Mean Length of Utterance and Other Quantitative Measures of Spontaneous Speech in Russian-Speaking Children

Abstract

Purpose This study investigated methodological and theoretical aspects of using mean length of utterance (MLU) and its alternatives in cross-linguistic research and, in particular, its applicability to Russian—a language with a rich system of grammatical and derivational morphemes. Method We collected audio recordings of spontaneous speech samples from 27 Russian-speaking children aged between 2;9 and 5;7 (years;months) over individual play sessions. For each participant, we transcribed the first 100 complete utterances and coded them for several types of utterance length measurements, including length in morphemes (grammatical and derivational), words, and syllables. At a sample level, we calculated the average number of produced unique grammatical forms, getting an alternative quantitative estimate of children's morphosyntactic abilities. Results A combination of Pearson correlation analysis and Bland–Altman difference plots established that MLU can be reliably used in Russian-speaking children aged around 3;0. The average number of unique grammatical forms remains a sensitive measurement of language capabilities even in older children aged over 3;6. Two quantitative measurements, MLU in syllables and morphemes, show good agreement, suggesting that these measurements can be used interchangeably across studies. Sample size analysis revealed that samples under 75 utterances do not provide sufficient reliability for estimating a child's MLU. Conclusions This article demonstrated that MLU can be used in young Russian-speaking children under 3;0–3;6. Also, we showed that the classical morpheme calculation approach can be substituted with counting syllables, which is more time efficient in the absence of automated parsers and is potentially more appropriate for some (e.g., polysynthetic) languages. Our proposed alternative to MLU—the average number of grammatical forms in a sample—appears to be a more sensitive measurement of language capabilities even in older children.

Early linguistic reference to first and second person depends on social understanding as well as language skills: Evidence from Czech 30-month-olds

“…Most words in Czech are morphologically complex but it is not clear if children at this early age fully represent the complex morphological structure of many Czech words. In order to be conservative, and given very high correlations between MLU in morphemes and words in a similar language, Russian (Tomas & Dorofeeva, 2019), MLU in words was used.…”

Mean Length of Utterance: A study of early language development in four Southern Bantu languages

“…Several scholars also argue that, in older children, further linguistic complexity may involve internal embedding rather than additional length (Oosthuizen & Southwood, 2009) and a decrease in morphological growth (Parker & Brorson, 2005). Various studies have reported different ages at which MLU may no longer be a sensitive measure (see Allen & Dench, 2015;Cheung, 1998;Ezeizabarrena & Garcia Fernandez, 2018;Oosthuizen & Southwood, 2009;Rice et al, 2006Rice et al, , 2010Scarborough et al, 1991;Tomas & Dorofeeva, 2019;Wu, 2020).…”

“…Moreover, a single interactive event may not comprehensively represent a child's language abilities (Oosthuizen & Southwood, 2009;Southwood & Russell, 2004). Although R. Brown (1973) recommended using samples of 50 to 100 utterances, some studies have cautioned against using samples containing fewer than 175 utterances (Gavin & Giles, 1996;Oosthuizen & Southwood, 2009;Tomas & Dorofeeva, 2019).…”

“…During early childhood, children show considerable variation in language skills when considered by age (Frank et al, 2021). MLU correlates significantly with age, but there is also considerable variability in MLU at specific ages (Dethorne et al, 2005;Tomas & Dorofeeva, 2019;Vasilyeva et al, 2008). R. Brown (1973) has argued that MLU is a more accurate tool for predicting children's expressive language abilities than age because MLU permits the identification of children at similar levels of constructional complexity regardless of chronological age.…”

“…In many languages, using words or morphemes to measure MLU appears to be equally valid, even among languages that are morphologically more complex and typologically distant from English, such as Basque (Ezeizabarrena & Garcia Fernandez, 2018). However, in some synthetic languages like Russian and agglutinative languages like Turkish, morpheme counts are more accurate when calculating MLU (Ege, 2010;Tomas & Dorofeeva, 2019). There are, however, many other typologically distinct and morphologically complex languages, such as Bantu languages, where these questions remain untested.…”