Dog owners who claim their pets understand everything they say may be right, according to recent study findings from the UK. Researchers at the University of Sussex, School of Psychology show that dogs actually process speech in a similar way to humans. They reportedly listen to our words, not just our intonation.

According to the study, published in the November 26, 2014, edition of Current Biology, mammal communication researchers tested more than 250 dogs to see how they responded to a set of spoken commands. They found that, like humans, dogs use different parts of the brain to process the verbal components of a familiar sentence and the emotion or intonation of the speaker.

Researchers Victoria Ratcliffe, PhD candidate, and David Reby, PhD, stress that their study does not suggest that dogs can understand the full complexity of human speech, but that their perception of speech parallels that of humans.

“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,” said Ratcliffe. “Whether it’s familiar, male or female, and its emotional content.”

The authors report that 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.

How Dogs Process Speech

The researchers enlisted the help of dogs and their owners for the study. Individual dogs were simultaneously played a human speech sound through speakers on both the left and the right of them, the significance being that the right ear sends information to the left-hand side of the brain, and vice-versa.

If the dog turned toward the left speaker, it would mean that the information they were listening to in the sound was primarily being processed in the right side of the dog’s brain. If it turned to the right, it would mean the information was being processed in the left side of the brain.

The results showed that when the speech was meaningful for the dogs (a familiar command), but the voice features such as gender or intonation had been attenuated or removed, the dogs were more likely to turn to the right, therefore showing a left-hemispheric bias.

Results indicated that if the command was in a foreign language, or if the phonemes were put into the wrong order, so the sound ceased to be meaningful to the dog, the reverse bias was observed. The study suggests that dogs pay attention to the verbal content of human speech and perceive it in a way that broadly parallels human perception.

“We would like to investigate if dogs show these similarities to humans because they have been selected to respond to human verbal commands during domestication, or if wild animals would also display these asymmetries if they were exposed to similar levels of speech during their development,” said Dr Reby. “This 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.”

Source: Current Biology, and University of Sussex