Children with high-functioning autism, children with specific language impairment, children with autism and language impairment, and controls produced sentences after a prompt to form a sentence using a specific word. The sentences were analyzed for syntactic complexity. Children with language impairment, regardless of autism diagnosis, made less complex sentences than their age peers. However, children with autism and language impairment exhibited a broader range of ability than children with language impairment alone. Children with high-functioning autism without concomitant structural language impairment created sentences of similar complexity to age peers. Word variables also influenced sentence complexity, with word meaning (abstract vs. concrete) having the most robust effect and word frequency having a negligible effect. Implications for this study in relation to double-deficit and syntactic bootstrapping models are discussed.

Fourteen young adults participated in a cross-modal picture priming study. Perspective shift processing, in four types of relative clause sentences and in control sentences, was assessed using reaction times. Predictions were: 1) the easier the perspective shifts, the faster the reaction times and 2) subject relative clauses would reveal a priming effect versus attenuated or no priming in object relative clauses due to difficulty following perspective. A priming effect was observed for 1- switch relative clause sentences and for control sentences, while no priming effect was observed for 0 switch, 1+ switch, or 2 switch sentences. Results suggest that variations in local syntactic constructions and word order facilitated relative clause processing. Violations of semantic expectations and noun-noun-verb distance in following perspective can both contribute to the complexity of relative clause processing.

In recent years, computer software has been used to assist in the analysis of clinical language samples. However, this software has been unable to accurately identify complex syntactic structures such as adverbial clauses. Complex structures, including the adverbial clause, are of interest in child language due to differences in the development of this structure between children with and without language impairment. The present study investigated the accuracy of new software, called Cx, in identifying adverbial clauses. Two separate collections of language samples were used. One collection included 10 children with language impairment, 10 age-matched peers, and 10 language-matched peers. A second collection contained language from 174 students in first grade, third grade, fifth grade, and junior college. There was high total agreement between computerized and manual analysis with an overall Kappa level of .895.

La Théorie Usage et Construction (TUC) postule que l’enfant développe son langage, et plus précisément ses formes morphosyntaxiques, grâce à l’utilisation de processus cognitifs généraux qui permettent un mécanisme de complexification et de généralisation de ses propres productions ainsi que de celles issues de l’input. L’approche cognitivo-fonctionnelle n’a été appliquée à la dysphasie que dans peu d’études. De plus, l'acquisition de la syntaxe complexe chez l'enfant dysphasique est un domaine délaissé dans la littérature existante. Ainsi, dans ce travail de thèse, nous nous sommes intéressés aux difficultés des enfants dysphasiques pour la complexité morphosyntaxique à travers la lunette de la TUC, et ce en utilisant à les fois des tâches expérimentales et des situations de génération de langage spontané. Nous postulions que la complexité, concept au cœur de notre travail, est définie par ce qui est cognitivement coûteux, désignant ainsi les formes linguistiques rares, longues ou imbriquées. Notre travail met en évidence que les enfants dysphasiques peuvent être productifs seulement avec les schémas fréquents dans le langage qui leur est adressé, alors que les structures complexes, peu fréquentes dans l’input, sont particulièrement difficiles à appréhender pour eux. Dès lors, ces enfants ont besoin d’être confrontés à davantage d’exemplaires et de contextes de pratique pour que la masse critique suffisante soit atteinte et que l’apprentissage de constructions soit possible. Enfin, un lien relativement clair entre la difficulté de complexification syntaxique et les troubles de la généralisation est mis en évidence. / The Construction and Usage-based Theory (CUT) argues that children develop their language, and more precisely morphosyntactic structures, thanks to the use of general cognitive processes by complexifying and generalizing their own prior productions and productions used in the input. These hypotheses have been tested in children with specific language impairment (SLI) in very few studies. Moreover, development of complex syntax is a little studied area in the literature. Thus, the current doctoral thesis focused on complex syntax difficulties of children with SLI using spontaneous language samples and experimental tasks. This work defines complexity as linguistics forms which are rare, long or nested and more generally cognitively costly. The results obtained show that children with SLI use frequent forms heard in the input productively, whereas complex forms, which are rare in the input are difficult for them. These children need to be exposed to more exemplars and practice settings to reach critical mass and making possible learning of constructions. Finally, this current doctoral thesis highlights a relatively obvious link between complex syntax difficulties and lack of generalization of construction schemas.