For the first time, researchers have shown that not only humans can differentiate between different languages: The brains of dogs also show different activity patterns, depending on whether the four-legged friend is familiar with the language they hear or not. This is particularly clear in older dogs who have had a long time in their lives to get to know the sound of a language. In addition, the four-legged friends recognize whether the spoken words are actually a language. Non-linguistic sound fragments are processed in a different brain region.
Even before human babies learn to speak, they can recognize and differentiate between different languages. Since communication through language plays a key role for humans, our brain has developed in the course of evolution in such a way that it can recognize, systematize and reproduce linguistic patterns. But is this ability uniquely human? How do animals perceive our language? Are there differences between different human languages for our four-legged companions?
From Spain to Hungary
Laura Cuaya from Eötvös Loránd University in Hungary asked herself this question when she and her dog Kun-kun moved from Mexico to Hungary. “Before, I only spoke to him in Spanish,” says Cuaya. “That’s why I asked myself whether Kun-kun had noticed that the people in Budapest speak a different language, namely Hungarian.” To find out, she and her colleague Kun-kun and 17 other dogs trained on it, all in one Lying brain scanner. In this way, the researchers were able to follow the brain activity of the animals while they listened to excerpts from the book “The Little Prince” by Antoine de Saint-Exupéry via headphones – sometimes in Spanish, sometimes in Hungarian.
“All dogs had only heard one of the two languages from their owners, so that we could compare a very familiar language with a completely unknown one,” reports Cuaya. “We also played the dogs with dismantled versions of these excerpts that sound completely unnatural. So we could test whether they even recognize the difference between language and non-language. “
Different brain activity
The result: depending on whether the dogs heard the non-linguistic scraps of sound or one of the two languages, different activity patterns were found in their primary auditory cortex. In this area of the brain, sounds are processed and classified according to volume and pitch. Based on the brain activity in the primary auditory cortex, the researchers could not tell whether the dogs heard Spanish or Hungarian, but they could tell whether it was speech or non-speech. However, it is unclear whether this makes a qualitative difference for the animals: “While human brains are specially adjusted to language, dog brains may simply recognize the naturalness of the sound,” explains Cuaya’s colleague Raúl Hernández-Pérez.
A finer distinction was found in the dogs’ secondary auditory cortex. This region is responsible for the detailed processing of sounds – in humans, among other things, for recognizing words and melodies as such. The dogs also showed different activity patterns depending on whether they heard a known or an unfamiliar language. The older the dog, the clearer the differences became. “Every language is characterized by a multitude of auditory regularities. Our results suggest that during their life with humans, dogs perceive the auditory regularities of the language they are confronted with, ”says Hernández-Pérez.
Unique to man’s best friend?
The study shows for the first time that non-human brains are also able to distinguish and recognize different human languages. “This is exciting because it shows that the ability to learn the regularities of a language is not just a human being,” says Cuaya’s colleague Attila Andics. It has not yet been clarified whether this is a specialty of dogs or whether other animals also have this ability. “Dogs have lived with humans for tens of thousands of years,” says Andics. “It is possible that this has resulted in changes in your brain that make you better speech listeners. Future studies will have to find out whether this is actually the case. “
Source: Laura Cuaya (Eötvös Loránd University, Hungary) et al., NeuroImage, doi: 10.1016 / j.neuroimage.2021.118811