Abstract
PURPOSE: Developmental language disorder (DLD) is a prevalent neurodevelopmental condition that affects approximately 7% of children in the United States. One notable characteristic of DLD is difficulty in mastering nonadjacent dependencies, such as the third-person singular -s or passive construction be -ed. This study examines behavioral and electrophysiological measures of nonadjacent dependencies learning in children with DLD in the context of a visual grammar-like learning paradigm. METHOD: Fifty-one children (22 DLD, 29 typical language development [TD]) aged 8;0-12;4 (years;months) completed an aXb/cXd grammar learning task, followed by an immediate and 1-week follow-up test. Neurophysiological responses to grammatical and nongrammatical stimuli were measured by recording electroencephalography during the immediate test. RESULTS: Children with and without DLD performed similarly and above chance level during the immediate test. Performance on the follow-up test indicated improved accuracy in children with TD. The DLD group, on the other hand, no longer exhibited above chance-level performance, pointing to limited consolidation. Event-related potentials extracted in relation to the grammaticality of the test items highlighted processing differences in responses to grammatical violations between the two groups (TD and DLD). While a P600 was found sensitive to grammatical violations in the TD group, a frontal N400-like activation was found sensitive to violations in the DLD group. These findings are interpreted to suggest familiarity-based associative learning rather than rule-based processing in children with DLD. CONCLUSION: Children with DLD achieved comparable scores on the immediate behavioral test as their TD peers but did not show evidence of rule abstraction and long-term retention.