City University of New York (CUNY) CUNY Academic Works All Dissertations, Theses, and Capstone Projects Dissertations, Theses, and Capstone Projects 2-2014 The Developmental Trajectory of Contour Integration in Autism Spectrum Disorders Ted S. Altschuler Graduate Center, City University of New York How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_etds/1417 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] The developmental trajectory of contour integration in autism spectrum disorders By TED S. ALTSCHULER A dissertation submitted to the Graduate Faculty in Psychology, sub program in Cognitive Neuroscience, in partial fulfillment of the requirements for the degree of Doctor of Philosophy, The City University of New York 2014 © 2014 TED S. ALTSCHULER All Rights Reserved ii The manuscript has been read and accepted for the Graduate Faculty in Psychology in satisfaction of the Dissertation requirements for the degree of Doctor of Philosophy John J. Foxe, PhD Chair of Examining Committee Maureen O’Connor, PhD Executive Officer Sophie Molholm, PhD Jennifer Mangels, PhD Hilary Gomes, PhD Lynne E. Bernstein, Phd Supervisory Committee THE CITY UNIVERSITY OF NEW YORK iii Abstract The developmental trajectory of contour integration in autism spectrum disorders by TED S. ALTSCHULER Adviser: John J. Foxe, PhD Sensory input is inherently ambiguous and complex, so perception is believed to be achieved by combining incoming sensory information with prior knowledge. One model envisions the grouping of sensory features (the local dimensions of stimuli) to be the outcome of a predictive process relying on prior experience (the global dimension of stimuli) to disambiguate possible configurations those elements could take. Contour integration, the linking of aligned but separate visual elements, is one example of perceptual grouping. Kanizsa-type illusory contour (IC) stimuli have been widely used to explore contour integration processing. Consisting of two conditions which differ only in the alignment of their inducing elements, one induces the experience of a shape apparently defined by a contour and the second does not. This contour has no counterpart in actual visual space – it is the visual system that fills-in the gap between inducing elements. A well-tested electrophysiological index associated with this process (the IC- effect) provided us with a metric of the visual system’s contribution to contour integration. Using visually evoked potentials (VEP), we began by probing the limits of this metric to three manipulations of contour parameters previously shown to impact subjective experience of illusion strength. Next we detailed the developmental trajectory of contour integration processes over childhood and adolescence. Finally, because persons with autism spectrum disorders (ASDs) have demonstrated an altered balance of global and local processing, we hypothesized iv that contour integration may be atypical. We compared typical development to development in persons with ASDs to reveal possible mechanisms underlying this processing difference. Our manipulations resulted in no differences in the strength of the IC-effect in adults or children in either group. However, timing of the IC-effect was delayed in two instances: 1) peak latency was delayed by increasing the extent of contour to be filled-in relative to overall IC size and 2) onset latency was delayed in participants with ASDs relative to their neurotypical counterparts. v Acknowledgments This dissertation is the product of five years of study through which I have been guided with dedication, humor, and wisdom by my mentor, John Foxe, to whom I owe great thanks. In addition, his close collaborator Sophie Molholm, and a group of teachers not limited to, but including Jennifer Mangels, Nancy Foldi, Vivian Tartter, Jeffrey Halperin, David Masur, Ronda Facchini, Natalie Russo, and Hilary Gomes each gave generously of their time and knowledge and were challenging or nurturing, as the occasion demanded. I thank each of them and hope to continue our relationship long into the future. My colleagues at The Sheryl and Daniel R. Tishman Cognitive Neurophysiology Laboratory are a warmly collaborative bunch to whom I am truly grateful. Finally, Michael and mom have shown me extraordinary patience and support. I love them and would never have made it through a mid-career personal revolution without them. Some guys buy a little red sports car. I got a PhD in neuroscience… go figure. vi Dedication FOR MICHAEL vii Table of Contents Chapter One – General Introduction 1.1 Perceptual Completion and Autism Spectrum Disorders 1 1.2 The Stimulus Class – Kanizsa illusory contours 5 1.3 The Metric – Visual evoked potentials 7 1.4 The Questions Prompting these investigations 11 1.5 Autism Spectrum Disorders – Phenotype, epidemiology, diagnosis 13 1.6 Autism Spectrum Disorders – Evidence of connective pathology 18 1.7 Sensory Differences in ASDs 25 1.8 Local and Global Processing 37 1.9 Typical Visual Processing from Features to Objects 41 1.10 Contour Completion or Filling-in 56 1.11 Typical Development of Object Processing, Grouping, and Completion 65 1.12 Grouping, Binding, Closure, and Object Processing in ASDs 72 Figures 88 Bibliography 98 Chapter Two – Early electrophysiological indices of illusory contour processing within the lateral occipital complex are virtually impervious to manipulations of illusion strength. Introduction 123 Methods 126 Results 133 Discussion 142 Figures 150 Bibliography 160 Chapter Three – The effort to close the gap: Tracking the development of illusory contour processing from childhood to adulthood with high-density electrical mapping Introduction 165 Methods 170 Results 176 Discussion 180 Tables & Figures 191 Bibliography 208 viii Chapter Four – It’s all in the timing: delayed feedback in autism spectrum disorders may weaken predictive mechanisms during contour integration Introduction 215 Methods 219 Results 225 Discussion 226 Tables & Figures 229 Bibliography 234 Chapter Five - Electrophysiological indices of illusory contour show typical amplitude but delayed timing in autism spectrum disorders Introduction 240 Methods 245 Results 250 Discussion 254 Tables & Figures 260 Bibliography 272 Chapter Six - General Discussion 278 Figures 300 Bibliography 304 ix List of Tables 3a Participant Descriptive Data 191 3b N1 Latencies Across Age Group and Condition 191 3c Component and Effect Amplitudes Across Age Group 191 4a Participant Descriptive Data 229 5a Participant Descriptive Data 260 5b Interaction IC-effect x hemiscalp x extent 260 5c Interaction IC-effect x hemiscalp x extent x diagnosis 260 5d VEP amplitude (N1) x extent 261 5e VEP amplitude (Ncl) x extent 261 x List of Illustrations, charts, diagrams, 1.1 Grating stimuli 89 1.2 Texture stimuli 89 1.3 Hierarchical stimuli 91 1.4 Gestalt groupings 91 1.5 Fragmentation 91 1.6 Tilt illusion 93 1.7 Color-spreading illusory stimuli 93 1.8 Degraded pictures paradigm schematic 95 1.9 Theoretical framework 97 1.10 Gabor path stimuli 97 2.1 Stimulus and IC-effect example 151 2.2 Support ratio 151 2.3 Experimental manipulations and timecourse 153 2.4 IC-effect waveforms and topographies 155 2.5 Statistical cluster plots 167 2.6 N1 waveforms and topographies 159 2.7 Dipole source analysis 159 3.1 IC stimuli manipulations/experimental time course 193 3.2 Stimuli and effect examples 193 3.3 VEP waveforms 195 3.4 Regression scatter plot 197 3.5 P1 main effect 199 3.6 Statistical cluster plots 201 3.7 Topographies – posterior 203 3.8 Topographies – anterior 205 3.9 Dipole source analyses 207 4.1 IC-Effect waveforms 231 4.2 Latency difference – waveforms and topographies 233 5.1 VEP Waveforms 263 5.2 IC difference bar graphs 265 5.3 IC difference scatterplot (N1) 265 5.4 Ratio IC difference to P1 bar graph 267 5.5 IC difference scatterplot (Ncl) 267 5.6 IC diff topographies 269 5.7 Dipole source analyses 271 6.1 IC processing model 301 6.2 Correlations IC-effect with CSS and RRB scores 303 xi Chapter One Introduction Bit by bit Putting it together. Piece by piece Only way to make a work of art. Every moment makes a contribution Every little detail plays a part Having just a vision’s no solution Everything depends on execution Putting it together That’s what counts Ounce by ounce Putting it together Small amounts, Adding up to make a work of art (Sondheim, S., 2010) 1.1 Perceptual completion and Autism Spectrum Disorders – A way to understand global/local processing differences? I have no trouble noticing the little details that no one else seems to see, and in fact I have no choice but to see every little detail. I'll see the tiny plants in the concrete cracks, the placement of hair on the people around me, the light damage on cars beside me, the exact words and pictures of all the advertisements... I can't block that out, I can't just glance over it and move on, I have to stop and LOOK at every little thing before the whole scene makes sense. Every time there is a change in the scene, I have to look at everything all over again and re-draw the entire picture in my head before I can move on. If I don't, there are blank spots in my "scene" – Ari “Visual Perception” from her blog Perception Ari 12/6/2010 (Akari, 2010) In a typical environment human beings are confronted with a barrage of information. The air, your hand, the page you are reading now, their molecules are arrayed one after the other without the defined edges we perceive between them. We are typically unaware of how visual perception organizes the information surrounding us into discrete bundles, distinguishing what we experience as objects from each other as well as from everything else.