Dogs detect words by their consonants; this is what a new study published in Science and carried out by researchers at Eötvös Loránd University has brought to light. Through a comparative analysis of brain activity, measured with electroencephalograms, in 20 humans and 20 dogs, the researchers found that dogs process human speech using mechanisms very similar to our own.
It’s not only the acoustic loudness of the sounds that matters; detecting common patterns in speech is another factor that seems to facilitate dogs’ understanding. The scientists conclude that dogs’ ability to comprehend speech is largely due to the many years of domestication the species has undergone; after all, isn’t that how the saying goes?
Dogs Detect Words
Dogs, like humans, tend to rely more on consonants than on vowels when identifying the boundaries of words in speech, according to a study published in Science led by Hungarian researchers.
The canine brain segments speech into word-like units in a way that had previously only been observed in humans, indicates the study led by Eötvös Loránd University (ELTE).
The results suggest that efficient speech processing is not necessarily a consequence of humanity’s exclusive linguistic abilities, but that there may be similar forms in both species without requiring human-specific capacities.
In many human languages, consonants often provide more useful information for identifying words than vowel sounds.
In fact, infants increasingly rely on consonants to segment continuous speech around the first year of life, moving away from their greater initial dependence on acoustically prominent vowels.
The team investigated whether this consonant bias is specifically human as a result of language acquisition, or whether it could arise in other species exposed to human speech.
For that purpose, pet dogs are a useful model, better than laboratory ones, because they are spoken to daily. Moreover, they are capable of detecting changes in individual sounds and extracting words from continuous human speech.
Dogs differ in the amount of human speech they are exposed to during early life, which allows examining whether early exposure to speech influences the development of a consonant bias.
The team compared EEG responses in the brains of 20 adult humans and as many dogs while they listened to continuous sequences of meaningless three-syllable words.
The words followed patterns based either on consonants or on vowels, and a third set did not present consistent lexical patterns. None of the sounds clearly marked where one word ended and another began.
Although vowels carried more acoustic energy and, therefore, were more prominent from a perceptual standpoint, the design allowed testing whether humans and dogs preferentially followed consonant-based lexical patterns.
The results highlight that dogs, just like humans, tend to rely more on consonants than on vowels when identifying the boundaries of words in speech.
Since the vowels in the experiment had greater acoustic intensity, the preference for consonants cannot be attributed simply to the sounds being louder, the journal explained.
Instead, it is possible that consonants are more useful for detecting patterns that help to divide continuous speech into words.
This bias was also observed in dogs that had been exposed to human speech both in an early and in a later stage of life.
That circumstance suggests that prolonged early exposure is not necessary and that statistical learning (the ability to recognize recurring patterns) may be sufficient to produce it.
The team considers that the consonant bias in dogs could reflect, on one hand, their domestication history and exposure to human language, but also a broader auditory or cognitive capacity that predates domestication.
