Purpose: Despite the apparent primacy of syntactic deficits, children with developmental language disorder (DLD) often also evidence lexical impairments. In particular, it has been argued that this population have difficulty forming lexical representations that are detailed enough to support effective spoken word processing. In order to better understand this deficit, a meta-analysis of studies testing children with DLD in the auditory lexical decision task was conducted. The objective was to provide summary effect size estimates for accuracy and response time measures for comparisons to age- and language-matched control groups.
Method: Two thousand three hundred seventy-two records were initially identified through electronic searches and expert consultation, with this cohort reduced to 9 through duplicate removal and the application of eligibility and quality criteria. The final study cohort included 499 children aged 3;8-11;4 (years;months).
Results: Multivariate analysis suggests that children with DLD were significantly less accurate in the auditory lexical decision task than age-matched controls. For the response time estimate, however, confidence intervals for the same group comparison crossed 0, suggesting no reliable difference between groups. Confidence intervals also crossed 0 for language-matched control estimates for both accuracy and response time, suggesting no reliable difference between groups on either measure.
Conclusion: Results broadly support the hypothesis that children with DLD have difficulty in forming detailed lexical representations relative to age- though not language-matched peers. However, further work is required to determine the performance profiles of potential subgroups and the impact of manipulating different lexical characteristics, such as the position and degree of nonword error, phonotactic probability, and semantic network size.