Role of Two Types of Syntactic Embedding in Belief Attribution in Adults with or Without Asperger Syndrome

The role of syntax in belief attribution (BA) is not completely understood in healthy adults and understudied in adults with autism spectrum disorder. Embedded syntax could be useful either for the development of Theory of Mind (ToM) ( account) or more generally over the lifespan ( account). Two hypotheses have been explored, one suggesting that embedding itself (Relatives and Complement sentences and account) is important for ToM and another one considering that the embedding of a false proposition into a true one (Complement sentences and account) is important. The goals of this study were to evaluate (1) the role of syntax in ToM ( vs. account), (2) the type of syntax implied in ToM ( vs. account), and (3) the verbally mediated strategies which compensate for ToM deficits in adults with Asperger Syndrome (AS). Fifty NeuroTypical (NT) adults and 22 adults with AS were involved in a forced-choice task including ±ToM tasks (BA and a control task, physical causation, PC) under four Interference conditions (silence, syllable repetition, relative sentences repetition, and complement sentences repetition). The non-significant ±ToM × Interference interaction effect in the NT group did not support the account and thus suggests that syntax is useful only for ToM development (i.e., account). Results also indicated that repeating complement clauses put NT participants in a dual task whereas repeating relative clauses did not, suggesting that repeating relatives is easier for NT than repeating complements. This could be an argument in favor of the account. However, this result should be interpreted with caution because our results did not support the account. Moreover, AS participants (but not NT participants) were more disrupted by ±ToM tasks when asked to repeat complement sentences compared to relative clause sentences. This result is in favor of the account and indirectly suggests verbally mediated strategies for ToM in AS. To summarize, our results are in favor of the account in NT and of and accounts in adults with AS. Overall, this suggests that adults with AS use complement syntax to compensate for ToM deficits.