Australian children have been the focus of pioneering studies of early language development. These contemporary Australian population studies of language growth and patterns over time are producing a vastly different picture from the boutique studies of the early 1970’s that positioned language development so firmly as an outcome of maternal input.
The findings from these population studies are reshaping what we believe about children’s language development and about who (or what) is in charge of it. From among the children who start talking early or late and from the vast majority of typically developing children emerges a picture of a remarkably robust developmental endowment. Do genes matter? Does starting late produce onward disadvantage? Do early starters rocket off the chart? And, what do these findings tell us about the design of more optimal expectations and opportunities for the development of all children?
Late language emergence (LLE)
In 2007 Professor Stephen Zubrick and a team of researchers conducted a study of 1,766 two-year-old children in Western Australia. Children typically say their first words between about 18 and 24 months of age. However, some children are late in starting to talk. By asking parents a series of questions about their child, researchers were able to accurately measure late language emergence (LLE). It was discovered that 13% of all 2 year olds in Western Australia will have LLE which equates to approximately 4,450 in today’s population. Of these 13% approximately 70% were male. It was also identified that the earlier predictors of LLE at age 2 are almost entirely “internal” to the child and were not related to characteristics of the mother or to the wider environment except for family size (those children coming from larger families experienced a later start to their language development).
The same children were then observed over a five-year period. Further studies showed the language developmental gap between those with LLE and those without lessened by the time the children were 7 years of age. Many of these children “caught up” to their peers, and among those who were still late talkers by age 7, there were equal proportions of boys and girls. This means that boys must have accelerated their language growth to close the age-two gender gap.
What are the causes of change in the growth of language development?
In 2002 a longitude study involving 10,000 Australian children aged 4 to 8 years of age was conducted to help identify what influenced changes in language development. This study allowed the research team to extensively examine characteristics of the child, mother and family that influenced the growth of language development. Results showed 53% of the variance in vocabulary growth was predicted by the age of the child alone while 11 identified predictors predicted only 7% of the variance in vocabulary growth. As such it was not possible to better predict language growth in children.
The 11 predictors of vocabulary growth:
1. low birthweight;
2. non English speaking background;
3. low school readiness;
4. low family income;
5. low maternal education;
6. maternal mental health distress;
7. low maternal parenting consistency;
8. coming from a family with four or more siblings;
9. child not being read to;
10. high child temperament reactivity and;
11. area socio economic disadvantage.
These were very poor predictors of vocabulary growth. This led the researchers to explore what was happening to the child’s vocabulary growth over time by looking at whether they were low in their vocabulary performance or average or high. How much did these children change over time? Diagram 1 shows the average vocabulary growth from ages 4 to 8. This shows that vocabulary increases for all the groups, but changes in the slopes of the lines, particularly for the low group, suggests that children may be moving categories. It was also noticed that although the highs went up, and that they had plenty of room to go higher, they didn’t “rocket” off the chart.
Through tracking individual children, it was possible to see that children are indeed moving around. The lows are moving towards the middle and high in the latter years while those who were originally placed in the high group have plateaued or dropped into the middle tier. The research team was also able to examine the impact of vocabulary growth on onward literacy at age 10 by adding a measure of literacy (Diagram 2).
What does this mean? Children are constantly moving and their developmental growth is not always predictable.
Implications of poor prediction
Children are not developmental “rockets” nor do they become rockets. They evolve and require guidance and support from the early years onwards regardless of where they are in terms of language development. Current predictors of language and literacy development are very poor and show us that policies and services will have to fit both stable/unstable and predictable/unpredictable language and literacy patterns. The findings show that helping children develop faster than their typically developing peers (helping children the “catch” up,) is a hugely challenging task. Simply targeting the poor performers at early ages will not provide the range of developmental support that many children will need at later points. Under- and over-servicing children is unavoidable. If not, those who are not identified as “risks” may slip through the cracks and fall behind as more attention is given to those who have been identified as “risks” in the early years.
Services will need to provide multiple developmental opportunities or as Professor Zubrick refers to as “touches” across childhood with lots of entry points. As educators, parents and carers it is our responsibility to work together so that each child receives these “touches” throughout their childhood.
(Source: The University of Western Australia)