Global Language Control in Bilingual Language Processing Roy Seo A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington 2019 Reading Committee: Chantel S Prat, Chair Ione Fine Andrea Stocco Program Authorized to Offer Degree: Psychology ©Copyright 2019 Roy Seo University of Washington Abstract Global Language Control in Bilingual Language Processing Roy Seo Chair of the Supervisory Committee: Chantel S. Prat Department of Psychology The majority of research on language processes has been conducted using monolingual English speakers, although more than fifty percent of current world population is bilingual. As a consequence, our understanding of language is limited, particularly with respect to the types of processes that are unique to bilinguals. Bilingual language processing differs from monolingual language processing in that it requires global language control to resolve a conflict arising from simultaneous activation of two languages. My doctoral dissertation will summarize the results of four studies aimed at understanding the neurocognitive bases of the processes by which bilinguals execute such global language control. CHAPTER 1. INTRODUCTION .................................................................................................................................. 5 CHAPTER 2. MANUSCRIPT 1 ................................................................................................................................. 12 2.1 ABSTRACT ............................................................................................................................................................. 13 2.2 INTRODUCTION ...................................................................................................................................................... 14 2.3. MATERIALS AND METHODS ..................................................................................................................................... 23 2.4. RESULTS .............................................................................................................................................................. 37 2.5. DISCUSSION .......................................................................................................................................................... 57 2.6. CONCLUSIONS AND CAVEATS ................................................................................................................................... 67 2.7. FUNDING ............................................................................................................................................................. 69 2.8. ACKNOWLEDGEMENT ........................................................................................................................................... 69 2.9. SUPPLEMENTARY MATERIAL .................................................................................................................................... 69 2.10. REFERENCES ....................................................................................................................................................... 70 CHAPTER 3. MANUSCRIPT 2 ................................................................................................................................. 82 3.1. ABSTRACT ............................................................................................................................................................ 83 3.2. INTRODUCTION ..................................................................................................................................................... 84 3.2. EXPERIMENT 1 METHOD ......................................................................................................................................... 89 3.3. MATERIALS .......................................................................................................................................................... 91 3.3. EXPERIMENT 1 RESULTS .......................................................................................................................................... 98 3.4. EXPERIMENT 1 DISCUSSION ................................................................................................................................... 103 3.5. EXPERIMENT 2 METHOD ....................................................................................................................................... 104 3.6. EXPERIMENT 2 RESULTS ........................................................................................................................................ 109 3.7. EXPERIMENT 2 DISCUSSION ................................................................................................................................... 114 3.8. GENERAL DISCUSSION .......................................................................................................................................... 114 3.9. REFERENCES ....................................................................................................................................................... 119 CHAPTER 4. MANUSCRIPT 3 ............................................................................................................................... 124 4.1. ABSTRACT .......................................................................................................................................................... 125 4.2. METHOD ........................................................................................................................................................... 134 4.3. RESULTS ............................................................................................................................................................ 147 4.4. DISCUSSION ........................................................................................................................................................ 158 4.5. CONCLUSION ...................................................................................................................................................... 171 4.6. REFERENCES ....................................................................................................................................................... 172 CHAPTER 5. DISCUSSION .................................................................................................................................... 179 5.1. MORPHO -SYNTACTIC RULE EXECUTION RECRUITS REGIONS PREVIOUSLY IMPLICATED IN LEXICO -SEMANTIC TASKS ................. 179 5.2. GLOBAL AND LOCAL CONTROL MECHANISMS RECRUIT SEPARABLE BUT OVERLAPPING NEURAL MECHANISMS ....................... 180 5.3. GLOBAL LANGUAGE CONTROL MECHANISMS ARE MORE EFFICIENT THAN ARE LOCAL CONTROL MECHANISMS ..................... 181 5.4. VARIABILITY IN PROACTIVE AND REACTIVE BILINGUAL GLOBAL LANGUAGE CONTROL MECHANISMS .................................... 182 5.5. WHAT IS IN CONTROL OF BILINGUAL LANGUAGE ? ...................................................................................................... 183 5.5.1. The role of the anterior cingulate cortex. ............................................................................................... 183 5.5.2. The role of basal ganglia. ........................................................................................................................ 184 CHAPTER 6. SUMMARY ...................................................................................................................................... 187 CHAPTER 7. REFERENCES ................................................................................................................................... 188 Chapter 1. Introduction More than fifty percent of the population are bilingual (Shin & Kominsky, 2010), but the majority of research on the neurobiology of language processes has been concentrated on monolingual English speakers (Kovelman, Baker, & Petitto, 2008; Marian & Spivey, 2003; Watson & Bialystok, 1991). As a consequence, our understanding of linguistic processes in the brain are limited, in particular with respect to the facet of language that is unique to bilinguals (Abutalebi & Green 2007; Bialystok & Kroll, 2017; Guo, Misra, & Kroll, 2011). Considerable research on bilingual language processing has shown that both languages are simultaneously co- activated and compete for selection during bilingual language use (Costa, Miozzo, & Caramazza 1999; Hatzidaki, Branigan, & Pickering, 2011; Kroll, Bobb & Wodniecka, 2006; Goldrick, Putnam, Schwarz, 2016). As a result, bilingual language processing demands an additional management mechanism that selects between languages. This process, defined by De Groot and Christoffels (2006) as global language control , is the primary focus of my dissertation research. I am particularly interested in the mechanisms by which global language is accomplished, how they compare to local language control mechanisms shared by monolinguals and bilinguals, and involve the online selection of word forms and application of grammatical rules within a target language. The Adaptive Control Hypothesis (ACH) first proposed by Abutalebi and Green (2007, see also Green & Abutalebi, 2013 for an updated version) is the most comprehensive existing proposal of the neurobiological mechanisms by which bilinguals accomplish language control. According to the ACH, bilingual language control