Dogs Understand Words and Intonation of Human Speech, New Study Finds
According to a study led by Dr. Attila Andics of the Eötvös Loránd University in Budapest, Hungary, dogs use the left hemisphere to process words and the auditory region of the right hemisphere to process intonation, and praising activates dog’s reward center only when both words and intonation match.
Trained dogs around fMRI scanner. Image credit: Eniko Kubinyi.
Words are the basic building blocks of human languages, but they are hardly ever found in nonhuman vocal communications.
Intonation is another way that information is conveyed through speech, where, for example, praises tend to be conveyed with higher and more varying pitch.
Humans understand speech through both vocabulary and intonation.
Dr. Andics and his colleagues from Semmelweis University and the Eötvös Loránd University explored whether dogs also depend on both mechanisms.
“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,” Dr. Andics explained.
“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.”
The team trained thirteen dogs to lay completely motionless in an fMRI brain scanner.
“fMRI provides a non-invasive, harmless way of measurement that dogs enjoy to take part of,” said study co-author Dr. Márta Gácsi, of the Eötvös Loránd University.
“We measured dogs’ brain activity as they listened to their trainer’s speech,” added Anna Gábor, also from the Eötvös Loránd University.
Dogs were exposed to recordings of their trainers’ voices as the trainers spoke to them using multiple combinations of vocabulary and intonation, in both praising and neutral ways.
For example, trainers spoke praise words with a praising intonation, praise words with a neutral intonation, neutral words with a praising intonation, and neutral words with neutral intonation.
The results reveal that, regardless of intonation, dogs process vocabulary, recognizing each word as distinct, and further, that they do so in a way similar to humans, using the left hemisphere of the brain.
The scientists found that dogs, like humans, process intonation separately from vocabulary, in auditory regions in the right hemisphere of the brain.
Lastly, they found that the dogs relied on both word meaning and intonation when processing the reward value of utterances.
Thus, dogs seem to understand both human words and intonation.
“It is possible that selective forces during domestication could have supported the emergence of the brain structure underlying this capability in dogs, but, such rapid evolution of speech-related hemispheric asymmetries is unlikely,” the scientists said.
The findings, published in the journal Science , also have important conclusions about humans.
“Our research sheds new light on the emergence of words during language evolution,” Dr. Andics said.
“What makes words uniquely human is not a special neural capacity, but our invention of using them.”