A new study was the first step in understanding how dogs understand human speech, and researchers found that dogs use the left hemisphere of their brains to process words where the right hemisphere is used to process vocal intonation and when words and intonation match, the brain region with the dogs’ reward center is activated.
Researchers of The Family Dog Project have conducted the first comparative fMRI study that took a closer look at voice-sensitive regions in the brains of both humans and “man’s best friend.” This study was the first step in understanding how dogs understand human speech. The researchers found that dogs use the left hemisphere of their brains to process words and the right hemisphere to process vocal intonation. In addition, the researchers found that when words and intonation match, such as when praising a dog, it triggers the animal's “reward center,” according to a press release.
The Family Dog Project is the brainchild of three institutions: Eötvös Loránd University, Department of Ethology, MTA TTK Comparative Behavioural Research Group, and the MTA-ELTE Comparative Ethology Research Group. The Project is one of the largest research groups pertaining to dogs in the world and it strives to study both the cognitive and behavioral aspects of the relationship between humans and their dogs. The study authors take into account that both humans and dogs experience similar social environments, and so vocalization from dogs and from humans is relevant to both species.
The researchers found that the neural mechanisms that are involved in processing speech are not just found in humans. If placed in an environment that contains a number of words, even animals that are incapable of speaking can form “word meaning representations,” according to the press release.
Lead researcher, Attila Andics of the Department of Ethology and MTA-ELTE Comparative Ethology Research Group at Eötvös Loránd University, Budapest, explained, “During speech processing, there is a well-known distribution of labor in the human brain. It is mainly the left hemisphere’s job to process word meaning, and the right hemisphere’s job to process intonation. But the human brain not only separately analyzes what we say and how we say it, but also integrates the two types of information, to arrive at a unified meaning. Our findings suggest that dogs can also do all that, and they use very similar brain mechanisms.”
Using fMRI, functional magnetic resonance imaging, a procedure that analyzes changes in blood flow to measure brain activity, the researchers scanned the brain activity of thirteen dogs as they listened to their trainers speak. The dogs were unrestrained and had been specifically trained to lay motionless in the scanner for three 6-minute runs. The developer of the training method, Márta Gácsi, ethologist and study author, said, “fMRI provides a non-invasive, harmless way of measurement that dogs enjoy to take part of.”
When speaking of the process, Anna Gábor, PhD student and author of the study, said, “Dogs heard praise words in praising intonation, praise words in neutral intonation, and also neutral conjunction words, meaningless to them, in praising and neutral intonations. We looked for brain regions that differentiated between meaningful and meaningless words, or between praising and non-praising intonations.”
The fMRI results indicated that when it comes to processing “meaningful” words, dogs prefer to use the left hemisphere of their brain, independent of intonation. When it came to differentiating between praising and non-praising intonations, dogs used the right hemisphere of their brains. According to the press release, “This was the same auditory brain region that this group of researchers previously found in dogs for processing emotional non-speech sounds from both dogs and humans, suggesting that intonation processing mechanisms are not specific to speech.”
Additionally, the dogs’ area of the brain that serves as the “reward center” was activated by praise, according to the press release. However, it was only activated when the dogs received praise paired with positive praising vocal intonation.
When speaking of the findings related to praise, Dr. Andics said, “It shows that for dogs, a nice praise can very well work as a reward, but it works best if both the words and the intonation are praising. So dogs not only tell apart what we say and how we say it, but they can also combine the two, for a correct interpretation of what those words really meant. Again, this is very similar to what human beings do.”
With the assistance of these findings, researchers feel that “communication and cooperation” between dogs and their human counterparts can improve and become even more efficient.