For the first time, researchers have shown that dogs can perceive differences between human languages.
As detailed in a new study published on Thursday in the peer-reviewed journal NeuroImage, dog brains can detect and distinguish the difference between familiar and unfamiliar speech patterns, and, crucially, between languages.
A team of researchers from Eötvös Loránd University in Budapest tested language processing in 18 dogs trained to lay still in a magnetic resonance imaging (fMRI) machine. The pups were played excerpts of children’s novella The Little Prince in Spanish and Hungarian, which were languages all of them had heard only one of from their owners. The researchers also played backward versions of each track to test the dogs’ ability to recognize scrambled versus natural speech.
The researchers studied the dogs’ brain patterns as they listened to the tracks. They observed that different regions of the brain lit up when scrambled and normal speech were played, and different patterns were found when familiar and unfamiliar languages were played.
“Dogs are an excellent model because they have been living and cooperating with humans for thousands of years,” Laura Cuaya, first author on the study and researcher at Eötvös Loránd, told Motherboard in an email. “When we wonder if another species cares about what humans do, it is inevitable to think of dogs.”
Their research aim was to test for a skill called language discrimination, or the ability to recognize auditory regularities, like syllable structure, stress patterns, and pitch characteristics inherent in a particular language. Humans have this ability, and past studies have identified the superior temporal cortex (the part of the brain responsible for auditory processing) as the region responsible for this. Rats and sparrows have also been found with the ability to discern different languages after training, the paper notes.
Indeed, as they studied brain activity while the dogs listened to varying tracks, the researchers spotted movement in sound-sensitive regions that convey a general capacity for speech detection. Older canines and those with longer heads, in particular, appeared better at processing human auditory cues, the researchers said.
This happens in two stages for dogs, Cuaya explained. First, their brains detect whether a sound is speech or not, based on the ‘naturalness’ of the audio. Then, in a higher level of processing in the secondary auditory cortex, their brains discern whether a language is familiar or not.
Cuaya said that her interest in this research was born out of her experience with her own dog: Kun-kun was trained in Spanish while the pair lived in Mexico, but when she moved him to Budapest, where he was suddenly immersed in a new language, she began to wonder how he fared around both languages.
“Kun-kun is a very significant part of my personal and professional life. I like to think of my dogs as colleagues (and of course, my cat is our supervisor),” she told Motherboard.
Now, she’s shown that Kun-kun and other dogs can tell when they’re immersed in a new language, and hopes her finding will be a step toward understanding further the development of speech perception in canines like Kun-kun.
Attila Andics, senior author on the study and research fellow in the Family Dog Project at Eötvös Loránd, believes dogs might be uniquely equipped to understand human languages given their legacy of inter-species proximity—their findings open a door to figuring this out.
“We do not know whether this capacity is dogs’ specialty, or general among non-human species,” Andics said in the press release. “It is possible that the brain changes from the tens of thousand years that dogs have been living with humans have made them better language listeners, but this is not necessarily the case. Future studies will have to find this out.”