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Investigating the Correlates of Weak Central Coherence in Autism Investigating the correlates of weak central coherence in autism. Elizabeth Milne A thesis submitted for the degree of Doctor of Philosophy (Ph.D) University of London 2003 University College London Department of Human Communication Science, 2 Wakefield Street, London, WCIN IPF ProQuest Number: 10015024 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10015024 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT It has been suggested that autism is characterised by a cognitive style biased towards local rather than global information processing. This cognitive style is known as weak central coherence. There is a wealth of experimental evidence which illustrates that when compared to controls, individuals with autism show superior performance on tasks which require detail-focussed information processing. There is also emerging evidence that some individuals with autism have a deficit in the perception of coherent motion. This thesis presents the argument that deficit in a single aspect of visual processing could underlie both abnormalities in motion detection and the lack of global bias or weak central coherence shown in visual tasks in autism. Using random dot kinematograms to measure coherent motion detection and traditional tests of central coherence and local / global information processing (the children’s embedded figures test and Navon tasks) it was found that not all the children with autism in the sample had weak central coherence when compared to matched controls and that only a sub-group of children had specific difficulty in detecting coherent motion. However in some cases significant relationships between variables indicated that the children with poor motion detection ability were also the ones who showed superior performance on the CEFT and a lack of global bias in the Navon task. The findings are discussed in terms of areas of the visual magnocellular pathway / dorsal stream which might underlie both a deficit in coherent motion detection and a lack of global bias in autism. ACKNOWLEDGEMENTS I’ve really enjoyed the time spent on this PhD and I owe most of that to John Swettenham and Ruth Campbell who have been extremely insightful, good- natured and supportive throughout every stage of this thesis. There are many other people who I have had the privilege to learn from in the past three years and thanks must go to Mike Coleman, Marcin Szczerbinski, Sarah White, and Peter Hansen. I’d also like to thank Mrs Petts and the staff and children at the Marlborough Unit, Axton Chase School and Hillingdon Manor School. I’m greatly indebted to Victoria Milne and her tireless ability to pilot cognitive tasks, and Simon Hamilton who has shared wholeheartedly the emotional and intellectual challenges that I’ve faced in the last three years. This work has been generously supported by an ESRC studentship and UCL graduate school. Table of Contents A b str a c t.......................................................................................................................................................... 2 Acknowledgements.................................................................................................................................... 3 Table o f C o n te n ts.......................................................................................................................................4 List of Tables............................................................................................................................................... 8 List of Figures............................................................................................................................................10 List of Abbreviations .............................................................................................................................. 12 1 CHAPTER ONE. LITERATURE REVIEW............................................................................13 1.1 A im o f t h e t h e s is ......................................................................................................13 1.2 W h a t is a u t is m ? ................................................................................. 13 1.3 S e n s o r y s y s t e m abnormalities in a u t is m ...............................................................15 1.4 T h e BRAIN BASIS OF AUTISM .................................................................................................. 17 1.5 E v id e n c e f o r a v is u a l m o t io n p e r c e p t io n d e f ic it in a u t is m .................... 22 1.6 T h e W e a k C e n t r a l C o h e r e n c e H y p o t h e s is..........................................................23 1.6.1 Conceptual C o herence .............................................................................................24 1.6.2 V isual Perceptual Coherence .............................................................................. 26 1.7 S u m m a r y ....................................................................................................................................... 31 2 CHAPTER TWO. THE VISUAL SYSTEM, AND THE HYPOTHESIS OF THIS THESIS.................................................................................................. 33 2.1 P a r a l l e l p r o c e s s in g in th e v is u a l s y s t e m ............................................................33 2.1.1 Pre -cortical processing ........................................................................................... 33 2.1.2 From THE LGN t o V I.....................................................................................................36 2.1.3 FROM AREA VI ................................................................................................................. 38 2.2 T h e r o l e o f t h e magnocellular st r e a m in c o g n it iv e p r o c e s s e s 40 3 CHAPTER THREE. INDIVIDUAL DIFFERENCES IN COHERENT MOTION DETECTION, IS THERE A RELATIONSHIP WITH WEAK CENTRAL COHERENCE?...................................................................... 46 3.1 Introduction .............................................................................................................................46 3.1.1 G e n e r a l methodology ...................................................................................................47 3.2 St u d y 1. M o t io n c o h e r e n c e d e t e c t io n in a u t is m .............................................. 50 3.2.1 Introduction ........................................................................................................................50 3.2.2 M e t h o d .................................................................................... 52 3.2.3 Re s u l t s ............................................................................................................................ 53 3.2.4 D is c u s s io n ............................................................................................................................... 57 3.3 St u d y 2 - T h e c h il d r e n ’s e m b e d d e d f ig u r e s t e s t (C E F T ) .............................57 3.3.1 Introduction ........................................................................................................................57 3.3.2 M e t h o d ......................................................................................................................................61 3.3.3 Re s u l t s ......................................................................................................................................62 3.3.4 D is c u s s io n ............................................................................................................................... 67 3.4 S t u d y 3. T h e Na v o n t a s k .....................................................................................................68 3.4.1 Introduction ........................................................................................................................68 3.4.2 M e t h o d ......................................................................................................................................69 3.4.3 R e s u l t s ..................................................................................................................................... 72 3.4.4 D is c u s s io n ............................................................................................................................... 76 3.5 P a r t t w o . Is t h e r e a relationship b e t w e e n m o t io n p r o c e s s in g a n d CENTRAL COHERENCE?...........................................................................................................................77 3.5.1 M e t h o d ......................................................................................................................................78 3.5.2 Results AND D is c u s s io n .................................................................................................
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