Thanks to a surprising brain trick, dogs really do ‘understand’ human speech, study finds

Dogs may understand more about human speech than previously thought. A new study has found that canine brains process spoken language in a way that researchers had previously considered uniquely human.

Scientists discovered that dogs can use consonants to break continuous streams of sounds into individual words, a process known as a “consonant bias”. Until now, this feature had been documented in humans and had not even been observed in primates, despite their closer evolutionary relationship to people.

Dogs use consonants to identify words

Researchers compared the brain responses of 20 humans and 20 companion dogs while they listened to speech. Their analysis, published in the journal Science, found that both species were better at recognising word patterns when consonants provided the structure of words rather than vowels.

The dogs' brains also synchronised with the rhythm of consonant-based words in a pattern similar to that seen in human brains.

“This is the first evidence that a consonant bias can also emerge in the brain of a species other than humans,” co-author Kinga G. Tóth said.

The findings challenge the idea that the brain needs specifically human language abilities to develop such a way of processing speech. “These findings suggest that the brain's tuning to speech, and specifically the emergence of consonant bias, does not require a pre-wired brain and human-like language abilities,” said Attila Andics of Eötvös Loránd University.

“Instead, regular exposure to speech may be enough to change how the brain functions and to give rise to processing characteristics previously observed only in humans, even in a species evolutionarily distant from us.”

Speech exposure may shape the canine brain

The researchers also compared family pets with dogs that had spent their early months in shelters or on the streets.

Both groups developed the same strong consonant bias, suggesting that prolonged exposure to human speech, rather than a particular upbringing, may help shape this aspect of the canine brain.

The researchers also found an important difference between humans and dogs. People were able to detect words built around vowel patterns as well, although they performed better when consonants carried the word structure.

Dogs, by comparison, did not show the same ability to detect the less familiar vowel-based patterns. Researchers said this may indicate that humans are better at learning unexpected linguistic patterns.

Some dogs can learn words by listening in

The findings add to growing research into how dogs process human language.

A separate study published earlier this year found that some highly skilled dogs could learn new words simply by listening to their owners' conversations. Researchers said the dogs needed to follow their owner's gaze and attention, recognise communicative signals and identify individual words from a continuous flow of speech.

That ability had also been considered largely unique to humans. The researchers found that some dogs displayed language-learning behaviours comparable to those seen in children between 18 and 23 months old.

“Under the right conditions, some dogs present behaviours strikingly similar to those of young children,” said lead author Dr Shany Dror of the University for Veterinary Medicine in Vienna.

Together, the findings suggest that a dog's ability to pick up patterns in human speech may be rooted not only in training, but also in the way its brain adapts to living alongside people.