Transsaccadic Memory: Working Memory in Action by Adam Frost A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Psychology © Copyright by Adam Frost 2020 Transsaccadic Memory: Working Memory in Action Adam Frost Doctor of Philosophy Department of Psychology University of Toronto 2020 Abstract Transsaccadic memory is the process by which visual information is maintained and spatially updated across eye movements. Transsaccadic memory resembles general visuospatial working memory in many ways, but it is unclear whether the two functions do share common faculties, or if the transsaccadic functions are underpinned by specialized mechanisms given the unique demands of maintaining spatial constancy across eye movements. Six experiments are presented in this thesis to address this question. In Chapter 2, I found that transsaccadic memory performance is predicted by performance on a 2-Back task, demonstrating commonalities with general visuospatial working memory. I also found, however, that performance on a change detection task did not predict transsaccadic memory performance, indicating a dissociation between a well-established contemporary measure of visuospatial working memory and transsaccadic memory. Change detection performance also failed to predict performance on the 2-Back task, so in Chapter 3, four variants of the change detection task were created to test possible explanations for the dissociations. All change detection tasks correlated strongly with the standard change detection task, but a correlation with the 2-Back task was seen only with a change detection variant where the availability of contextual spatial information during the test phase was minimized. This version of the change detection task was then tested against the transsaccadic task in Chapter 4, along with 2-Back and a no-saccade baseline for the ii transsaccadic task to isolate saccade-related performance components. Doing so, two saccade- related components were found that predicted performance on the working memory measures, though only one of these components explained variance across all tasks. I conclude that transsaccadic memory does appear to share faculties with general visuospatial working memory, but that like visuospatial working memory itself, it is a multifaceted construct. iii Acknowledgements This PhD thesis was made possible by the support of a broad community, and I would like to express my appreciation to some individuals whose contributions have been especially important. I'd first like to thank Matthias Niemeier for providing a lab where I could pursue ideas with all the material and intellectual resources that I could possibly need. Matthias has been an inexhaustible well of theoretical insights and is a role model for the breadth of knowledge and expertise that a person can attain, while also being a kind and generous mentor. I am very fortunate to have had the distinguished John Kennedy and Mark Schmuckler provide their guidance and feedback throughout this PhD; their insights and generous spirit helped the thesis find its form. I'd also like to thank Susanne Ferber for introducing me to working memory research and providing me with the tools to start working in that domain. Matthias has extended his own expertise by building a lab of highly capable researchers, who have themselves been invaluable resources to me. Ada Le gave up many lab hours during her final year to help me debug MATLAB code, and generally helped me develop effective research practices. She also played a crucial role in introducing me to the broader community at the University of Toronto, and connected me to a number of great researchers through her role as president of the Psychology Graduate Students’ Association. I'd like to thank Jiaqing Chen for her statistics prowess, fastidious attention to detail, and general good nature, and Lawrence Guo for introducing me to powerful new machine learning methods through his collaborations with Adrian Nestor. I would also like to thank my newer lab mates, Nina Lee, Teddy Cheung, and Simar Moussaoui for bringing their fresh ideas with them. My research assistants contributed more hours than I can count towards data collection and data processing, so I’d like to express my appreciation to Harsh Parikh, Jagjot Kaur, George Tomou, Andrew Laughlin, Marija Zivcevska, Samreen Aziz, Aleem Ahmad, Mihilkumar Patel and Erind Alushaj. The administrative team at the University of Toronto provided flawless support throughout my graduate school career, ensuring that deadlines were met and providing the means to make my studies financially viable. Ann Lang, Nina Dhir, Kathleen Cook and Ainsley Lawson were all especially noteworthy in that regard, and I am grateful for their contributions. I would like to thank the Natural Sciences and Engineering Research Council of Canada, and the University of Toronto for their financial support. iv On a personal level, the process of completing this thesis was made possible through the patience and emotional support of Anita Nipen, who agreed to convert our living room into an office so that I could finish writing during the coronavirus pandemic. I’d like to thank my dear friends Vincent Man, Michael Weiss, Buddhika Bellana, Britt Caron, Olivia Podolak Lewandowska, Nick Diamond, Iva Brunec, Mike Armson and Ed O’Neil for their comradery and their wisdom. They are all formidable researchers in their respective domains, and I owe a debt of gratitude to the psychology department for building culture that attracts people of their quality. Finally, I’d like to thank my parents Larry and Wendy Frost for providing the foundation for this entire enterprise. v Table of Contents Acknowledgements ........................................................................................................................ iv Table of Contents ........................................................................................................................... vi List of Tables ................................................................................................................................. ix List of Figures ..................................................................................................................................x Chapter 1 ..........................................................................................................................................1 General Introduction ...................................................................................................................1 Spatial stability across saccades ...........................................................................................1 The neurophysiology of transsaccadic spatial constancy ....................................................2 Transsaccadic memory .........................................................................................................4 Visual Working Memory .....................................................................................................6 Visual Working Memory VS. Transsaccadic Working Memory ......................................11 Present Research ................................................................................................................12 Chapter 2 ........................................................................................................................................14 Working memory in action: Inspecting the systematic and unsystematic errors of spatial memory across saccades ...........................................................................................................14 Abstract ..............................................................................................................................14 Introduction ........................................................................................................................14 Experiment 1 ......................................................................................................................17 2.3.2 Results and Discussion ..........................................................................................21 Experiment 2 ......................................................................................................................26 2.4.1 Participants .............................................................................................................26 2.4.2 Apparatus ...............................................................................................................27 2.4.3 Procedure ...............................................................................................................27 2.4.4 Results ....................................................................................................................30 Experiment 3 ......................................................................................................................36 vi 2.5.1 Participants .............................................................................................................36 2.5.2 Apparatus ...............................................................................................................36 2.5.3 Procedure ...............................................................................................................36 2.5.4 Results ....................................................................................................................39 General Discussion ............................................................................................................46