SEARCH Strategies and Audiovisual Speech PERCEPTION IN Children with AUTISM

Background: Individuals with autism often exhibit ineffective sensory processing, and integration of information across auditory and visual modes appears impaired (Iarocci & McDonald, 2006). Some of the deficits in sensory processing are consistent with impairments in the ability to efficiently organize sensory information through multiple sensory modalities, a process more formally known as intermodal processing. Deficits in intermodal processing may be related to some of the language impairments that characterize autism (Bebko et al. 2006), however; the process underlying this deficit is not well understood.

Objectives: The objectives of the current study are twofold. First, to identify search strategies that may suggest efficient and inefficient looking patterns in this type of task. Second, to examine how differences in these sequential search patterns may contribute to the understanding of differences in intermodal speech processing in children with TD and ASD.  

Methods: Fourteen children (ages 4-11) with an autism spectrum disorder (ASD) were matched with fourteen children with typical development (TD) based on chronological age, verbal and non-verbal abilities. The present study used eye-tracking with a preferential looking design which involved displaying four identical videos, offset in time, with an auditory track synchronous to only one of the videos. Videos contained either linguistic (person telling a story) or non-linguistic (hand playing a piano) stimuli. Data were analyzed on a per trial basis to assess the sequencing of looking patterns displayed by each participant. The time spent looking in each of the four quadrants was analyzed with the use of the Tobii eye-tracking software program. Within each of the four quadrants, Areas of Interest (AOIs) were identified to distinguish between 'relevant' and 'irrelevant' areas within and between the quadrants. For example, 'relevant' areas of the face were defined by the mouth and the eyes of the stimuli. Looking patterns in both groups were analyzed to determine efficient and inefficient looking patterns. Efficient looking patterns were characterized in one of two ways: 1) gaze shift from a 'relevant' AOI to another ‘relevant’ AOI, or 2) gaze shift from an ‘irrelevant’ area to a ’relevant’ area. Inefficient looking patterns were characterized by: 1) gaze shift from a ‘relevant’ AOI to an ‘irrelevant’ AOI, or 2) gaze shift between two ‘irrelevant’ AOIs.  

Results: Initial results for the linguistic stimuli showed more efficient transitions in the group of children with TD compared with the group with ASD. Specifically, the group with TD looked more from mouth to mouth, which is the most efficient search strategy. There were no group differences found for the non-linguistic stimuli. 

Conclusions: Group differences in sequential search strategies may help to clarify the underlying processes contributing to the observable differences in intermodal processing of linguistic information in children with Autism.