Atypical Influence of Visible Speech in Children with ASD

Background: In face-to-face conversation, when a speaker talks, the outcome of their speech and seen (visual). In some recent research, children with an autism spectrum disorder (ASD) have been reported to be less sensitive to the visible consequences of speech, even when gazing at the speaker’s face. However, the underlying mechanisms of deficits in audiovisual speech perception are still unknown.

Objectives: We employed a novel visual phonemic restoration paradigm to assess neural signatures (using event related potentials; ERPs) of audiovisual processing in typically developing children and in children with ASD.

Methods: Participants were 30 monolingual American English-speaking children (15 children with ASD= 12 males and 3 females and 15 neurotypical children = 5 males and 10 females; age range 6.40 to 14.20, mean age = 10.28 years, SD = 1.98 years). Two types of stimuli were alternately presented with video of a speaker saying the consonant-vowel syllable /ba/, while EEG was continuously recorded; 1) an auditory consonant-vowel syllable /ba/ or 2) a syllable in which the auditory cues for the consonant was substantially weakened, creating a stimulus which is more like /a/. In this paradigm, a visual /ba/ should cause the auditory /a/ to be perceived as /ba/ (a visual phonemic restoration) and cause an attenuated ERP discrimination response (measured with the mismatch negativity; MMN).

Results: Typically developing (TD) children exhibited an attenuated discrimination response (MMN) for as predicted, demonstrating a visible influence of seen on heard speech, however, children with ASD showed a large discrimination response, suggesting reduced influence of visual speech, this was evidenced as an interaction between group and the size of the MMN effect (F(1, 29) = 5.862, p = 0.022, η² = 0.132).

Conclusions: Typically developing children exhibited an attenuated response, demonstrating a visible influence of seen on heard speech. In contrast, children with ASD showed a large /ba/, /a/ discrimination response suggesting reduced influence of visual speech. These findings may implicate impaired integration of auditory and visual speech signals in ASD.