Developmental dyslexia and specific language impairment: distinct syntactic profiles?

Area of Science:

• Linguistics
• Developmental Psychology
• Neuroscience

Background:

• Developmental dyslexia (DD) and specific language impairment (SLI) share morphosyntactic deficits.
• The origins of these deficits, whether phonological or working memory-related, remain unclear.
• Syntactic complexity is hypothesized to be a key factor.

Purpose of the Study:

• To investigate syntactic complexity in French-speaking children with DD and SLI.
• To compare performance on accusative clitic pronouns (ACC3) versus definite determiners.
• To explore links between syntactic deficits and phonology or working memory.

Main Methods:

• Studied 42 children and adolescents (7-15 years) with DD and SLI, plus age-matched typically developing (TD) controls.
• Assessed production of ACC3 and homophonous definite determiners.
• Correlated performance with non-word repetition and digit span tasks.

Main Results:

• DD and SLI groups exhibited significant difficulties with ACC3 compared to TD controls.
• No difficulties were observed with simpler definite determiners, highlighting a specific syntactic complexity deficit.
• A correlation between ACC3 and backward digit span was found only in the SLI group, not DD.

Conclusions:

• Syntactic complexity, specifically ACC3 production, is impaired in both DD and SLI.
• The underlying causes of these syntactic deficits differ between DD and SLI.
• Working memory limitations may contribute to SLI syntactic deficits, but not typically to DD.