Word Learning by Preschool-Age Children With Developmental Language Disorder: Impaired Encoding and Robust Consolidation During Slow Mapping

Abstract

Purpose Learning novel words, including the specific phonemes that make up word forms, is a struggle for many individuals with developmental language disorder (DLD). Building robust representations of words includes encoding during periods of input and consolidation between periods of input. The primary purpose of the current study is to determine differences between children with DLD and with typical development (TD) in the encoding and consolidation of word forms during the slow mapping process. Method Preschool-age children (DLD = 9, TD = 9) were trained on nine form–referent pairs across multiple consecutive training days. Children's ability to name referents at the end of training days indicated their ability to encode forms. Children's ability to name referents at the beginning of training days after a period of overnight sleep indicated their ability to consolidate forms. Word learning was assessed 1 month after training to determine long-term retention of forms. Results Throughout training, children with DLD produced fewer forms correctly and produced forms with less phonological precision than children with TD. Thus, children with DLD demonstrated impaired encoding. However, children with and without DLD demonstrated a similar ability to consolidate forms between training days and to retain forms across a 1-month delay. Conclusions Difficulties with word form learning are primarily driven by deficits in encoding for children with DLD. Clinicians and educators can support encoding by providing children with adequate exposures to target words via robust training that occurs across multiple sessions. Supplemental Material https://doi.org/10.23641/asha.16746454

Word Learning by Preschool-Age Children: Differences in Encoding, Re-Encoding, and Consolidation Across Learners During Slow Mapping

“…However, the rate that they refine the phonological precision of the form across subsequent repetitions does not differ across individuals. We observed a similar result in Gordon et al (2021) . Children with DLD had poorer verbal working memory skills than children with TD, and they demonstrated poorer word learning performance overall.…”

“…Through the findings of the current study and Gordon et al (2021) we will gain an understanding of how variability in memory processes affects word learning in children with TD and DLD. It is important to understand variability across children with TD, in their own right, to inform educational practices.…”

“…In Gordon et al (2021) and this study we implemented a similar methodology. In Gordon et al (2021) , we included children with developmental language disorder (DLD, n = 9) and TD ( n = 9) matched on age, biological sex, and maternal education. Our key question was how children with and without DLD varied in encoding and consolidation during slow mapping.…”

“…In this study, we included a unique sample of 43 children with TD with a broader range of verbal working memory skills, vocabulary knowledge, and maternal education than Gordon et al (2021) . Our primary question was whether the rate of word learning for children with TD is driven by their ability to encode forms, consolidate forms, or both.…”

Multiple Mechanisms of Word Learning in Late-Talking Children: A Longitudinal Study

“…This may have resulted in a reduced ability to produce both words already in the lexicon (real words) and to utilise existing knowledge to produce novel words. Similarly, children with DLD show difficulty encoding novel words, though they are able to consolidate new words on par with TD children once they are encoded, indicating that the precision of phonological representations during the initial encoding of novel words may affect children's ability to build expressive vocabulary (Bishop et al, 2012;Gordon et al, 2021). Notably, although the majority of LT children reached the normal range for TD expressive vocabulary at 3;0-and 3;5-years-old, they still had much lower expressive vocabulary scores than the TD group.…”