Individual differences and the effect of face configuration information in the McGurk effect.

The McGurk effect, which denotes the influence of visual information on audiovisual speech perception, is less frequently observed in individuals with autism spectrum disorder (ASD) compared to those without it; the reason for this remains unclear. Several studies have suggested that facial configuration context might play a role in this difference. More specifically, people with ASD show a local processing bias for faces-that is, they process global face information to a lesser extent. This study examined the role of facial configuration context in the McGurk effect in 46 healthy students. Adopting an analogue approach using the Autism-Spectrum Quotient (AQ), we sought to determine whether this facial configuration context is crucial to previously observed reductions in the McGurk effect in people with ASD. Lip-reading and audiovisual syllable identification tasks were assessed via presentation of upright normal, inverted normal, upright Thatcher-type, and inverted Thatcher-type faces. When the Thatcher-type face was presented, perceivers were found to be sensitive to the misoriented facial characteristics, causing them to perceive a weaker McGurk effect than when the normal face was presented (this is known as the McThatcher effect). Additionally, the McGurk effect was weaker in individuals with high AQ scores than in those with low AQ scores in the incongruent audiovisual condition, regardless of their ability to read lips or process facial configuration contexts. Our findings, therefore, do not support the assumption that individuals with ASD show a weaker McGurk effect due to a difficulty in processing facial configuration context.