Atypical phonemic discrimination but not audiovisual speech integration in children with autism and the broader autism phenotype

When a speaker talks, the consequences of this can be heard (audio) and seen (visual). We use a novel visual phonemic restoration task to assess behavioral discrimination and neural signatures (ERP) of audiovisual processing in typically developing children with a range of social and communicative skill and in children with autism. In an auditory oddball design we presented two types of stimuli to the listener, a clear exemplar of an auditory consonant-vowel syllable /ba/ and a syllable in which the auditory cues for the consonant was substantially weakened, creating a stimulus which is more like /a/. All speech tokens were paired with a face producing /ba/ or a face with a pixelated mouth, effectively masking visual speech articulation. In this paradigm, the visual /ba/ should cause the auditory /a/ to be perceived as /ba/, creating an attenuated oddball response (phonemic restoration), but the pixelated video should not have this effect. Across two studies we observed behavioral and ERP effects that are consistent with phonemic restoration overall; however, autism-like traits and autism were associated with overall reductions in phonemic discrimination regardless of face context, suggesting that autism may be associated with impairments in speech processing but not AV speech integration.