Morphological and Inhibitory Skills in Monolingual and Bilingual Children With and Without Developmental Language Disorder.

Purpose: This study examined the language and nonverbal inhibitory control skills of Italian monolingual and bilingual typically developing (TD) preschoolers with Italian as their second language and of age-matched monolingual and bilingual peers with developmental language disorder (DLD).

Method: Four groups of preschoolers were enrolled: 30 TD Italian monolinguals, 24 TD bilinguals, 19 Italian monolinguals with DLD, and 19 bilinguals with DLD. All children were assessed in Italian on vocabulary, receptive morphosyntax, and morphological markers for DLD in the Italian language (i.e., third-person verb inflections, definite articles, third-person direct-object clitic pronouns, simple prepositions) and nonverbal inhibitory control skills. Group performance was compared using a series of one-way analyses of variance.

Results: Monolingual and bilingual children with DLD achieved significantly lower performance in all language measures compared to both TD monolingual and bilingual children. However, TD bilinguals, although comprehensively showing better language skills than monolinguals with DLD, achieved a performance closer to that of monolinguals with DLD but significantly higher than that of bilinguals with DLD. Both TD monolinguals and bilinguals showed better results than both DLD groups in inhibitory control tasks, particularly in the interference suppression task.

Conclusions: This study provides a picture of language and inhibitory control characteristics of children with various language profiles and adds to the literature on potential markers of DLD among bilingual children. These results suggest that the assessment of nonlinguistic markers, which are associated with language impairment, could be a useful approach to better specify the diagnosis of DLD and reduce cases of misdiagnosis in the context of bilingualism.