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Project

Little things, big things: Perceptual organization in children with and without ASD

Autism spectrum disorder (ASD) refers to an early-onset neurodevelopmental condition that is characterized by deficits in social reciprocity and communication, as well as restricted, repetitive patterns of behavior or interest (American Psychiatric Association, 2013). Epidemiological evidence suggests a strong role for genetics in the etiology of ASD, but the actual specifics have yet remained unclear. Shah and Frith (1983, 1993) were the first to publish results suggestive of enhanced local, detailed-oriented and reduced global visual processing in individuals with ASD. Following their initial reports, this research topic has grown into one of the most extensively researched aspects of vision in ASD. Unfortunately, research evidence remains mixed and results often seem to contradict each other. 

Inspired by this research field, this doctoral thesis project set out to provide new insights into atypical visual processing in ASD, by formally assessing the current state of the affairs as well as developing new and improved ways of mapping atypicalities in local and global visual processing in ASD. This thesis bundles two meta-analyses as well as four behavioral studies, which all focused on local, detail-oriented versus global information processing, in individuals with ASD and/or typically developing individuals.

Chapter 2 and 3 discuss a meta-analysis on local and global visual processing of non-social, static stimuli and of motion stimuli, respectively, in individuals with ASD compared to typically developing controls. Chapter 4, 5 and 6 each discuss a behavioral study on local and global visual processing in children with and without ASD (aged 8-15 years old). In Chapter 4 we investigated sensitivity to hierarchical stimuli, with high stimulus variability and spatial uncertainty under various attentional modes. In Chapter 5 we investigated the use of ensemble perception, and evaluated both member-identification and mean-discrimination. In Chapter 6 we investigated the strength of an implicit grouping cue on multiple object tracking. Chapter 7 discusses a developmental study, which investigated the developmental trajectory of two types of grouping cues in typically developing children, aged 9 to 16 years old, using an extended version of the design used in Chapter 6.

The results of this doctoral thesis argue for a small, though significant difference in visual processing in individuals with ASD compared to typically developing individuals. While the evidence of both meta-analyses is clear in suggesting such a difference, the results of the behavioral studies are less unambiguous. Taken together, the evidence put forward implies that differences in local vs. global visual processing in ASD compared to typically developing are best conceptualized as differences in perceptual style rather than in terms of (in)abilities or deficits. Future research is necessary to pinpoint the exact nature and character of these atypicalities in visual information processing as well as to clarify their relation to everyday life functioning with ASD.

Date:22 Oct 2012 →  21 Dec 2016
Keywords:Autism spectrum disorder, Vision research, Meta-analysis
Disciplines:Animal experimental and comparative psychology, Applied psychology, Human experimental psychology
Project type:PhD project