Error Types in Synchrony Judgements of Audiovisual Stimuli in Children with Autism Spectrum Disorders

Background:

Intermodal perception (IMP), the ability of integrating multiple sensory information (e.g., visual and auditory) into a single, coherent perception, is crucial to different aspects of development (e.g., Bahrick, 2010). Atypical IMP has been found in individuals with autism spectrum disorders (ASD) (e.g., Bebko et al., 2013; Iarocci & McDonald, 2006; Stevenson et al., 2014), and there has been a growing appreciation of potential links between the sensory experiences of those with ASD and social-communicative deficits. For example, Bebko et al., 2006 found a linguistic-specific deficit in children with ASD when discriminating the synchrony of audiovisual stimuli using a preferential looking paradigm.

Objectives:

The current study attempts to expand on the results of Bebko et al., 2006, by using a task requiring an explicit response about whether auditory and visual stimuli are synchronous (synchrony judgement). Patterns of correct responses and error types were analyzed to gain a better understanding of what is contributing to atypical IMP in ASD.

Methods:

Twenty children with ASD (M= 12.7 years, SD=2.96) and thirty non-clinical children (TD) (M=11.9 years, SD= 3.05) were asked to determine whether audio and visual components of a stimulus were synchronous or not. Five stimulus types were presented: social-linguistic (SL: someone reading a story), social-non-linguistic (SNL: a person making popping sounds), non-social-non-linguistic (NSNL: e.g., a hand playing the piano), and emotion (EH: someone laughing or crying).

Results:

The ASD group (M= 77.36%) had a significantly lower percentage of correct synchrony judgements versus the TD group (M = 85.66%), F(1,49)=6.575, p=.013. The proportions of errors made were examined by stimulus type in a 2-way mixed model ANOVA. A significant main effect was found for stimulus type, where both groups made more judgement errors for the emotion stimuli. A within-group post-hoc analysis showed that the TD group made more errors for the positive affect versus negative affect, t(1,29)=2.467, p=.019, while the ASD group made equal mistakes on both types of the EH stimuli.

Errors were also separated out by synchrony type: that is, responding as synchronous when the stimulus was asynchronous, and vice versa. A 2-way mixed model ANOVA with error types and group yielded a significant main effect of error type. Both groups were less likely to misidentify a synchronous stimulus as asynchronous. A within-group post-hoc analysis showed that the ASD participants were more likely to erroneously respond that an asynchronous visual-leading stimuli was synchronous than for audio-leading stimuli, t(1.19)=2.658.This difference was not observed in the TD group.

Conclusions:

The more explicit judgements required in this task were expected to help participants with ASD overcome their difficulties with audiovisual IMP in more subtle tasks. However, the ASD group made significantly more errors in a synchrony judgement task, even though the asynchronous stimuli were offset by 1 second, a very large offset. The present findings indicate that helping to focus the participants’ attention to the task by requesting a concrete motor response was not sufficient to help overcome the underlying audiovisual IMP issues. Further research is needed to better understand these challenges.