Lexico-semantic and morphosyntactic processing in French-speaking adolescents with and without developmental language disorder

CodirectionBien que la communauté scientifique soit toujours à la recherche d'une caractéristique déterminante du trouble développemental du langage (TDL), les difficultés d'accord sujet-verbe, et par extension morphosyntaxiques, ont été identifiées comme un marqueur du TDL chez les enfants anglophones, autant chez les enfants du préscolaire que les plus vieux. Cependant, des études sur les enfants francophones d'âge préscolaire suggèrent que les déficits morphosyntaxiques ne seraient pas un marqueur fiable du TDL. Puisque que certains aspects de la morphosyntaxe en français ne sont acquis que vers l’âge de huit ans chez les enfants au développement typique, tels que l'accord en nombre des verbes sous-réguliers et irréguliers, ci-après SOUSIRR, les déficits morphosyntaxiques pourraient être un marqueur du TDL en français uniquement vers la (pré-)adolescence. Cette thèse a pour objectifs de déterminer si les (pré-)adolescents francophones au développement typique ont acquis l'accord en nombre des verbes SOUSIRR, si les (pré)adolescents francophones avec un TDL ont des déficits d'accord en nombre des verbes SOUSIRR, et à établir si la morphosyntaxe est un domaine de faiblesse par rapport à la lexico-sémantique dans cette population. L'accord en nombre des verbes SOUSIRR et les compétences morphosyntaxiques ont été évalués à l'aide de tâches ciblant les niveaux comportemental et neurocognitif en utilisant des tâches linguistiques et des potentiels évoqués (PÉ). De plus, nous avons développé des prédictions basées sur deux théories touchant les compétences morphosyntaxiques chez les (pré-)adolescents atteints de TDL : l'hypothèse du déficit procédural (Ullman & Pierpont, 2005 ; Ullman et al., 2020), et l'hypothèse du ralentissement généralisé (Kail, 1994). Cette thèse est composée de trois manuscrits pour publication. Le premier évalue les compétences des participants dans plusieurs domaines linguistiques, à l'aide de tâches comportementales typiquement utilisées en orthophonie et dans la recherche sur l’acquisition du langage. Les données révèlent des déficits lexico-sémantiques et morphosyntaxiques chez les participants avec un TDL, mais suggèrent qu'une tâche d'accord en nombre des verbes SOUSIRR était la meilleure pour discriminer les participants avec et sans TDL. Le deuxième article présente une étude innovante de PÉs utilisant uniquement des phrases grammaticales, présentées simultanément avec des images sémantiquement ou grammaticalement congruentes et incongruentes, afin d'évaluer le traitement morphosyntaxique et lexico-sémantique des phrases au niveau neurocognitif. Les résultats provenant de vingt-huit adultes francophones montrent qu'ils ont présenté les composantes PÉs attendues et comparables aux études utilisant des phrases agrammaticales. Ces données ont servi de référence pour établir si nos participants avec et sans TDL avaient un traitement linguistique mature. Le troisième article a testé cette nouvelle expérimentation avec nos participants (pré )adolescents. Les résultats suggèrent que, contrairement à la morphosyntaxe, la lexico-sémantique est une force relative chez les adolescents avec un TDL lors du traitement de l'information linguistique au niveau neurocognitif. Dans l'ensemble, cette thèse révèle que la morphosyntaxe est particulièrement altérée chez les adolescents francophones avec un TDL. Nous discutons les résultats en relation avec la pratique clinique orthophonique et soulignons l'importance d'examiner les processus neurocognitifs dans l'étude du TDL.Although the scientific community is still searching for a defining characteristic of developmental language disorder (DLD), problems with subject-verb agreement, and by extension morphosyntax, have been identified as a hallmark of English-speaking preschoolers and older children with DLD. However, in studies of French-speaking preschoolers with DLD, morphosyntax has not been found to be a specific linguistic weakness. Since there is evidence that some aspects of morphosyntax in French are acquired by children with typical language (TL) development only later in childhood, such as subregular and irregular subject-verb number agreement, henceforth SUBIRR, morphosyntax has been argued to be a French marker for DLD only in older childhood and adolescence. The present thesis aimed to determine if French speaking (pre-)teenagers with TL have acquired SUBIRR number agreement, resolve whether French-speaking (pre-)teenagers with DLD are impaired on SUBIRR number agreement, and establish whether morphosyntax is an area of weakness as compared to lexico-semantics in this population. SUBIRR number agreement and morphosyntactic skills were evaluated with tasks targeting the behavioural and neurocognitive levels using linguistics tasks and event-related potentials (ERP). Furthermore, we contrasted two theories’ predictions on morphosyntactic skills in (pre-)teens with DLD : the procedural deficit hypothesis (Ullman & Pierpont, 2005; Ullman et al., 2020), and the generalized slowing hypothesis (Kail, 1994). This thesis is composed of three manuscripts for publication. The first evaluated our participants’ skills in multiple linguistic domains with behavioural tasks typical of clinical and research settings. Data reveal impairments in the DLD group in both lexico-semantic and morphosyntactic domains but suggest that a SUBIRR number agreement task was best at discriminating DLD from controls. The second article presents a novel ERP experimental design using only grammatical sentences, presented simultaneously with semantically and grammatically congruent or incongruent images, to assess morphosyntactic and lexico-semantic sentence processing at the neurocognitive level. Data from twenty-eight French-speaking adults show that they elicited the expected ERP components found in previous studies using ungrammatical sentences. These data served as a reference to establish whether our participants with and without TL process sentences in a mature way. The third article tested this novel ERP experiment with our (pre-)teen participants. We tested predictions of the procedural deficit hypothesis which states that children with DLD should have impaired morphosyntax due to an underlying procedural memory deficit, and the generalized slowing hypothesis, which proposes that all linguistic domains should be impaired due to an underlying processing deficit. This experimental design was run on teens with and without DLD. Although some processing delays were found in the DLD group, results on most conditions better fit the procedural deficit hypothesis. This study suggests that, in contrast with morphosyntax, lexico-semantics is a relative strength in teenagers with DLD when processing linguistic information at the neurocognitive level. Overall, this thesis reveals that morphosyntax, tested through SUBIRR number agreement, is especially impaired in French-speaking teens with DLD when compared to their TL peers. We discuss the findings in relation to clinical practice and highlight the importance of examining neurocognitive processes in language assessment

Experimental methods to study atypical language development

In this chapter we present current issues on experimental methods in the study of atypical language development with a focus on developmental language disorders (DLD). We first present a short history of terminology surrounding DLD and follow this with a discussion of critical topics related to DLD assessment including cross-linguistic research, multilingualism, persisting disorders in teenagers, age-differences (pre-school, school age, adolescence, and adults) in manifestations and domains studied, language comprehension versus production, and cognitive assessment. We also bring focus to the question of matching control groups in the study of atypical language development. We present the most common methods used in the investigation of language impairments from the behavioural and neurocognitive perspectives. We provide an overview of the issues related to establishing equivalence between groups with and without language impairments. We conclude with recommendations for practice and future directions in the study of atypical language development

Eliciting ERP components for morphosyntactic agreement mismatches in perfectly grammatical sentences

The present event-related brain potential (ERP) study investigates mechanisms underlying the processing of morphosyntactic information during real-time auditory sentence comprehension in French. Employing an auditory-visual sentence-picture matching paradigm, we investigated two types of anomalies using entirely grammatical auditory stimuli: (i) semantic mismatches between visually presented actions and spoken verbs, and (ii) number mismatches between visually presented agents and corresponding morphosyntactic number markers in the spoken sentences (determiners, pronouns in liaison contexts, and verb-final “inflection”). We varied the type and amount of number cues available in each sentence using two manipulations. First, we manipulated the verb type, by using verbs whose number cue was audible through subject (clitic) pronoun liaison (liaison verbs) as well as verbs whose number cue was audible on the verb ending (consonant-final verbs). Second, we manipulated the pre-verbal context: each sentence was preceded either by a neutral context providing no number cue, or by a subject noun phrase containing a subject number cue on the determiner. Twenty-two French-speaking adults participated in the experiment. While sentence judgment accuracy was high, participants’ ERP responses were modulated by the type of mismatch encountered. Lexico-semantic mismatches on the verb elicited the expected N400 and additional negativities. Determiner number mismatches elicited early anterior negativities, N400s and P600s. Verb number mismatches elicited biphasic N400-P600 patterns. However, pronoun + verb liaison mismatches yielded this pattern only in the plural, while consonant-final changes did so in the singular and the plural. Furthermore, an additional sustained frontal negativity was observed in two of the four verb mismatch conditions: plural liaison and singular consonant-final forms. This study highlights the different contributions of number cues in oral language processing and is the first to investigate whether auditory-visual mismatches can elicit errors reminiscent of outright grammatical errors. Our results emphasize that neurocognitive mechanisms underlying number agreement in French are modulated by the type of cue that is used to identify auditory-visual mismatches

Identifying linguistic markers of French-speaking teenagers with developmental language disorder : which tasks matter?

Purpose:This research aimed to identify reliable tasks discriminating French-speaking adolescents with developmental language disorder (DLD) from theirpeers with typical language (TL) and to assess which linguistic domains repre-sent areas of particular weakness in DLD. Unlike English, morphosyntax has notbeen identified as a special area of weakness when compared with lexicose-mantics in French preschoolers with DLD. Since there is evidence that subject–verb number agreement is consolidated in later childhood, one might expectmorphosyntax to be a particular weakness and marker of French DLD only in(pre)adolescence.Method:We administered 20 subtasks that assessed linguistic and phonolo-gical working memory skills of two groups: 17 adolescents clinically identifiedas having DLD (M= 14.1 years) and 20 (pre)teens with TL (M= 12.2 years).Using robust statistics that are less affected by outliers, we selected the mostdiscriminating subtasks between our groups, calculated their optimal cutoffscore, and derived diagnostic accuracy statistics. We combined these subtasksin a multivariable model to identify which subtasks contributed the most to theidentification of DLD.Results:Seven subtasks were selected as discriminating between our groups,and three showed outstanding diagnostic accuracy: Recalling Sentences, a multi-word task assessing lexicosemantic skills, and a subject–verb number agreementproduction task. When combined, we found that the latter contributed the mostto our multivariable model.Conclusion:This study provides evidence that the most relevant markers toidentify DLD in French teenagers are tasks assessing lexicosemantics and mor-phosyntactic domains, and that morphosyntax should be considered an impor-tant area of weakness in French-speaking teenagers with DLD

Number agreement processing in adolescents with and without developmental language disorder (DLD): evidence from event-related brain potentials

Abstract In morphologically richer languages, including French, one must learn the specific properties of number agreement in order to understand the language, and this learning process continues into adolescence. This study examined similarities and differences between French-speaking adolescents with and without developmental language disorder (DLD) when processing number agreement, and investigated how morpho-syntactic regularity affected language processing. Using event-related potentials (ERP) and only grammatical sentences with audio-visual mismatches, we studied ERP correlates to three types of number agreement: (1) regular determiner agreement in noun phrases, (2) regular subject-verb plural liaison, and (3) irregular subject-verb agreement. We also included a lexico-semantic mismatch condition to investigate lexico-semantic processing in our participants. 17 adolescents with DLD (M = 14.1 years) and 20 (pre)teens with typical language (TL, M = 12.2 years) participated in the study. Our results suggest three patterns. First, French-speaking teenagers without DLD are still consolidating their neurocognitive processing of morpho-syntactic number agreement and generally display ERP profiles typical of lower language proficiency than adult native speakers. Second, differences in morphosyntactic processing between teenagers with and without DLD seem to be limited to rule-based (regular) number agreement. Third, there is little evidence for corresponding differences in lexico-semantic processing

Linguistic markers for French teenagers with DLD (Courteau et al., 2023)

Purpose: This research aimed to identify reliable tasks discriminating French-speaking adolescents with developmental language disorder (DLD) from their peers with typical language (TL) and to assess which linguistic domains represent areas of particular weakness in DLD. Unlike English, morphosyntax has not been identified as a special area of weakness when compared with lexicosemantics in French preschoolers with DLD. Since there is evidence that subject–verb number agreement is consolidated in later childhood, one might expect morphosyntax to be a particular weakness and marker of French DLD only in (pre)adolescence. Method: We administered 20 subtasks that assessed linguistic and phonological working memory skills of two groups: 17 adolescents clinically identified as having DLD (M = 14;09 [years;months]) and 20 (pre)teens with TL (M = 12;21). Using robust statistics that are less affected by outliers, we selected the most discriminating subtasks between our groups, calculated their optimal cutoff score, and derived diagnostic accuracy statistics. We combined these subtasks in a multivariable model to identify which subtasks contributed the most to the identification of DLD. Results: Seven subtasks were selected as discriminating between our groups, and three showed outstanding diagnostic accuracy: Recalling Sentences, a multiword task assessing lexicosemantic skills, and a subject–verb number agreement production task. When combined, we found that the latter contributed the most to our multivariable model. Conclusion: This study provides evidence that the most relevant markers to identify DLD in French teenagers are tasks assessing lexicosemantics and morphosyntactic domains, and that morphosyntax should be considered an important area of weakness in French-speaking teenagers with DLD. Supplemental Material S1. Additional information on the tasks used in this research as well as additional analyses and results. Courteau, É., Loignon, G., Steinhauer, K., & Royle, P. (2023). Identifying linguistic markers of French-speaking teenagers with developmental language disorder: Which tasks matter? Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2022_JSLHR-21-00541 </p