Adults with Autism Spectrum Disorder Demonstrate Increased Disfluency in Spontaneous Speech but Not in Reading
Purpose: This study aimed to analyse the frequency and types of disfluencies in spontaneous speech and reading among adults with autism spectrum disorder (ASD) compared to neurotypical adults.
Method: The participants were 56 Dutch-speaking adults, 28 with ASD and 28 age- and gender-matched controls. Samples of spontaneous speech and text reading were orthographically transcribed, and the speech disfluencies were identified and classified, using an expanded version of the Illinois Disfluency Classification System. The frequencies of stuttering-like disfluencies (SLDs), other disfluencies (ODs), word-final disfluencies (WFDs), and total disfluencies (TDs) were calculated.
Results: Adults with ASD exhibited significantly more SLDs and WFDs in spontaneous speech than the control group. While no statistically significant differences were observed between both groups in reading, a trend towards increased WFDs was noted.
Conclusions: Adults with ASD exhibit increased speech disfluencies, more specific SLDs and WFDs, in spontaneous speech, than neurotypical adults, but not during reading. This discrepancy may arise because spontaneous speech requires real-time language formulation and social communication skills, which can differ in ASD, whereas reading offers an external linguistic structure that reduces cognitive and social processing demands. Increased speech disfluencies may impact how speech is perceived in terms of intelligibility and/or social communication dynamics.
