How children with Developmental Language Disorders learn lexical categories?

Developmental Language Disorders (DLD) are linked to a deficit in the generalization of morphosyntactic structures. Children with DLD have difficulty in abstracting constructions schemas and in applying them to new instances (Leroy et al., 2014). This could be due to a problem with analogical reasoning and with the comparison of different forms to detect a similar relational structure (Krzemien et al., 2017 ; Leroy et al., 2012). These hypotheses have been investigated in the non-verbal domain and in morphosyntax, but little is known about the generalization of children with DLD in the lexical area. In this study, we examine the first and second order generalization in control and DLD children for new lexical categories. We make the assumption that DLD are linked to an impairment in the ability to generalize new vocabulary. We therefore use new words associated with different categories: there are three types of entity categories (objects, animated objects and non-solid substances) as well as two types of relational categories (relational role and relational object). Children are provided with an exemplar of a new category and are asked to find another one among three solutions. This allows us to evaluate the second order generalization and the acquisition of the pertinent feature (shape, texture, relation, etc.) to use in order to categorize non-familiar referents. If they fail, they are shown two exemplars of this same category and if they fail again, they are shown three exemplars. This permits us to examine the first order generalization and the ability to benefit from the comparison of several exemplars in order to generalize a new word appropriately. Fifteen children with DLD have been recruited and matched to children without language disorders on age and non-verbal intellectual quotient on the one hand, and on a measure of vocabulary comprehension on the other hand.