Bilingualism and intellectual developmental disorders: heresy, utopia, or possible reality

The idea that learning two languages can have a negative effect on language development, particularly in children with developmental disorders, has long prevailed in the scientific literature and is still firmly entrenched in the collective mind. In this context, the association of intellectual development disorders (IDD) and bilingualism may seem incongruous. Compared with the growing body of research on the bilingual development of neurotypical children, few studies have focused on bilingual education in IDD. Most of these studies are case or small group studies, which makes it difficult to generalise the results to a larger population. Nevertheless, the conclusions of these studies all seem to converge, and two important points should be noted: (1) children with IDD are able to achieve effective bilingualism and (2) knowledge of a second language does not have a negative impact on the development of the first language or on the non-linguistic profile of the children. In this presentation, we will review the current state of knowledge in this field and present some empirical studies conducted in our research unit with young children with IDD without autistic features.