By scanning the brains of dogs, researchers from Hungary have learned that our canine companions don't just care about what we say, it's also very important about how how we say it. Which means they can tell when you're feeding them a load of crap. Image: Eniko Kubinyi
Dogs are capable of discerning vocabulary words and the intonation of human speech, according to a new study published in Science. Like humans, dogs use the left hemisphere of their brain to process words, and the right hemisphere to process intonation, which is the way our voices rise and fall when we talk. So when we tell our dogs that they're being "such a good boy!" they understand the vocabulary, but they also need to hear the sincerity and enthusiasm in our voices for them to actually believe it.
Our brains analyse the words we hear and how the words were said, and then integrates these two types of information to arrive at a unified, coherent meaning. "Our findings suggest that dogs can also do all that, and they use very similar brain mechanisms," noted lead researcher Attila Andics, who works out of Budapest's Eötvös Loránd University, in a statement.
Image: Eniko Kubinyi
To arrive at this conclusion, Andics and his team trained 13 dogs to lay completely motionless in a fMRI brain scanner. The scientists measured the brain activity of each dog as they listened to their trainer's speech. The words were delivered in praising intonation and neutral intonation, along with neutral conjunction words (which were meaningless to the dogs) in both praising and neutral intonations. Looking at the brain scans, the researchers looked for brain regions that differentiated between meaningful and meaningless words, or between praising and non-praising intonations.
Scans showed that praise activated the dogs' reward centre, the part of the brain that responds to pleasurable stimuli, such as as food, sex and being petted. Revealingly, the reward centre only became active when dogs heard praise words in praising intonation, that is, praises delivered with higher and more varying pitch.
Image: Eniko Kubinyi
"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," said Andics. "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 brains do."
For those familiar with dogs, the results of this study will probably seem unsurprising. But there's more to this research than initially meets the eye. Dogs, unlike humans, are incapable of generating words. Yet, they're capable of comprehending language and the emotional cues we use to help convey the true meaning and intent of our words. That's incredible for a species that never evolved to speak or develop its own language.
This research suggests that humans probably evolved the ability to grasp the meaning of words earlier than previously assumed. What's more, the neural mechanisms required to process speech are not unique to the human brain. The researchers say it's possible that domestication and artificial selection endowed dogs with this capacity, but admit it's unlikely. As Andics put it, "What makes words uniquely human is not a special neural capacity, but our invention of using them."