Abstract

Common language difficulties observed in English-speaking children with Down syndrome (DS) and developmental language disorder (DLD) include challenges with marking tense and agreement on verbs, particularly with BE verbs. In addition, difficulties with syntactic movement may further exacerbate these challenges, often resulting in increased omission errors. A complexity-based approach to treatment target selection has been suggested as one method to address these needs. Therefore, this single-case design study examined the effects of a complexity-based treatment approach for one participant with Down syndrome. Specifically, this study investigated the effects of targeting a more complex treated structure, auxiliary BE questions, and the potential for generalization to simpler related untreated structures, including auxiliary BE sentences, copula BE questions, and copula BE sentences. The participant completed baseline, treatment, and post-treatment phases, allowing performance during intervention to be compared with baseline levels. The participant in this study did not demonstrate a reliable treatment effect for the treated Auxiliary BE question structure but did have a mild positive effect on related, untreated structures from the complexity approach. This generalization on all untreated structures indicated that the treatment was influencing other language structures. Outcomes from this study provide additional support for the use of a complexity-based approach to promote generalization to untreated structures when selecting morphosyntactic treatment targets for children with Down syndrome. Keywords: Down syndrome, morphosyntax, complexity-approach

Degree

MS

College and Department

David O. McKay School of Education; Communication Disorders

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2026-06-10

Document Type

Thesis

Keywords

Down syndrome, morphosyntax, complexity-approach

Language

english

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