Newborns can isolate words from speech

Babies are born with the ability to pick out distinct words from continuous speech, according to a study published in the journal Developmental Science.

Picking out individual words is a necessary first step for language development, but it’s challenging because speech lacks clear boundaries.

“Language is incredibly complicated,” says lead author Ana Flò, from the Cognitive Neuroimaging Unit at NeuroSpin, France. “We often think of language as being made up of words, but words often blur together when we talk.”

Infants appear to have worked out how to detect words by the middle of their first year. But it’s not clear whether they have these “segmentation abilities” from birth or develop them through language exposure and/or brain development.

In two different but related experiments, each with 40 three-day old babies born from Italian mothers, the international team of researchers independently tested two mechanisms known to be used to segregate speech.

The first involves the ability to compute arrangements of syllables, known as statistical distribution cues. Speech is comprised of consonants and vowels that join to form syllables, then words and phrases. These combine in a predictable manner, giving clues to word boundaries.

The second mechanism is known as prosody – the melody of language – which helps to identify when a word starts and stops.

In both experiments, babies were exposed to a three-minute familiarisation phase involving a stream of syllables that gave either statistical distribution or prosody cues.

The researchers used a non-invasive brain imaging technique, Near-Infrared Spectroscopy, during a subsequent test phase to show if infants could identify word boundaries.

They found that the newborns were able to detect distinct words in both conditions. That means they can use both mechanisms, independently from each other.

“Our study showed that at just three days old, without understanding what it means, they are able to pick out individual words from speech,” Flò says.

The findings also suggest that “newborns have remarkable short-term memory capacities”, the authors write.

“We think this study highlights how sentient newborn babies really are and how much information they are absorbing,” says co-investigator Alissa Ferry from the University of Manchester, UK.

“That’s quite important for new parents and gives them some insights into how their baby is listening to them.”

Although the results suggest the crucial ability to detect words from speech is innate, the researchers suggest this skill could have been developed prenatally while listening to speech from the womb – a possibility needing further investigation.