Dog brains segment speech into words in a way previously seen only in humans, a new study from Hungary finds. This suggests that efficient speech processing is not necessarily a consequence of humans' unique language abilities: regular exposure to speech alone can reshape how the brain functions, even in a mammalian species evolutionarily distant from humans. The discovery by the Neuroethology of Communication Lab at the ELTE Department of Ethology, Budapest was published in Science.
Humans and language have a unique relationship. No other species possesses language abilities as complex as ours, and the human brain is particularly sensitive to the characteristics of speech. But there is a long-standing mystery: do we process speech so efficiently because our brains are inherently built this way, or because we are constantly exposed to speech?
"Words are made up of two main types of speech sounds: vowels and consonants. Although vowels are louder and more noticeable, consonants usually form the skeleton of words. In a continuous speech stream, it is easier to detect individual words when we focus on consonants. And from infancy onward, this is exactly what the human brain tends to do. This phenomenon is known as the consonant bias," says Attila Andics, cognitive neuroscientist, head of the ERC-funded Neuroethology of Communication Lab, and corresponding author of the study.
"But does the emergence of consonant bias—that is, becoming tuned to speech—require the kind of complex language abilities that are unique to humans? Does it require a brain that is inherently wired differently? Or could tuning to speech arise through simple pattern learning, based on principles also present in other animal species that cannot speak?" asks Andics.
To find out, researchers from the Neuroethology Research Group compared the brain responses of 20 humans and 20 companion dogs to speech. Video abstract of the study.
"We reasoned that if the preference for consonants—the acoustically less salient type of speech sound—requires uniquely human language abilities to develop, then other species should not show such a preference. Not even dogs, despite spending much of their lives surrounded by human speech," explains Boglárka Morvai, biologist and postdoctoral researcher at the Neuroethology Research Group, co-first author of the study.
"If, on the other hand, tuning to speech is based on simple forms of pattern learning from repeatedly heard speech, then a consonant bias should also emerge in the dog brain—even though such a bias has not previously been found in primate species much more closely related to humans," Morvai continues.
During the experiment, the human and dog participants listened to continuous, unsegmented speech streams. Consonants and vowels alternated throughout these streams, with no pauses or other acoustic cues separating them. The streams differed in whether they contained recurring patterns and, if so, what kind. There were three types. In the first one, recurring consonant patterns formed consecutive three-syllable words—or, more precisely, word skeletons, because the vowels occurring between the consonants could vary freely. In the second type, the situation was reversed: recurring vowel patterns formed the skeleton of the words. Finally, the third, control type contained no recurring patterns at all, so the syllables did not form words but followed one another in a random order.
To measure brain activity, the researchers used non-invasive EEG, recording the brain's electrical activity through electrodes placed on the scalp. They also relied on a special neural phenomenon called neural synchronization: our brain activity can take on the rhythm that we detect in the sounds we hear. And the more reliably we detect that rhythm, the more rhythmic the brain response becomes. The researchers expected that if a species' brain has a preference for consonants, it should follow the rhythm of the words more easily when consonants form the structure of those words.
The results revealed striking similarities between the two species. "In the consonant-structured speech streams, the dog brains, just like the human brains, successfully synchronized with the rhythm of the words. In both species, this synchronization was stronger than in either the vowel-structured or the control streams. This is the first evidence that a consonant bias can also emerge in the brain of a species other than humans," says Kinga G. Tóth, psychologist, the study's other co-first author and a doctoral researcher in the group.
The timing of the brain responses provided further evidence for a consonant bias in dogs. Around 400 ms after the beginning of each word, a distinct change appeared in the brain's electrical activity in both humans and dogs—but only for consonant-structured words. This time window is precisely the one known to reflect the segmentation of continuous speech into individual words.
"The study also revealed that this tuning to the characteristics of speech does not emerge only in dogs that were already living in a speech-rich environment during the first months of life, when they are especially sensitive to social experiences. Dogs that had spent their first three months living on the street or in a shelter, rather than as family pets, showed a similarly strong consonant bias," G. Tóth adds. "This provides further evidence that consonant bias does not require pre-wired language-processing mechanisms that emerge during a specific early developmental period. Instead, this neural preference may also emerge through relatively simple forms of pattern learning."
The researchers also observed two interesting differences between the species. First, humans were able to detect words defined by vowel patterns as well, although less successfully than when consonants formed the word structure. Dogs, however, were not. This suggests that when it comes to learning unexpected, non-preferred linguistic patterns, humans may perform better.
The second difference concerned what other rhythms the two species detected in the speech streams. The syllable rhythm appeared in the brain responses of both species, but only the human brain synchronized with the rhythm of the speech sounds. This suggests that the human brain can process continuous speech at a finer resolution: for us, each speech sound is a separate unit, whereas for dogs, syllables form the smallest units of processing.
"Taken together, 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," Andics concludes. "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."
Original study:
B. Morvai, K. G. Tóth, M. Boros, D. S. Rácz, I. Iotchev, K. Szabó, A. Andics (2026), Neural evidence that dogs segment the speech they hear with a humanlike consonant bias, Science, doi: 10.1126/science.adw7709
The research was funded by:
the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (950159); the National Brain Programme of the Hungarian Academy of Sciences (NAP2022-I-3/2022, NAP4-2026-6/2026); the European Union's Horizon Europe Framework programme under the Marie Skłodowska-Curie Grant Agreement (101168998); the Ministry and Culture of Innovation of Hungary through the National Research, Development and Innovation Fund, financed under the Cooperative Doctoral Program (KDP_2023_ELTE_C2304666), and the Eötvös Loránd University (ELTE).
