This study aims to investigate possible factors contributing to subject-verb agreement errors in Swedish junior and senior high school students' English written production. The sample data is collected from the Swedish Learner English Corpus (SLEC), which comprises student texts produced in a classroom setting. The texts are randomly chosen but evenly distributed in terms of binary gender, school year, and type of high school program. In this study, the texts included in the scope are written by students attending a Swedish-speaking school with Swedish as their first language. Errors are classified as overgeneralization or transfer and further classified in relation to the subject type, the verb type, and the distance between the subject and the verb. The classification of all correct instances of subject-verb agreement is also performed to further investigate possible error explanations. A total of 41 agreement errors were found in 24 texts written by students in the 9th and 11th grades. The results show that overgeneralization is more frequent than transfer errors. Overgeneralization suggests that the students are aware of the third-singular form but do not always apply it correctly, while transfer errors show a potential lack of awareness or attention to the form. In both cases, the errors indicate that these students have not automatized the principle yet. Errors are often related to subject types “a pronoun” or “a noun/noun phrase" and the verb be, which is the most frequently used verb. Most of the errors occur when the subject and the verb are in immediate contact, and more than half of them involve a relative pronoun as subject, which indicates that the learners have misinterpreted the grammatical principle or have not fully acquired it. Overuse of the third-person singular form can also be an effect of teaching and explicit learning, which makes learners apply the form whenever it seems possible and relevant.

MA (ELT) / Department of Engliish / Learning English as a second language by the South African learners of English First Additional Language (FAL) causes many challenges, such as committing errors in concord as there are differences between the learners’ mother tongue and the target language. Even at Grade 12 level, which is the exit point to institutions of higher learning or to the workplace, learners still display some deficiencies in the mastery of the English concord. This happens despite the fact that, in many South African schools, English is used as a medium of instruction and learnt as a First Additional Language (FAL) especially at high schools. Through the analysis of the written concord errors committed by the 72 of the 720 sampled Grade 12 English FAL learners in Vhembe District, the study answered to two questions which formed its cornerstone which are: what are the most common types of written concord/ subject-verb agreement errors which are committed by Grade 12 FAL learners and what are the causes thereof? The study employed both the quantitative and the qualitative methods to pursue the primary question. Learners responded to the questionnaires and the researcher also analysed their teacher-marked English FAL composition scripts with the focus on concord/subject-verb agreement usage. The findings were that concord/subject-verb agreement was a challenge to the majority of the participants. There was not even a single question which recorded a 100% correct entry. The question on collective nouns was found to be the hardest to the participants while comparatively, the singular indefinite pronoun question recorded the best results. The learners’ written compositions were also found to have been marred by concord/subject-verb agreement errors. In most instances, the learners had resorted to simple sentences avoiding the complex sentence construction as those would have required complicated application of concord/ subject-verb agreement usage. Based on the findings, the following recommendations were made: teaching of grammar should be intensified, and that teachers of English should be retrained even if it will be through the in-service programmes

Codirection / Bien 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.