Identifying language impairment in bilingual children in France and in Germany.

BACKGROUND: The detection of specific language impairment (SLI) in children growing up bilingually presents particular challenges for clinicians. Non-word repetition (NWR) and sentence repetition (SR) tasks have proven to be the most accurate diagnostic tools for monolingual populations, raising the question of the extent of their usefulness in different bilingual populations. AIMS: To determine the diagnostic accuracy of NWR and SR tasks that incorporate phonological/syntactic complexity as discussed in recent linguistic theory. The tasks were developed as part of the Language Impairment Testing in Multilingual Settings (LITMUS) toolkit, in two different national settings, France and Germany, and investigated children with three different home languages: Arabic, Portuguese and Turkish. METHODS & PROCEDURES: NWR and SR tasks developed in parallel were administered to 151 bilingual children, aged 5;6-8;11, in France and in Germany, to 64 children in speech-language therapy (SLT) and to 87 children not in SLT, whose first language (L1) was Arabic, Portuguese or Turkish. Children were also administered standardized language tests in each of their languages to determine likely clinical status (typical development (TD) or SLI), and parents responded to a questionnaire including questions about early and current language use (bilingualism factors) and early language development (risk factors for SLI). Monolingual controls included 47 TD children and 29 children with SLI. Results were subjected to inter-group comparisons, to diagnostic accuracy calculation, and to correlation and multiple regression analyses. OUTCOMES & RESULTS: In accordance with previous studies, NWR and SR identified SLI in the monolingual children, yielding good to excellent diagnostic accuracy. Diagnostic accuracy in bilingual children was fair to good, generally distinguishing children likely to have SLI from children likely to have TD. Accuracy was necessarily linked to the determination of clinical status, which was based on standardized assessment in each of the child's languages. Positive early development, a composite risk factor for SLI, and not variables related to language exposure and use, generally emerged as the strongest predictor of performance on the two tasks, constituting additional, independent support for the efficacy of NWR and SR in identifying impairment in bilingual children. CONCLUSIONS & IMPLICATIONS: NWR and SR tasks informed by linguistic theory are appropriate for use as part of the diagnostic process for identifying language impairment in bilingual children for whom the language of assessment is different from the home language, in diverse sociolinguistic contexts.

What Machine Learning Can Tell Us About the Role of Language Dominance in the Diagnostic Accuracy of German LITMUS Non-word and Sentence Repetition Tasks.

The present study investigates the performance of 21 monolingual and 56 bilingual children aged 5;6-9;0 on German LITMUS-sentence-repetition (SRT; Hamann et al., 2013) and non-word-repetition-tasks (NWRT; Grimm et al., 2014), which were constructed in accordance with the LITMUS-principles (Language Impairment Testing in Multilingual Settings; Armon-Lotem et al., 2015). Both tasks incorporate phonologically and syntactically complex structures shown to be cross-linguistically challenging for children with Specific Language Impairment (SLI) and aim at minimizing bias against bilingual children while still being indicative of the presence of language impairment across language combinations (see Marinis and Armon-Lotem, 2015; for sentence-repetition; Chiat, 2015 for non-word-repetition). Given the great variability in bilingual language exposure and the potential effect of language experience on language performance in bilingual children, we examined whether background variables related to bilingualism, particularly, the degree language dominance as measured by relative amount of use and exposure, could compromise the diagnostic accuracy of the German LITMUS-SRT and NWRT. We further investigated whether a combination of the two tasks provides better diagnostic accuracy and helps avoid cases of misdiagnosis. To address this, we used an unsupervised machine learning algorithm, the Partitioning-Around-Medoids (PAM, Kaufman and Rousseeuw, 2009), for deriving a clinical category for the children as ± language-impaired based on their performance scores on SRT and NWRT (in isolation and combined) while withholding information about their clinical status based on standardized assessment in their first (home language, L1) and second language (societal language, L2). Subsequently, we calculated diagnostic accuracy and used regression analysis to investigate which background variables (age of onset, length of exposure, degree of language dominance, socio-economic-status, and risk factors for SLI) best explained clinical-group-membership yielded from the PAM-analysis based on the children's NWRT and SRT performance scores. Results show that although language-dominance clearly influences the performance of bilingual typically developing children, especially in the SRT, the diagnostic accuracy of the tools is not compromised by language dominance: while risk factors for SLI were significant predictors for clinical group membership in all models, language dominance did not contribute at all to explaining clinical cluster membership as typically developing or SLI based on any of the combinations of the SRT and NWRT variables. Additionally, results confirm that a combination of SRT scored by correct target structure and the structurally more complex language-dependent part of the NWRT yields better diagnostic accuracy than single measures and is only sensitive to risk factors for SLI and not to dominance levels or SES.