Exploring cross-linguistic differences in parental input and their associations with child expressive language in ASD: Bulgarian versus English comparison.

Background: Parental input plays a central role in typical language acquisition and development. In autism spectrum disorder (ASD), characterized by social communicative and language difficulties, parental input presents an important avenue for investigation as a target for intervention. A rich body of literature has identified which aspects of grammatical complexity and lexical diversity are most associated with child language ability in both typical development and autism. Yet, the majority of these studies are conducted with English-speaking children, thus potentially overlooking nuances in parental input derived from cross-linguistic variation.

Aims: To examine the differences in verbal parental input to Bulgarian- and English-speaking children with ASD. To examine whether aspects of verbal parental input found to be concurrent predictors of English-speaking children's expressive language ability are also predictors of the expressive language of Bulgarian-speaking children with ASD.

Methods & procedures: We compared parental input to Bulgarian-speaking (N = 37; 2;7-9;10 years) and English-speaking (N = 37; 1;8-4;9 years) children with ASD matched on expressive language. Parent-child interactions were collected during free play with developmentally appropriate toys. These interactions were transcribed, and key measures of parental input were extracted.

Outcomes & results: English-speaking parents produced more word tokens and word types than Bulgarian-speaking parents. However, Bulgarian parents produced more verbs in relation to nouns and used more statements and exclamations but asked fewer questions than English-speaking parents. In addition, child age and parents' use of questions were significant concurrent predictors of child expressive vocabulary.

Conclusions & implications: This is one of the first studies to conduct a cross-linguistic comparison of parental input in ASD. The differences found emphasize the need to further study parental input to Bulgarian children and adapt naturalistic parent-mediated interventions to the local language and its specific characteristics.

What this paper adds: What is already known on the subject A rich body of literature has identified the specific aspects of grammatical complexity, lexical diversity, and question-asking that are concurrently and longitudinally associated with the language ability of children with typical development and of children with ASD. Yet, the majority of these studies are conducted with English-speaking children. What this paper adds to the existing knowledge The present study finds that there are specific differences in verbal parental input to Bulgarian- and English-speaking children with autism in terms of lexical composition and question-asking. Bulgarian parents used more verbs than nouns, and the opposite pattern was found for English-speaking parents. In addition, Bulgarian parents asked fewer questions but used more statements and exclamations. Nevertheless, parental question use was significantly correlated with children's language ability across both groups, suggesting that question-asking should be further examined as a potential target for parent-mediated language interventions for Bulgarian children with autism. What are the potential or actual clinical implications of this work? Most language and social communication interventions for autism are designed and piloted with English-speaking children. These interventions are often simply translated and used in different countries, with different populations and in different contexts. However, considering that one of the defining characteristics of autism is language difficulty, more studies should examine (1) how these language difficulties manifest in languages other than English, and (2) what characterizes verbal parental input in these other contexts. Such research investigations should inform future language and social communication interventions. The present study emphasizes the cross-linguistic differences between Bulgarian- and English-speaking parents' verbal input to their children with autism.