Audiovisual integration of emotional signals and its interaction with attention in Autism Spectrum Disorder

Background: Attentional impairments are among the most consistently reported cognitive deficits in Autism Spectrum Disorders (ASD), and have profound implications for several clinical features of the disorder. Disruptions in the attentional system are particularly explicit in the patient’s ability to shift attention between auditory and visual modalities. Several older studies have yielded suggestions that multisensory integration (MSI) is impaired in individuals with ASD. The critical question, however, remains whether anomalous patterns of MSI arise from deficits in specific processes related to integration abilities, or from impairments in attentional capacity.

Objectives: The focus of the present study was on the influence of attention on the integration of emotional visual and auditory information in ASD individuals, using Event-related potentials (ERPs).

Methods: ERPs following emotionally congruent and incongruent face-voice pairs were measured in 23 high-functioning, adult ASD individuals and age- and IQ-matched controls. MSI was studied while attention was directed to both modalities or while participants were either mildly (1D) or heavily (2D) distracted. ERPs to audiovisual stimuli (AV) were compared with the sum of the ERPs to auditory and visual stimuli, measuring low-level MSI. The difference in ERP activity to congruent and incongruent AV stimuli indicated higher-order, or emotion related, MSI.

Results: Low-level MSI was similarly observed in both groups and was shown to be strongest for the fully attended condition. Higher-order MSI was observed most clearly in the fully attended condition, but only for controls. ASD individuals did show higher-order MSI, but only in the 1D condition. In the 2D condition neither group showed MSI.

Conclusions: ASD individuals are able to process multisensory emotional stimuli on lower as well as higher levels of processing. However, optimal processing occurs while ASD individuals are mildly distracted from the emotion eliciting event. Implications for clinical features of the disorder are discussed.