When neurobiologist Laura V. Cuaya moved from Mexico to Hungary with her border collie, Kun-kun, she wondered whether the dog could tell that people were speaking another language.
“We know that people, even preverbal human infants, notice the difference,” says Cuaya in a statement. “But maybe dogs do not bother. After all, we never draw our dogs' attention to how a specific language sounds.”
To find out, Cuaya and her team of researchers at Eötvös Loránd University in Budapest trained eighteen dogs of various breeds, including Kun-kun, to lay in a brain scanner while listening to excerpts from the children’s book The Little Prince in both Spanish and Hungarian. All dogs had only heard one of the two languages from their owners.
The researchers found that the two languages triggered different activity patterns in the part of the brain that processes complex sounds, showing for the first time that a non-human brain can differentiate between languages. The results of the study were published in NeuroImage.
"It is a very exciting study because it shows that the ability to grasp the sounds and rhythms of a familiar language is something accessible to non-humans,” Amritha Mallikarjun, a researcher at the Penn Vet Working Dog Center in Philadelphia who wasn’t involved in the study, tells NPR’s Alejandra Marquez Janse and Christopher Intagliata.
The researchers also found that older dogs could tell the languages apart better. “It seems that the longer a dog lives with its humans, the better it learns how their language sounds,” a video abstract of the research explains.
The team also tested whether the dogs could distinguish between speech and non-speech by playing scrambled Spanish and Hungarian versions of the excerpts to the dogs. They found that no matter which language the dogs listened to, they could tell the difference between nonsense words and human speech. Unlike human brains, which have neural processes tuned for speech, though, the dogs may have simply been responding to the “naturalness of the sound,” study coauthor Raúl Hernández-Pérez says in a statement.
Other research has shown that some animal species behaviorally respond differently to separate languages, but it is unclear whether dogs have a unique listening ability.
"It is actually a very exciting follow-up research question whether the thousands of years of domestication gave dogs some advantage for speech processing," Attila Andics, senior author of the study, tells CNN’s Sandee LaMotte.