Puppies' response to speech could shed light on baby-talk, suggests study

Puppies prick up their ears to human cooing but adult dogs are unmoved by it, according to a new study.

Scientists have found that humans use a sing-song cadence, similar to that used towards babies, when talking to dogs – regardless of the age of the animal. But the tone only draws the attention of puppies: older dogs showed no preference over normal human speech.

“The use of pet-directed speech is extremely widespread, but its functional value has barely been studied,” said Nicolas Mathevon, lead author of the research from the University of Lyon at Saint-Etienne.

The research, he adds, could also shed light on human use of baby-talk: both might have a common purpose in attempting to engage with a listener that cannot speak.

In the first stage of the research, 30 women were each presented with images of a puppy, an adult dog and an elderly canine and recorded uttering a sentence involving phrases such as “hello cutie!”, “who’s a good boy?” and “come here sweetie pie!”. They were also asked to repeat the phrase in their normal tone to a researcher.

The researchers found that when talking to dogs, humans typically use higher-pitched, slower tempo speech with a greater degree of variation in pitch than when talking to each other. The effect was most pronounced when chatting to puppies, with participants increasing their pitch by 21% on average compared to normal speech.Mathevon says the results, published in the journal Proceedings of the Royal Society B by researchers from the UK, US and France, provide clues as to why humans address their pets in a similar way to babies. “The fact that human speakers employ dog-directed speech to communicate with dogs of all ages is interesting because it could mean that we use this kind of speech pattern when we want to facilitate interaction with a non-speaking listener, and not only a juvenile listener,” said Mathevon.

The researchers also found that while puppies showed no difference in response between puppy-talk over speech directed at adult dogs, they did show a greater response to puppy-talk over human-directed speech. Adult dogs, on the other hand, showed no difference in their response to the recordings.

That is unexpected, the authors say, and could be down to dogs showing less interest in the voices of strangers as they age. Alternatively, the use of dog-directed speech might tap into an innate receptiveness to high-pitched sounds in puppies – a trait that disappears as they age.

Evan MacLean, evolutionary anthropologist at the University of Arizona, said that the research was another piece of evidence of the overlap between human-dog and parent-child relationships. “As a result of selection for juvenile traits, dogs emit a lot of signals that scream ‘baby’ to humans, which can facilitate special kinds of interactions with dogs, normally reserved for children,” he said. “The question we don’t have a great answer to is whether there are long term functional consequences of interacting with dogs in this way (e.g. effects on word learning), or if this is just a byproduct of the baby-like cues that dogs inundate us with.”

But Catherine Laing, a researcher in neuroscience at Duke University in North Carolina who was not involved in the study, disagreed with the suggestion that similarities in the pitch of baby-talk and pet-talk indicates a link to non-speaking listeners. She points out that the two forms of speech have many differences – not only in the type of words used and how they are articulated, but also in the interactions between listener and adult.

“Baby-talk [or infant-directed speech] is complex and aimed at supporting language learning, and we can’t say the same about the observations made in this paper,” she said.