Mean Length of Utterance in Czech Toddlers: Validity Estimates and Comparison of Words, Morphemes, and Syllables.

PURPOSE: We examined the properties of mean length of utterance (MLU) in Czech, a morphologically complex Slavic language. We compared the scores of MLU calculated in different units and based on different sample lengths and assessed its validity against another transcript and test-based measures. METHOD: One hundred nine children were recorded during free-play at 2;6 and 3;11 (years;months). We compared MLU in syllables, morphemes, and words (MLUw) in transcripts of different lengths (50, 75, 100, and all available utterances). For evaluating the validity of MLU, we also calculated Index of Productive Syntax (IPSyn) and number of different words (NDW) and used results of receptive vocabulary and grammar comprehension tests. RESULTS: The different MLU measures based on different sample lengths correlated closely with MLU in transcripts of all utterances (all rs > .87). We found mostly strong correlations between MLU, IPSyn, and NDW at both time points and weak or moderate correlations between MLU and grammar and vocabulary. Regression models showed the significant unique effect of MLUw at 2;6 for MLUw (ß = .29) and grammar (ß = .33) at 3;11 and vocabulary (ß = .27) at 3;7. CONCLUSION: MLUw based on all utterances was confirmed as a valid measure of early language skills in Czech, as it is stable in time and shows concurrent and predictive relations with other transcript-based and test-based measures. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25215203.

Sentence Imitation With Masked Morphemes in Czech: Memory, Morpheme Frequency, and Morphological Richness.

Purpose This study examined two markers of language impairment (LI) in a single experiment, testing sentence imitation and grammatical morphology production using an imitation task with masked morphemes. One goal was to test predictions of the morphological richness account of LI in Czech. We also tested the independent contributions of language and memory skills to sentence imitation performance. Method Seventeen children with LI (5;1-7;6 [years;months]) and 17 vocabulary-matched typically developing (TD) children (3;8-4;11) were administered a sentence imitation task where each sentence had one noun or verb ending replaced by a coughing sound. In addition, a receptive vocabulary and the digit span (backward and forward) tasks were administered. Results Children with LI were significantly less accurate than TD children in sentence imitation task. Both vocabulary and digit span had unique effects on sentence imitation scores. Children with LI were less successful in imitating the target words, especially verbs. However, if they succeeded, their completions of the masked morphemes were no less accurate than in TD children. The accuracy of completions was affected by the morpheme frequency and homophony, but these effects were similar in TD and affected children. Conclusions Sentence imitation is a measure of language skills and verbal memory. Results on morpheme completions are consistent with processing models of LI, but some predictions of the morphological richness model were not confirmed. The results suggest that children with LI might have a deficit in organizing morphosyntactic relations in sentences, rather than in morphological processing proper.