The Relationship between Cognitive and Morphological Skills: Evidence from Turkish Kindergarten Children

This study investigated the role of domain-general cognitive processes, specifically inhibitorycontrol, verbal working memory (WM), and nonverbal reasoning, on children’s productivegrammar skills, focusing on Turkish past tense (e.g., fırçala-DI brush-PAST.3sg) and causativesuffix (e.g., fırçala-t-TI brush-CAUSE.3sg), representing the broader categories of inflectionalversus derivational morphology, respectively. We tested 84 5-year-old Turkish-learning childrenfrom a densely populated district in Istanbul, Türkiye on a sentence completion task to assess theuse of morphology. Children were more successful in producing the correct suffix for the pasttense than causative suffix, when using both familiar and pseudo verbs. Zero-order correlationsshowed significant relations between correct suffix use and all cognitive assessments. However,regression analyses revealed that only nonverbal reasoning predicted children’s overall correctsuffix use and inhibition predicted it only for the past tense with pseudo verbs. Hence, childrenwho have better reasoning abilities may have more robustly abstracted the grammar rules of theirnative language. Children with better inhibitory control can more effectively suppress the primedpresent tense verb and correctly use the past tense. This ability is particularly evident whendealing with pseudo verbs, which make the task more abstract. These findings imply theconsideration of domain-general cognition in the development of abstract grammar in childhood.