The Language-Cognition Interface in ASD: Complement Sentences and False-Belief Reasoning

Background: Theory of Mind (ToM) is often affected in individuals with Autism Spectrum Disorders (ASD). Previous work on ASD has identified links between ToM abilities and knowledge of sentential complements, with the hypothesis that this component of language provides a tool for children with ASD to figure out solutions to ToM tasks. However studies on ASD are yet to show if the impact of complementation on ToM performance carries over to instances where ToM is assessed nonverbally. As such, the links identified between ToM and complementation tasks may stem from linguistic difficulties that impact scores across the measures used, rather than from the role played by sentential complements in mental representation.

Objectives: The goals of this study were to assess (1) if links between ToM and sentential complements are still present when ToM tasks are non-verbal (2) if complements play a special role in ToM reasoning as compared to other language abilities in ASD. 

Methods: 34 children with ASD (mean 8.2 years) and 24 TD children (mean 10.5 years) with similar non-verbal mental age (mean 8.5 years) and general language abilities (vocabulary and morphosyntax) were asked to complete False Belief (FB) tasks following the classical Sally-Anne procedure (verbal ToM), and a picture sequencing task by Baron Cohen, Leslie, & Frith (1986) which relied on the imputing of a FB (non-verbal ToM). Children were also assessed for their comprehension of complements with a French adaptation of de Villiers & Pyers (2002) memory for complements’ task. 

Results: Consistent with previous studies, significant correlations were observed between sentential complements and verbal FB success in TD children (τ(21)=0.50, p=0.01), as well as in children with ASD (τ(21)=0.50, p=0.006). In both groups, these links persisted after controlling for mental age (τ(21)=0.47, p=0.003; τ(21)=0.41, p=0.01), morphosyntax (τ(21)=0.47, p=0.003; τ(21)=0.33, p=0.04) and lexical abilities (τ(21)=0.44, p=0.005 and τ(16)=0.42, p=0.02). However the correlation between measures of sentential complements and non-verbal ToM was significant only in the ASD group (τ(31)=0.38, p=0.009), and this remained when controlling for mental age (τ(31)=0.32, p=0.009) or general morphosyntax (τ(31)=0.34, p=0.006), however not when controlling for vocabulary (τ(20)=0.27, p=0.10). One explanation is that vocabulary development may be an indication of how rich a conversational experience children have had and how much they have been in tune to it. 

Conclusions: Our results show that links between complement sentences and ToM carry over to instances where ToM is assessed nonverbally uniquely in our ASD group, thus providing new evidence in favour of the view that complementation may provide a means for FB representation for individuals on the autistic spectrum. Moreover this study provides support for the view that, as compared to general morphosyntax, complement sentences play a privileged role in FB success. 

Baron‐Cohen, S., Leslie, A. M., & Frith, U. (1986). Mechanical, behavioural and intentional understanding of picture stories in autistic children. British Journal of developmental psychology, 4(2), 113-125.

De Villiers, J. G., & Pyers, J. E. (2002). Complements to cognition: A longitudinal study of the relationship between complex syntax and false-belief-understanding. Cognitive Development, 17(1), 1037-1060.