Humans are born with operational language processing and memory capacities and can use at least two types of cues to segment otherwise continuous speech, a key first step in language acquisition, according to a new study published in the journal Developmental Science.
Newborns have innate skills needed to pick out words. Image credit: Cheryl Holt.
“Before infants can learn words, they must identify those words in continuous speech,” said study first author Dr. Ana Flò of NeuroSpin Center and her colleagues from the Scuola Internazionale di Studi Avanzati and the Universities of Liverpool and Manchester.
“Yet, the speech signal lacks obvious boundary markers, which poses a potential problem for language acquisition.”
“By the middle of the first year, infants seem to have solved this problem, but it is unknown if segmentation abilities are present from birth, or if they only emerge after sufficient language exposure and/or brain maturation.”
Dr. Flò and co-authors conducted experiments to find the cues crucial for the segmentation of human speech.
They played the infants a 3.5-min audio clip in which four meaningless words were buried in a stream of syllables.
Using a technique called near-infrared spectroscopy, they were able to measure how much was absorbed, telling them which parts of the brain were active.
The team discovered two mechanisms in three-day-old infants, which give them the skills to pick out words in a stream of sounds.
The first mechanism is known as prosody, the melody of language, allow us to recognize when a word starts and stops.
The second is called the statistics of language, which describes how we compute the frequency of when sounds in a word come together.
“Language in incredibly complicated and this study is about understanding how infants try to make sense of it when they first hear it,” Dr. Flò said.
“We often think of language as being made up of words, but words often blur together when we talk. So one of the first steps to learn language is to pick out the words.”
“Our study shows that at just three days old, without understanding what it means, they are able pick out individual words from speech. And we have identified two important tools that we are almost certainly born with, that gives them the ability to do this.”
“We think this study highlights how sentient newborn babies really are and how much information they are absorbing. That’s quite important for new parents and gives them some insight into how their baby is listening to them,” said study co-author Dr. Alissa Ferry, from the University of Manchester.
“We then had the infants listen to individual words and found that their brains responded differently to the words that they heard than to slightly different words,” said co-author Dr. Perrine Brusini, from the University of Liverpool.
“This showed that even from birth infants can pick out individual words from language.”
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Ana Fló et al. Newborns are sensitive to multiple cues for word segmentation in continuous speech. Developmental Science, published online January 25, 2019; doi: 10.1111/desc.12802
