In a fascinating study done by Attila Andics and his colleagues of Eötvös Loránd University, it has been revealed that dogs don’t only understand the words we speak, but can also interpret the intonation that is used.
Before the research could be conducted, the dogs had to be trained to lie still in an MRI scanner awake and without restraints for a number of minutes. Their brain activities were then measured while they listened to their trainers.
Speech consist of both words, which are the elementary building blocks of language, and intonations. A higher and more varying pitch is for example used when praise is expressed. As humans, we use both the intonation and the actual words to interpret what is being communicated. The research focused on determining whether dogs also depend on both factors when we speak to them.
The trainers were asked to use multiple combinations of words and intonation, in both neutral and praising ways. Praise words were used with a praising intonation, neutral words with a praising intonation, and then both praise and neutral words were used with neutral intonation.
Functional magnetic resonance imaging was used to analyze the dogs’ brain activity as they listened to each combination spoken by the trainers. The results reveal that dogs process vocabulary and recognize distinct words, regardless of intonation. They do so using the left hemisphere of the brain similar to the way humans do.
Intonation is also processed in auditory regions in the right hemisphere of the brain, separately from vocabulary. This mechanism is also similar to what humans use.
The reward regions of the dog’s brains were also monitored in the same study. This showed that the dogs responded best when praising words and praising intonation were used in combination. Andics notes that this means that dogs are able to combine words and intonation to interpret correctly what the words really meant, rather than simply being able to separate the intonation from the words.
Important insights into the neural networks needed to understand speech have been revealed by these results. It could mean that both dogs and humans had similar networks that were already in place before language evolved. These networks were later adapted to process speech. The authors do however admit that the domestication of dogs could have resulted in selective forces that led to the emergence of the brain structure underlying this capability.
It is however unlikely that such fast evolution of speech related hemispheric asymmetries could occur over a relatively short time. It is more likely that an ancient brain function exists in both humans and dogs. Over time, this function has been utilized to link random sound structures to meanings.
Study has been published in the journal Science.