Développement lexical dans le cadre d’une déficience intellectuelle : le point sur la question

Introduction

Lexical development of children with intellectual disability has received poor attention in the scientific literature compared to general language development. PubMed and Scopus databases identify around 13,000 peer-reviewed scientific publications on general language development of people with intellectual disabilities and 20 times fewer results on lexical development.

Discussion

The studies analyzed in this article refer to two distinct fields of research: (1) the comparative study of children with disabilities and neurotypical children's developmental trajectories and (2) the description of the referential content of the lexicon and of the learning process. The first line of research describes the general shape of the lexical acquisition trajectory of children with intellectual disabilities; trajectory marked by a later and less important lexical explosion than the one observed in neurotypical children. It is also marked by the highlighting of the respective influence of mental age and chronological age (or life experience) in lexical development; the first being involved in the development of both the expressive and receptive side of the vocabulary and the second impacting only the receptive side. The second line of research gives elements of explanation for the problem identified in the mastery of complex areas of the lexicon (abstract words or relational vocabulary). These difficulties are often interpreted in terms of a deficit of conceptual knowledge and therefore of access to semantic memory. This line of research also describes the use of lexical constraints and principles in children with intellectual disabilities. The conclusions of these studies highlight abilities to generalize new words to new examples comparable to those observed in neurotypical children. The intersyndromic variability, more particularly the specific lexical profiles of people with trisomy 21 and those with Williams syndrome, crosses the two lines of research and makes it possible to identify what is specific to intellectual disability from what is specific to a particular syndrome. However, many questions still remain unanswered.