Beyond the forest and the trees

: a cross-sectional investigation into local and global information processing in visual perception and language in typical development and autism spectrum disorder

Abstract

This investigation aimed to deepen our understanding of local and global processing (LGP) in visualperception and language in typical development (TD) and autism spectrum disorders (ASD). In TD, aglobal bias is commonly found, while results for ASD vary. Still unclear is whether LGP in ASD followdevelopmental trajectories that are delayed or qualitatively different, but also whether it is indeedatypical. Uncertain is also how stimulus- and task-dependent factors influence processing styles. Theseissues were explored. A further aim was to illuminate the applicability of explanatory theories for poorerglobal processing in ASD: weak central coherence (WCC), language impairment (LI), and executivedysfunction (ED) theory.After an introductory Chapter 1, Chapters 2 to 4 give a review of the literature regarding LGP in visionand language, followed by an overview of the aims of this investigation (Chapter 5) and themethodology (Chapter 6). The first experimental study (Chapter 7) addressed perceptual and cognitiveaspects of LGP in TD adults and demonstrated a flexible global bias which was mainly independent ofstimulus characteristics. The next two studies included cross-sectional TD and ASD samples that weretested on a wider battery of visual (Chapter 8) and language tasks (Chapter 9) in order to investigatedevelopmental aspects of LGP, compare processing in the typical and clinical sample, and examine therelationship of different LGP tasks within and across domains as well as the links between LGP,language abilities, and autistic traits (Chapter 10).The analyses revealed that the ASD groups performed in a manner comparable to TD participants,although there were indications for a developmental delay in ASD. LGP indicators did not correlatewithin or between modalities. Neither the WCC nor LI theory were fully supported by the findings.Instead, ED are suggested to be the underlying factor that influenced performance.

Date of Award	15 May 2018
Original language	English
Supervisor	Joel Talcott (Supervisor) & Mila Vulchanova (Supervisor)