Boundaries between Developmental Language Disorders and Typical Performance Blurred in Young Children

A new study by researchers at the HSE Language and Brain Centre and the Institute of Linguistics of the Russian Academy of Sciences can change the current understanding of language acquisition in young children, revealing that the boundaries between typical performance and developmental disorders are not as clear-cut as previously believed. Having tested more than 100 Russian-speaking children between the ages of 4 and 7, the researchers discovered that some children diagnosed with developmental language disorders (DLD) performed on par with their peers who did not have speech and language diagnoses. The study has been published in the Journal of Speech, Language, and Hearing Research.

Characterising the language abilities of children with developmental language disorders (DLD) poses a challenge for researchers, since each child exhibits a distinct language profile, and attempts to classify them into homogeneous groups are not always successful. The diversity of symptoms is most accurately explained by the continuum/spectrum model, wherein language profiles are described as varying degrees of development within specific language levels, rather a simple dichotomy of norm versus disorder. 

Researchers at the HSE Language and Brain Centre suggest that a continuum/spectrum model could describe language development patterns not only in children with DLD but also in typically developing children with varied timelines and patterns of language acquisition. To test this hypothesis, the researchers assessed the language abilities of Russian-speaking children with DLD aged 4 to 7 years, matching them with typically developing (TD) peers.

The children's performance in the production and comprehension of sounds, words, sentences and text was evaluated using 11 subtests of the standardised Russian Child Language Assessment Battery (RuCLAB). These skills correspond to the phonological, lexical, morphosyntactic and discursive levels of the language.

The children were tasked with listening to pairs of words and determining whether they were identical, repeating non-words, and associating words with corresponding pictures. For example, when prompted to identify a butterfly in a picture, they were required to select it from among three distracting images: grandmother, fly, and grandfather. In the final task, they listened to a fairy tale, answered questions, and produced picture-based stories complete with exposition, climax, and resolution.

The study revealed two mixed groups where diagnosis did not affect the language performance—children with and without DLD demonstrated both good and poor skills. Thus, the first group included children with higher test scores (TD =45 and DLD = 24), whereas the second group comprised children with lower test scores (TD = 8 and DLD = 29). 

In the group with higher scores, children faced challenges at one or two language levels, depending on the age: four-year-olds scored lower at both the phonological and discursive levels, whereas children aged 5-7 struggled with only one level (either phonological or discursive). 

Additionally, children in the lower-scoring group, irrespective of age, demonstrated poor performance at two and sometimes all four language levels. The researchers have thus confirmed their hypothesis that the continuum/spectrum approach can be used to evaluate individual performance across various language levels in both typically developing children and those with DLD.

There is little experimental evidence to support the application of the continuum/spectrum model to a clinical group of children diagnosed with DLD. Our paper, along with findings from other studies on autism spectrum disorders and attention-deficit/hyperactivity disorder, demonstrate the significant potential of this approach for evaluating speech and language development. Applying an integrated approach to DLD diagnosis will enable clinicians to tailor their interventions to each child's unique needs, focusing on specific language disorders and their severity.

Anastasia Lopukhina
Co-author of the paper, Research Fellow, Royal Holloway, University of London

In contrast to children with DLD, none of the typically developing children encountered challenges at the morphosyntactic level, demonstrating proficiency in correctly using and combining grammatical structures to construct sentences.

We found that the language performance of both children with DLD and typically developing children can vary from high to low across all levels of comprehension and production. Children situated in the middle of this spectrum exhibit individual strengths and weaknesses depending upon the extent of development at a specific language level. To characterise a child's language profile, tasks evaluating all language levels should be used. For an accurate diagnosis of a child's development, conducting a comprehensive assessment of their language abilities is crucial.

Militina Gomozova
Co-author of the paper, Junior Research Fellow, Centre for Language and Brain, HSE University

During the study, the researchers also discovered which combinations of language levels resulted in the highest number of errors. Understanding such combinations is essential for the development of effective therapy methods.
IQ

June 07