Familiality of visual perceptual styles: Local and global visual processing in autism and first-degree relatives

Background: Individuals with ASD often demonstrate a local visual processing bias, with some evidence showing concurrent impaired global processing. Atypicalities in global visual processing are associated with increased ASD symptom severity, shedding light into potential cognitive mechanisms contributing to the ASD phenotype. Visual perceptual and social attentional differences have also been documented more subtly among parents of individuals with ASD. However, prior studies of local/global visual processing in parents show mixed findings, and primarily use accuracy and reaction time measures alone, which may not confer enough specificity to capture sub-clinical differences. This study aimed to address this gap by implementing an objective measurement of local and global perception via eye tracking in ASD and their parents. Methods: Participants included 161 individuals (n=32 individuals with ASD and n=30 controls; n=56 parents of individuals with ASD and n=43 control parents), who completed two interactive tasks that tap local/global visual processing, while their gaze was tracked on an eye tracker. To examine local/global visual processing, performance (i.e., accuracy and reaction time) and a suite of eye-tracking variables were calculated. A series of linear mixed effects models assessed ASD versus control and ASD parent versus control parent group differences. Within-family associations of local/global perception, and associations with ASD-related clinical and subclinical traits were also examined. Results: Significant differences emerged for performance (i.e., accuracy and/or reaction time) indices during more complex tasks in both proband and parent groups. Eye-tracking results further revealed evidence of reduced global versus local visual processing in ASD and ASD parent groups, with the ASD group demonstrating heightened local processing, in addition to reduced global perception, and parents showing evidence of a diminished bias towards global stimuli, but without indications of heightened local processing. Within family similarities of processing styles were observed for ASD parent-child pairs, which were not found in control families. Finally, heightened local processing was related to more severe restricted and repetitive behaviors in individuals with ASD; whereas heightened local processing was unexpectedly associated with better pragmatic language abilities was observed in both ASD proband and ASD parent groups. Conclusions: Findings demonstrated robust local/global visual processing differences using eye tracking in individuals with ASD, alongside more subtle, and nuanced differences in parents that together could point to underlying neurobiological differences in visual perception. Within-family associations observed suggest that visual processing styles uniquely co-segregate in ASD families, and add to evidence that visual processing styles may be heritable, genetically meaningful features of the broader autism spectrum.