Inner Speech and Self Ordered Pointing Performance In Autism Spectrum Disorder

Background:  

Language has been implicated in a variety of controlling functions apart from merely acting as a conduit for transferring thoughts and ideas. A cognitive conception of language holds that language – inner speech in particular – can service executive functioning (Holland & Low, 2010). The engagement of implicit verbalization for problem solving is especially relevant to illuminating the nature of executive function deficits in children with autism spectrum disorder (referred to as ASD). Inner speech seems to be available to ASD for short-term maintenance and storage of verbal and phonological information, but there appears to be irregularities in its application (Whitehouse et al., 2006; Williams et al., 2008). Holland and Low posited that autistic weaknesses in inner speech use may be especially evident in terms of when and how sub-vocal rehearsal is recruited to support central executive control processes.

Objectives:

Uing a dual task paradigm, we tested whether articulatory suppression would have any disruptive effect on executive working memory in ASD.

Methods:  

Participants with ASD and typically developing (TD) matched controls were administered verbal and nonverbal variants of Petrides and Milner’s (1982) Self-ordered Pointing Test (SOPT). The SOPT is a non-spatial, self-monitoring test that requires generation of novel responses while monitoring actions already made and retained in working memory with choices yet to be made. The SOPT was administered using a 15” ELO Touch Screen Computer. Participants completed the verbal and non-verbal SOPT silently by themselves or concurrently with a secondary task that required the overt recitation of a familiar sequence (repeatedly saying the days of the week). The underlying logic was that if the secondary task (articulatory suppression) disrupts performance on the primary task relative to a silent output condition, subvocal speech used by the secondary task is inferred to be involved in performance on the primary task.

Results:  

We found a robust effect whereby ASD, compared to the IQ and language matched TD group, performed poorer on the verbal but not on the nonverbal variant of the SOPT. Moreover, ASD did not appear to recruit inner speech to facilitate verbal SOPT performance: there was no detrimental effect of articulatory suppression on accuracy in the verbal SOPT variant for ASD compared to the control group.

Conclusions:  

The results indicated that ASD do not appear to recruit internal verbal representations for assistance with the self-regulation and monitoring of a sequence of actions by the central executive. Consequently, given that inner speech partly contributes to supporting executive control over setting up, maintaining and operating task-specific programmes, and that ASD do not show any effect of articulatory suppression on executive working memory, the study of suppression effects in a dual-task paradigm may be especially sensitive to revealing potential limitations of the self-regulatory qualities provided by inner speech function in autism spectrum disorder.