When you talk to your dog, does she ever tilt her head back and forth in the cutest possible way, looking like she’s trying to figure out what you’re telling her?
That may be just what she’s doing, according to a new study by the School of Psychology at the University of Sussex, published in the Nov. 26 issue of the journal Current Biology.
The researchers discovered that dogs process human speech in the same way as we humans process each other’s speech — by using different hemispheres of the brain.
“Humans mainly use the left hemisphere of their brain to process the verbal content of speech and the right hemisphere to process the characteristics of the voice — whether it’s familiar, male or female — and its emotional content,” doctoral candidate Victoria Ratcliffe (in the photo), who conducted the research with Dr. David Reby, said in a press release.
“Previous studies have shown that other mammals also have hemispheric biases when processing their own species’ vocalizations, but no one had ever looked at whether biases existed in domesticated animals in response to the different components of human speech.”
In the study, more than 250 dogs were tested to see how they responded to spoken commands. Participants included dogs from the the local RSPCA as well as dog walkers’ clients. Each dog heard human speech through speakers that were placed on their left and right sides. (The right ear sends information to the left side of the brain, and vice versa.)
The dogs were more likely to turn to the right when the speech they heard was meaningful (such as the command, “Come on then”), and also when voice features such as gender or intonation were reduced or removed.
However, if the speech they heard was in a foreign language or if the phonemes (sounds that distinguish one word from another) had been scrambled — for example, they heard “Thon om ken” instead of “Come on then” — the dogs were more likely to turn to the left.
“Although we cannot say to what extent they understand the complexity of the verbal content, our study does suggest that dogs pay attention to this information in human speech and that they perceive its content in a way that broadly parallels human perception,” Ratcliffe said.
Dr. Reby said the researchers would like to investigate whether wild animals also display similar left brain/right brain speech processing, or if it’s something unique to dogs, “because they have been selected to respond to human verbal commands during domestication.”
He said such a study “would advance our understanding of the evolution of speech perception in humans by revealing whether hemispheric specializations for processing its different communicative components are uniquely human or instead shared with other mammals.”
Photo via University of Sussex