ATTENTIONAL RESOURCES IN UNILATERAL SPATIAL NEGLECT Kjersti Mæhlum Walle Sunnaas Rehabilitation Hospital Department of Research Department of Psychology Faculty of Social Sciences University of Oslo © Kjersti Mæhlum Walle, 2018 Series of dissertations submitted to the Faculty of Social Sciences, University of Oslo No. XXX ISSN XXXX-XXXX All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission. Cover: Print production: Reprosentralen, University of Oslo. ii ACKNOWLEDGEMENTS “In examining disease, we gain wisdom about anatomy and physiology and biology. In examining the person with disease, we gain wisdom about life.” (Oliver W. Sacks) I would like to express my sincere gratitude to all the patients who have devoted so much of their time and energy to participate in this project. They allowed this study to be accomplished. Despite all the challenges they were faced with, they were willing to contribute in research so that it can assist others in the future. While spending their valuable time and effort, participating in this project, they taught me more than simply the clinical matters reported in this thesis, but also the important qualities in life: courage, persistence, patience, enthusiasm and kindness. Additionally, my sincere thanks to those who contributed as control participants as well as those who helped out in the pilot phase of our project. I am deeply thankful to my supervisor, Prof. Bruno Laeng. You have been endlessly supportive throughout this project. Thanks to your initiative and perseverance to pursuit new ideas we have arrived at the present findings. I am grateful for your valuable advice, our fruitful discussions, and your guidance throughout this journey. I would also like to express my gratitude to my co-supervisors, Dr. Jan Egil Nordvik and Dr. Frank Becker, who have also helped direct the aims and scopes of this project. I am grateful for all your insightful comments and observations as well as the challenging questions which have encouraged me to view our findings from different perspectives. Your optimism throughout this process has been very much appreciated. Besides my supervisors I would like to extend my thanks to the rest of my project committee: Prof. Anne-Kristine Schanke, Dr. Thomas Espeseth, Dr. Markus Handal Sneve, Dr. Sveinung Tornås, Dr. Lars Tjelta Westlie, and Dr. Tor Endestad. I am grateful for your contributions in the planning of this project. Some of you have also co-authored in articles, and I appreciate all the meticulous comments and insightful suggestions you have made on earlier manuscripts. I am grateful for all the inspiration and encouragement I have received from my colleagues at the Department of Research at Sunnaas Rehabilitation Hospital throughout this research project. A special thanks goes to Johan Stanghelle and Annette Juelsen who have been nothing but supportive, and to Solveig Lægreid Hauger for inspirational talks at the office. I am particularly grateful for the assistance given by Hillary Lynn Kyler: your help in testing patients, preparing data sets and co-authoring on one of the papers are so much appreciated. Thank you for all the fun days at the office. I would also like to express my appreciation to all Sunnaas colleagues down at the Aker Hospital Office for uplifting words and for welcoming me with an available desk at the office at any time. Special thanks to my friends at the Department of Psychology at the University of Oslo for stimulating discussions, advice and support, and for all the fun we have had in the last few iii years. In particular, I am grateful to Anine Riege, who has given me warm encouragement as well as constructive comments. Your brilliant idea of having a thesis bootcamp was priceless and clearly got me through some of the heavy lifting. I am also thankful for all the backing and enthusiasm I have received from Athanasia Monica Mowinkel, Unni Sulutvedt, Anee Karin Lee, Karine Porpino Viana, and Olga Chelnokova. Thank you also to Torgeir Moberget for lending me your office while you were at Berkeley. I am appreciative to everyone who helped improve my work by providing useful advice and feedback. Thank you to Nikolai Olavi Czajkowski and Ragnhild Sørum Falk for your great statistical guidance, and Bjørn Tore Heyerdal who helped me with Excel formulas for preprocessing data. My cousin, Espen Rusten, who has been just as busy with his Ph.D. as I have been with mine, still showed up right away when I needed advice. Matthew Patten provided great advice and perspective during the last phase of the Ph.D. and also contributed by proofreading. I would also like to thank Branka Spehar who allowed me an amazing research stay at UNSW Australia. You gave me and my family such a warm welcome and will always be appreciated. A special thank you to the Norwegian ExtraFoundation for Health and Rehabilitation as well as Sunnaas Rehabilitation Hospital for funding my work. I am grateful to the Department of Psychology, University of Oslo, for granting me admission to the Ph.D. program. I am privileged to have the most fantastic parents, Eva and Karl. You have always been there for me, and especially during these last few years you have helped in so many ways. I will be forever grateful for all the love and support that I receive from you. I would also like to thank my brother, Pål, and my sister, Heidi, for their continuous and unconditional support. I am so lucky to be your little sister. Heartfelt appreciations to my extended family who have contributed with so much love and care. Special thanks to all the friends that I have been blessed with. Thank you for still being there for me, although I have been buried in books and papers these last few years. Last, but so definitely not the least, I owe my deepest gratitude to my wonderful husband Jan- Christian. With your encouragement, your invaluable pep-talks, your immense patience and all the healthy distractions you have provided me with during these years, you have made this adventure possible. While encouraging long hours at the office and rewarding me with the most tasteful gourmet dinners, you also made sure the PhD did not take over our lives. You believe in me like no-one else and you make me believe in myself. You, and our amazing, insightful and caring daughters, Alvilde Sofie and Emmeline Aurora, are what I value most in life. You have provided me with a sound perspective, taught me about the importance of a healthy work-life balance, and it is your endless love and support that have helped me complete this journey. I love my family. This thesis is dedicated to them. iv TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................................ III LIST OF ARTICLES ........................................................................................................................ VII GENERAL SUMMARY ..................................................................................................................... IX INTRODUCTION ................................................................................................................................. 1 VISUAL ATTENTION ............................................................................................................................. 2 CLINICAL ASPECTS OF NEGLECT .......................................................................................................... 5 Spatial symptoms of neglect ............................................................................................................ 7 Non-spatial deficits associated with neglect .................................................................................... 9 THEORETICAL ACCOUNTS ON NEGLECT ............................................................................................ 11 The inter-hemispheric rivalry hypothesis ...................................................................................... 12 The attention-arousal hypothesis and hypokinesia ........................................................................ 13 The impaired covert orienting of attention hypothesis .................................................................. 14 MEASURING THE PATHOLOGY OF ATTENTION ................................................................................. 14 Eye-tracking .................................................................................................................................. 15 Pupillometry .................................................................................................................................. 18 Multiple object tracking (MOT) .................................................................................................... 20 Binocular rivalry ............................................................................................................................ 22 MAIN RESEARCH OBJECTIVES .................................................................................................. 24 ARTICLE I: ........................................................................................................................................... 24 Unilateral neglect post stroke: Saccade frequencies indicate directional hypokinesia while fixation distributions suggest compensational mechanism ........................................................... 24 ARTICLE II ..........................................................................................................................................