Child Language Lab

The Canberra Longitudinal Child Language (CLCL) project was run out of the Research School of Psychology’s Language Lab at the Australian National University. CI Evan Kidd led the CLCL project and is director of the lab, which aims to study and understand the causes and consequences of individual differences in language acquisition and processing across the lifespan. CoEDL assisted this endeavour by funding CLCL to study how language processing skills in infancy influence language development in children before primary school.

CLCL followed over 100 typically developing children from the age of 9 months to 5 years. The team recruited its participant families in the early days of the Centre and began testing in May 2015. Although COVID-19 threatened to scuttle the final round of CLCL testing, adaptability and dedication on the part of both the researchers and the parental participants enabled the project to complete testing of the large cohort of young Canberrans as planned in 2020.

Families visited the lab every three to six months to test with electroencephalograms (EEGs), eye-tracking tasks and other exercises involving productive language. Every so often between visits, families would record their interactions for 12-hour blocks to help researchers understand the type of language children were exposed to every day.

Overall, the project provides a detailed look at how children become competent speakers and processors of their native language, in this case Australian English. It has revealed many significant results about how children build their linguistic system from the ground up.

Some highlights include:

• The discovery that 9-month-old infants differ widely in their ability to find words in continuous speech, which was revealed through brain recordings using EEG.
• Children’s vocabulary growth is closely linked to the degree to which they engage others in conversation, as revealed through day-long recordings of their language environment.
• By 2.5 months children are beginning to store and access words according to the same principles used by adults.
• Children’s grammatical development is linked to early vocabulary development, with knowledge of individual structures showing evidence that children gradually refine their knowledge by learning from mistaken predictions about what people say.

Beyond the lab, many other CoEDL members worked with CLCL, including CI Anne Cutler (†) and Affiliate Caroline Junge. The project also led to several adjacent collaborations, including:

• A study of conceptual cueing effects with Stephanie Goodhew, supported by Transdisciplinary and Innovation seed funding
• An eye-tracking study of language production in the Australian Indigenous free word-order language Murrinpatha with CI Rachel Nordlinger and CoEDL postdoc Gabriela Garrido Rodriguez [1]
• A cross-Partner Institution collaboration with the Universities of Liverpool and Manchester through the ESRC International Centre for Language and Communicative Development (LuCiD)
• A paper on structural priming in New Mexico Spanish with CI Catherine Travis and PI Rena Torres Cacoullos [2]
• A special issue of First Language on acquisition of indigenous languages in minority and traditional contexts [3]

By investing in longitudinal research like this, CoEDL has enabled unique and ground-breaking insights.

One paper co-authored by Evan and postdoc Seamus Donnelly unveiled a reciprocal relationship between early vocabulary levels and conversational turn-taking between infants and parents [4]. This important result suggests that infants play an active role in their own early language development.

The value of the data generated in CLCL testing is also enormous. The EEG tests, for example, yielded one of the largest datasets ever collected for language processing in young children, opening the doors to countless research possibilities.

“Language is super important,” Evan said. “We know that children’s spoken language is one of the best predictors of scholastic achievement, literacy, and also of other social processes.”

Thus, while testing concluded in 2020, insights from the CLCL project will be rolling in for many years — all made possible by the dedication of the participant families.

“I am so humbled by their commitment,” Evan said, reflecting on the honour of working with these families and watching the children grow up. “They’ll probably be 20 years old, and we’ll still be here publishing their data.”