it was a whole new world for everyone. In Budapest, people are very friendly with dogs. When people talked to Kun-kun, I wondered if he picked up the language difference. And happily, this question fitted with the goals of the Neuroethology of Communication Lab.”

Listening to Language

For their study, researchers recruited Kun-kun and 17 other dogs, who had been previously trained to lie still in a brain scanner for functional magnetic resonance imaging (fMRI).

The dogs were played speech excerpts from “The Little Prince” in Spanish and Hungarian. Each of the dogs had heard only one of the two languages: Hungarian was the familiar language of 16 dogs, Spanish of the other two dogs. That allowed them to compare a very familiar language with a completely unfamiliar one.

Researchers also played scrambled versions of the excerpts to the dogs. These were nonsensical and completely unnatural. This was to test whether they could tell the difference between speech and nonspeech.

They compared the brain responses to the two different languages and to speech and nonspeech.

“We found distinct cerebral regions for both processes: for speech detection (speech vs. non-speech), the primary auditory cortex, and for language recognition (familiar language vs. unfamiliar language), the secondary auditory cortex,” Cuaya says.

“Our results may suggest a hierarchy processing in the dog's brain to process speech. In the first stage, their brain would detect whether a sound is speech or not. Then, in the second stage, their brain would identify whether the speech is a familiar language or not.”

The results were published in the journal NeuroImage.

Exposure and Age

Researchers found that no matter which language the dogs were listening to, the primary auditory cortex of the dogs’ brains could distinguish between speech and scrambled, nonspeech.

"Dog brains, like human brains, can distinguish between speech and nonspeech. But the mechanism underlying this speech detection ability may be different from speech sensitivity in humans: whereas human brains are specially tuned to speech, dog brains may simply detect the naturalness of the sound,” says Raúl Hernández-Pérez, coauthor of the study.

They also determined that dog brains could differentiate between Spanish and Hungarian. Those patterns were found in a different region of the brain called the secondary auditory cortex.

Researchers found that the older the dog was, the better their brain was able to tell the difference between a familiar and unfamiliar language. That suggests that the longer dogs live with their people and are exposed to a language, the more they understand how their language sounds.

“As we could not control the amount of exposure to language in our study, we used the dog age as an indirect measure of the time dogs have been exposed to a given language,” Cuaya says. “I hypothesize that dogs with a closer relationship with humans will better distinguish languages. It could be great if future studies test puppies to control the exposure to a language better.”

Dogs as Models

Researchers are curious whether this language differentiation is unique to dogs or whether other non-human animals may also be able to distinguish between languages.

“A variety of auditory regularities characterizes each language. For example, sometimes, we cannot identify what language we are listening to. However, we can likely recognize its general origin (e.g., an Asian or Romance language) because of its auditory regularities,” Cuaya explains.

“Detecting regularities is something that brains do very well, not only humans or dogs' brains. It is highly likely that other species can be trained to differentiate between languages successfully.”

But Cuaya points out that in their study, dogs weren’t “trained.”

“Their brains detected the difference spontaneously, perhaps due to the domestication process," she says. "While it is likely that other species can differentiate between complex sounds, it is possible that just a few species are interested in the human language.”

Researchers believe the findings are important because by studying dogs, they can have a broader picture of the evolution of speech perception.

“Dogs are an excellent model because they have been living—and cooperating—with humans for thousands of years. When we wonder if another species cares about what humans do, it is inevitable to think of dogs. In the case of language perception, we can learn, for example, that different brains—with different evolutive paths—can carry out a similar process,” Cuaya says.

“Also, as someone with dogs in my family, it is lovely to know that dogs are picking up subtle cues of their social environment all the time.”

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