Electrophysiological correlates of predictive coding of auditory location in the perception of natural audiovisual events

In many natural audiovisual events (e.g., a clap of the two hands), the visual signal precedes the sound and thus allows observers to predict when, where, and which sound will occur. Previous studies have reported that there are distinct neural correlates of temporal (when) versus phonetic/semantic (which) content on audiovisual integration. Here we examined the effect of visual prediction of auditory location (where) in audiovisual biological motion stimuli by varying the spatial congruency between the auditory and visual parts. Visual stimuli were presented centrally, whereas auditory stimuli were presented either centrally or at 90° azimuth. Typical sub-additive amplitude reductions (AV − V < A) were found for the auditory N1 and P2 for spatially congruent and incongruent conditions. The new finding is that this N1 suppression was greater for the spatially congruent stimuli. A very early audiovisual interaction was also found at 40–60 ms (P50) in the spatially congruent condition, while no effect of congruency was found on the suppression of the P2. This indicates that visual prediction of auditory location can be coded very early in auditory processing

Sub-clinical levels of autistic traits impair multisensory integration of audiovisual speech

Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder characterized by restricted interests, repetitive behavior, deficits in social communication and atypical multisensory perception. ASD symptoms are found to varying degrees in the general population. While impairments in multisensory speech processing are widely reported in clinical ASD populations, the impact of sub-clinical levels of autistic traits on multisensory speech perception is still unclear. The present study examined audiovisual (AV) speech processing in a large non-clinical adult population in relation to autistic traits measured by the Autism Quotient. AV speech processing was assessed using the McGurk illusion, a simultaneity judgment task and a spoken word recognition task in background noise. We found that difficulty with Imagination was associated with lower susceptibility to the McGurk illusion. Furthermore, difficulty with Attention-switching was associated with a wider temporal binding window and reduced gain from lip-read speech. These results demonstrate that sub-clinical ASD symptomatology is related to reduced AV speech processing performance, and are consistent with the notion of a spectrum of ASD traits that extends into the general population