Centre for Language Studies / Baby and Child Research Center / Radboud University
Abstract: A substantial group of toddlers shows a significantly slower language development in the absence of other cognitive or hearing impairments. Many of these toddlers develop a developmental language disorder (DLD). Identifying early predictors is important to distinguish late talkers from children with a DLD. Based on children's production data, we have long known that there is substantial variation among children, both in terms of onset of speech as in the variation in production patterns. Most children are diagnosed as at risk for DLD based on production data, but usually not before the age of four, which is relatively late. Therefore, insights into individual variation in speech perception tasks or variation in the quantity and quality of input data may help identifying predictors at an earlier stage. In both domains, several studies have identified correlations between early perception measures in the lab and/or input data at home and language outcomes in typically developing (TD) children, but only few studies have compared online and offline measures at early ages in children with (a suspicion of) DLD.
In this talk, I will present a series of studies on 3;6-year-old children with a suspicion of DLD and typically developing age-matched peers. First, we studied word recognition and word prediction in a visual world paradigm using eye tracking; and second, we collected language input using daylong recordings at home (LENA) in typically developing children as well as children with (a suspicion of DLD). For the DLD-group we also have various (offline) standardized language measures.
Results from the perception studies show that children with a suspicion of DLD perform differently from typically developing children. Moreover, for these children word recognition and word production (online measures) correlate with (offline) standardized language measures. Interestingly, within the DLD-group prediction behavior varied considerably, and was positively correlated with expressive vocabulary scores. Reaction time shifts were negatively correlated with language comprehension scores. Finally, slower shifts in word recognition were related to smaller prediction effects. Results from the LENA study show that toddlers with (a suspicion of) DLD vocalize less at home than their TD peers. They also hear fewer adult words and experience fewer conversational turns. In the DLD-group the LENA measures Conversational Turn Count (CTC) and Child Vocalization Count (AWC) were correlated to receptive vocabulary, but not to Adult Word Count (AWC).
We discuss consequences and future directions to further investigate early predictors.