Production of noun suffixes by Turkish-speaking children with developmental language disorder and their typically developing peers

LITMUS Turkish sentence repetition test: The best items, effect of scoring and diagnostic accuracy

PURPOSE

This study aimed to examine LITMUS Turkish Sentence Repetition Test's (LITMUS-TR) diagnostic accuracy, as well as the best scoring method and most distinguishing test items. We also sought to ascertain whether age has an impact on the sensitivity and specificity.

METHOD

Two hundred and fifty children with typical language development (TD) between the ages of 4 and 7, as well as 44 children with developmental language disorder (DLD), took part in the study. Data was collected using TODİL, LITMUS-TR, and the pediatric family interview form. LITMUS-TR was graded using four different methods.

RESULTS

The performance of children with DLD in each score type was lower and the number of errors higher than those with TD. All items have excellent or acceptable item difficulty and discrimination values for binary scoring and total number of errors. LITMUS-TR's most distinctive items were complex structures with dependencies, such as syntactic movement and embedding. LITMUS-TR had high diagnostic accuracy for the whole test (0.887) and each scoring method. A separate analysis of each age group showed sensitivity and specificity above 0.80.

CONCLUSIONS

When employed as a supportive objective measure, LITMUS-TR was proven to be an effective diagnostic tool for DLD, with age influencing the diagnostic accuracy outcomes.

Verb morphology in Turkish-speaking children with and without DLD: the role of morphophonology

In this study, we examined the verb morphology system of Turkish-speaking preschoolers with developmental language disorder (DLD) and compared their use to that of two groups of typically developing (TD) children. We report data from a total of 80 monolingual children - 40 children with DLD, 20 TD age-matched children and 20 TD younger MLU-matched children. Language samples obtained from the children served as the source of the data. The results show that the children with DLD were less accurate in their use of verb suffixes than both the younger and the age-matched TD children. The most frequent error types included use of bare stems, omission of the suffix, and replacing one finite verb suffix with another. The distinction between witnessed past and reported past also posed a challenge. Multi-level model results showed that phonemic length and irregular morphophonology were the best predictors of the children's level of accuracy. These results indicate that even though Turkish is considered a "verb friendly" language, children with DLD do not succeed in closing the gap with their TD peers. The complex interplay of morphology and phonology in Turkish appears to be the major obstacle for children with DLD acquiring this agglutinative language.