Have you ever thought about what you sound like to your dog? Unless you’re using words you’ve already taught your dog, you might imagine you sound like the teacher in the Peanuts cartoons – just a bunch of wah, wah, wahs. But the reality is far more interesting as we ponder if dogs can understand different languages. Recent research in the journal NeuroImage has shown that dogs can distinguish familiar languages from unfamiliar ones and can even tell human language from nonsense sounds.
Recruiting Study Subjects
Researchers in the Department of Ethology at Eötvös Loránd University in Budapest, Hungary, wanted to investigate activity in canine brains when dogs heard a language they did not know. According to the university’s Department of Ethology newsletter, lead researcher Laura Cuaya’s move from Mexico to Hungary with her dog sparked the idea. Just as Cuaya was surrounded by a new and unfamiliar language, so was her pet Kun-kun, and she wondered if he noticed the change.
So, Cuaya and the scientists in her lab recruited 18 dogs, including Cuaya’s, and trained them to lie still in an MRI machine for a brain scan. There were six Border Collies, five Golden Retrievers, two Australian Shepherds, one Cocker Spaniel, and four mixed-breed dogs. They were all adult animals between the ages of three and 11. Two of the dogs were familiar with Spanish, and the other participants were familiar with Hungarian.
Storytime in the MRI
While the dogs lay in the MRI machine, they listened to recordings from the classic children’s book The Little Prince by Antoine de Saint-Exupéry. Female narrators, one a native Hungarian speaker and one a native Spanish speaker, read the story in an engaging tone of voice to sound as natural as possible. Sometimes the dogs heard a recording in Hungarian, sometimes a recording in Spanish, and sometimes a computer-scrambled recording that no longer resembled human speech at all.
While the dogs listened to the different recordings, the MRI machine scanned their brains to measure activity during each condition. However, the dogs were free to leave the machine at any time, and the trainer and their owner were both in the scanning room to help the pet feel comfortable.
Different Brain Activity
Then it was time to analyze the results. First, the scientists looked at whether the dogs could distinguish speech of any kind from non-speech. And they could. The primary auditory cortex of the canine brains showed distinct activity patterns, depending on whether the subjects heard the scrambled passages or the original recordings. However, this does not necessarily mean canine brains are tuned to speech like human brains are. It may simply be that the dogs could tell the difference between natural and unnatural sounds.
Next, the scientists compared the brain scans from when the dogs heard a familiar language versus an unfamiliar one. And again, the scans indicated the dogs could tell the difference, this time in a different area of the brain known as the secondary auditory cortex. Both these brain regions are located inside the temporal cortex, and the researchers hypothesize that they allow dogs to process speech in two steps. The primary auditory cortex determines whether or not a sound is speech; then the secondary auditory cortex tells dogs if this is a language they recognize.
Older Dogs Showed a Greater Response
It is amazing to think dogs can tell Hungarian from Spanish, especially from words they likely are not familiar with. After all, the passages from The Little Prince probably were not peppered with “sit,” “stay,” and “paw.” Amazingly, dogs are the first non-human animal to show this ability to distinguish between languages. And they did it spontaneously. No training was required.
However, we talk to our dogs all the time, and even when we are not directly addressing them, they are bathed in our communication. Surely they absorb the patterns and rhythms of our speech. That notion was supported by the study. Interestingly, the brains of the older dogs showed more activity in their secondary auditory cortex. That hints that these animals were better able to distinguish between the two languages. All those additional years spent living with people might have provided them more familiarity with the languages spoken in their homes.
Different human languages have different sounds and patterns, so other animals may be capable of doing this too. But dogs as a species have lived alongside humans for thousands of years. Perhaps they have evolved a special ability to recognize our speech. In fact, a recent study from the same university on the acoustic bases of human voice identity processing in dogs showed that dogs can recognize their owner from voice alone – no visuals or odors required.
There is no doubt dogs want to hear what we have to say, but future research could explore whether this human language perception is unique to their species. In the meantime, it seems that, far from sounding like the Peanuts teacher, your voice and the language you are speaking are comfortably familiar to your dog.