Project description

This thesis work is divided into four studies. A first study compared autistic people with speech onset delay, without speech onset delay, and with early mastery of speech, in order to better understand the nature of specific interests that characterize adults with autism. This study tested the hypothesis that speech delay or, conversely, early mastery of speech, orients the nature and verbal relationships of autistic interests in adulthood. Semi-structured interviews were carried out with autistic people about their intense interests. Then, perceptual and thematic dimensions were defined with a priori descriptors. The perceived function and advantages of the interests was also explored.

The following studies will look at the factors that may or may not differentiate speech onset delay in autism.. Thus, Study 2 compared visual specificities in autism without Speech Onset Delay (no SOD) to autism with Speech Onset Delay (SOD). The groups (no SOD, SOD and controls) showed no deficit in the construction of global representations. The typical performances of autistic people in tasks requiring global treatment do not correspond to the hypothesis of low central coherence induced by a global deficit (Frith, 2003; Happe and Frith, 2006).

The purpose of Study 3 was to investigate the influence of prior knowledge of language, in the form of phonemic categorical knowledge, on speech perception in autistic adults. As categorical phonemic knowledge is shaped by experience and language skills, we further distinguished autistic participants with SOD or without a history of speech delay (no SOD); the control group was composed of typical individuals matched by age, non-verbal intelligence and reading skills. We also controlled the influence of short-term auditory and verbal retention skills by administering repetition tasks of word and non-word lists. The preservation of categorical perception in verbal autistic adults observed in this study challenges models claiming a reduced influence of prior knowledge on perception in autism. 

Study 4 used the same conditions and hypotheses as Study 3 in order to verify them with autistic children. Results similar to Study 3 have been reported.