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Linguistic Illusions in Children with Down Syndrome, Specific Language Impairment and Typical Language Development

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Improving grammatical standing of stigmatised dialects to help diagnose and treat language disorders

All over the world, children are stigmatised because of the variety of a standard language they speak: some are misdiagnosed with a language disorder; and other children who may in fact present communication difficulties due to a language disorder are not diagnosed, their impairment instead considered a characteristic of their dialect. EU-funded research dove deeper into this phenomenon.


For Marie Skłodowska-Curie fellow Christiana Christodoulou, the concept of ‘linguistic illusions’ is key to understanding ambiguities as to whether a grammatical inaccuracy is due to a language difficulty or a variation of the grammatical phenomenon in the respective dialect. “Linguistic illusions are surfacing effects,” she explains. “For example, the absence of the final ‘s’ in the sentence ‘He run(s) every day’ might seem to be the result of a grammatical difficulty/language disorder. In reality however, it can be caused by other factors, such as articulatory limitations, differences in the phonological system, or a difference in whether ‘s’ is pronounced or not in that position in a specific dialect's grammar.”

A focus on two stigmatised varieties of American English

The EU-funded LINGUISTIC ILLUSIONS project that Christodoulou coordinated along with Ianthi Maria Tsimpli, examined acquisition of grammar at different ages in two populations – typically developing children, and children, adolescents and adults diagnosed with Down’s syndrome – across two varieties of American English: Southern English (SE) and Southern African American Vernacular English (AAE). “In this project,” she says, “the notion of linguistic illusions comes from the fact that certain characteristics of the two southern varieties of English under investigation are often misperceived as lack of grammatical knowledge, despite the extensive linguistic research showing that they are in fact characteristics of the dialect.” Christodoulou’s team, hosted by the University of Mississippi, collected and analysed data from approximately 270 participants and produced millions of data points, realising without doubt the largest study on language development and use/production of SE and AAE. While data analysis has not been fully completed, some key initial results have emerged. For example, the results revealed the highest percentages of medium-high and high risk for a language disorder amongst undiagnosed typically developing children that the team had ever seen (37.6 % for SE-speaking children and 60.5 % for AAE-speaking children, a big leap from the typical expected range of 5-10 %). “We hypothesise that these unexpectedly high percentages are due to gaps in acquisition of grammar created by limited education or limited exposure to language before the age of 5, which makes the test produce false positives,” explains Christodoulou. This was further confirmed by additional testing the team conducted, which also showed that the two groups’ performance was more similar than the initial results suggested.

Practical application and future research

The formulation of developmental trajectories for each population was also a key objective of the project. So far, the team has finalised trajectories for four core linguistic categories (syntax, pragmatics, semantics and phonology) as well as for the production and comprehension of wh- questions. Developmental trajectories can track the development of specific grammatical phenomena across ages and shed light on whether a child’s performance is in line with that of their peers’, and where it might deviate. They will also be highly useful as guides for creating better-informed diagnosis and intervention plans. Results show that the SE and AAE population groups performed in parallel, both to each other and when compared to the Mainstream American English control group of speakers of the same age. Christodoulou has applied for funding to continue the research started in LINGUISTIC ILLUSIONS. “Given what we have uncovered through this project, our next step is to continue the research and address the high rates of risk for a language disorder as well as explore possibilities of reducing those percentages,” she concludes.


LINGUISTIC ILLUSIONS, language disorder, children, dialect, acquisition of grammar, developmental trajectories, Southern English, Southern African American Vernacular English

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