Anyone who has lived with a dog will find themselves occasionally cooing to their pup in slow-paced, high-pitched baby talk (OK, maybe most of the time). And a new study suggests that our canines respond to such dulcet tones—well, puppies do at least.
The study, published this week in the Proceedings of Royal Society B, shows that the baby-talk, also known as dog-directed speech, gets a big response from puppies. Older dogs, however, aren’t super impressed, reports Virginia Morell at Science.
The study’s researchers had 30 female volunteers look at photographs of dogs while reading standard dog-directed phrases, like “Who’s a good boy?” and “Hello cutie!” (they didn't use real dogs to minimize the speakers going off script). The volunteers also read the doggie praise to a human. The researchers found that women used the higher-pitched, sing-song baby-talk tone when reading the passages to the photos, making their voices 21 percent higher when reading to the puppy images. With the human, they spoke in their normal voice.
That was more or less expected. But when the researchers played recordings of the women’s voices to ten puppies and ten adult dogs at a New York animal shelter, there was a stark difference. The puppies went wild when they heard the dog-directed voices. Morell reports they barked and ran toward the loudspeaker, crouching down in a pose used to start a round of horseplay. When researchers played the same phrases using the women’s normal tone of voice, the puppies weren’t nearly as enthused.
The adult dogs, however, were a different story. “They didn’t care at all,” Nicolas Mathevon, a bioacoustician at the University of Lyon in Saint-Étienne, France, and co-author of the study tells Morell. “They had a quick look at the speaker, and then ignored it.”
There’s no clear reason why the puppies reacted so strongly to the baby talk and the mature animals didn't. It’s possible the higher-pitched tones stimulate a special response in the puppies. Mathevon tells Helen Briggs at the BBC that it may be related to a theory called the baby schema. In that hypothesis, humans evolved to find big eyes, big heads and round cheeks irresistibly cute. That helps parents bond with children, convincing them to spend the endless hours required to feed and tend to infants. Many of those cues are also found in baby animals.
But there may be more to the response. “One of the hypotheses was that we humans use this dog-directed speech because we are sensitive to the baby cues that come from the face of a small baby [animal] as we are sensitive to the faces of our babies,” he tells Briggs. “But actually our study demonstrates that we use pet-directed speech or infant-directed speech not only because of that but maybe we use this kind of speech pattern when we want to engage and interact with a non-speaking listener. Maybe this speaking strategy is used in any context when we feel that the listener may not fully master the language or has difficulty to understand us.”
Over time humans have bred dogs to be more baby-like, which only makes humans bond with them more, Evan Maclean, an evolutionary anthropologist at the University of Arizona not involved in the study tells Nicola Davis at The Guardian. “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 that are normally reserved for children,” he says. “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.”
So why did the older dogs just keep chewing their bones when they heard the strangers' voices coming from the speaker? “[M]aybe older dogs do not react that way because they are just more choosy and they want only to react with a familiar person,” Mathevon tells Briggs.