Comprehension of Mandarin Ba and Bei constructions in children with developmental language disorder: evidence for the edge feature underspecification hypothesis

Previous research has found that syntactic structures involving movement operations pose challenges for children with Developmental Language Disorder (DLD). Mandarin offers a particularly informative testing ground due to its distinct Ba and Bei constructions, both involving post-verbal object movement. Although both constructions exemplify non-canonical word orders, their relative acquisition difficulty remains debated. This study compared the comprehension of Ba and Bei constructions among Mandarin-speaking children with DLD (4;2–5;11 years) and their typically developing peers, including age-matched (TDA, 4;3–5;8 years) and younger (TDY, 3;2–4;3 years) children, using a picture sentence matching task. Results revealed that children with DLD performed significantly better on Ba than on Bei constructions and were significantly less accurate than both TD groups on Ba and Bei constructions. The DLD group produced a greater proportion of thematic role reversal errors in Bei constructions, with such errors also present, though less frequent, in Ba constructions. Individual-differences analyses within the DLD group provided no clear evidence that working memory (WM) or processing speed (PS) were associated with overall comprehension accuracy or that these associations varied across sentence types. These findings suggest that the observed Ba–Bei asymmetry and error patterns are not fully explained by the WM and PS measures included in the present study. The findings are consistent with the Edge Feature Underspecification Hypothesis, which attributes difficulty with movement dependencies to underspecified edge features. Moreover, difficulties with Ba constructions indicate vulnerability to non-canonical sentence comprehension beyond Bei-specific intervention effects. The study refines theoretical accounts of movement-based impairments and provides practical implications for the diagnosis and early intervention of syntactic deficits in DLD.