par Maes, Pauline 
Président du jury Luffin, Xavier
Promoteur Kissine, Mikhail
Publication Non publié, 2022-01-26
Président du jury Luffin, Xavier
Promoteur Kissine, Mikhail
Publication Non publié, 2022-01-26
Thèse de doctorat
| Résumé : | Socio-communicative interaction is known to be central to language acquisition in typically developing (TD) children. As such, TD infants’ natural inclination for the socially relevant events in their environment is said to facilitate the acquisition process. Atypicalities in interactions with others as well as a reduced tendency to orient towards naturally occurring social stimuli lie at the core of the characterization of autism spectrum disorder. Interestingly though, despite initial and persistent socio-communicative disabilities, around 70% of autistic children eventually manage to acquire functional speech.In this dissertation, I provide an in-depth description of the social attention and linguistic abilities of 61 three- to five-year-old autistic children, including many with no or limited language, and 61 age-matched TD children. More specifically, this dissertation is divided into three parts, each of which reports studies based on specific population samples pooled from this larger sample of 122 children.Part 1 reports findings from three passive free-viewing eye-tracking tasks which target different features of visual social attention in the two groups of children. The three tasks assess whether the children are sensitive to the socially relevant information in the presented stimuli: pointing fingers, the eyes and the mouth regions, and gaze direction. Results from eye-tracking task 1 showed that autistic children failed to discriminate intentional and incidental pointing gestures. Results from eye-tracking task 2 showed that both autistic and TD children’s visual attention were attracted by the mouth as an adult started speaking, but that TD, and not autistic, children rapidly shifted their attention back to the eyes as the actor continued speaking. Results from eye-tracking task 3 showed that autistic children were sensitive to gaze direction by showing a typical preference for direct over obvious averted gaze and an atypical preference for subtle averted over direct gaze. In addition, results indicated that autistic children’s social attention abilities were not linked to either concurrent or later levels of expressive vocabulary. Overall, the results in Part 1 suggest that autistic children, regardless of their level of language, present both preserved and diminished patterns of social attention.Part 2 seeks to qualitatively describe oral productions retrieved from detailed transcriptions of naturalistic speech samples (a parent-child interaction and an experimenter-child interaction) in a subsample of 59 autistic children. A cluster analysis revealed the existence of five different patterns of linguistic behavior in this sample. The five clusters were then described and compared in terms of language, psychometric and demographic measures. Clusters 1 and 4, identified as verbal, produced mainly phrases and isolated words, respectively. Clusters 2, 3 and 5 were identified as non- or minimally verbal. Cluster 2 produced barely anything. Cluster 3 produced a fair amount of preverbal and syllabic productions. Cluster 5 produced a lot of syllabic productions, especially. Age and socioeconomic status, typical language development predictors, were not related to cluster membership. Cognitive abilities and autistic symptomatology severity, however, were related to cluster membership, with children in clusters 1 and 4 having higher cognitive abilities and milder autistic symptomatology than those in clusters 2, 3 and 5. It is very likely that the causes for the success or failure to acquire language by that point differ between clusters.Part 3 reports a detailed investigation of the structural language and acoustical specificities of the speech of a subsample of the ten most verbal autistic children, matched pairwise on age, nonverbal IQ, and socioeconomic status with a subsample of ten TD children. Results showed that, in a very strictly matched sample of autistic and TD children, few between-group differences remained in the structural language and acoustical features of their speech. The autistic children significantly differed from their peers only by a restricted use of vocabulary items during spontaneous speech (diminished lexical diversity), which is likely to be constrained by the production of echolalic utterances. This detailed analysis confirms that some autistic children are able to achieve very high levels of language in terms of structure and phonological system by preschool age.Taken together, the results of the three parts combined illustrate the great heterogeneity of language acquisition trajectories in ASD. The lack of a consistent association between typical predictors and patterns of language acquisition and language profiles in the ASD group suggest that looking at autistic language acquisition and development through an exclusively typical lens may not suffice to understand its complexity. |
