THE NEURAL BASES OF THE BILINGUAL ADVANTAGE IN COGNITIVE CONTROL

167 Pages·2014·1.31 MB·English

ABSTRACT

Title of Document: THE NEURAL BASES OF THE BILINGUAL ADVANTAGE
IN COGNITIVE CONTROL: AN INVESTIGATION OF
CONFLICT ADAPTATION PHENOMENA

Susan Elizabeth Teubner-Rhodes, Doctor of Philosophy, 2014

Directed By: Professor Michael Dougherty, Department of Psychology

The present dissertation examines the effects of bilingualism on cognitive control,
the ability to regulate attention, particularly in the face of multiple, competing sources of
information. Across four experiments, I assess the conflict monitoring theory of the so-
called “bilingual advantage”, which states that bilinguals are better than monolinguals at
detecting conflict between multiple sources of information and flexibly recruiting
cognitive control to resolve such competition. In Experiment 1, I show that conflict
adaptation, the phenomenon that individuals get better at resolving conflict immediately
after encountering conflict, occurs across domains, a pre-requisite to determining whether
bilingualism can improve conflict monitoring on non-linguistic tasks. Experiments 2 and
3 compare behavioral and neural conflict adaptation effects in bilinguals and
monolinguals. I find that bilinguals are more accurate at detecting initial conflicts and
show corresponding increases in activation in neural regions implicated in language-
switching. Finally, Experiment 4 extends the bilingual advantage in conflict monitoring
to syntactic ambiguity resolution and recognition memory.
THE NEURAL BASES OF THE BILINGUAL ADVANTAGE IN COGNITIVE
CONTROL: AN INVESTIGATION OF CONFLICT ADAPTATION PHENOMENA.

By

Susan Elizabeth Teubner-Rhodes.

Dissertation submitted to the Faculty of the Graduate School of the
University of Maryland, College Park, in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
2014

Advisory Committee:
Professor Michael Dougherty, Chair
Assistant Professor Jared Novick
Assistant Professor Donald J. Bolger
Assistant Professor Robert Slevc
Professor Colin Phillips
© Copyright by
Susan Elizabeth Teubner-Rhodes
2014
Acknowledgements

I would like to thank Cristina Martin, Jennifer Johnson, Kayla Velnoskey, Moulshri
Mohan, Sunmee Huh, Marc Levender, Eva Lenoir, Abigail Schadegg, Marissa Goon,
Anastasia Kouloganes, Judy Gerstenblith, and Jack Lee for their assistance with subject
recruitment and data collection. I also thank Irene Kan, Anna Drummey, Lauren Nutile,
Lauren Krupa, Alan Mishler, Ryan Corbett, Llorenç Andreu, Monica Sanz-Torrent, and
John Trueswell for their important intellectual contributions to this work. I especially
thank DJ Bolger for his help in setting-up fMRI data collection and for critical analysis
discussions. Finally, I thank my advisors, Jared Novick and Michael Dougherty, for their
invaluable guidance, input, and support. Portions of this work were supported by NSF-
IGERT training grant DGE-0801465 and by the University of Maryland Center for
Advanced Study of Language.
ii
Table of Contents

Acknowledgements ......................................................................................................... ii

Table of Contents ........................................................................................................... iii

List of Tables .................................................................................................................. v

List of Figures ............................................................................................................... vii

Chapter 1: Introduction ................................................................................................... 1
Overview of Cognitive Control ................................................................................ 1
Review of the Bilingual Advantage .......................................................................... 3
Rationale for the Present Studies .............................................................................. 7

Chapter 2: Experiment 1 ............................................................................................... 11
Overview ................................................................................................................. 11
Method .................................................................................................................... 15
Participants .......................................................................................................... 14
Materials ............................................................................................................. 16
Procedure ............................................................................................................ 16
Results ..................................................................................................................... 21
Discussion ............................................................................................................... 22

Chapter 3: Experiment 2 ............................................................................................... 30
Overview ................................................................................................................. 30
Method .................................................................................................................... 35
Participants .......................................................................................................... 35
Materials and Procedure ..................................................................................... 36
Results ..................................................................................................................... 37
Interference Results ............................................................................................ 38
Conflict Adaptation Results ................................................................................ 40
Discussion ............................................................................................................... 45
Interference Effects ............................................................................................. 45
Conflict Adaptation Effects ................................................................................ 47
Conclusions ......................................................................................................... 48

Chapter 4: Experiment 3 ............................................................................................... 49
Overview ................................................................................................................. 49
Method .................................................................................................................... 54
Participants .......................................................................................................... 54
Materials ............................................................................................................. 55
Procedure ............................................................................................................ 57
Image Acquisition ............................................................................................... 58
Image Processing ................................................................................................ 59
iii
Results ..................................................................................................................... 60
Accuracy ............................................................................................................. 60
Reaction Time ..................................................................................................... 62
fMRI Results ....................................................................................................... 63
Discussion ............................................................................................................... 69

Chapter 5: Experiment 4 .............................................................................................. 78
Overview ................................................................................................................. 78
How Robust is the Effect of Bilingualism on Cognitive Control? ..................... 79
Do the Effects of Bilingualism Cascade into On-line Sentence Processing? ..... 80
Study Overview .................................................................................................. 83
Method .................................................................................................................... 86
Participants .......................................................................................................... 86
Materials and Procedure ..................................................................................... 89
Results and Discussion ........................................................................................... 93
General Analyses ................................................................................................ 93
N-back Performance ........................................................................................... 94
Sentence Processing Performance .................................................................... 106
General Discussion: Experiment 4 ........................................................................ 114
N-back Performance ......................................................................................... 115
Sentence Processing Performance .................................................................... 117
Caveats and Limitations .................................................................................... 119
Concluding Remarks ......................................................................................... 121

Chapter 6: General Discussion .................................................................................. 123

Appendices ................................................................................................................. 126

Bibliography ............................................................................................................... 141

This Table of Contents is automatically generated by MS Word, linked to the Heading
formats used within the Chapter text.
iv
List of Tables

Table 1. Accuracy and Reaction Time on Stroop Trials by Preceding Sentence Type
Table 2. Proportion Correct (and Standard Error) by Preceding Trial and Language
Group

Table 3. Mean RTs (and Standard Errors) for the Interference Effect by Language
Group

Table 4. Mean Proportion Correct (and Standard Error) by Language Group and
Preceding Trial Type

Table 5. Mean RT (and Standard Error) by Language Group and Conflict Adaptation
Condition

Table 6. Regions of Activation for CI>II by Language Group
Table 7. Mean Beta Values (and Standard Error) for BOLD activity on CI and II
trials in ROIs

Table 8. Parental Education and Occupation Criteria for SES Composite Scores

Table 9. Mean (and Standard Deviation) of Accuracy for the High and No-conflict N-
back Tasks

Table 10. Logistic Mixed-effects Models of Accuracy for High- and Low-Conflict N-
back: Significant Model Parameters

Table 11. Mean (and Standard Deviation) RTs for the High and No-conflict N-back
Tasks

Table 12. Linear Mixed-effects Models of RT for High- and No-conflict N-back:
Significant Model Parameters

Table 13. Mean (and Standard Deviation) of Sentence Comprehension Accuracy for
Bilinguals and Monolinguals for Each Sentence Type at Pretest and Posttest

Table 14. Logistic Mixed-effects Models of Accuracy on Sentence Comprehension
Probes: Significant Model Parameters

Table 15. Linear Mixed-effects Models of Residual Sentence Reading Times by
Region: Significant Model Parameters

v
Table 16. Mean Outlier-reset and Residual Reading Times for the Disambiguating
Regions of the Subject- and Object-cleft Items, Pooled across Pretest and Posttest
and across Monolinguals and Bilinguals

vi
List of Figures
Figure 1. Proportion correct by current trial type and language group.

Figure 2. Reaction time by current trial type and language group.

Figure 3. Proportion correct by language group and conflict adaptation condition.

Figure 4. Reaction time by language group and conflict adaptation condition.

Figure 5. Proportion correct for bilinguals and monolinguals by conflict adaptation
condition.

Figure 6. Significant activation for CI-II (p < .001, uncorrected) in each language group.

Figure 7. Significant group differences in activation for CI-II (p < .001, uncorrected).

Figure 8. Schematic of the study design.

Figure 9. Accuracy on the high-conflict N-back task by language group.

Figure 10. Accuracy on the no-conflict N-back task by language group.

Figure 11. Reaction time (in ms) for bilinguals and monolinguals on the high-conflict N-
back task by (A) trial type and (B) block.

Figure 12. Reaction time (in ms) on the no-conflict N-back task by trial type.

vii
Chapter 1: Introduction

Overview of Cognitive Control
The physical world is rife with diverse stimuli in constant competition with one
another. In order to make appropriate decisions in the face of such competition,
individuals must direct their attention to goal-relevant input, ignore extraneous
information, and resolve among conflicting alternatives. Take, for example, the case of
American citizens trying to cross the street on a first visit to the United Kingdom, where
the cars drive on the other side of the road. Having a lifetime of experience of looking left
before stepping off of the sidewalk, they may persist in looking left despite their new
environment. Thus, assuming that the travelers’ goal is to avoid being run over, the
habitual response conflicts with the contextually-appropriate response of looking in the
direction of oncoming traffic. Individuals employ cognitive control, or the ability to
regulate mental behavior, in order to resolve among conflicting alternatives and to
override pre-potent responses1, like the one in the previous example. The purpose of the
present dissertation is to examine how cognitive control is shaped by experience by
investigating how the experience of having to maintain and use two different languages
(i.e., bilingualism) influences cognitive control abilities.

1 Whether the selection of the correct alternative is due to inhibition of irrelevant mental
representations or to facilitation of the relevant representation is contested. This debate does not bear
on the present studies, and will not be discussed further. Any references to selection via inhibition or
facilitation are not meant as support for one or the other hypothesis, but merely as a convenient
description of the process of conflict resolution.
1