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Gaining a better understanding of multilingual children’s language development

Gaining a better understanding of multilingual children’s language development

Katherine Demuth

Distinguished Professor Katherine Demuth—an ARC Australian Laureate Fellow at the Department of Linguistics at Macquarie University, and Director of the Child Language Lab there—is leading a research team that is using both brain imaging and behavioural methods to look at children’s processes acquisition of language.  

Part of the goal of the research is to better understand the typical course of language development in children who come from multilingual backgrounds, and to then be able to more effectively identify those with developmental language disorder. These children can then be helped once the nature of the problem is understood, leading to more effective intervention, better child health and wellbeing, and improved educational outcomes.

Professor Demuth’s research team has focussed on children’s learning of grammar to provide insights into this developmental process. For instance, the ability to effectively use grammatical inflections, such as plurals and present/past tense, has often been used as a clinical marker of developmental language disorder. However, for bilingual children, especially at the preschool level, it can be difficult to tell if there is a serious language problem, or if they are just still learning English.

“For example, there is a large population of Mandarin Chinese speakers in Sydney—Mandarin makes up about 3.2% of the languages other than English spoken at home. The sound system of Mandarin doesn’t have a lot of word-final sounds like those found in English inflections,” says Professor Demuth, who is investigating whether this affects their acquisition of English grammar.

To determine the language knowledge of small children, Professor Demuth’s research team is using comprehension experiments with specially designed software installed on iPads.

“We can take these iPads into preschools to test the language abilities of bilingual children from many different language backgrounds. This can reveal which children are more at risk of not learning the basics of English grammar. The software is a good tool for practicing language too.

“Some of these preschoolers have not yet learned these grammatical morphemes by the time they go to school, raising questions about how this affects their later language and learning abilities more generally. Along with postdoc Nan Xu Rattanasone, we are hoping to follow these children longitudinally to determine how and when these issues are resolved,” says Professor Demuth.

One of the outcomes of this project has been to share research findings on immigrant and Indigenous children who are growing up in a bilingual environment at home, at workshops for clinicians, parents and educators. Many people are asking: How do we know if these children are school ready?

Another aspect of Professor Demuth’s research is to use these grammatical tools with children with hearing loss, who have a different suite of challenges in learning language.

“With hearing loss, there are all kinds of questions about which aspects of words children are actually hearing. Some of these grammatical inflections include fricative sounds like ‘s’ or ‘z’—high frequency sounds that hearing aids don’t transmit very well—so these sounds are particularly challenging for those with hearing loss,” says Professor Demuth.

“If you lose your hearing as an adult, you still have a good language model—whereas children don’t, they’re trying to create it, so their language challenges are quite different to those of adults who are losing their hearing.”

Children with hearing loss can also have difficulty with other subtleties of meaning, for instance in detecting humour, where cues to jokes and irony can be indicated by changes in intonation, which are not transmitted well by cochlear implants.

Professor Demuth’s research group is also working as part of the ARC Centre of Excellence in Cognition and its Disorders, based at Macquarie University. With cognitive scientists they are working with electroencephalography (EEG) and eye tracking methods to study language acquisition processes in the brain.

“Our EEG studies have produced some interesting results suggesting that sensitivity to grammatical morphemes may be processed differently in older children and adults.

“Our eye tracking methods are also examining listen effort in both pre-schoolers and school-aged children. Our software shows pictures on a screen—perhaps a box and a fox—and when we play the audio we can see how fast their eyes look to the correct image. In children with hearing loss, this can reveal if they are hearing the ‘f’ or the ‘b’ correctly, leading to intervention if needed,” says Professor Demuth.

Professor Demuth says that the research begun by her Australian Laureate Fellowship will be carried forward in several interesting directions over the next few years.

“Some of the bilingual work will be followed up longitudinally, and the space is wide open to do more research on children with hearing loss. Here we are working with service providers, amongst many other partners, because they are really interested to know the effects of their intervention on these children’s language development over time.

“All of this is the outgrowth of my Australian Laureate Fellowship project,” says Professor Demuth.

“Young children’s attention spans are short, so it often takes three times as many toddlers to collect the same amount of data that older children could manage. Thanks largely to the support of the Australian Laureate Fellowship, my research team is one of the few in Australia that can conduct detailed language acquisition studies with preschoolers,” says Professor Demuth.

“It has been a fantastic opportunity for both Australia and the field to learn more about how children learn language, and the challenges and opportunities to support them along the way.”


Image: Professor Katherine Demuth. Provided by Professor Demuth.

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