It’s the eternal question for pet owners: Does your dog understand what you’re saying? Even if Fido doesn’t “get” your words, surely he gets your tone when you let loose about another accident on the carpet. But a new imaging study shows that dogs’ brains respond to actual words, not just the tone in which they’re said. The study will likely shake up research into the origins of language, scientists say, as well as gratify dog lovers.
“It’s an important study that shows that basic aspects of speech perception can be shared with quite distant relatives,” says Tecumseh Fitch, a cognitive biologist at the University of Vienna, who was not involved in the work.
Words, the basic building blocks of human languages, are seldom found among other species. Bottlenose dolphins and green-rumped parrotlets make sounds that function like names, and animals including chickens, prairie dogs, and some primates utter alarm calls that identify specific predators. Dogs don’t produce words, but some are known to recognize more than 1000 human words—behavior that suggests they may attach meaning to human sounds. The new study shows that it is indeed the words themselves—and not the tone in which they're spoken or the context in which they're used—that dogs comprehend.
To find out how dogs process human speech, Attila Andics, a neuroscientist at Eötvös Loránd University in Budapest, and his colleagues used brain scanners and 13 willing family dogs from four breeds: border collies, golden retrievers, Chinese crested dogs, and German shepherds. The dogs had been trained to lie motionless in the scanner while they listened to recordings of their trainer’s voice. The dogs heard meaningful words (“well done!” in Hungarian) in a praising tone and in a neutral tone. They also heard meaningless words (“as if”) in a neutral or praising tone of voice.
When the scientists analyzed the brain scans, they saw that—regardless of the trainer’s intonation—the dogs processed the meaningful words in the left hemisphere of the brain, just as humans do, they write this week in Science. But the dogs didn’t do this for the meaningless words. “There’s no acoustic reason for this difference,” Andics says. “It shows that these words have meaning to dogs.”
The dogs also processed intonation in the right hemisphere of their brains, also like humans. And when they heard words of praise delivered in a praising tone, yet another part of their brain lit up: the reward area. Meaning and tone enhanced each other. “They integrate the two types of information to interpret what they heard, just as we do,” Andics says.
The new results add to scientists’ knowledge of how canine brains process human speech. Dogs have brain areas dedicated to interpreting voices, distinguishing sounds (in the left hemisphere), and analyzing the sounds that convey emotions (in the right hemisphere).
The finding “doesn’t mean that dogs understand everything we say,” says Julie Hecht, who studies canine behavior and cognition at City University of New York in New York City and who was not involved in the study. “But our words and intonations are not meaningless to dogs.” Fitch hopes that similar studies will be done on other domestic animals and on human-raised wolves to see how much of this ability is hardwired in dogs and how much is due to growing up among talking humans.