Individual differences in heart rate response and expressive behavior during social emotions: effects of resting cardiac vagal tone and culture, and relation to the default mode network

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Individual Differences in Heart Rate Response and Expressive Behavior
during Social Emotions:
Effects of Resting Cardiac Vagal Tone and Culture,
and Relation to the Default Mode Network

Xiao-Fei Yang

Mary Helen Immordino-Yang, Advisor

A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY

December 2013

© 2013
Xiao-Fei Yang
All rights reserved.

i
Acknowledgments
I would like to express my deepest gratitude to my advisor Dr. Mary Helen
Immordino-Yang for introducing me to the exciting cross-cultural social emotion project,
and for being a great mentor, collaborator, role model and friend over the years. Without
her guidance and encouragement, this work would not have been possible. My heartfelt
appreciation goes to Dr. Savio Wong for teaching me fMRI and psychophysiology
techniques, and for being a great friend. It was because of his influence, I became
interested in heart rate physiology and vagal modulation of the heart.
I would like to thank Drs. Antonio and Hanna Damasio for giving me the
opportunity to learn and grow at the Brain and Creativity Institute, and for inspiring me to
be a better scientist. I would also like to thank my dissertation committee, Drs. Bosco
Tjan and Wendy Wood, and my qualifying committee, Drs. Antoine Bechara and James
Knowles for their helpful suggestions and comments.
I am forever indebted to my friends and colleagues at the Brain and Creativity
Institute and the Neuroscience Graduate Program for their inspiring conversations and
comradeship, especially Helder Filipe, Glenn Fox, Kingson Man and Dr. Tong Sheng for
their countless helpful discussions, comments and suggestions on my dissertation project
and their criticism and comments on my qualifying and defense presentations.
I am grateful to everyone who has provided help during data collection and
analyses for this project. I would like to thank Dr. Zhonglin Lu for setting up the
collaboration with Beijing Normal University, Dr. Renlai Zhou and Litao Zhu for their
generous help in recruiting subjects and securing access to the MRI scanner at BNU, and
Jiancheng Zhuang for help with MRI data collection at the USC Dornsife Imaging center.

ii
I would like to thank Drs. Jonas Kaplan and Sarah Gimbel for their help with fMRI data
analyses. I would also like to thank all the research assistants who helped with behavior
coding and other data analyses, among them Mark Lay, Brook Sanders, Andrew
Goldman, Denise Yeung, Russel Atticus and Jacob Flores.
I would like to thank my parents 杨宝荣 (Yang BaoRong) and 魏月芳 (Wei
YueFang) for their unconditional love and support, and for encouraging me to travel far
away from home to pursue my dreams.
Very special thanks to my fiancé Joseph Mullin for his love, encouragement and
patience, for keeping me on track during the final stage, and for proofreading my
dissertation and assisting with formatting.
This work is supported by the Brain and Creativity Institute, the USC
Neuroscience Graduate Program, the USC Graduate School and the USC US-China
Institute Summer Fieldwork Grant.

iii
Table of Contents
Acknowledgments .............................................................................................................. i
List of Figures ................................................................................................................... iv
List of Tables .................................................................................................................... iv
Abbreviations .....................................................................................................................v
Abstract ............................................................................................................................. vi

General Introduction .........................................................................................................1
Background ............................................................................................... 2
Research methods ...................................................................................... 4
Overview of chapters ................................................................................. 6
References ................................................................................................. 8
Chapter 1. Cultural Background and Resting Cardiac Vagal Tone Independently
Influence Natural Emotional Expressiveness ..........................................................10
Abstract ................................................................................................... 11
Introduction ............................................................................................. 12
Methods ................................................................................................... 15
Results ..................................................................................................... 22
Discussion ............................................................................................... 25
References ............................................................................................... 29
Chapter 2. Cultural Differences in Heart Rate Response during Social Emotion and
Relations to Individuals’ Expressiveness ................................................................34
Abstract ................................................................................................... 35
Introduction ............................................................................................. 36
Methods ................................................................................................... 37
Results ..................................................................................................... 39
Discussion ............................................................................................... 43
References ............................................................................................... 47
Chapter 3. Orienting Heart Rate Deceleration during Social Emotion Processing
Predicts Deactivation in Default Mode Network Regions ......................................50
Abstract ................................................................................................... 51
Introduction ............................................................................................. 52
Methods ................................................................................................... 54
Results ..................................................................................................... 62
Discussion ............................................................................................... 66
References ............................................................................................... 69
General Conclusion ..........................................................................................................74
References ............................................................................................... 79

iv
List of Figures
Figure 1-1. Examples of participants' behavior during the interview and corresponding
codes for expressiveness. .............................................................................. 19
Figure 1-2. Scatterplot and bar graph depicting the effects of resting RSA and cultural
group on expressiveness. ............................................................................... 23
Figure 1-3. Bar graph depicting the cultural group by gender interaction effect on
expressiveness. . ............................................................................................ 24
Figure 1-4. Scatterplot depicting the relationship between resting RSA and cultural
orientation in bicultural AA participants. ...................................................... 25
Figure 2-1. The average pattern of heart rate response. ................................................... 40
Figure 2-2. Bar graph depicting cultural group effect on the three components of heart
rate response. ................................................................................................. 42
Figure 2-3. Scatterplot depicting the relationship between the three components of
heart rate response and expressiveness ......................................................... 43
Figure 3-1. Depiction of the anatomically defined DMN mask, displayed on a
template brain. ............................................................................................... 61
Figure 3-2. Representative images of neural regions from within the DMN whose
activity inversely correlated with HRD magnitude on a trial-by-trial basis
during the physical conditions. ...................................................................... 63
Figure 3-3. Representative image of the neural region from within the DMN whose
average activity inversely correlated with average HRD magnitude across
participants during the mental conditions. .................................................... 65
Figure 3-4. Representative images of the neural regions from within the DMN whose
average activity inversely correlated with average HRD magnitude across
participants during the physical conditions ................................................... 65

List of Tables
Table 1-1. Summary of descriptive statistics of expressiveness and resting RSA. ......... 22
Table 3-1. Descriptive statistics of HRD during the mental conditions and during the
physical conditions. ....................................................................................... 62
Table 3-2. Voxel clusters from within the DMN whose activity inversely correlated
with HRD magnitude on a trial-by-trial basis during the physical
conditions. ..................................................................................................... 63
Table 3-3. Voxel clusters from within the DMN whose activity inversely correlated
with HRD magnitude across participants during the mental conditions and
during the physical conditions ....................................................................... 64

v
Abbreviations
A1 first acceleration component of heart rate response
A2 secondary acceleration component of heart rate response
AA second-generation East Asian American
AG angular gyrus
AS admiration for skill
AV admiration for virtue
BOLD blood oxygenation level dependent
bpm beats per minute (unit of heart rate)
CH Chinese
CPP compassion for physical pain
CSP compassion for social pain
D/HRD deceleration component of heart rate response
DMN default mode network
dMPFC dorsal medial prefrontal cortex
ECG electrocardiogram
fMRI functional magnetic resonance imagining
GEQc general ethnicity questionnaire Chinese version
MNI Montreal Neurological Institute (standardized neuroanatomical space)
MPFC medial prefrontal cortex
NA American, not of Asian descent
PCC posterior cingulate cortex
RSA respiratory sinus arrhythmia

vi
Abstract
Individuals differ in the way they respond in emotional situations. These
differences can be attributed in part to variations in cultural experiences and biological
predispositions. To better understand these differences, here I studied individuals’ natural
expressive behavior and heart rate responses during social emotion processing, and
compared them across cultural groups with different ideals and norms for expressiveness:
Chinese, second-generation East Asian American, and American not of Asian descent. I
concurrently examined the contribution from resting cardiac vagal tone, an important
biological factor for emotion regulation ability. I also probed the relationships between
heart rate deceleration, an autonomic response thought to facilitate attention towards the
immediate external environment, and neural activity in brain regions within the default
mode network, a brain system whose activity is suppressed (deactivation) during tasks
that require attention into the environment.
My dissertation is comprised of three chapters. In Chapter 1, I demonstrated that
resting cardiac vagal tone and cultural background independently (additive effects with
no interaction) predicted how expressive participants were during a private emotion-
induction interview. I also found that higher resting cardiac vagal tone was related to
stronger East Asian cultural orientation in bicultural East Asian American participants.
In Chapter 2, I identified the average heart rate response pattern when participants
viewed a series of social emotion-inducing narrative stimuli. This response pattern can be
resolved into two phases: an earlier phase related to processing of the emotional stimuli
and a later phase related to deliberation of emotional feelings. I found that resting cardiac

vii
vagal tone modulated heart rate response during the earlier phase, while cultural
background modulated heart rate response during the later phase.
In chapter 3, I demonstrated that greater heart rate deceleration consistently
predicted deactivation in the precuneus and posterior cingulate cortex, which comprise
the posterior medial node of the default mode network. No cultural differences in these
relationships were found.
General Introduction

2
Background
Emotion behavior is modulated by biological predispositions, such as resting
cardiac vagal tone, as well as cultural ideals and values about emotional arousal.
Resting cardiac vagal tone is an index for the constant parasympathetic input to
the heart via the vagus nerve. It acts as a protective vagal “break” to maintain a relatively
slow resting heart rate by inhibiting spontaneous firing rate of the cardiac pacemaker at
the sinoatrial node. The vagal break can be increased or decreased to rapidly modulate
heart rate, and allows an individual to engage or disengage with an object or another
individual according to situational needs (Porges, 2001). Therefore, resting cardiac vagal
tone reflects the flexibility of parasympathetic modulation. This measure has been
considered a positive factor for emotion regulation and prosocial behavior (Porges, 2001,
2007). Higher resting cardiac vagal tone has been linked with less negative emotional
expression during social interactions (Pu, Schmeichel, & Demaree, 2010).
Expressive behavior is also strongly shaped by cultural ideals and values.
Research suggests that East Asian cultures value calmness and low arousal states, while
Western cultures value excitement and high arousal states (Tsai, 2007). For example,
while responding to emotional stimuli in controlled laboratory settings, East Asians tend
to be less expressive compared to their Western counterparts, a pattern more readily
observed in social situations than in non-social situations (Ekman, 1973; Tsai,
Chentsova-Dutton, Freire-Bebeau, & Przymus, 2002; Tsai & Levenson, 1997). However,
since no studies have investigated how cultural background and resting cardiac vagal tone
together influence natural emotional expressiveness, it is not clear whether these factors
interact or contribute additively. Further, no studies have explored the interplay between

3
resting cardiac vagal tone and adopted cultural identity in individuals living in a
bicultural environment, such as East Asian Americans. Is it possible that individuals with
a biological system supporting better emotion regulation ability are predisposed towards
adopting East Asian cultural values and practices?
Although cultural values for arousal would also predict East-West differences in
emotion-related autonomic arousal, e.g. differences in heart rate response, such
differences have rarely been found (e.g. Drummond & Quah, 2001; Levenson, Ekman,
Heider, & Friesen, 1992; Tsai & Levenson, 1997). Most previous studies examined heart
rate responses averaged over a prolonged period of time (1 min or longer; e.g.
Drummond & Quah, 2001; Tsai & Levenson, 1997). However, heart rate responses are
highly dynamic, changing on the order of seconds. For example, heart rate responses
elicited by brief aversive auditory stimuli are characterized by a tri-phasic waveform,
with a brief initial deceleration (~0.5 sec), followed by a short acceleration (~4.5 sec) and
finally a late moderate deceleration (~6.5 sec; Gatchel & Lang, 1973). Could it be that
cultural effect exists when these different components are examined separately, and is
cancelled out when heart rate is averaged over the 6-second period?
Among the heart rate response components mentioned above, the late moderate
heart rate deceleration is considered a component of the orienting response. This
deceleration is driven mainly by increased vagal outflow to the heart and is accompanied
by reduced somatic activity (Porges, 2007). Orienting heart rate deceleration is
considered an important adaptive function that facilitates attention to the external
environment and heightens sensory receptivity toward stimuli (Gatchel & Lang, 1973,
1974). Although this response is well studied in relation to emotion responding, no

4
studies have explored the relationship between emotion-related orienting heart rate
deceleration and brain systems involved in attention shifts between externally- and
internally-focused processing. The default mode network (DMN) is a group of brain
regions with increased activity during awake but non-attentive states (Greicius & Menon,
2004; Raichle & Snyder, 2007). Activity in the DMN is suppressed (deactivation) during
tasks that require attention into the environment. Given that orienting heart rate
deceleration facilitates externally focused attention, would it predict simultaneous
deactivation in DMN regions? And would this relationship be modulated by cultural
ideals?
Research methods
To address the above questions, I used data from a larger cross-culture social
emotion project that I designed and conducted together with my advisor, Dr. Mary Helen
Immordino-Yang. This project adapted a protocol developed by Dr. Immordino-Yang
and Drs. Hanna and Antonio Damasio that investigated neural correlates of admiration
and compassion (Immordino-Yang, McColl, Damasio, & Damasio, 2009), and extended
it to a cross-cultural context.
Three participant groups that differ in norms and values for interpersonal
relationship and emotional expressiveness versus calmness were recruited: Chinese in
Beijing, second-generation East Asian Americans and Americans not of Asian descent in
Los Angeles. The protocol involved 1) a two-hour one-on-one private emotion-induction
interview session where participants discussed their feelings towards admiration- and
compassion-inducing narratives, 2) a baseline ECG recording session to measure resting

5
cardiac vagal tone, and 3) a simultaneous functional magnetic resonance imagining
(fMRI) and electrocardiogram (ECG) recording session where participants viewed 5-
second reminders of the same emotion inducing narratives, followed by periods of 13-
second dark screen for reflection and deliberation.
Admiration and compassion of two different levels of complexity were induced
using narratives about real people’s experiences. One type pertains to another person’s
immediate physical/cognitive state, e.g. solving a Rubik’s cube blind folded (to induce
admiration for skill, AS) or painfully injuring one’s leg (to induce compassion for
physical pain, CPP). The other type pertains to another person’s longer-term
social/psychological state, e.g. having dedicated one’s life to helping others less fortunate
(to induce admiration for virtue, AV) or having lost a loved one (to induce compassion
for social pain, CSP). A control condition included narratives that are engaging but not
particularly emotional.
This protocol provided a unique opportunity that allowed me to 1) examine the
effects of cultural background and resting cardiac vagal tone on individuals’ natural
expressive behavior during the interview session, 2) characterize heart rate response
patterns during admiration and compassion, and examine cultural modulation on different
components of heart rate response, and 3) examine the relationship between heart rate
deceleration and DMN deactivation by comparing simultaneously measured heart rate
response and blood oxygenation level dependent (BOLD) signal.

6
Overview of chapters
Chapter 1: Cultural background and resting cardiac vagal tone independently
influence natural emotional expressiveness
I examined how cultural background and resting cardiac vagal tone together shape
natural expressive behavior during social emotion. I found that resting cardiac vagal tone
and cultural background independently (additive effects with no interaction) influenced
participants’ expressiveness while viewing CPP narratives in the emotion-induction
interview. Intriguingly, I also found that in bicultural second-generation East Asian
American participants, higher vagal tone is related to stronger East Asian culture
orientation, suggesting a possible interplay between biological predisposition for
calmness and adopted cultural values and practices in these participants.
Chapter 2: Cultural differences in heart rate response during social emotion and
relations to individuals’ expressiveness
I first identified the average heart rate response pattern related to the processing
and experience of a variety of admirations and compassions. The average heart rate
response took a tri-phasic form, which consisted of a first acceleration (A1) that peaked
at around 4 seconds, followed by a deceleration (D) that peaked at around 6 seconds and
finally a secondary acceleration (A2) that peaked at around 10 seconds. The first two
components were related to processing of the reminder video stimuli, while the third one
was related to deliberation of emotional feelings. I then examined whether these different
components were modulated by cultural background and resting cardiac vagal tone, and
whether they related to participants’ natural expressiveness during the emotion-induction
interview. I found that a more reactive heart rate response pattern during the early

7
stimulus-processing phase (A1 & D) was related to lower resting cardiac vagal tone and
to greater expressiveness during the emotion-induction interview, but these components
did not differ across cultural groups. Heart rate response during the later deliberation
phase (A2) was not related to individual’s expressiveness or resting cardiac vagal tone,
but was modulated by culture background. The response was lowest for the Chinese
culture group, followed by the East-Asian American group and highest for the American
group not of Asian descent.
Chapter 3: Orienting heart rate deceleration during social emotion processing
predicts deactivation in default mode network regions
I examined the deceleration component of the heart rate response in more details.
This response relates to the act of orienting to and processing of the reminder stimuli. I
compared magnitudes of heart rate deceleration across social emotions of two different
levels of complexity and related them to deactivation in the default mode network
regions. I found that narratives relating to protagonists’ physical action or ability (AS and
CPP) elicited greater heart rate deceleration, compared to narratives relating to
protagonist’s mental quality or accomplishment (AV and CSP). Within individuals, trial-
by-trial variation in heart rate deceleration predicted deactivation in the default mode
network regions. Across individuals, those who showed greater average heart rate
deceleration also showed greater deactivation in the DMN. No culture effects on these
relationships were found. To my knowledge, this is the first study to demonstrate the
relationship between orienting heart rate deceleration and DMN deactivation during
social emotion processing.

8
References
Bradley, M. M. (2009). Natural selective attention: orienting and emotion.
Psychophysiology, 46(1), 1–11. doi:10.1111/j.1469-8986.2008.00702.x
Drummond, P. D., & Quah, S. H. (2001). The effect of expressing anger on
cardiovascular reactivity and facial blood flow in Chinese and Caucasians.
Psychophysiology, 38(2), 190–6. doi: 10.1111/1469-8986.3820190
Ekman, P. (1973). Cross-cultural studies of facial expression. In P. Ekman (Ed.), Darwin
and Facial Expression: A Century of Research in Review (1st ed., pp. 169–220).
Academic Press, Inc.
Gatchel, R. J., & Lang, P. J. (1973). Accuracy of psychophysical judgments and
physiological response amplitude. Journal of Experimental Psychology, 98(1), 175–
183. doi:10.1037/h0034312
Gatchel, R. J., & Lang, P. J. (1974). Effects of interstimulus interval length and
variability on habituation of autonomic components of the orienting response.
Journal of Experimental Psychology, 103(4), 802–804. doi:10.1037/h0037208
Greicius, M. D., & Menon, V. (2004). Default-mode activity during a passive sensory
task: uncoupled from deactivation but impacting activation. Journal of cognitive
neuroscience, 16(9), 1484–92. doi:10.1162/0898929042568532
Immordino-Yang, M. H., McColl, A., Damasio, H., & Damasio, A. R. (2009). Neural
correlates of admiration and compassion. Proceedings of the National Academy of
Sciences of the United States of America, 106(19), 8021–6.
doi:10.1073/pnas.0810363106

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Levenson, R. W., Ekman, P., Heider, K., & Friesen, W. V. (1992). Emotion and
autonomic nervous system activity in the Minangkabau of west Sumatra. Journal of
Personality and Social Psychology, 62(6), 972–88. doi: 10.1037/0022-
3514.62.6.972
Porges, S. W. (2001). The polyvagal theory: phylogenetic substrates of a social nervous
system. International Journal of Psychophysiology, 42(2), 123–146. doi:
10.1016/S0167-8760(01)00162-3
Porges, S. W. (2007). The polyvagal perspective. Biological Psychology, 74(2), 116–143.
doi: 10.1016/j.biopsycho.2006.06.009
Pu, J., Schmeichel, B. J., & Demaree, H. A. (2010). Cardiac vagal control predicts
spontaneous regulation of negative emotional expression and subsequent cognitive
performance. Biological Psychology, 84(3), 531–540.
doi:10.1016/j.biopsycho.2009.07.006
Raichle, M. E., & Snyder, A. Z. (2007). A default mode of brain function: a brief history
of an evolving idea. NeuroImage, 37(4), 1083–90; discussion 1097–9.
doi:10.1016/j.neuroimage.2007.02.041
Tsai, J. L., Chentsova-Dutton, Y., Freire-Bebeau, L., & Przymus, D. E. (2002).
Emotional expression and physiology in European Americans and Hmong
Americans. Emotion, 2(4), 380–97. doi: 10.1037/1528-3542.2.4.380
Tsai, J. L., & Levenson, R. W. (1997). Cultural Influences on Emotional Responding:
Chinese American and European American Dating Couples During Interpersonal
Conflict. Journal of Cross-Cultural Psychology, 28(5), 600–625.
doi:10.1177/0022022197285006
Chapter 1
Cultural Background and Resting Cardiac Vagal Tone
Independently Influence Natural Emotional Expressiveness

11
Abstract
Behavioral displays of emotion (expressiveness) are shaped by cultural values and
biological predispositions for emotion regulation abilities, such as resting cardiac vagal
tone. However, as no studies have investigated how cultural background and resting
cardiac vagal tone together influence natural emotional expressiveness, it is not clear
whether these factors interact or contribute additively. Here, expressiveness was
examined in three groups of participants: Chinese (CH), second-generation East Asian
American (AA), and American not of Asian descent (NA).
During a private, videotaped interview, participants reacted to video clips
depicting painful physical injuries caused by accidents. Baseline electrocardiograms were
collected separately to measure individuals’ resting cardiac vagal tone. I found that
cultural background and resting cardiac vagal tone independently (additively) influenced
expressiveness. Controlling for differences in vagal tone, groups’ expressiveness differed
in accordance to cultural norms: the CH group was less expressive than the NA group,
and the AA group fell in the middle. This effect was driven mainly by the male
participants. Controlling for group differences, higher resting cardiac vagal tone predicted
less expressiveness. In the bicultural AA group, higher resting cardiac vagal tone was
associated with stronger reported East Asian culture orientation. Our results suggest that
cultural background and resting cardiac vagal tone contribute independently to emotional
expressiveness, and that cultural shaping of emotional displays is stronger in male
participants. Further, resting cardiac vagal tone may predispose bicultural individuals
toward adopting particular cultural values.

12
Introduction
Cultural shaping of behavioral display of emotions (expressiveness) has long been
noticed. East Asian cultures have been described to promote emotion moderation and
control, while western cultures have been described to encourage emotion expression
(Bond, 1993; Russell & Yik, 1996). Individuals from these two cultures also differ in the
emotional states they strive to feel: East Asians value calmness and low arousal states,
while Westerners value excitement and high arousal states (Tsai, 2007).
This difference has been thought to stem from how individuals in these cultures
position themselves in relation to others (Kitayama, Markus, & Kurokawa, 2000; Markus
& Kitayama, 1991). East Asian cultures, such as Chinese culture, emphasize the
interdependence between one and another. In interdependent cultures, the primary social
goal for an individual is to fit in and maintain harmony in interpersonal relationships.
Individuals are more concerned that one’s emotion expression may inconvenience others,
and are therefore more likely to suppress expression of emotions (Kim & Sherman,
2007). By contrast, Western cultures, such as American culture, emphasize one’s
independence from others. In independent cultures, the primary social goal for an
individual is to stand out and express one’s uniqueness. Individuals tend to use free
expression of emotion as a way of asserting themselves (Markus & Kitayama, 1991).
Empirical studies confirmed these observations and theories. While responding to
emotional stimuli in controlled laboratory settings, East Asians were less expressive
compared to their Western counterparts (Ekman, 1973; Tsai, Chentsova-Dutton, Freire-
Bebeau, & Przymus, 2002; Jeanne L Tsai & Levenson, 1997). Because cultural
differences in expressiveness are related to cultural values about interpersonal

13
relationships, these differences are more readily observed in social situations versus non-
social situations (Friesen, 1973).
Emotional expressiveness is also modulated by biological predispositions. The
myelinated vagal branch of the autonomic system plays an important role in emotion
regulation (Porges, Doussard-Roosevelt, & Maiti, 1994). There is constant vagal outflow
to the heart, acting as a protective “brake” to maintain a relatively slow baseline heart
rate. Depending on situational needs, the vagal brake can be rapidly decreased to trigger
fight and flight response, or increased to promote calmness (Porges, 2001). The capacity
of the brake reflects the overall flexibility or regulatory capability of the system.
Resting cardiac vagal tone, an index for myelinated vagal modulation of the heart,
has been considered a positive biological factor for emotion regulation (Porges, 2007).
Respiratory sinus arrhythmia (RSA), the oscillation in heart rate in sync with normal
breathing, has been widely used as a non-invasive measure of cardiac vagal tone
(Demaree, Pu, Robinson, Schmeichel, & Everhart, 2006; Denver, Reed, & Porges, 2007;
Grossman & Taylor, 2007). Participants with higher resting RSA are more likely to
spontaneously suppress negative emotional expression during a social discussion (Pu, et
al., 2010).
To my knowledge, most studies on cardiac vagal tone and emotion regulation
were done with Western participants (e.g. Oveis et al., 2009; Pu, Schmeichel, &
Demaree, 2010). No studies of cultural differences in emotion behavior took into
consideration individual variations in resting cardiac vagal tone. It is therefore unclear
whether the same relationship between cardiac vagal tone and emotion regulation holds
in a different cultural context. It is also unclear whether the observed cultural differences

14
in emotional expressiveness were in fact due to differences in cardiac vagal tone across
ethnic groups. Further, no studies have explored the relationship between cultural
orientation and the ability to regulate emotion in bicultural East Asian American
participants. Would higher resting cardiac vagal tone predispose bicultural participants
towards adopting cultural values and practices that emphasize emotion moderation?
To answer these questions, I investigated the effects of resting cardiac vagal tone
and cultural background on natural emotional expressiveness in three groups of
participants: Chinese in Beijing (CH), second-generation East Asian Americans (AA) and
Americans not of Asian descent (NA) in Los Angeles. I also tested the relationship
between resting cardiac vagal tone and cultural identity within the East Asian American
group.
I hypothesized that, consistent with theoretical accounts and previous findings,
CH group would be the least expressive and NA group would be the most expressive
among the three participant groups. Across all the participants, those with higher resting
RSA would be less expressive.
The absence of social expectation for calmness and emotion moderation in NA
group could lead to emotion behavior driven mainly by biological propensity, resulting in
a stronger relationship between expressiveness and resting cardiac vagal tone in this
group. The same absence could also lead to a lesser need of utilizing the vagal brake for
emotion regulation, resulting in a weaker relationship between expressiveness and resting
RSA. I therefor hypothesized that the tightness of relationship between resting RSA and
expressiveness would vary across the cultural groups (a cultural group by resting RSA
interaction effect).

15
Further, I hypothesized that within the AA group, those with stronger East Asian
cultural orientation would be less expressive. And those with higher resting RSA would
show stronger East Asian cultural orientation.
Methods
Participants. Three groups of volunteers participated in the study:
Chinese Group (CH): 14 monolingual Mandarin-speaking Chinese participants
were recruited from the Beijing Normal University community (7 females; average age
22.2 years, SD = 2.15). All were born to monolingual Mandarin-speaking parents and
raised in Mainland China, and none had resided outside of China.
East Asian American Group (AA): 16 second-generation East Asian American
participants (8 females; average age 20.4 years, SD = 1.44) were recruited from the
University of Southern California community in Los Angeles. Participants’ parents had
been born and raised in East Asia and had moved to the United States as adults.
Participants themselves had lived in the United States from before the age of 6 (13 had
been born in the U.S.). All participants in this group reported English as their primary
language. A proportion also reported minimal (1 participant) to moderate (9 participants)
fluency in spoken Mandarin, used mainly for communicating with family.
Non-Asian American Group (NA): 16 monolingual English-speaking American
participants not of Asian descent (8 females; average age 22.4 years, SD = 2.87; 12
identified as Caucasian-American, 2 as Latino-American and 2 as African-American)
were recruited from the University of Southern California community in Los Angeles.
Participants had been born and raised in the United States. Participants’ parents were

16
monolingual English-speaking Americans raised in the U.S. The ethnic make-up of the
group was representative of the make-up of the USC American student community,
excluding Asian-American representation. (Language adapted from Immordino-Yang,
Yang, & Damasio, under review.)
Protocols
Social emotion interview
In a one-on-one private social emotion interview (Immordino-Yang, McColl,
Damasio, & Damasio, 2009), participants were exposed to a series of true narratives
about real people’s experiences, and discussed their feelings in regards to the narratives
with a female experimenter of the same nationality (MHIY conducted the interviews in
Los Angeles; XFY conducted those in Beijing).
The narratives presented fell into the following categories: 1) Admiration for
virtue (narratives involved demonstrations of marked self-sacrifice and dedication to
helping others); 2) Admiration for skill (narratives involved demonstrations of
exceptional talents in athletics, the arts, or other domains); 3) Compassion for social pain
(narratives involved situations of bereavement, social rejection, and other forms of
psychological pain); 4) Compassion for physical pain (narratives depicted accidental
bodily injuries, e.g., sports accidents) and 5) Control social processing (narratives
involved interesting situations with real people, such as a man describing his adventures
abroad, that were not as emotionally evocative as narratives in the other categories).
There are 10 narratives in each category, with a total of 50 narratives. The physical
injuries shown were not the result of malevolence, and the participants were reassured

17
that the injuries had no long-term implications. To preclude eliciting disgust, no open
wounds were shown. Half of the narratives were about native English speaking
protagonists and half about native Mandarin speaking protagonists. All participants saw
the same video stimuli, subtitled in the participants’ native language. These narratives
were extensively piloted to ensure their cultural equivalence in emotional meaning and
impact.
Prior to data collection, the experimenters extensively rehearsed the scripted
narratives and reviewed together videotapes of practice interview sessions, with the aim
of relaying the narratives consistently and equivalently. Each scripted narrative took over
60-90 seconds to recount, and was accompanied by a combination of audio, video and
still images presented on a laptop computer. Interviews were conducted in the
participants’ home city (Los Angeles or Beijing) at a private location on the university
campus and were videotaped. (Language adapted from Immordino-Yang, Yang, &
Damasio, under review.)
Baseline ECG recording
Following the interview, participants underwent a baseline ECG recording session
for calculation of resting RSA. During the recording, participants were instructed to relax
with their eyes closed and to synchronize their breaths to an audio cue (delivered at 0.25
Hz) for 5 minutes. ECG was measured using three MRI-compatible electrodes placed on
the participant’s chest and sampled at a rate of 1000 Hz.

18
Analysis
Behavioral expressiveness coding
Independent raters coded each participant’s videotaped behavioral reaction to the
narratives depicting painful physical injuries (designed to induce compassion for physical
pain) with the sound off. We chose to measure expressiveness during this condition,
because participants’ reactions to physical injuries are relatively automatic and less
modulated by cognitive processes, and therefore would be more likely to reflect natural
behavior tendencies. Raters were blind to the hypotheses. Participants’ reactions for each
stimulus were rated on a scale of 1-4 (see Figure 1-1):
1. Participant remained calm and showed no visible change in expression;
2. Participant tightened his/her facial muscles and noticeably blinked his/her eyes;
3. Participant flinched, visibly tightened his/her shoulder muscles, and/or covered
his/her face with his/her hand(s);
4. Participant showed strong expression and avoidant behavior; either pushing
back his/her chair from the table or turning his/her upper body away from the
stimulus while displaying a tight facial expression.

19

Figure 1-1. Examples of participants' behavior during the interview and corresponding codes for
expressiveness.

The coding was accomplished by three expert raters: one Chinese, one second-
generation Chinese-American, and one American not of Asian descent. Each participant’s
reactions were independently coded by at least two raters, one of whom was from the
participant’s own ethnic group. Inter-rater-reliability scores for these measurements were
all within the “excellent” range (Cohen’s Kappa > 0.84). In addition, to validate the
rating reliability across ethnic groups, 20% of Chinese participants’ reactions were rated
by an American rater not of Asian descent, and 20% of American participants’ reactions
(including AA and NA participants) were rated by a Chinese rater from China. Inter-
20
rater-reliability scores were again within the “excellent” range (Cohen’s Kappa > 0.83).
Finally, discrepancies between raters were resolved by discussion.
The average of the three highest scores for each participant was calculated to
produce an expressiveness score. A general linear model was used to test the effects of
resting RSA and cultural background on expressiveness. A resting RSA by cultural
background interaction term was also included in the model.
Cultural orientation of bicultural East Asian American participants
Each Asian American participant’s cultural orientation was assessed based on self
reports of behaviors and practices that reflect cultural orientation, including 1) levels of
exposure to East Asian culture, 2) parents’ parenting style, 3) East Asian language use, 4)
preference for the ethnicity of romantic partner and 5) preference for the ethnicity of
friends.
Cultural orientation scores range from 1 (strongly biased towards Western
culture) to 5 (strongly biased toward East Asian culture). A subset of the participants (n =
10) also completed the general ethnicity questionnaire Chinese version (GEQc; J. L. Tsai,
Ying, & Lee, 2000), a validated measure for cultural orientation. Strong correlations were
found between GEQc scoring and scoring obtained from the methods described above
(r[8] = 0.68, p = 0.03), the original scoring was therefore kept in the current analysis.
Calculating resting cardiac vagal tone
ECG recordings were preprocessed in AcqKnowledge 9.32 (Biopac) to identify the
R peaks of the QRS complex. The resulting intervals between R peaks were plotted and
visually inspected for artifacts. Misidentified R peaks were manually corrected. Using

21
Kubios HRV (kubios.uku.fi/), RR interval series were then uniformly re-sampled at 4 Hz
using cubic spline interpolation, detrended using smooth prior regularization (Tarvainen,
Ranta-Aho, & Karjalainen, 2002) to remove slow fluctuation, and subjected to power
spectrum analysis using fast Fourier transformation. High frequency (0.15-0.4 Hz,
roughly the breathing frequency) power of RR interval time series was used as a measure
of resting RSA.
Resting RSA is expressed both in normalized units and in absolute high frequency
power (Task Force of the European Society of Cardiology and the North American
Society of Pacing Electrophysiology, 1996). RSA in normalized units (RSA
nu
) was
calculated as the relative value (in percentage) of high frequency power in proportion to
the total power minus the very low frequency (< 0.04 Hz) power. Representation of RSA
in normalized unit is thought to reflect the balanced behavior of the two main branches of
the autonomic system (Malliani, Pagani, Lombardi, & Cerutti, 1991; Pagani et al., 1986).
This calculation minimizes the effect of changes in total power on RSA measure (Task
Force of the European Society of Cardiology and the North American Society of Pacing
Electrophysiology, 1996).
Absolute high frequency power was log transformed to improve statistical
distribution (RSA
LN
), as recommended by Lewis, Furman, McCool, & Porges (2012).
However, extreme values were still present after this procedure: one female AA
participant’s score were 3.24 standard deviations away from group mean, and 4
participants’ (one male CH participant, one male and one female AA participants and one
female NA participant) score were more than 2 standard deviations away from the group
mean. These extreme values violate statistical assumptions and could cause problems in

22
the following analyses. RSA
nu
and RSA
LN
were highly correlated (with outliers: r[45] =
0.65, p < 0.001; without outliers: r[40] = 0.70, p < 0.001). When extreme values were
removed, results obtain with RSA
LN
were consistent with that obtained with RSA
nu
. I
therefore only included results from RSA
nu
. From here on, RSA
nu
was referred to as RSA
for simplicity.
Results
See Table 1-1 for a summary of descriptive statistics. All statistics reported are
two-tailed and thresholded at α < 0.05, unless specified otherwise.
Table 1-1. Summary of descriptive statistics of expressiveness and resting RSA.
Chinese (CH)
East-Asian American
(AA)

American, Non-Asian
(NA)
Male Female Male Female Male Female
Expressiveness (SD) 1.67 (0.27) 2.24 (0.60) 2.33 (0.50) 2.17 (0.44) 2.79 (0.53) 2.33 (0.31)
Resting RSA (SD) 57.2 (21.5) 64.7 (15.9) 59.0 (19.2) 75.7 (18.0) 38.7 (18.2) 67.1 (13.3)

Effects of cultural background and resting RSA on expressiveness
Groups did not differ in resting RSA (F[2,44] = 2.04, p = 0.14). Female
participants had significantly higher resting RSA than male participants (t[45] = 3.67, p =
0.001). No age effect on resting RSA was found (r[45] = -0.16, p = 0.28). However, a
group difference in age was found (F[2,44] = 6.18, p = 0.004): AA participants are
significantly younger than CH (Tukey HSD, p = 0.006) and NA participants (Tukey
HSD, p = 0.024). To avoid confounding effects, gender and age were included in the

23
model as covariates when testing the effects of cultural background and resting RSA on
expressiveness.
I did not find a resting RSA by cultural background interaction effect on
expressiveness (F[2,38] = 0.47, p = 0.63). The interaction term was therefore removed
from the model. As hypothesized, I found significant main effects of resting RSA
(F[1,40] = 10.27, p = 0.004) and cultural background on expressiveness (F[2,40] = 5.59,
p = 0.007). The direction of effects was also as hypothesized: participants with higher
resting RSA were less expressive during the interview (see Figure 1-2A); the CH group
was the least expressive, and the NA group was the most expressive among the three
groups (linear contrast, p = 0.005; see Figure 1-2B).
Within the AA group, participants with stronger orientation to East Asian culture
were less expressive during the interview (r[14] = -0.48, p = 0.03, one-tailed).

Figure 1-2. A. Scatterplot depicting the relationship between resting RSA and expressiveness.
Expressiveness was adjusted for gender and age effects. Data for the three cultural groups are plotted
separately. Linear trend lines were also plotted for each group separately. Notice the trend lines are largely

24
parallel to each other, indicating that culture does not modulate the relationship between resting RSA and
expressiveness. B. Bar graph depicting cultural group effect on expressiveness independent of resting RSA.
Expressiveness was adjusted for resting RSA, gender and age. Notice that CH group was the least
expressive, NA group was the most expressive and the AA group fell in the middle.

Culture by gender interaction on expressiveness
Culture by gender, culture by age, RSA by gender and RSA by age interactions
were probed. All were non-significant (p > 0.50), except a gender by cultural group
interaction (F[2,38] = 3.43, p = 0.04). Repeating the main test for male and female
participants separately revealed that the cultural group differences in expressivity is
driven by group effects in male participants (F[2,18] = 10.53, p = 0.001), and
expressiveness in female participants did not differ across groups (F[1,18] = 0.13, p =
0.88). See Figure 1-3.

Figure 1-3. Bar graph depicting the cultural group by gender interaction effect on expressiveness. Colors
representing the different groups are the same as in Figure 1-2. Expressiveness was adjusted for resting

25
RSA, gender and age. Notice that a significant cultural group effect was present only in the male
participants.

Resting RSA predicts cultural orientation in bicultural participants
In bicultural AA participant group, those with higher resting RSA also showed
stronger orientation to East Asian culture (r[12] = 0.69, p = 0.006), controlling for age
and gender. See Figure 1-4.

Figure 1-4. Scatterplot depicting the relationship between resting RSA and cultural orientation in bicultural
AA participants. Cultural orientation was adjusted for gender and age effects.

Discussion
Expressive behavior during emotion is supported by underlying biological
systems and is modulated by cultural ideals. Here I examined how cultural ideals and
resting cardiac vagal tone, a biological predisposition for emotion regulation and
calmness, together influenced natural expressiveness in three groups of participants,

26
Chinese in Beijing, and East Asian American and American not of Asian descent in Los
Angeles. Participants’ natural expressiveness was coded as they reacted to video clips
depicting unknown others substantiating painful physical injuries during a private
emotion-induction interview.
Participants with higher resting cardiac vagal tone were less expressive, an effect
consistent across all three groups. Consistent with known cultural differences in emotion
behavior, Chinese participants were less expressive than American participants, an effect
unrelated to resting cardiac vagal tone. Strengthening the interpretation that the group
differences observed are related to cultural ideals for emotion expression, within the
bicultural Asian American group, participants who self-reported as having stronger East
Asian cultural orientation were also less expressive. I did not find the hypothesized
cultural group by vagal tone interaction. That is, the effects of cultural ideal and vagal
tone on expressiveness are additive and statistically independent from each other,
suggesting that cultural modulation of behavior is not achieved through modulating the
vagal brake.
I found an unexpected gender by cultural group interaction effect on
expressiveness. Follow up analyses revealed that the cultural effect was only seen in the
male participants. I suspect that this might be related to the fact that the interviews were
all conducted by female experimenters. In front of a female experimenter, the male
participants might be under more pressure to behave in accordance with cultural norm.
However, since such gender by culture interaction effect on emotion expressiveness was
rarely found in the literature (e.g. Tsai et al., 2002; Tsai, Levenson, & Carstensen, 2000),
the generalizability of this finding is unclear.

27
Lastly, in East Asian American participants, I found a strong relationship between
resting cardiac vagal tone and cultural orientation. These participants are raised in a
bicultural context. Their parents are originally from East Asian countries, so their home
environment is predominantly East Asian (Chinese). At the same time, they are also
exposed to American culture in general. Although the sample size is small, this finding
points to an intriguing interplay between biological predisposition for calmness and
cultural identity in bicultural individuals. It is possible that higher resting cardiac vagal
tone predisposes bicultural individuals to adopting a cultural identity that values emotion
moderation and calmness. It is also possible that cultural practices of emotion moderation
since early childhood shapes the development of the biological system, leading to higher
resting cardiac vagal tone (see Kok & Fredrickson, 2010 for an example of behavior
practices changing vagal tone). Because resting cardiac vagal tone has been linked to
relatively stable temperamental emotion reactivity in young children (Calkins, 1997), and
has been shown to be stable during early childhood (9 months to 3 years of age; Porges,
Doussard-Roosevelt, Portales, & Suess, 1994) and during early adolescence (9 to 11
years of age; El-Sheikh, 2005), the first possibility seems more likely. Future longitudinal
studies are needed to investigate these hypotheses.
In summary, the current study demonstrated the combined effect of cultural and
biological factors on individual’s natural emotion behavior. Expressive behavior is
supported by a cascade of physiological processes. The expressiveness examined here is
only a coarse snapshot of the final outcome. In order to further elucidate the underlying
process, in Chapter 2, I will examine how cultural ideals and vagal tone modulates

28
dynamic changes in heart rate response during the processing of social emotions, and
how they are related to expressiveness.

29
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Chapter 2
Cultural Differences in Heart Rate Response during Social
Emotion and Relations to Individuals’ Expressiveness

35
Abstract
East Asian cultures value calmness and low arousal states, while Western cultures
value excitement and high arousal states. Although cultural values for arousal would
predict East-West differences in emotion-related autonomic arousal, e.g. differences in
heart rate response, such differences have rarely been found. Here I used an event-related
design to capture dynamic changes in heart rate response during social emotions in
Chinese, second-generation East Asian American, and American participants (not of
Asian descent). In contrast to most previous studies, in which heart rate responses were
averaged over a prolonged period of time (1 min or longer), here I examined whether
particular components of the heart rate response, dynamically changing on the order of
seconds, would be modulated by cultural background. I also tested whether individuals
with a more reactive heart rate response pattern had been more behaviorally expressive
during a previous open-ended and naturalistic social emotions interview.
I found that a more reactive heart rate response pattern during the early stimulus-
processing phase was related to greater expressiveness during the emotion-induction
interview and lower resting cardiac vagal tone, but the pattern did not differ across
cultural groups. Heart rate response during the later deliberation phase was not related to
individual’s expressiveness or vagal tone, but was related to culture. The response was
lowest for the Chinese culture group, followed by the Asian American group and highest
for the American group not of Asian descent. To my knowledge, this is the first study to
demonstrate a cultural effect on emotion-related heart rate responses.

36
Introduction
East Asian and Western cultures differ in values and norms around emotion
arousal and expressiveness (Bond, 1993; Markus & Kitayama, 1991; Russell, 1994; Tsai,
2007). Supporting these observations and theoretical accounts, cultural group differences
in emotion-related expressive behavior were consistently found (Ekman, 1973; Tsai,
Chentsova-Dutton, Freire-Bebeau, & Przymus, 2002; Tsai & Levenson, 1997; see also
findings in Chapter 1). These differences in values and norms would also predict cultural
differences in emotion-related autonomic arousal, e.g. differences in heart rate response.
However, such differences have rarely been found (e.g. Drummond & Quah, 2001;
Levenson, Ekman, Heider, & Friesen, 1992; Tsai & Levenson, 1997).
A potential methodological issue may have caused this lack of positive findings.
Most previous studies examining cultural differences in emotion responding averaged
heart rate response over a prolonged period of time (1 min or longer; e.g. Drummond &
Quah, 2001; Tsai & Levenson, 1997). However, heart rate responses are highly dynamic,
changing on the order of seconds. For example, heart rate responses elicited by brief
aversive auditory stimuli are characterized by a tri-phasic waveform, with a brief initial
deceleration (~0.5 sec), followed by a short acceleration (~4.5 sec) and finally a late
moderate deceleration (~6.5 sec; Gatchel & Lang, 1973). Cultural ideals may
differentially influence these components, and the effect may be cancelled out when heart
rate is averaged over the 6-second period. Supporting this speculation, while Tsai et al
(1997) did not find differences in mean heart rate response between East Asian and
Caucasian American couples during discussions of conflicts in their relationships, they
found less heart rate variation in East Asian comparing to Caucasian participants.

37
To address this issue, I used an event-related design to capture dynamic changes
in heart rate response during social emotions. Adapting methods described in Gatchel &
Lang (1973), I first characterized the average heart rate response waveform, and then
separately examined cultural effects on each of the components. I also tested whether
different components of heart rate response are modulated by vagal tone, and whether
they are related to individual’s natural expressiveness during the emotion-induction
interview.
Methods
Participants. Three groups of volunteers participated in the study: Chinese (CH)
in Beijing, second-generation East Asian American (AA) and American not of Asian
descent (NA) in Los Angeles. See Chapter 1 for more information on the participant
groups.
Procedures
Emotion-induction interview
Participants took part in a one-on-one private emotion induction-interview,
conducted by an experimenter of the same nationality as the participant (MHIY
conducted the interviews in Los Angeles; XFY conducted those in Beijing). During the
interview, participants were presented with narratives depicting true experiences of real
non-famous people (not actors or celebrities). Narrative stimuli depicted stories involving
remarkable altruism (to induce admiration for virtue); skillful feats (to induce admiration
for skill); social exclusion or grief (to induce compassion for social pain); accidental

38
physical injuries (to induce compassion for physical pain); relatively less emotional
social situations (the control condition). There are 10 narratives in each category,
totaling 50 narratives.
See Chapter 1 for more details on the emotion-induction interview protocol and
the narrative stimuli.
Baseline ECG recording
Following the interview, participants underwent a baseline ECG recording session
for calculation of resting RSA. Resting RSA is expressed in normalized units. See
Chapter 1 for more details on this measure.
ECG recording during social emotion task
After the preparation session, participants underwent ECG recording with
simultaneous fMRI scanning as they viewed 5-second reminder videos depicting the crux
of each narrative with one sentence of verbal information from the preparation session
delivered both auditorily and transcribed underneath the image in stationary text. Each
stimulus presentation was preceded by a 2-second fixation cross, and followed by 13
seconds of dark screen for reflection and deliberation. For each stimulus presentation,
participants reported via button press the real-time strength of their feeling once they
became aware of it. Each narrative was shown twice during the course of the experiment,
but never twice during the same run, for a total of 100 trials divided into four runs of
approximately 9 minutes each.
39
Analysis
ECG data acquisition and processing
ECG was measured using three MRI-compatible electrodes placed on the
participant’s chest and sampled at a rate of 1000 Hz for baseline recording, and at a rate
of 4000 Hz during the social emotion task. ECG recordings were preprocessed in
AcqKnowledge 9.32 (Biopac) to identify the R peaks of the QRS complex. The resulting
intervals between R peaks were plotted and visually inspected for artifacts. Misidentified
R peaks were manually corrected. RR interval series were then uniformly re-sampled at 4
Hz using cubic spline interpolation (Kubios HRV; kubios.uku.fi/).
Uniformly sampled RR interval series were transformed into heart rate series (in
beats per minute, bpm). For each trial, average heart rate during the 2-second gray screen
preceding the trial was used as a baseline. Heart-rate response during the trial was
calculated as heart-rate change over the 18 seconds following stimulus onset relative to
pre-trial baseline. For each participant, heart rate responses for the same narrative
condition were averaged, creating 5 average heart rate response waveforms.
Results
All statistics reported are two-tailed and thresholded at α < 0.05.
Average heart rate response waveform during social emotion processing
Averaging heart rate response across all participants and all trials revealed an
average heart rate response pattern. The average heart rate response took a tri-phasic
form, which consisted of a first acceleration component (A1) peaked at around 4 seconds,

40
followed by a deceleration component (D) peaked at around 6 seconds and finally a
secondary acceleration component (A2) peaked at around 10 seconds (Figure 2-1).

Figure 2-1. Averaged heart rate response across all participants and all conditions to illustrate the average
pattern. The heart rate response during social emotion processing consists of three components: an initial
acceleration (A1), a deceleration (D) and a second acceleration (A2). Stimulus presentation starts at time 0.
The shaded area indicates the duration of stimulus presentation.

With an understanding of the heart rate response pattern during social emotion
processing, the three heart rate response components were measured for each participant
and for each condition using the following method: A1 was measured as the heart rate
change at the fastest peak from stimuli onset until 4 seconds after stimulus onset; D was
measured as the heart rate change at the slowest peak from A1 until 8 seconds after
stimulus onset; A2 was measured as the heart rate change at the fastest peak after D until
18 seconds after stimulus onset (before the next stimulus is presented). This approach
took into account that participants may not have responded at the same speed, and

41
captured the full dynamic of heart rate response.
Because the three components were consistent across the 5 conditions
(Cronbach’s alpha > 0.74), average A1, D and A2 across five conditions were calculated
for each participant. One female AA participant’s A1 and A2 data were identified as
outliers and excluded from further analyses, because her data were more than 2 standard
deviations away from the group mean.
Vagal tone effects on heart rate response
Resting RSA predicted magnitude of D (higher resting RSA related to lower heart
rate, r[44] = -0.30, p = 0.04). No relationships with A1 or A2 were found (p > 0.64).
Cultural group effects on heart rate response
Cultural effects on A1, D and A2 were tested using three separate general linear
models. To rule out the possibility that the observed cultural effects may be driven by
differences in resting cardiac vagal tone, resting RSA was included in the model as a
covariate. Age and gender were also included.
Planed linear contrast revealed a cultural effect on A2 (F[1,39] = 5.27, p = 0.03),
but not A1 (F[1,39] = 0.57, p = 0.83) or D (F[1,39] = 0.23, p = 0.63; See Figure 2-2). No
significant effects of age and gender were found (p > 0.25). The same trend held when
each narrative condition was tested separately.

42

Figure 2-2. Bar graph depicting the cultural group effect on the three components of heart rate response
during social emotion processing. Heart rate change was adjusted for resting RSA, gender and age. Notice
that the cultural group difference was found only in the A2 component.

Relationship between expressiveness and heart rate response
Participants’ expressiveness during the emotion-induction interview was
positively related to A1 (r[42] = 0.30, p = 0.05). No relationship with D or A2 were
found (p > 0.15)
As discussed in Chapter 1, there were a significant culture effects and a culture by
gender interaction effect on expressiveness. Such effects may have masked relationships
between components of heart rate response and expressiveness. To test whether different
components of heart rate response would explain individual variation in expressiveness

43
above and beyond the culture and gender effects, expressiveness was adjusted for cultural
groups, gender and cultural group by gender interaction effects. This procedure revealed
that expressiveness was positively related to A1 (r[42] = 0.24, p = 0.12; after removing
the data point at the lower right corner, which has a cook’s distance of 0.68 and was
determined as a highly influential data point [Bollen & Jackman, 1985], r[41] = 0.38, p =
0.01; Figure 2-3A) and to D (r[43] = 0.35, one-tailed p = 0.02; Figure 2-3B). No such
effects were found for A2 (r[42] = 0.14, one-tailed p = 0.19; Figure 2-3C).

Figure 2-3. Scatterplot depicting the relationship between the three components of heart rate response and
expressiveness. Expressiveness was adjusted for culture, gender and culture by gender interaction effects.
Data for the three cultural groups are plotted separately. Linear trend lines are also plotted. Notice that
significant relationships were only seen for A1 and D, but not A2.

Discussion
Eastern and Western cultures differ in values about emotional arousal (Tsai,
2007), however, demonstrations of cultural difference in emotion-related autonomic
arousal have been elusive. Here, instead of averaging over a prolonged period as in most

44
previous studies, I was able to uncover a cultural effect using an event-related design to
capture dynamic changes in heart rate response during social emotion processing.
Heart rate response during social emotion processing consists of three distinct
components: a first acceleration, a deceleration and a final acceleration. Considering the
temporal profile of these responses, the first two components are related to the processing
of the reminder stimuli, while the third one is related to the reflection/deliberation period.
The functional significance of the first two components are interpreted in relation
to previous research on heart rate responses following auditory stimuli (Gatchel & Lang,
1973, 1974) and emotional picture presentations (Bradley, 2009; Lang, Greenwald,
Bradley, & Hamm, 1993). The first acceleration component is a startle reflex in response
to the sudden onset of the stimulus (Graham & Clifton, 1966). The deceleration
component is an orienting response that facilitates attention to the external environment
and heightens sensory receptivity toward stimuli (Gatchel & Lang, 1973, 1974).
Consistent with the notion that this deceleration component is a mainly vagal driven
phenomenon (Graham & Clifton, 1966; Hare, 1972), magnitude of this component is
predicted by resting RSA.
Higher startle acceleration in response to sudden stimuli, such as a brief loud tone,
is considered an index of lower threshold for defense response (less calm). Individuals
with lower threshold for defense responses also tend to show less heart rate deceleration
when presented with unpleasant emotional stimuli (Hodes, Cook, & Lang, 1985;
Sánchez-Navarro, Martínez-Selva, & Román, 2006). Therefore, greater startle
acceleration (A1) and less orienting deceleration (D) can be considered a more reactive
heart rate response pattern. This reactive response pattern predicted participants’

45
expressiveness during the emotion-induction interview, especially when cultural and
gender modulations on the behavior display of emotion arousal were controlled for.
It is worth noting that expressiveness and heart rate responses were measured at
different times and in two very different settings. We made this methodological decision
to maximize the ecological validity of the expressiveness measure. Participants’ behavior
during the interview was not restricted by any psychophysiological recording equipment,
so that they could react in a way that reflected their natural behavioral inclinations. Even
though the heart rate response patterns described here were not the same ones that were
directly associated with expressiveness, strong correlations were found. This suggests
that these measures captured stable, trait-level characteristics of participants’ behavior.
No direct correspondences of the second acceleration component were found in
the literature. This component is likely related to emotional arousal while participants
reflected upon the stimuli and deliberated on their emotional feelings. This component
was unrelated to expressiveness, but showed a significant cultural effect. These findings
suggest that while culture does not modulate heart rate responses during the processing of
social emotion stimuli, it modulates the amount of cardiac arousal when participants were
reflecting upon and deliberating on their emotional feelings. While previous literature
suggested that cultural effects on emotional responding are more detectable in social
situations versus non-social situations (Friesen, 1973; Tsai et al., 2002), the culture effect
on cardiac arousal was found when participants were lying in the dark scanner room by
themselves. It is possible that knowing their physiological responses and brain activity
were being recorded was enough to make the situation “social”. It is also possible that
these differences reflected participants’ learned ways of responding in emotional

46
situations, regardless of being social or not.
Importantly, although cultural groups differed in expressiveness and heart rate
responses during emotion deliberation, they did not differ in reported feeling strength
(F[2,43] = 0.84, p = 0.92). And no relationships were found between reported feeling
strength and any of the heart rate response components (p < 0.64). These findings suggest
that the observed cultural and individual differences in emotion-related behaved and heart
rate arousal may reflect different styles of reacting in emotional situation that do not alter
the strength of emotion experience.
In summary, this study demonstrated the power of studying dynamic changes in
heart rate responses during emotion processing. To my knowledge, this is the first study
to uncover cultural differences in emotion-related cardiac arousal predicted by East Asian
and Western cultural differences in values and norms around arousal.

47
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Lang, P. J., Greenwald, M. K., Bradley, M. M., & Hamm, A. O. (1993). Looking at
pictures: Affective, facial, visceral, and behavioral reactions. Psychophysiology,
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Levenson, R. W., Ekman, P., Heider, K., & Friesen, W. V. (1992). Emotion and
autonomic nervous system activity in the Minangkabau of west Sumatra. Journal of
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doi:10.1177/0022022197285006
Chapter 3
Orienting Heart Rate Deceleration during Social Emotion Processing Predicts
Deactivation in Default Mode Network Regions

51
Abstract
Heart rate deceleration (HRD) following the presentation of a new stimulus has
been considered a component of the orienting response. HRD facilitates outwardly
focused attention and heightens sensory receptivity to stimuli. The default mode network
(DMN) is a group of brain regions that show increased activity level during awake and
non-attentive states, and decreased activity level (deactivation) during tasks that require
attention into the environment. No studies so far have related HRD during emotion
processing to DMN deactivation. Here, electrocardiogram and functional MRI were
recorded simultaneously while three groups of participants, Chinese in Beijing, East
Asian American and American (not of Asian descent) in Los Angeles, reacted to video
clips depicting a series of admiration and compassion-inducing social narratives. Greater
HRD was observed during social emotions that drew attention outward, i.e. those about
another person’s physical action or ability, compared to social emotions that turned
attention inward, i.e. those about another person’s mental quality or accomplishment.
Greater HRD consistently predicted deactivation in precuneus/posterior cingulate cortex
node of the default mode network (DMN). This relationship held both within and across
individuals, and no cultural differences were found. To my knowledge, this is the first
study linking HRD and DMN deactivation during emotion processing.

52
Introduction
In Chapter 2, I identified heart rate deceleration (HRD) as a part of the average
heart rate response pattern during the processing of a variety of admiration- and
compassion-inducing narratives. Here, I examined how this component was related to
brain activity.
HRD following presentation of a new stimulus is an important adaptive function
that facilitates attention to the external environment and heightens sensory receptivity
toward stimuli (Gatchel & Lang, 1973, 1974). This response is driven mainly by
increased vagal outflow to the heart, and is accompanied by reduced somatic activity
(Porges, 2007). As the stimulus repeats, HRD response diminishes because it becomes
familiar and less salient (Lang & Hnatiow, 1962).
In the brain, attention shifts between the external environment and the internal
thoughts are robustly reflected in the activity level of the default mode network (DMN;
Raichle et al., 2001). DMN is a group of brain regions with increased activity level
during awake but non-attentive states, and decreased activity level (deactivation) during
tasks that require attention into the environment (Greicius & Menon, 2004; Raichle et al.,
2001). Similar to the HRD habituation following stimulus repetitions, repeatedly
practiced, less attention-demanding tasks produced more spontaneous thoughts irrelevant
to the task, and were associated with increased activity in the DMN (Binder et al., 1999;
McKiernan, Kaufman, Kucera-Thompson, & Binder, 2003). The DMN also supports a
variety of social processing tasks that require self-referential and reflective processes
(Buckner & Carroll, 2007; Spreng & Grady, 2010; Spreng, Mar, & Kim, 2009), such as
attributing mental states to others (Lieberman, 2007; Saxe & Kanwisher, 2003) and

53
feeling emotions about others’ social situations (Bruneau, Pluta, & Saxe, 2012;
Immordino-Yang, McColl, Damasio, & Damasio, 2009). I was therefore particularly
interested in the relationship between HRD and DMN activity during social emotion
processing.
Interestingly, Napadow and colleagues (2012) found that acupuncture
stimulations that elicited heart rate decelerations were associated with greater
deactivation in the DMN regions comparing to those that did not, and that within-subject
variation in magnitude of HRD correlates with the degree of deactivation in the DMN.
However, it is unclear what kind of mental process was related to acupuncture induced
HRD, and whether this pattern is specific to the sensory processing related to acupuncture
stimulation, or can be generalized to emotion processing.
To address these questions, here I simultaneously collected electrocardiogram
(ECG) and BOLD fMRI as participants reacted to a series social narratives designed to
induce admiration and compassion (Immordino-Yang et al., 2009). The narrative
protagonist’s situation varied along a critical dimension: while some pertained to another
person’s mental states, such as admiration for moral intentions or compassion for
psychological distress, others pertained to another person’s physical states, such as
admiration for skillful performance and compassion for painful physical injury. Feeling
social emotions about others’ mental states is a more internally focused process, because
it requires abstract deliberations about complex social circumstances and history that are
not immediately apparent from the other person’s outward behavior and physical
situation (Immordino-Yang, 2010). Feeling social emotions about others’ physical states
is a more externally focused process, because it requires attending to the protagonist’s

54
bodily situation and movement. Consistent with the different attention focuses associated
with these social emotions, previous analyses have revealed that when contrasted to
social emotion about other’s physical states, social emotion about other’s mental states
strongly activates the DMN (Immordino-Yang et al., 2009). These two types of social
emotions were therefore examined separately.
Given that HRD facilitates externally focused attention, and that neural activity in
the DMN is suppressed when attention is directed outwardly to the environment, I
hypothesized that greater HRD would be related to greater deactivation in the DMN
during social emotion processing. I expected this relationship to hold as each participant
dynamically shifted his/her attention on a trial-by-trial basis. I also expected this
relationship to hold across individuals, that is, when responses during all trials were
averaged, individuals with greater HRD would also show greater DMN deactivation.
Given the different attention focuses associated with these two types of social
emotions, I hypothesized that participants would show greater HRD during social
emotions about another person’s physical state compared to those about another person’s
mental state.
As discussed in Chapter 2, no cultural effects were found on HRD. I therefore did
not expect a cultural effect on the above-hypothesized relationships.
Methods
Participants. 14 monolingual Mandarin-speaking Chinese participants in Beijing
(7 females; average age 22.2 years, SD = 2.15), 16 second-generation East Asian
American participants (8 females; average age 20.4 years, SD = 1.44) and 16
monolingual English-speaking American participants not of Asian descent (8 females;

55
average age 22.4 years, SD = 2.87) participated in the experiment. (See chapter 1 and 2
for details on participants.)
Procedures
Emotion-induction interview
To ensure successful induction of the target social emotions, participants
underwent a preparatory session where they were exposed to a longer and more detailed
version of the narrative stimuli they would see later in the scanner. During this one-on-
one private interview, participants talked about their feelings towards the narratives with
an experimenter of the same nationality (MHIY conducted the interviews in Los Angeles;
XFY conducted those in Beijing). Interviews were conducted in the participants’ home
city (LA or Beijing) at a private location on the university campus and were videotaped.
See Chapter 1 for more details on the interview protocol.
Neuroimaging session with simultaneous ECG recording
After the preparation session, participants underwent BOLD fMRI with
simultaneous ECG recording as they viewed 5-second reminder videos depicting the crux
of each narrative with one sentence of verbal information from the preparation session
delivered both auditorily and transcribed underneath the image in stationary text. Each
stimulus presentation was preceded by a 2-second fixation cross, and followed by 13
seconds of dark screen for reflection and deliberation. For each stimulus presentation,
participants reported via button press the real-time strength of their feeling once they
became aware of it. Each narrative was shown twice over the course of the experiment,

56
never twice during the same run, for a total of 100 trials divided into four runs of
approximately 9 minutes each. (Language adapted from Immordino-Yang, Yang, &
Damasio, under review.)
Stimuli
The narratives presented to participants are about true experiences of non-famous
people (not actors or celebrities), some of which were meant to induce strong social
emotional reactions in participants, and some of which were less emotionally evocative.
The narratives fell into five categories, with 10 stimuli in each.
Two of the categories involve narratives about others mental states (for ease of
description, these conditions will be referred to as the mental conditions):
Admiration for virtue (AV): Narratives involved people performing highly
virtuous, morally admirable acts. The narratives emphasized dedication to an important
cause despite difficult obstacles, and did not include displays of notable skill.
Compassion for social pain (CSP): Narratives involved people in states of grief,
despair, social rejection, or other difficult psychological circumstances. No physical pain
was evident in these narratives, and the troubling circumstances were discerned from the
descriptions, rather than being apparent in the images shown.
Two of the categories involve narratives about others physical states (for ease of
description, these conditions will be referred to as the physical conditions):
Admiration for skill (AS): Narratives involved people adeptly performing rare and
difficult feats, e.g., an athletic or musical performance, with both physical and cognitive

57
components. No physically or socially painful acts were shown, and the skillful feats,
although amazing, did not imply a virtuous protagonist or reveal a virtuous act.
Compassion for physical pain (CPP): Narratives involved people sustaining a
physical injury caused by sports and other mishaps and had no moral or social
implications. The injuries were not the result of malevolence, and the participants were
reassured that the injuries had no long-term implications. To preclude eliciting disgust, no
open wounds were shown.
A control condition (ctrl) was also included. Control narratives involved
comparable living, mentally competent people engaged in or discussing how they felt
about typical activities under commonplace social circumstances. These circumstances
were engaging but not emotion provoking. Since the focus of the current study is HRD
during social emotion processing, results from the control condition were not reported
here. (Language adapted from Immordino-Yang, Yang, & Damasio, under review.)
fMRI data acquisition and preprocessing
The same scanner model and sequences were used to collect neuroimaging data at
BNU Imaging Center for Brain Research and at USC Dana and David Dornsife
Neuroimaging Center. Whole brain images were acquired using a Siemens 3 Tesla
MAGNETON TIM Trio scanner with a 12-channel matrix head coil. Functional scans
were acquired using a T2* weighted Echo Planar (EPI) sequence (TR=2 sec, TE=30 ms,
flip angle=90) with a voxel resolution of 3mm  3mm  4.5mm. Thirty-two continuous
transverse slices were acquired to cover the whole brain and brain stem. Functional data
were acquired continuously for the duration of each run, with breaks between runs.
58
Anatomical images were acquired using a magnetization prepared rapid acquisition
gradient (MPRAGE) sequence (TI=900 ms, TR=1950 ms, TE=2.26 ms, flip angle=7 )
with an isotropic voxel resolution of 1mm.
Data were processed using SPM8 (Wellcome Department of Cognitive
Neurology, London, UK) in MATLAB 2009b (MathWorks, Inc.). Functional images
were slice timing corrected, motion corrected and co-registered to the anatomical image.
Anatomical images were segmented and normalized to MNI space (Montreal
Neurological Institute) using tissue probabilistic maps (segmentation, SPM8). The same
normalization transformation was applied to the functional images. The images were
then resampled into a resolution of 2x2x2 mm and smoothed using an 8-mm full-width,
half-maximum Gaussian kernel. Data were subjected to session-specific grand mean
scaling, high-pass filtering with a cut-off period of 128 seconds and auto-correlation
correction using an autoregressive model of order 1.
ECG data acquisition and preprocessing
ECG was measured using a BIOPAC MP150 system with three MRI-compatible
electrodes placed on the participant’s chest and sampled at a rate of 4000 Hz. ECG
recordings were preprocessed in AcqKnowledge 9.32 (BIOPAC Systems, Inc.) to extract
the R peaks of the QRS complex. The resulting intervals between R peaks were plotted
and manually corrected for artifacts. RR interval series were then uniformly re-sampled
at 4 Hz using cubic spline interpolation (Kubios HRV; kubios.uku.fi/).
Uniformly sampled RR interval series were transformed into heart rate series (in
beats per min, bpm). For each trial, average heart rate during the 2-second gray screen
preceding the trial was used as a baseline. Heart rate response time course during the trial

59
was calculated as heart rate change over the 18 seconds following stimulus onset relative
to pre-trial baseline.
For each participant, heart rate responses for the same narrative condition were
averaged, creating 5 average heart rate response waveforms. HRD was measured for each
participant and for each condition using the same method described in Chapter 2.
Because heart rate deceleration magnitudes were highly correlated between the two
mental conditions (AV and CSP, r[44] = 0.53, p < 0.001), and between the two physical
conditions (AS and CPP, r[44] = 0.61, p < 0.001), and because the focus of the current
study is to contrast heart rate deceleration during these two forms of social emotion
processing, HRD were averaged between AV and CSP and between AS and CPP. One
female AA participant’s average HRD during physical conditions were 4.23 standard
deviations away from group mean. This subject’s data were identified as outliers and
excluded from further analyses.
The same method was used to measure HRD for a single trial.
Testing trial-by-trial relationship between HRD and DMN deactivation
Two-level analyses were used to examine trial-by-trial relationships between
heart rate deceleration and BOLD activity. At the individual level, parametric modulation
models were used. The 5-second video presentation of each trial was modeled as a boxcar
and convolved with the standard hemodynamic response function. The resulting function
was then multiplied by the HRD magnitude (absolute value) from the same trial. In
essence, this model captures BOLD activity that 1) was related to processing reminder
stimuli and 2) had magnitude varying parametrically with trial-by-trial HRD. To ensure

60
that the effects were not driven by mean differences in HRD across conditions, the five
conditions were modeled separately. Contrast maps representing the average HRD
modulation effect were calculated for the physical conditions (AS and CPP) and for the
mental conditions (AV and CSP). At the group level, these two types of contrast maps
were entered into 2 separate one-sample t-tests to test for consistent effects.
Group differences in trial-by-trial relationship between HRD and DMN
deactivation were tested using a one-way ANOVA.
Testing cross-subject relationships between average HRD and average DMN
deactivation
Two-level analyses were used to examine the cross-subject relationships between
average HRD and DMN deactivation. At the individual level, boxcar functions convolved
with standard hemodynamic response function were used to model BOLD activity related
to the processing of the 5-sec reminder video stimuli. The five conditions were modeled
separately. Two contrast maps were calculated for each participant. One is the physical
conditions (AS and CPP) combined versus the implicit baseline. The other is the mental
conditions (AV and CSP) combined versus the implicit baseline. At the group level, these
two types of contrast maps were entered into two whole brain regression analyses, with
the corresponding average HRD magnitudes (absolute value) as regressors.
A cultural group by HRD interaction model was used to test whether the cross-
subject relationship between HRD and DMN deactivation differed across cultural groups.

61
Examining and thresholding of fMRI results
Because I have a priori hypotheses about the DMN, results were only examined
within an anatomically defined DMN mask to increase statistical power by reducing
multiple comparisons. The mask was pre-defined using the Automated Anatomical
Labeling Atlas (Tzourio-Mazoyer et al., 2002) to include precuneus, posterior cingulate
cortices, medial prefrontal cortices and angular gyri; see Figure 3-1.

Figure 3-1. Depiction of the anatomically defined DMN mask, displayed on a template brain. The vertical
lines in the left panel indicate the position of the sagittal slices.

I imposed on the group-level results a statistical threshold of p < 0.005 and a
cluster extent threshold of 80 voxels, which corresponds to p < 0.05 controlling for
multiple comparisons. The cluster extent threshold was determined by 10,000 Monte
Carlo simulation iterations conducted using the AlphaSim program in AFNI
(http://afni.nimh.nih.gov/afni/). The criteria input to AlphaSim were: uncorrected p-value
of 0.005, voxel size of 2×2×2, spatial smoothing kernel of 8 mm, and the number of
voxels in the mask (24519 voxels). (Method adapted from Yang, Bossmann, Schiffhauer,
Jordan, & Immordino-Yang, 2013)

62
Results
Heart rate results
No group differences in HRD were found for physical conditions (F[2,42] = 0.15;
p = 0.86). However, there is a marginal group differences in HRD for mental conditions
(F[2,42] = 2.46; p = 0.10), driven by the higher HRD in the AA group. See Table 3-1 for
a summary of the descriptive statistics.
As hypothesized, participants showed greater HRD during social emotions about
another person’s physical state than those about another person’s mental state (t[44] =
2.14, p = 0.04). The same trend held in the CH and NA group, but not in the AA group.
Table 3-1. Descriptive statistics of HRD during the mental conditions (AV and CSP) and during the
physical conditions (AS and CPP). HRD is presented in units of beats per minute (bpm).

Chinese
(CH)

East-Asian American
(AA)

American, Non-Asian
(NA)
Mental conditions (SD)
-0.78 (1.09) -1.67 (1.29) -0.92 (1.15)
Physical conditions (SD)
-1.41 (0.83) -1.47 (1.64) -1.69 (1.65)

fMRI results
Within-subject relationship between HRD and DMN deactivation
During the physical conditions, the trial-by-trial relationship between HRD
magnitude and BOLD deactivation was found in DMN regions, including the
precuneus/posterior cingulate cortex, bilateral angular gyri and the dorsal medial
prefrontal cortex (see Figure 3-2 and Table 3-2). However, no such relationship was
found during the mental conditions (even at a more lenient threshold of p < 0.01

63
uncorrected with a cluster threshold of 80 voxels).
Group differences in trial-by-trial relationships between HRD and DMN
deactivation was tested using a one-way ANOVA model. Group difference was found in
one dMPFC cluster (x = 10, y = 62, z = 20, cluster size = 122, z-score = 3.25) during the
physical conditions. No other group differences were found.
Table 3-2. Voxel clusters from within the DMN whose activity inversely correlated with HRD magnitude
on a trial-by-trial basis during the physical conditions (AS and CPP). Coordinates of the peak voxel are
given in Montreal neurological institute (MNI) space. Clusters are significant at p < 0.05, corrected for
multiple comparisons; those significant at p < 0.001 are marked**.
Coordinates
Brain region x y z cluster size z-score
Precuneus/PCC -10 -44 26 5180** 4.80
dMPFC 0 26 38 1002** 4.03
Angular gyrus 40 -50 30 1182** 5.47
-40 -62 50 890** 4.93
Notes: PCC: posterior cingulate cortex; dMPFC: dorsal medial prefrontal cortex.

Figure 3-2. Representative images of neural regions from within the DMN whose activity inversely
correlated with HRD magnitude on a trial-by-trial basis during the physical conditions (AS and CPP).
Results are thresholded at p < 0.05, corrected for multiple comparisons. MNI coordinates of the axial and
sagittal planes are given. Notes: PCC: posterior cingulate cortex; dMPFC: dorsal medial prefrontal cortex;
AG: angular gyrus.

64
Cross-subject relationship between HRD and DMN deactivation
During both mental and physical conditions, participants with greater HRD
showed greater deactivation in DMN regions, including the precuneus and posterior
cingulate cortex (See Figure 3-3&3-4 and Table 3-3). Additional results during the
physical conditions were observed in bilateral angular gyri and the medial prefrontal
cortex (see Figure 3-4 and Table 3-3).
Group difference in cross-subject relationships between HRD and DMN was
found in one ventral MPFC cluster (x = 12, y = 62, z = -2, cluster size = 101, z-score =
4.39) during the physical conditions. No other group differences were found.
Table 3-3. Voxel clusters from within the DMN whose activity inversely correlated with average HRD
magnitude across participants during the mental conditions (AV and CSP; A) and during the physical
conditions (AS and CPP; B). Coordinates of the peak voxel are given in MNI space. Clusters are significant
at p < 0.05, corrected for multiple comparisons; those significant at p < 0.001 are marked*; those
significant at p < 0.001 are marked**.
Coordinates
Brain region x y z cluster size z-score
A. Mental conditions
Precuneus/PCC 0 -60 52 740** 3.72
B. Physical conditions
Precuneus/PCC 20 -62 30 1911** 4.18
MPFC 12 56 -8 2659** 4.43

Angular gyrus 40 -52 30 160* 3.32
-50 -54 26 192** 3.74
Notes: PCC: posterior cingulate cortex; MPFC: medial prefrontal cortex.

65

Figure 3-3. Representative image of the neural region from within the DMN whose average activity
inversely correlated with average HRD magnitude across participants during the mental conditions (AV
and CSP). Results are thresholded at p < 0.05, corrected for multiple comparisons. MNI coordinates of the
sagittal plane is given. Notes: PCC: posterior cingulate cortex.

Figure 3-4. Representative images of the neural regions from within the DMN whose average activity
inversely correlated with average HRD magnitude across participants during the physical conditions (AS
and CPP). Results are thresholded at p < 0.05, corrected for multiple comparisons. MNI coordinates of the
axial and sagittal planes are given. Notes: PCC: posterior cingulate cortex; MPFC: medial prefrontal cortex;
AG: angular gyrus.

66
Discussion
In the current study, I investigated the relationship between orienting HRD and
deactivation in the DMN regions during the processing of a variety of admiration- and
compassion-inducing narratives.
I found that HRD predicted the level of deactivation in the DMN. The relationship
held when tested within each individual on a trial-by-trial basis, suggesting that the
variations in orienting HRD facilitated dynamic shifts between inwardly focused and
outwardly focused attention. The relationship also held when tested across subject using
average HRD magnitude and average DMN deactivation, suggesting that the relationship
captured reflected trait-level individual differences in styles of social emotion processing.
The most consistent relationship was observed in the ventral precuneus and posterior
cingulate cortex, the central hub of the DMN (Andrews-Hanna, Reidler, Sepulcre, Poulin,
& Buckner, 2010). This sector was shown to be specifically involved in interoceptive
processing and internally focus thoughts (Gusnard, Akbudak, Shulman, & Raichle, 2001;
Johnson et al., 2002; Leech, Kamourieh, Beckmann, & Sharp, 2011; Northoff &
Bermpohl, 2004). These findings were mostly consistent across the three cultural groups,
suggesting that the relationships captured here may reflect a basic biological process that
is not modulated by cultural ideals.
However, these patterns were reliably seen only during social emotions about
another person’s physical state, but not those about another person’s mental state.
Previous analyses have shown that social emotions about another person’s mental state
strongly activate the DMN. These social emotions likely evoked additional mental
processes at activated the DMN, such as self-referential processing (Kelley et al., 2002)

67
and autobiographical recall (Immordino-Yang & Singh, 2011; Spreng et al., 2009; Yang
et al., 2013), which did not relate parametrically to attention shifts.
Related, greater HRD was evoked during social emotions about other’s physical
states than during those about other’s mental states. These results mirrored their
differential recruitment of the DMN, and are consistent with the outwardly versus
internally focused attention required in processing these social emotion-inducing
narratives.
This finding has implications for understanding the role of HRD in social emotion
processing. In earlier studies, higher HRD elicited by video clips depicting another
person in distress was shown to predict more empathic concern and willingness to donate
more time or money to help the protagonist (Eisenberg, Fabes, Miller, & Fultz, 1989).
HRD was therefore conceptualized as an important autonomic index for empathic
concern and prosociality. However, conflicting results were found in other studies (See
Hastings, Zahn-Waxler, & McShane, 2006 for a review), raising question about the
validity of the conceptualization. Results reported here suggest that while reduced HRD
in these contexts could reflect less attention toward the protagonist’s suffering and
indicate less empathic concern, the same reduced HRD could also reflect an internally
focused reflective process that leads to deeper empathic understanding of the
protagonist’s mental suffering. In future examination of HRD during social emotion
processing, distinguishing between internally- and externally focused processes may help
to reconcile the conflicting findings.
Surprisingly, in the AA group, magnitude of HRD during the mental condition
was not distinguishable from that during the physical conditions, which is inconsistent

68
with my hypothesis. This unexpected pattern could be related to the fact that these
participants grew up in a bicultural context. Having to regularly switch between different
cultural modes according to the context could make these participants hyper vigilant to
external stimuli (see Yang, Yang, & Lust, 2011 for an example of bicultural experience
influencing cognition). Because the AA group is significantly younger than the CH and
NA groups, this pattern could also be a developmental effect. The functional organization
of the DMN continues to mature until early adulthood (Fair et al., 2008). Effectively
shifting attention away from external environment to engage in internally focused
reflection may be a skill that is still maturing in these participants.
In summary, to my knowledge, this is the first study to relate orienting heart rate
deceleration and deactivation in the default mode network brain regions during social
emotion processing. Findings provide insight into the neural processing that supports the
attention facilitating effect of heart rate deceleration.

69
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and Social Psychology, 57(1), 55–66. doi:10.1037/0022-3514.57.1.55
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M., Raichle, M. E., et al. (2008). The maturing architecture of the brain’s default
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America, 105(10), 4028–32. doi:10.1073/pnas.0800376105
Gatchel, R. J., & Lang, P. J. (1973). Accuracy of psychophysical judgments and
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183. doi:10.1037/h0034312

70
Gatchel, R. J., & Lang, P. J. (1974). Effects of interstimulus interval length and
variability on habituation of autonomic components of the orienting response.
Journal of Experimental Psychology, 103(4), 802–804. doi:10.1037/h0037208
Greicius, M. D., & Menon, V. (2004). Default-mode activity during a passive sensory
task: uncoupled from deactivation but impacting activation. Journal of cognitive
neuroscience, 16(9), 1484–92. doi:10.1162/0898929042568532
Gusnard, D. A., Akbudak, E., Shulman, G. L., & Raichle, M. E. (2001). Medial
prefrontal cortex and self-referential mental activity: relation to a default mode of
brain function. Proceedings of the National Academy of Sciences of the United
States of America, 98(7), 4259–64. doi:10.1073/pnas.071043098
Hastings, P. D., Zahn-Waxler, C., & McShane, K. (2006). We are, by nature, moral
creatures: Biological bases of concern for others. In M. Killen & J. G. Smetana
(Eds.), Handbook of moral development (pp. 483–516). Mahwah, NJ, US: Lawrence
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Immordino-Yang, M. H. (2010). Toward a microdevelopmental, interdisciplinary
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Immordino-Yang, M. H., McColl, A., Damasio, H., & Damasio, A. R. (2009). Neural
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Immordino-Yang, M. H., & Singh, V. (2011). Hippocampal contributions to the
processing of social emotions. Human brain mapping. doi:10.1002/hbm.21485

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72
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General Conclusion

75
Although emotion behavior is supported by biological mechanisms and shaped by
cultural ideals, no studies so far have investigated how cultural experiences and
biological predispositions together influence emotion related expressive behavior and
heart rate responses. In my dissertation, I measured natural expressive behavior, heart
rate responses and brain activity during social emotion processing in three groups of
participants that differed in cultural ideals for emotion arousal (Tsai, 2007): Chinese in
Beijing, second-generation East Asian American and American not of Asian descent in
Los Angeles. Resting cardiac vagal tone, a positive biological factor for emotion
regulation (Porges, Doussard-Roosevelt, & Maiti, 1994), was also taken into account.
Overall, findings from the first two chapters suggest that resting cardiac vagal
tone and cultural ideals about emotion arousal may shape emotion behavior through
different mechanisms. When participants reacted to the initial presentation of emotional
stimuli, vagal tone and cultural background independently predicted expressiveness, and
only vagal tone but not cultural background influenced heart rate response. It is possible
that while resting cardiac vagal tone modulates the initial emotion-related autonomic
arousal (Porges et al., 1994), cultural ideals act like a filter to modulate how much of the
underlying autonomic arousal one would display (Ekman, 1971; Matsumoto, 1990).
When participants were deliberating their emotional feelings, a cultural effect on
their heart rate arousal was found, suggesting that cultural modulation of emotion-related
autonomic arousal is a relatively slow process. Critically, none of these measures
modulated the participants' reported emotion strength, suggesting that the individual and
cultural differences found may reflect a response style that is not related to the strength of
subjective emotion experience. Results also suggest an intriguing interplay between

76
culture identity and a biological factor for emotion regulation: Higher resting cardiac
vagal tone may predispose bicultural individuals toward adopting culture values and
practices that encourage emotion moderation and calmness.
The third chapter examined the dynamic relationship between the heart and the
brain during social emotion processing. Participants’ heart rate deceleration while
viewing admiration- and compassion-inducing narratives predicted deactivation in the
default mode network. Heart rate deceleration is an autonomic response that facilitates
outward attention (Gatchel & Lang, 1973, 1974). The default mode network is a brain
system that supports internally focused process (Greicius & Menon, 2004; Raichle et al.,
2001). These findings provide insight into the neural processing that supports the
attention facilitating effect of heart rate deceleration, and suggest that with proper
application, heart rate deactivation can be used as a peripheral proxy for default mode
network activity. I also demonstrated that social emotions about other's physical states
evoked greater heart rate deceleration than those about other's mental states did, which is
consistent with the attention focuses associated with these two types of social emotion
processing.
The thesis makes several contributions. First, this is the first study to
simultaneously examine the effects of cultural ideals for arousal and resting cardiac vagal
tone on natural expressive behavior. Second, the study demonstrated the power of
examining heart rate response as a dynamic process, which leads to the first
demonstration of cultural effect on heart rate response during emotion processing. Lastly,
this is also the first study to relate a heart rate deceleration response during emotion
processing, which facilitates attention towards the environment, to activity in brain

77
systems involved in attention shifts between externally- and internally-focused
processing.
Electrocardiogram is a robust and easy to acquire physiological measure.
Comparing to fMRI, ECG is less restricting, more resistant to motion artifact and
portable, and yet still provides rich information about the psychophysiological and
neurobiological processes that are not observable from overt behavior. These features
make it a particularly useful measure in situations where brain scans are not available or
not suitable. Although it was not done in the current study, it is possible to acquire ECG
(especially with the available wireless technology) from participants who are behaving
freely and naturally. As the field of affective and cultural neuroscience moves forward to
incorporate ethnographic approaches and to investigate human behavior in social
interactions outside the restricted lab environment (Immordino-Yang, 2013; Seligman &
Brown, 2010), autonomic measures such as ECG can be a especially valuable tool.
This study has several limitations. First, this study focused on examining the
vagal modulation of the heart, and did not investigate sympathetic arousal during the
task. I was forced to make this choice because we did not have the equipment to measure
galvanic skin response (a response purely driven by the sympathetic nervous system) at
the Beijing Norm University site. On-going studies in the lab would examine the shifts in
balance between parasympathetic and sympatric activity during these processes. Second,
the current study cannot address the origin of the observed cultural effects. On-going
study in the lab started exploring the development of previously observed cultural effects
by studying adolescents from East Asian and Latino immigrant families in Los Angeles.

78
In conclusion, this study is my initial examination of the biological and cultural
effects on emotion behavior, incorporating three levels of analyses, including behavior,
psychophysiology and neuroimaging. These methodologies and their findings should
prove to be useful for further studies on biological and neurological basis of emotion and
its modulation by cultural experiences.

79
References
Ekman, P. (1971). Universals and cultural differences in facial expressions of emotion.
Nebraska Symposium on Motivation, 19, 207–283.
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physiological response amplitude. Journal of Experimental Psychology, 98(1), 175–
183. doi:10.1037/h0034312
Gatchel, R. J., & Lang, P. J. (1974). Effects of interstimulus interval length and
variability on habituation of autonomic components of the orienting response.
Journal of Experimental Psychology, 103(4), 802–804. doi:10.1037/h0037208
Greicius, M. D., & Menon, V. (2004). Default-mode activity during a passive sensory
task: uncoupled from deactivation but impacting activation. Journal of cognitive
neuroscience, 16(9), 1484–92. doi:10.1162/0898929042568532
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Neuroscientific With Ethnographic Approaches. Psychological Inquiry, 24(1), 42–
46. doi:10.1080/1047840X.2013.770278
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correlates of admiration and compassion. Proceedings of the National Academy of
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doi:10.1073/pnas.0810363106
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and Emotion, 14(3), 195–214. doi:10.1007/BF00995569

80
Porges, S. W., Doussard-Roosevelt, J. A., & Maiti, A. K. (1994). Vagal tone and the
physiological regulation of emotion. Monographs of the Society for Research in
Child Development, 59(2/3), 167–186.
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Shulman, G. L. (2001). A default mode of brain function. Proceedings of the
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doi:10.1073/pnas.98.2.676
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anthropology and cultural neuroscience. Social cognitive and affective neuroscience,
5(2-3), 130–7. doi:10.1093/scan/nsp032
Tsai, J. L. (2007). Ideal affect: Cultural causes and behavioral consequences.
Perspectives on Psychological Science, 2(3), 242–259. doi:10.1111/j.1745-
6916.2007.00043.x

Abstract (if available)

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University of Southern California Dissertations and Theses

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Creator Yang, Xiao-Fei (author)

Core Title Individual differences in heart rate response and expressive behavior during social emotions: effects of resting cardiac vagal tone and culture, and relation to the default mode network

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Neuroscience

Publication Date 09/11/2013

Defense Date 06/10/2013

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag admiration,compassion,culture,default mode network,heart rate response,natural expressive behavior,OAI-PMH Harvest,resting cardiac vagal tone

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Advisor Immordino-Yang, Mary Helen (committee chair), Damasio, Antonio (committee member), Tjan, Bosco S. (committee member), Wood, Wendy (committee member)

Creator Email xiaofei312@gmail.com,xiaofeiy@usc.edu

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