Scientists have put dogs through brain scans to confirm what pet owners already suspected: Dogs not only comprehend the words we speak, but also how we say them.
The patterns of brain activity suggest that dogs process the words of their trainers much as humans do.
“There is a well-known distribution of labor in the human brain,” Attila Andics of Hungary’s Eötvös Loránd University said in a news release. “It is mainly the left hemisphere’s job to process word meaning, and the right hemisphere’s job to process intonation. 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 findings, which are being published in this week’s issue of the journal Science, are based on functional magnetic resonance imaging, or fMRI.
Andics and his colleagues trained 13 dogs to lie still in an fMRI brain scanner and listen to a series of words recorded by their trainers. The recordings included words of praise as well as neutral words. Both sets of words were spoken with a high-pitched praising intonation as well as with a flat, neutral intonation.
The dogs responded to the words of praise with heightened brain activity in the left hemisphere, whether or not they were spoken in a praising tone.
To distinguish between a praising and a neutral intonation, the dogs activated a region in their brain’s right hemisphere. That same region, known as the right middle ectosylvian gyrus, was previously found to be a center for processing emotional sounds from other dogs as well as from humans.
The dogs’ reward center in the brain was activated only when dogs heard words of praise that were spoken with a praising intonation.
“It shows that for dogs, a nice praise can very well work as a reward, but it works best if both words and intonation match,” Andics said. “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.”
The findings provide an additional neurological underpinning for the millennia-old linkage between humans and dogs. It’s important to note, however, that the dogs in the experiment listened to their trainer’s familiar voice. They wouldn’t necessarily respond in the same way to words of praise spoken by someone else (for example, in English rather than Hungarian).
Andics said the findings also carry implications for the evolution of human speech. ““Our research sheds new light on the emergence of words during language evolution,” he said. “What makes words uniquely human is not a special neural capacity, but our invention of using them.”
The research report, “Neural Mechanisms for Lexical Processing in Dogs,” will appear in Friday’s issue of Science. In addition to Andics, the authors include A. Gábor, M. Gácsi, T. Faragó, D. Szabó and Á. Miklósi.