Babies may realise some words go together from six months old

Babies as young as six months old may understand that certain words and concepts are related to each other, according to research published in the Proceedings of the National Academy of Science.

The study also found that babies were more likely to be able to understand a word when they had been more exposed to adults talking about the objects around them.

The team of researchers investigated whether six-month-old babies could understand ‘cross-word relations’, that is, the link between certain words and the concepts that go with them.

In order to gauge word comprehension, 51 babies and their caregivers were shown pairs of images that were related, such as ‘foot and hand’ or unrelated, such as ‘foot and milk’. For each pair, the caregiver, who couldn’t see the screen, was prompted to name one of the images out loud while an eye-tracking device followed the baby’s gaze.

This eye-tracking data was used to show that babies understood that the meanings of some groups of words, such as ‘juice and milk,’ are more alike than other groups, such as ‘juice and car’.

The results showed that babies spent significantly more time looking at the image that was named when the two images were unrelated than when they were related.

Lead author Elika Bergelson (right), assistant professor of psychology and neuroscience at Duke University, North Carolina, said, ‘Even though there aren’t many overt signals of language knowledge in babies, language is definitely developing furiously under the surface.

‘They may not know the full-fledged adult meaning of a word, but they seem to recognise that there is something more similar about the meaning of these words than those words.’

Photo credit: Yuri Vaysgant

Dr Bergelson explained that the logic is that if babies look more at an image after it gets named than they did before they heard the words, they know something about what the words mean. If they had no idea that juice and milk had something to do with each other they would have looked for similar lengths of time at the unrelated items, such as car and juice.

The researchers also used audio and video recordings to investigate whether the babies’ home environment could be linked to early receptive vocabulary.

The results found that the proportion of time parents spent talking about visible objects in their immediate surroundings at home correlated with babies’ overall comprehension in the eye tracking test.

Dr Bergelson said, ‘This work is a first step in understanding the nature of infants' early word knowledge and how it ties to their environment.

‘Even in the very early stages of comprehension, babies seem to know something about how words relate to each other, and already by six months, measurable aspects of their home environment predict how much of this early level of knowledge they have. There are clear follow-ups for potential intervention work with children who might be at-risk for language delays or deficits.

‘My take-home to parents always is, the more you can talk to your kid, the better. Because they are listening and learning from what you say, even if it doesn’t appear to be so.’

Sandra Waxman, a professor of psychology at Northwestern University in Illinois, who was not involved in the study, called the findings ‘an exciting first step’ in identifying how babies learn words and how their vocabulary is influenced by the language they hear around them.

However, Professor Waxman warned against drawing any conclusions about how adults should speak to babies.

‘Before anyone says, “this is what parents need to be doing”, we need further studies to tease apart how culture, context and the age of the infant can affect their learning,’ she said.

•  ‘Nature and origins of the lexicon in 6-mo-olds’ was published online on 20 November and in the journal Proceedings of the National Academy of Sciences, vol. 114 no. 47.