Processing canonical and non-canonical word orders in Turkish: behavioral and ERP evidence from adults and children

Introduction Turkish permits grammatical non-canonical word order while morphological case marking disambiguates thematic roles. Methods We examined comprehension accuracy and verb-locked event-related potentials (ERPs) to Turkish canonical subject-object-verb (SOV) and non-canonical object-subject-verb (OSV) sentences in adults ( n = 67; 18–44 years) and children ( n = 37; 4.3–9.7 years). Results Accuracy was lower for OSV than SOV in both groups, with a significantly larger SOV-OSV accuracy difference in children. Adults showed a late posterior OSV > SOV positivity, with significant effects in several prespecified windows within the 600–1,200-ms interval, consistent with increased sentence-final processing demands associated with the non-canonical configuration at the final verb. Children showed no reliable corresponding positivity after correction for multiple comparisons. Critically, however, Group × Sentence Type interactions did not survive correction, providing insufficient evidence that the magnitude of the SOV-OSV ERP effect differed between adults and children. Within children, chronological age showed no reliable linear or quadratic association with the behavioral or ERP SOV-OSV difference across the sampled age range. By contrast, stronger grammatical ability predicted higher comprehension accuracy in both sentence types beyond age; the same general pattern was obtained for broader language ability. Neither grammatical nor broader language ability reliably modulated the SOV-OSV ERP difference. Discussion Overall, the findings suggest that the availability of morphosyntactic case cues does not by itself entail adult-like efficiency in integrating those cues during sentence comprehension, and that developmental patterns may be expressed differently across behavioral and electrophysiological measures.