Language counts The role of morphosyntax in the numerical development of children with and without developmental language disorder

This dissertation investigates how kindergartners with and without Developmental Language Disorder (DLD) acquire cardinals and ordinals in two languages: Dutch and Czech. These languages might show different developmental patterns, because morphosyntactic cues relevant to number are relatively transparent in Dutch, but more opaque in Czech. The book also examines how Dutch children’s numerical abilities relate to broader linguistic and cognitive skills.
This work is the first to document not only quantitative, but also qualitative differences in numeracy performance between children with and without DLD. In Dutch, children with DLD made more mistakes and showed distinct error patterns in counting and ordinal comprehension. These errors appear to reflect difficulties with using relevant morphosyntactic cues. By contrast, Czech-speaking children with and without DLD differed significantly only in counting ability, and both Czech groups displayed similar error patterns to each other. These findings underscore the importance of examining numerical development cross-linguistically and suggest that numeracy difficulties associated with DLD may manifest differently depending on language background.
This dissertation further explores the role of statistical learning, i.e. the ability to detect patterns in (linguistic) input, in numeral acquisition. A novel cross-situational word learning experiment showed that adults can learn numerals from distributional information, but similar evidence was not found in children. The study offers concrete suggestions for future implementations of this cross-situational word learning experiment. Together, the findings of this thesis thus provide promising directions for future research on numerical acquisition in children with and without DLD.