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Autonomic and behavioral responses of children with autism to auditory stimulation

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Autonomic and behavioral responses of children with autism to auditory stimulation

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AUTONOMIC AND BEHAVIORAL RESPONSES OF CHILDREN WITH
AUTISM TO AUDITORY STIMULATION

by
Chia-Chen Megan Chang

A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements of the Degree
Doctor of Philosophy
(OCCUPATIONAL SCIENCE)

Copyright 2009 Chia-Chen Megan Chang

ii

ACKNOWLEDGEMENTS

I would like to express my deepest appreciation and thanks to the following
advisers who have helped me with my dissertation. First of all, to my two
dissertation chairpersons: Dr. Diane Parham for her guidance, enthusiasm, and
patience during many revisions, and Dr. Florence Clark, for her wisdom, advice, and
encouragement in applying and writing for grants. I would also like to thank my
committee members: Dr. Erna Blanche who was always there to support, advise, and
inspire me with “what if ”; Dr. Chih-Ping Chou who was generously supportive and
shared his expertise in statistics; Dr. Michael Dawson who led me into the beauty of
psychophysiological world by opening the door for my research; Dr. Anne Schell
who gave unselfishly of her time to guide me in understanding the nuts and bolts of
psychophysiology. Finally, I would also like to extend my gratitude to Dr. Ann
Neville-Jan, who was in my guidance committee, for all of her support; to Dr. Julie
McLaughlin Gray and Dr. Bonnie Kennedy for their assistance and referrals in
subject recruitments; and to Dr. Sharon Cermak for her kind and patient advice
during the revision process.
I also want to thank the following clinics and therapists for allowing me to
recruit participants without whose invaluable assistance this work would not have
been completed. They are Center for Developing Kids, Dr. Susan Spitzer Clinic,
Gallagher Pediatric Therapy, Play to Learn Center at the Glendale Adventist
Hospital, Pediatric Therapy Network, and Therapy West. My special thanks go to the

iii

following therapists for their friendship and support: Jeanine Blanchard, Stefanie
Bodison, Catherine Crowley, Java DeLaura, Juliana Gutierrez, Janet Hifumi, Minako
Hongo, Lawrene Kovalenko, Traci Jones Martinez, Diane Soohoo, Shelby Surfas,
Aileen Tolentino, Melissa Tong, and Holly Wills.
Furthermore, I am greatly indebted to the following institutions and
foundations which provided valued media and allowed me to reach out to the parent
support group: Family Resources Center at the East Los Angeles Regional Center
(ELARC), Foundation for Disabled Youths (FFDY), Chinese Parents Association for
the Disabled (CPAD), Parent’s Place at the city of West Covina, and Talk About
Curing Autism (TACA).
My most sincere gratitude goes to the parents and children for generously
donating their family and leisure time for participation in this study. I can never
forget their concerns, support, encouragement, and assistance in spreading the word
about this study. Words are inadequate to express my heartfelt thanks. Each of them
will hold a special place in my memory.
I also owe many thanks to Debra Mandel for her advice on recruitment skills
and layout for flyers; to Olivia Forster, OSB, and Mary Ann Murphy for editing and
proofreading the previous drafts.
Last but not least, I want to take this opportunity to thank my friends and
family members for their support over the years. My aunt, Telan Hu, OSB, merits
special mention for her love, her constant encouragement, and her prompt responses
to my calls for help in editing my first draft. Countless thanks go to my sister Jocelyn

iv

for constantly inquiring about my graduation date and my brother Hank for his
technical support. Foremost, a heart full of gratitude goes to my parents, Helen and
William, for their sacrifice, endurance, and unwavering love in constantly
encouraging me to pursue my educational goals. To them, I dedicate this work.
Finally, my gratitude also goes to the California Foundation for Occupational
Therapy (CFOT) for supporting this research.

v

TABLE OF CONTENTS

ACKNOWLEDGEMENTS

ii
LIST OF TABLES

viii
LIST OF FIGURES

ix
ABSTRACT

x
CHAPTER 1: PROBLEM STATEMENT 1
Rationale and significance of the study 1
Research design 5
Research questions and hypotheses 5
Assumptions 6

CHAPTER 2: LITERATURE REVIEW 8
Overview 8
Diagnosis and prevalence in autism spectrum disorders (ASD) 8
Sensory modulation difficulties in children with autism 10
Over-responsiveness 14
Under-responsiveness 14
Sensory Seeking 15
Sensory responsiveness and occupation 16
Clinical research on sensory modulation difficulties in autism 18
Psychophysiology 21
Electrodermal activity (EDA) 21
Previous electrodermal activity findings on children with autism 25
Past Studies Using the Sensory Challenge Protocol (SCP) 30
Summary 32

CHAPTER 3: METHODOLOGY 33
Overview 33
Recruitment procedures 33
Subjects 35
Children with Autism 36
Typically-Developing Children 38
Instruments 40
Social Communication Questionnaire (SCQ) Lifetime Form 40
Sensory Processing Measure (SPM) Home Form 41
Psychophysiological measures 45

vi

Sensory Challenge Protocol (SCP) 45
Autonomic Variables 46
Laboratory Procedures 50
Data analysis 52

CHAPTER 4: RESULTS 57
Overview 57
Comparisons of Electrodermal Activity (EDA) Measures between
Children with Autism and Typically-Developing Children
57
Confounding effect of gender, age and ethnicity 60
Gender 61
Age 63
Ethnicity 66
Correlations among the EDA Variables 68
Summary of the EDA Findings 69
Analysis for the Sensory Processing Measure (SPM) Home Form 70
Comparisons of EDA Measures between Some Problems Range
and Definite Dysfunction Range in Children with Autism
73
Correlations among the SPM Variables and the EDA Variables 75
Summary of Results 76

CHAPTER 5: DISCUSSION 78
Summary of the Results 78
Influence of gender, age, and ethnicity on EDA findings 79
Consistency of EDA Findings with Previous Research 81
Relationship of Electrodermal Activity (EDA) to Behavioral
Reports
84
Auditory Behavioral Problems in Children with Autism 85
Study Limitations 86
Conclusions 89

REFERENCES 90

APPENDIX

Appendix A: Diagnostic criteria for Autistic Disorder

98
Appendix B: All Auditory Questions Grouped by Patterns

100
Appendix C: Distribution Plots for EDA variables

102
Appendix D: Intercorrelations among all EDA Variables 110

vii

Appendix E: T-tests for all EDA Measures between Some
Problems Range and Definite Dysfunction Range in
Children with Autism

112
Appendix F: Intercorrelations between the SPM Variables and all
EDA Variables

114
Appendix G: Glossary

117
Appendix H: Subject Recruitment Flyers

121
Appendix I: Parental Consent and Child Assent Form

124
Appendix J: Demographic Information Form

131
Appendix K: Social Communication Questionnaire (SCQ),
Lifetime Form

135
Appendix L: Sensory Processing Measure (SPM) Home Form

138
Appendix M: Questionnaire of the Four Additional Auditory
Questions
142

viii

LIST OF TABLES

Table 1: Descriptors and definitions for the three types of responsiveness

16
Table 2: Definitions and typical values for electrodermal measures

25
Table 3: Services Received at the Time of the Recruitment in Children with
Autism

38
Table 4: Demographic Information by Study Group

40
Table 5: Comparisons of EDA Measures for Children with Autism (AD)
and Typically-Developing Children (TD)

60
Table 6: Comparisons of EDA Measures between Genders in the TD group

61
Table 7: Comparisons of EDA Measures between the AD and TD Groups
for the Boys Only

63
Table 8: ANOVA between the Age Groups and Study Groups

65
Table 9: ANOVA between the Ethnicity Groups and Study Groups

67
Table 10: Intercorrelations among Six EDA Variables for the AD and TD
Groups

69
Table 11: Sensory Processing Measure (SPM) Home Form Interpretive
Ranges for the Study Groups

71
Table 12: Sensory Processing Measure (SPM) Home Form Scores for the
Study Groups

72
Table 13: Intercorrelations among the SPM Variables for the AD and TD
Groups

73
Table 14: T-tests for the Selected EDA Measures between Some Problems
Range and Definite Dysfunction Range in Children with Autism

74
Table 15: Intercorrelations Between the SPM Variables and the EDA
Variables for the AD and TD Groups

76

ix

LIST OF FIGURES

Figure 1: Components of an Skin Conductance Response

24
Figure 2: The Sensory Challenge Protocol

52

x

ABSTRACT

This study investigated the relationship between autonomic reactivity and
behavioral responses to auditory stimulation in 22 high-functioning children with
autism (AD) and twenty typically-developing children (TD). A primary purpose was
to examine whether the AD and TD groups differed with respect to autonomic
activity at rest and following auditory stimulation. An additional purpose was to
investigate whether the severity of behavioral difficulties with auditory stimuli in
everyday life, as reported by parents, was associated with electrodermal responses to
auditory stimuli presented in a controlled laboratory setting. Electrodermal activity
(EDA) was measured at rest and in response to two auditory stimuli, a tone and a
siren, using the Sensory Challenge Protocol. Behavioral difficulties were measured
with the Sensory Processing Measure (SPM) Home Form. T-tests were applied to
EDA variables to detect differences between the two study groups. Confounding
effects of gender, age, and ethnicity on EDA findings were also analyzed.
Associations between EDA measures and SPM scores were determined using
Pearson correlation procedures.
Results showed that the AD group had higher resting EDA levels and
stronger EDA reactivity to auditory stimuli than the TD group. These findings
suggest that the children with autism generally had higher arousal levels and were
more physiologically reactive to auditory stimuli than the typically-developing
children. Parent responses on the SPM Home Form showed that 90% of the

xi

participants with autism had behavioral difficulties with auditory stimuli in naturally
occurring situations. Correlations between EDA and SPM measures indicated that
more severe behavioral difficulties with auditory stimuli were associated with higher
arousal levels and stronger physiological reactions to auditory stimuli. Overall,
results suggested that high arousal levels may underlie some behavioral problems
that children with autism experience in reaction to auditory stimuli in natural
environments.

1

CHAPTER 1: PROBLEM STATEMENT

The purpose of this study was to examine differences of behavioral and
autonomic nervous system responses to auditory stimuli in children with autism, as
measured by electrodermal activity (EDA) and parental reports. Specifically, this
research used the laboratory-based Sensory Challenge Protocol (SCP) (Miller et al.,
1999; Miller et al., 2001) to investigate patterns of sympathetic nervous system
responses to auditory stimuli among high functioning children with autistic disorder.
Moreover, the Sensory Processing Measure (SPM) Home Form (Parham, et al., 2007)
was used to measure parental perceptions of the behavior of these children in response
to sensory stimuli in everyday, natural environments. Using multiple t-test
comparisons, the EDA measures were analyzed to compare physiological differences
between children with autism and typically-developing children. Additionally,
associations between behavioral responses to auditory stimuli, as measured by the
SPM, and EDA variables were investigated with Pearson correlations.

Rationale and Significance of the Study
There has been very little research on the incidence of sensory problems in
children; however, sensory modulation difficulties are reported by parents of
otherwise typically-developing children as well as children with a variety of
developmental and learning disorders (Ahn et al., 2004; Ayres, 2005; Baranek et al.,
2006; Goldsmith et al., 2006). Sensory modulation is defined as a complex process by

2

which neural messages that convey information about the intensity, frequency,
duration, complexity, and novelty of sensory stimuli are adjusted by the central
nervous system (CNS) to enable adaptive behavior (Miller & Lane, 2000; Parham &
Mailloux, 2005). Children who have sensory modulation difficulties are hindered from
successfully performing daily activities, which provide them with a means to learn
skills, develop relationships, and meet biological needs that will support health and
well being (Parham & Mailloux, 2005; Wilcock, 1998).
The clinical literature suggests that three distinct patterns of sensory
modulation difficulties are commonly identified in clinical assessment: over-
responsiveness, under-responsiveness, and sensory seeking (Parham & Mailloux,
2005). Over-responsiveness refers to a state in which “the individual is disturbed by
ordinary sensory input and reacts defensively to it,” whereas under-responsiveness
describes a condition in which “the individual tends to ignore or be relatively
unaffected by sensory stimuli to which most people respond” (Parham & Mailloux,
2005, p. 410). Sensory seeking describes a person who “actively seeks out particular
kinds of sensations at higher frequencies or intensities than is typical” (Parham &
Mailloux, 2005, p. 410).
Sensory modulation difficulties are common among children with autism
(Ayres & Tickle, 1980; Baranek, 2002; Baranek et al., 2006; Dunn, Myles, & Orr,
2002; Kientz & Dunn, 1997; LeCouteur et al., 1989; Leekam et al., 2006; Ornitz,
Guthrie, & Farley, 1977; Rogers, Hepburn, & Wehner, 2003; Rogers & Ozonoff, 2005;
Volkmar, Cohen, & Paul, 1986). Children with autism often demonstrate abnormal

3

responses across multiple sensory domains; for instance, a child may be over-
responsive to both auditory and tactile stimuli (Ayres & Tickle, 1980; Baranek, 2002;
Leekam et al., 2006; Rogers, Hepburn, & Wehner, 2003; Rogers & Ozonoff, 2005).
Among the domains of sensory modulation difficulties, audition is the most
often reported sensory system that is affected, in terms of behavioral manifestations.
Drawing from parental reports and clinical observations, the percentage of children
with autism who have abnormal responses to auditory stimuli are estimated to range
from 24% to 100% (Baranek, Foster, & Berkson, 1997; Gomes et al., 2004; Greenspan
& Wieder, 1997; Volkmar, Cohen, & Paul, 1986).
Abnormal autonomic responses to auditory stimulation have been studied
using electrodermal measures, but findings have not been consistent. Some researchers
reported that children with autism demonstrated over-responsiveness to auditory
stimuli (Barry & James, 1988; James & Barry, 1984; Palkovitz & Wiesenfeld, 1980),
whereas other researchers discovered that children with autism were under-responsive
or non-responsive to auditory stimuli (Stevens & Gruzelier, 1984; Van Engeland,
1984). Researchers have not previously used electrodermal measures to determine if a
distinct autonomic pattern exists that is associated with auditory sensory seeking
behaviors of children with autism.
Overall, there is a relative scarcity of research that examines the possibility of
distinct subgroups of autonomic sensory responses among children with autism, even
though distinct behavioral responsiveness patterns have been noted in both clinical and
parental questionnaire data. Therefore, the purpose of this study was to explore

4

autonomic and behavioral patterns of sensory modulation difficulties among children
with autism. The study used measures of sympathetic nervous system (SNS) and
behavioral responses to auditory stimuli to examine whether autonomic activity in
children with autism differs from that of typically-developing children. The study also
addressed whether autonomic responses to auditory stimuli in a laboratory were
related to behavioral responses to auditory stimuli occurring in their everyday, natural
environments. SNS responses were measured through recordings of skin conductance,
i.e., electrodermal activity (EDA), during the Sensory Challenge Protocol (SCP),
which was administered in a laboratory setting. Behavioral patterns of response to
auditory stimuli were measured using a standardized parent questionnaire, the Sensory
Processing Measure (SPM) Home Form.
This study provided empirical evidence regarding atypical autonomic
responses to auditory stimulation in the children with autism, and furthermore
provided data to show a relationship between behavioral responses in everyday life
and autonomic profiles. Findings had implications for clinical practice. For example,
this and other larger studies may inform the design of clinical interventions that are
tailored to the child’s physiological and behavioral profile, and therefore are more
effective than existing interventions. Findings such as these also may help health and
education providers to plan appropriate school and home environments and daily
routines that will support the child’s comfort, engagement, and success in meaningful
occupations.

5

Research Design
This study investigated group differences in EDA at rest and in response to
auditory stimuli. In addition, associations between EDA and behavioral measures were
compared for children with and without autism. Participants were 22 children with
diagnoses of high-functioning autism, aged 5 to 12 years, as well as 20 typically
developing children across the same age range. In order to measure the children’s
electrodermal responses to sensory stimuli, a laboratory-based Sensory Challenge
Protocol was employed. Parental perceptions using the Sensory Processing Measure
(SPM) Home Form were also obtained. The electrodermal and behavioral data were
used in a series of comparisons between the children with autism and the typically-
developing children. Additionally, Pearson correlations were generated to examine the
association between autonomic and behavioral measures for each group.

Research Questions and Hypotheses
Research Question 1. Are the autonomic responses to auditory stimuli different for
children with autism compared to typically-developing children?
Hypothesis 1: Children with autism will have different arousal levels at rest, as
measured by the EDA when no stimuli are being administered, than the
typically-developing children.
Hypothesis 2: Children with autism will demonstrate different levels of
reactivity to auditory stimulation, as measured by EDA following
administration of auditory stimuli, than the typically-developing children.

6

Hypothesis 3: Children with autism will habituate to auditory stimuli at a
different rate than the typically-developing children, as measured by number of
trials on which the child responds to a repeated stimulus before returning to
baseline level of arousal.
Research Question 2. For children with autism, are autonomic responses to auditory
stimuli in a laboratory setting related to behavioral responses to auditory stimuli
occurring in their everyday, natural environments?
Hypothesis 4: EDA measures of resting arousal level will correlate
significantly with SPM measures of severity of behavior problems related to
auditory stimuli.
Hypothesis 5: EDA measures of reactivity to auditory stimuli will correlate
significantly with SPM measures of severity of behavior problems related to
auditory stimuli.

Assumptions
It is assumed that:
1. The children who were recruited into the autism study group were accurately
diagnosed.
2. The Sensory Processing Measure (SPM) Home Form provides a valid measure of
child behavioral responses to sensory experiences in natural environments.

7

3. The Sensory Challenge Protocol (SCP) enables a researcher to gather
psychophysiological data that accurately represent the child’s sympathetic activity
and responsiveness in ordinary conditions.

8

CHAPTER 2: LITERATURE REVIEW

Overview
This chapter reviews previous clinical and psychophysiological research
regarding sensory responsiveness in autistic children. The chapter begins with a
review of the diagnosis and prevalence of autism spectrum disorder (ASD) and then
addresses sensory processing difficulties in autistic children as related to their daily
activity as obtained from parental reports and to their responses to auditory stimulation
as measured by electrodermal activity (EDA). The Sensory Challenge Protocol (SCP)
will be introduced and recent research utilizing the SCP will also be discussed.

Diagnosis and Prevalence of Autism Spectrum Disorders (ASDs)
Autism spectrum disorder (ASD) is a group of neurodevelopmental syndromes
that are also known as pervasive developmental disorders (PDDs) (American
Psychiatric Association, 2000). The term ASD, however, is a more recent term used
“in order to recognize the commonality of these conditions with the paradigmatic
disorder, autistic disorder” (First & Tasman, 2004, p.127). Children with ASDs have
common features that include marked impairments in social interaction and language
use, restricted interests, and repetitive behaviors. There are five disorders grouped
under ASD: autistic disorder, Asperger’s disorder, Rett’s disorder, childhood
disintegrative disorder, and pervasive developmental disorder not otherwise specified
(PDD-NOS). This study will focus only on autistic disorder.

9

Autistic disorder has been categorized in the diagnostic systems of both the
ICD-10 (World Health Organization, 1992) and the DSM-IV-TR (American
Psychiatric Association, 2000), although the DSM-IV-TR is more commonly used in
the United States. According to the DSM-IV-TR (see Appendix A), autistic disorder is
characterized by behavioral abnormalities which cause severe social interaction and
communication problems, deficits in language skills, and a markedly restricted,
repetitive, or stereotyped repertoire of behaviors accompanied by limited interests and
activities. Other indicators are developmental delays in language and speech functions
(American Psychiatric Association, 2000). Children with autism have tremendous
difficulties engaging in the give-and-take of every-day human interaction and
interpreting abstract concepts such as jokes and the thoughts and feeling of others
(National Institute of Mental Health, 2004). They very often show no interest in social
interaction, avoid eye contact, and seem to prefer being alone. They might spend hours
on a certain behavior such as lining up trains or cars in a certain way rather than using
them for pretend play. Changing the routine may upset them and can be extremely
disturbing (National Institute of Mental Health, 2004).
Since autism was first described and named by Dr. Leo Kanner (1943), who
observed a group of children with similar social and communicative problems,
research on autism, and therefore our knowledge of autism, has steadily increased.
Based on a review of 30 epidemiological surveys published between 1966 and 2001,
the worldwide prevalence of Pervasive Developmental Disorders (PDD) ranged from
5.2 to 72.6 in every 10,000 (Fombonne, 2003). In the latest report by the Center for

10

Disease Control and Prevention’s (CDC) Autism and Developmental Disability
Monitoring Network (ADDM network), surveillance data were collected from
children aged 8 years identified as having an ASD from 14 sites in the United States
(CDC, 2007). The prevalence rate for ASD was 6.6 per 1,000 in 2002, that is,
approximately 1 in 150 children (CDC, 2007). In two population-based studies
conducted by CDC in Township, NJ, and Atlanta, GA, in 2003-2004, the prevalence
rate of children with ASD was 3.4 and 6.7 per 1,000 (Schieve, Rice, Boyle, Visser, &
Blumberg, 2006). In the state of California, the prevalence rate of autism for children
enrolled with Department of Developmental Services and the Regional Centers
(DDS/RC) has increased from 5.8 to 14.9 per 10,000 in the 8 years from 1987 to 1994
(Croen et al., 2007). It seems that the prevalence rate is still increasing; therefore,
understanding children with autism has become increasingly important.

Sensory Modulation Difficulties in Children with Autism
The diagnostic criteria for autistic disorder in the DSM-IV-TR do not include
sensory modulation difficulties as a required feature, even though they are fairly
common in children with autism. Unusual levels of response to sensory stimuli in
autistic children, who are highly attuned or even painfully sensitive to certain sounds,
textures, tastes and smells, have been one of the most frequently reported behaviors by
parents or caregivers (National Institute of Mental Health, 2004). That is, aversive
responses to ordinary stimuli, preoccupations with sensory features of objects, and
unusual reactions to sensory stimuli have been commonly reported in related literature

11

(Baranek, 2002; Baranek et al., 2006; Dunn, Myles, & Orr, 2002; Kientz & Dunn,
1997; LeCouteur, et al., 1989; Leekam et al., 2006; Ornitz, Guthrie, & Farley, 1977;
Rogers, Hepburn, & Wehner, 2003; Rogers & Ozonoff, 2005; Volkmar, Cohen, &
Paul, 1986). The sensory symptoms (abnormal responses to sensory stimuli) cross
multiple sensory domains in children with autism (Baranek, 2002; Leekam et al., 2006;
Rogers, Hepburn, & Wehner, 2003; Rogers & Ozonoff, 2005).
In order to describe these sensory symptoms in children with developmental
disorders, Rogers, Hepburn, and Wehner (2003) used parental reports on the Short
Sensory Profile (Dunn, 1999) with four groups of children – those with autism (N=26),
fragile X syndrome (N=20), developmental disabilities of mixed etiology (N=32), and
typically-developing children (N=24). Results revealed that children with autism had
significantly higher scores (indicating greater severity of problem behaviors) on
taste/smell sensitivity than all three other groups and significantly higher scores on the
categories of tactile sensitivity and auditory filtering than children in the
developmental disabilities and typically-developing groups. Similar results produced
by Leekam et al. (2006) showed that children with autism had sensory symptoms in
multiple sensory domains. They evaluated 16 children with autism spectrum disorders
(ASD) and 15 typically-developing children, aged 34-140 months. Sensory symptoms
in children with ASD were significantly different from those of the controls,
particularly with regard to visual, smell/taste and mixed proximal (smell, taste, touch,
and kinesthetic) senses.

12

Among all abnormal responses to stimuli, auditory symptoms are the most
noticeable and commonly studied because they are directly related to language. For
many young children with autism, the first reason for referral is often to evaluate
hearing impairment because of parental concern that the child does not respond to
people’s voices (Wing, 1966).
The percentages of the children with autism with abnormal responses to
auditory stimuli vary across studies, ranging from 24% to 100%. Greenspan and
Wieder (1997) found that in a review of 200 clinical charts over an 8-year period,
100% of children with autism between 22 months and 4 years of age had auditory
processing problems according to diagnostic workup data in the children’s charts.
However, it is not clear how the researchers determined that the children had auditory
processing problems, which probably included receptive language delays. The authors
also noted that Oversensitivity to sensation such as touch and sound was found in 19%
of children. Out of this 19%, 36% of children manifested a combination of over- and
under- responding (Greenspan & Wieder, 1997). Volkmar, Cohen, and Paul (1986)
discovered from parental reports that 68% of their study participants were very often
or almost always disturbed by noises. Moreover, Baranek, Foster, and Berkson (1997),
using teachers’ reports on a 54-item questionnaire, the Stereotypical Behavior
Checklist, SBC, revealed that approximately 30% of 88 children with developmental
disabilities such as mental retardation, autism, and a variety of syndromes were over-
responsive to auditory stimuli. Additionally, Gomes et al. (2004) reported that 24% of
their 46 participants, including children and teenagers 5-19 years old with autistic

13

spectrum disorder, displayed oversensitive responses to sound. Such rate differences
across studies could be due to differences in samples, such as age when recruited,
diagnosis, or inclusion and exclusion criteria, or differences in data collection
procedures, such as parental or teacher’s report, chart review, or instruments used for
evaluation. Volkmar, Cohen, and Paul (1986) used DSM-III criteria for the diagnosis
of participants, whereas other studies used the DSM-IV. Moreover, reports from
teachers and caregivers and chart reviews may be affected by possible bias.
Nevertheless, such information informs us that auditory processing difficulties are
commonly seen in children with autism.
All such unusual sensory responses can be considered indicators of sensory
modulation difficulty. Sensory modulation refers to a state of regulation in the central
nervous system (CNS) that generates appropriate graded responses to incoming
stimuli rather than under- or over-response to them (Ayres, 2005; Parham & Mailloux,
2005). The neural messages processed by the CNS convey information about the
intensity, frequency, duration, complexity, and novelty of sensory stimuli (Miller &
Lane, 2000).
Children with sensory modulation difficulty lack the ability to regulate and
organize responses to sensations in a graded and adaptive manner. Sensory modulation
difficulties are described in the clinical literature as falling into three common types:
over-responsiveness, under-responsiveness, and sensory seeking. (Parham & Mailloux,
2005) Such patterns are defined below and are summarized in Table 1.

14

Over-responsiveness
Over-responsiveness refers to a state of exaggerated and aversive response to
sensory stimuli (Baranek et al., 2006). In this state, an individual feels threatened by
ordinary sensory input and responds to it negatively (Parham & Mailloux, 2005). For
example, Temple Grandin (1995), an autistic person, told about her struggle with
sounds. She explained how loud noises made her feel pain as if a dentist were actually
drilling a nerve and how her roommate’s hair-dryer sounded like a plane taking off.
Similarly, another autistic child, Georgiani, would run to the corner of the house and
rock back and forth whenever he heard the phonograph (Stehli, 1991). Such examples
of exaggerated and aversive responses are classic indicators of over-responsiveness.
Thus, parents of autistic children with over-responsiveness may often see their
children respond in a extreme manner to an ordinary tone or sound.
Under-responsiveness
In contrast to over-responsiveness, under-responsiveness, also known as under-
responsivity or sensory dormancy, refers to a state in which an individual
demonstrates difficulties attending to or registering relevant sensory information
(Parham & Mailloux, 2005; Lai, Parham, & Johnson-Ecker, 1999). Autistic children
often lack response to sound or sufficient intensity of response to sensory stimuli
compared to typically-developing children (Baranek et al., 2006). Rapin (1991)
reported that, in clinical reports, autistic children often failed to respond when called,
and they could not interpret tone of voice adequately. Another clinical report showed

15

that some autistic children do not have observable responses to sirens. This has
aroused parents’ and caregivers’ safety concerns (Parham & Mailloux, 2005).
It is not uncommon to see autistic children exhibit more than one pattern across
different sensory domains; they may lack responses to some situations but react
defensively in other situations (Parham & Mailloux, 2005). Baranek et al. (2006) using
caregivers’ report of sensory behaviors on the Sensory Experiences Questionnaire
(SEQ) showed that under- and over-responsiveness coexist in some autistic children
between 5 months and 6 years old. This will be discussed again later in the clinical
research review.
Sensory Seeking
A third kind of sensory modulation difficulty, sensory seeking, refers to the
behavior of individuals who actively and frequently seek out sensory stimuli. It is
defined as an “individual actively seeks out particular kinds of sensations at higher
frequencies or intensities than is typical” (Parham & Mailloux, 2005, p. 410). This
pattern is sometimes considered as a form of under-responsiveness because the child
does not respond to intense sensory stimulation to the same degree that a typically-
developing child does (Parham & Mailloux, 2005). For instance, some sensory
seeking children would rather stomp than walk; they may fall on purpose or bump into
objects or people, or clap their hands forcefully (Parham & Mailloux, 2005). Such
behaviors in autistic children may disrupt their social interaction.

16

Table 1
Descriptors and definitions for three types of responsiveness

Over-
responsiveness
Under-
responsiveness
Sensory
Seeking
Descriptors Overreactive,
Sensory
defensiveness
Underreactive,
Sensory dormancy
Sensory seeking

Definition Overwhelmed by
ordinary sensory
input and reacts
negatively to it
Lack of response to
intense sensory
stimulation
Registers sensory
stimulation, but
constantly seeks out
more, that is, seeks
varied, novel and
intense sensations

Sensory Responsiveness and Occupation
Sensory modulation difficulties are commonly seen in children with autism
and cause great disruption to family life as well as inhibit a child’s engagement in
occupations. A child spends much time with family, which typically provides the child
with rich sources for learning and development (DeGrace, 200). However, in taking
care of a child with autism who has behavioral challenges, a family has to put their
lives “on hold” in order to meet the child’s special demands (DeGrace, 2004, P. 534).
This has a great impact on the family as family routines have to revolve around the
child with autism, and “there are no easy answers for negotiating it with a child with
autism” (DeGrace, 2004, P. 547). Parents of children with autism often report feeling
stressed and robbed of having typical family activities and rituals (DeGrace, 2004;

17

Larson, 2006). An example was provided by a parent of a son with autism (DeGrace,
2004),
It was such a nightmare, because [Chip] did not want to go in the ocean, he
didn’t want to go onto the dunes…. We had to go to the community, find a
community pool that was a camp… it was miserable… it was a nightmare…we
came home early because he was freaking out, screaming, writhing…we
left…it was a nightmare, it was really a nightmare. It could’ve been the most
fabulous, and I visualize sitting on the beach, two beach chairs, Chip playing in
the sand, you know what I mean, a typical day, like families, I know families
that go to the beach and they spend the day at the beach from early in the
morning until late at night and they eat meals on the beach.” (p. 546)

Not only may a family be deprived of some meaningful family activities and
rituals, but also the child with autism, due to his/her sensory processing difficulties,
may be deprived of engaging in occupations, which is a primary way of learning and
developing. That is a particular cause for concern among occupational scientists
because humans are occupational beings as a result of their biological and cultural
evolution (Wilcock, 1998). In other words, all human beings need occupations, which
are pursued intentionally and meaningfully (Parham, 2002) in order to meet an
individual’s needs. Fidler and Fidler (1978) also noted that “doing is viewed as
enabling the development and integration of the sensory, motor, cognitive, and
psychological systems; serving as a socializing agent, and verifying one’s efficacy as a
competent, contributing member of one’s society” (p.305). This is true even in
children, though it takes the form of play, learning, and social interaction. An
occupation is not only purposeful and meaningful, but also embedded in multiple
dimensions that occur in temporal, spatial, and socio-cultural contexts (Parham, 2002).

18

Clinical Research on Sensory Modulation Difficulties in Autism
In the past, in order to understand sensory processing difficulties in autistic
children, researchers have commonly studied this issue by using sensory processing
parental questionnaires regarding child behavior, such as the Diagnostic Interview for
Social and Communication Disorders (DISCO) (Leekam et al., 2006), Evaluation of
Sensory Processing (ESP) (VerMaas Lee, 1999), Sensory Profile (Dunn, 1994), Short
Sensory Profile (Dunn, 1999), and Sensory Experience Questionnaire (previously
named the Sensory Supplement Questionnaire) (Baranek, 1999b).
Leekam et al. (2006) used the Diagnostic Interview for Social and
Communication Disorders (DISCO) to interview parents to elicit detailed information
about a wide range of sensory responses in children and adults with autism. The
DISCO contains 21 items related to sensory abnormality, which were categorized into
three groups: auditory (3 items), visual (4 items), and proximal (e.g., touch, taste,
smell, kinaesthetic) (14 items). This study found that not only do autistic children have
sensory symptoms in multiple domains, but also both autistic children’s and adults’
sensory abnormalities were pervasive and persistent across age and ability.
Specifically, 94% of low functioning (N=16) and high (N=17) functioning autistic
children between 33-140 months had sensory symptoms, but only 33% of typically-
developing children (N=15) exhibited these phenomena. Furthermore, the high
functioning autism group in this study had more sensory symptoms and was more
affected across multiple sensory domains than a language impairment group (Leekam
et al., 2006).

19

VerMaas Lee’s (1999) research involved ratings on the Evaluation of Sensory
Processing (ESP), Research Version 3, the precursor to the Sensory Processing
Measure (SPM), Home Form to be used in this study. Parents of 31 typically-
developing children as well as those of 41 children with autism or Asperger’s disorder
completed the ESP. ESP is a sensory history questionnaire used to obtain parents’
perceptions of frequency of specific behaviors. It includes a total of 185 items grouped
according six different sensory systems: auditory, gustatory/olfactory, propioceptive,
tactile, vestibular, and visual. This study showed that even though autistic children
have differences in all sensory domains compared to typically-developing children,
auditory, tactile, vestibular, and seeking intense proprioceptive input are the most
significant (VerMaas Lee, 1999).
Similarly, Bettison (1996) reported that children ages 3-17 years old with
autistic disorder or Asperger’s disorder are sensitive to sounds and have difficulty with
auditory processing. These children were randomly selected into experimental and
control groups. The experimental group received auditory training developed by
Berard (1993) while the control group listened to selected, unmodified music. The
results showed that both groups demonstrated significant improvements in behavior
and severity of autism, suggesting that both forms of music may have a beneficial
effect for children with autism (Bettison, 1996).
In addition, Rogers, Hepburn, and Wehner (2003) studied four groups of
children aged between 12-50 months: those with autism (N=26), fragile X syndrome
(N=20), developmental disability of mixed etiology (N=32), and typically developing

20

children (N=24). The scores from children with autism on the Short Sensory Profile
scale for under-responsive, sensory seeking, and poor auditory processing indicated
more significant problems than typically developing children. This study also
indicated that the overall developmental level and IQ were not related to abnormal
sensory reactivity in children with autism and general developmental disorders
(Rogers, Hepburn, & Wehner, 2003).
Baranek et al. (2006) administered the Sensory Experience Questionnaire to
258 caregivers of children between 5-80 months in five diagnostic groups: those with
autism, PDD, DD/MR, other DD, and typically-developing. They demonstrated that
69% of children with autism have increased sensory symptoms compared to typically-
developing children as well as to those with developmental delays, especially on the
under-responsiveness subscales. More specifically, such under-responsiveness in both
social and non-social contexts differentiates the autism group from the controls. This
result indicates that regardless of the context, the uniqueness of this pattern prevails in
children with autism. Moreover, among these autistic children, 56% were over-
responsive, whereas 63% were under-responsive. This study also noted that 38% of
these children also manifested both symptoms of under-responsiveness and over-
responsiveness (Baranek et al., 2006).
All of the aforementioned studies, no matter what questionnaires are used,
suggested that children with autism spectrum disorders have observable abnormal
auditory responsiveness, with respect to behavior in everyday environments. Despite
the fact that each study recruited children with different age spans, the results across

21

studies showed that children with autism have distinguishable difficulties with
auditory stimuli that indicate over-, under-responsiveness and sensory seeking. In this
study, psychophysiological measures were used to corroborate the parent observations
regarding predictable patterns of sensory responsiveness in children with autism.

Psychophysiology
Electrodermal Activity (EDA)
As shown in the previous section of this proposal, at the behavioral level,
parental and teachers’ reports very often describe unusual responses to sensory stimuli
in autistic children. However, physiological findings are more variable. Additionally,
it is often presumed that the behaviors related to abnormal sensory stimuli are caused
by physiological dysfunction; nevertheless, research on this issue is scarce. In order to
better understand the cause of these behaviors and to explore different patterns of
responsiveness, in this study psychophysiological measures of electrodermal activity
in children with autism, therefore accentuating the connection between behavior and
psychophysiology.
In the past, researchers have used the measure of electrodermal activity (EDA,
previously named the galvanic skin response) to observe skin conductance level
changes in response to stimuli; however, no studies focused on distinct patterns of
sensory and behavioral responsiveness in autistic children. EDA measures skin
conductance changes when the sympathetic nervous system is excited by sensory
stimuli to activate the eccrine sweat gland. Specifically, silver-silver chloride

22

electrodes, which pass a very small current, are placed on the thenar and hypothenar
eminences of the non-dominant hand. The electrode cups are filled with saline
electrode paste, which is the conductive medium between the electrode and skin. The
EDA recording shows that the sympathetic nervous system responds to the
environment by increasing eccrine sweat gland activity (Hugdahl, 1995; McIntosh et
al., 1999). The changing electrical conductance of the skin, which is an objective and
quantifiable indicator, offers empirical evidence for sensory reactivity.
Tonic skin conductance level (SCL) and the phasic skin conductance response
(SCR) comprise two aspects of EDA (Dawson, Schell, & Filion, 2007). SCL reflects a
person’s tonic sympathetic activation in any situation, including at rest without
stimulation, whereas the SCR is a phasic response elicited by a given stimulus. The
orienting response (SCR-OR) is an event-related response that occurs between 0.8-4
seconds following onset of a stimulus. However, if SCR occurs in the absence of an
external stimulus, it is referred to as a non-specific SCR (NSR). An NSR can occur
during rest or during an interstimulus interval. By operational definition, SCR that
does not appear between 0.8-4 seconds after the onset of a stimulus is considered a
NSR. An NSR, like SCL, reflects tonic arousal as it is thought to be the manifestation
of spontaneous fluctuations in background arousal level (Dawson, Schell, & Filion,
2007).
The SCR is considered a component of the orienting response (OR), which is
described a state of attention shifting to a novel stimulus to enhance sensory
processing (Hugdahl, 1995; Stern, Ray, & Quigley, 2001; Sokolov, 1963). The OR has

23

been called the “what is it?” response (Stern, Ray, & Quigley, 2001, p. 57). The
orienting response is induced by the lateral frontal cortex when attention is focused on
a novel situation. The lateral frontal cortex is part of the orienting-arousal system,
which also includes limbic structures (amygdala and hippocampus), and the reticular
formation (Hugdahl, 1995). Besides the SCR, some other major components of the
OR include: decreased irrelevant motor activity, delayed respiration, and heart rate
deceleration (Stern, Ray, & Quigley, 2001).
A reliable characteristic of the orienting response is that it habituates with
repeated presentations of a stimulus (Hugdahl, 1995). Habituation means that a person
has adapted to a familiar, predictable stimulus and no longer responds to it. In the
Sensory Challenge Protocol (SCP), habituation is operationalized as the last stimulus
to which the child responds, which is defined as being immediately followed by two
consecutive trials with no response. Details regarding the SCP will be explained in
chapter 3.
Figure 1 illustrates the components of SCR, which include latency, rise time,
amplitude, and half-recovery time (Dawson, Schell, & Filion, 2007). Latency refers to
the period between the time the stimulus is given and the initiation of the response.
Rise-time is the interval between the onset of a response and the peak. Amplitude is
the difference in skin conductance between the onset and the peak of the response.
Half-recovery time is defined as the interval between the peak of response and the
point of half-recovery amplitude (Dawson, Schell, & Filion, 2007).

24

Table 2 provides the definitions and typical values of the major EDA
components (Dawson, Schell, & Filion, 2007). Tonic skin conductance level (SCL) is
typically between 2-20 μS. Nonspecific skin conductance response (NSR), also known
as spontaneous response, occurs 1-3 times per minute. Amplitude is usually between
0.2-1.0 μS.

Figure 1. Components of a Skin Conductance Response (Source:
Dawson, Schell, & Filion, 2007, P. 165) Used with permission

25

Table 2
Definitions and Typical Values for Electrodermal (EDA) Measures

Measure Definition Typical Values
SCL Tonic level of electrical conductivity of skin 2-20 μS

Frequency of
NSRs
Number of SCRs in absence of identifiable
eliciting stimulus

1-3 per min
SCR-Latency Period between the time the stimulus is given
and the initiation of the response

1-3 sec
SCR-Rise Time Interval between the onsets of the response to
the peak

1-3 sec
SCR-Amplitude Increase of skin response during each
stimulation

0.2-1.0 μS
SCR-Half
Recovery Time
Interval between the peak of sensory response
and the point of half recovery of amplitude

2-10 sec
SCR-Habituation First lack of response to a specific stimuli
followed by two consecutive trials with no
response
2-8 stimulus
presentations

Previous Electrodermal Activity (EDA) Findings on Children with Autism
Unusual sensory responses in children with autism have been reported using
psychophysiological measurements in the past, but the results have been inconsistent.
Palkovitz and Wiesenfeld (1980) recruited 10 children with autism between the ages
of 5.8 and 10 years and 10 typically-developing children of the same chronological
age to compare their responses to three types of auditory stimuli. This study involved
using stimuli which included a 5-sec 500-Hz pure tone, a spoken phrase (e.g., “Listen
Note. Adapted from: Dawson, Schell, & Filion, 2007, P. 165, used with permission

26

to me, [subject’s first name]”), and a spoken nonsense phrase (e.g., sponzel nirem,
shern). Each stimulus type was presented five times that constituted an order, and six
counterbalanced orders were arranged to control for a sequence effect. The results
revealed that autistic children demonstrated a significantly higher mean skin
conductance level at the onset of each stimulus and higher non-specific response
frequencies during inter-trial intervals than that of the normal group, indicating that
children with autism may be chronically hyperaroused. The overall mean magnitude
of the SCR in response to the stimuli in children with autism was higher than that of
normal children, but the difference was not significant. The reason could be that this
group of children with autism was comprised of both under-responsive and over-
responsive children; thus, the mean score might have represented the heterogeneous
composition of this group (Palkovitz & Wiesenfeld, 1980).
In two different studies, James and Barry (1984; Barry & James, 1988)
discovered that autistic children tend to be over-responsive and show less evidence of
habituation to auditory stimuli, compared to mentally-retarded and typically-
developing controls. In the 1984 study, they examined the electrodermal response to
simple auditory stimuli (50dB and 2400 Hz) in a total of 120 autistic, retarded, and
normal children. The forty children with autism, ranging in age from 4 years 6 months
to 16 years 11 months, were categorized into young (4.6-9.8 years) and old (10.4-
16.11 years) groups. The results revealed that children with autism in both age groups
displayed a significantly greater response magnitude to the auditory stimuli compared
to the control groups. This is an indication of over-responsiveness regardless of age

27

group. In addition, this study also noted that there was no evidence of non-responders
among the children with autism. Moreover, failure to show habituation was
characteristic of the children with autism, but not the control groups in this study. In
other words, these children with autism continued responding to auditory stimuli and
failed to show habituation, while the other two groups of controls habituated
significantly more often than the autistic group (James & Barry, 1984).
In the 1988 study, Barry and James again found that children with autism had
higher tonic electrodermal activity and greater magnitude of response to sounds
compared to mentally-retarded and typically-developing children. They examined 32
children with autism aged between 4 years 9 months and 17 years and 2 months, and
each child was matched according to gender, chronological age, and I.Q. with two
other groups. The auditory stimuli were provided by a microcomputer in an alternating
sequence of 2400 Hz tones at 50 and 33 dB. The results indicated that children with
autism in this study were over-responsive in that they had higher sympathetic activity
at rest and a higher magnitude of EDR to auditory stimuli. In addition, the children
with autism failed to show any reduction in response magnitude over trials, suggesting
that they were not able to habituate to repeatedly-presented pairs of stimuli (Barry &
James, 1988).
Using a different paradigm, Van Engeland (1984) recorded electrodermal
orienting responses in 35 children with autism, 38 child psychiatric patients with either
emotional or conduct disorders, 20 mentally-retarded children with Down syndrome,
and 45 typically-developing children. The children with autism, ages 7 to 17, were

28

individually matched by chronological age, handedness, and gender with normal and
mentally retarded children. Five of the children with autism also suffered from
epilepsy, and 8 exhibited neurological problems. All of the children received 24
acoustic stimuli of 85 dB, 1000 cps (cycles per second), one-second in duration
presented through bilateral headphones. The tonic skin conductance level was
recorded for a 5-minute period, and a spontaneous fluctuation (also known as non-
specific response, NSR) was scored when a change in skin conductance exceeded 0.05
micro-mho (μ-mho). The total of 138 children were split into high (H) and low (L)
spontaneous groups using 6 spontaneous fluctuations (NSR) a minute, recorded during
a 5-minute resting period, as a cutpoint. Six is the mode of the number of the
spontaneous fluctuations in the whole population. Moreover, the autistic group had a
significantly great number of nonresponders (30%) compared to the other three groups
(1-4%). In addition, when only children with normal range IQ (IQ ≥ 80) in the autistic
group were included in the analysis, 16% of children in both H and L subgroups did
not respond to the first trial, which supports the notion of under-responsiveness to
sound in a subgroups of autistic children. These children within the normal IQ range in
the L subgroup had a significantly shorter mean recovery time than the children in
normal group, whereas the children in H subgroup were different from normal and
child psychiatric children on mean recovery rate (Van Engeland, 1984). Unfortunately,
the direction of the difference when compared to other groups was not provided.
Stevens and Gruzelier (1984) examined 20 autistic children, ages 7-17 years,
who were individually matched with retarded and normal children by age, handedness,

29

and gender. This study used an electrodermal habituation paradigm that included a
two- tone sequence: 70dB, 1000Hz with one-second duration and 90dB, 1000Hz of 3-
second duration. The results showed no statistically significant differences in the
number of nonspecific responses to the two tones between the children with autism
and the other two groups. The response amplitudes in children with autism were
smaller than the other 2 groups, but no significant difference was found. However, the
researchers noticed that the children with autism not only had higher levels of tonic
skin conductance responses to tones and slower habituation rates, but also longer
response latency and rise time. Unlike the other two groups of children who had the
largest response to the first tone, the children with autism gave the largest response to
the second tone, which may be indicative of a delay in stimulus registration and under-
responsiveness (Stevens & Gruzelier, 1984).
Because Stevens and Gruzelier (1984) did not use the same electrodermal data
analysis methods as Van Engeland (1984), their results are not directly comparable,
although both studies suggest the existence of under-responsiveness among children
with autism. Findings from other studies demonstrated a high level of resting skin
conductance, large magnitude, and slow habituation in children with autism, which is
consistent with an over-responsiveness pattern (Barry & James, 1988; James & Barry,
1984; Palkovitz & Wiesenfeld, 1980).
No researchers have previously identified the third type of response pattern,
sensory seeking, among children with autism. However, Neary and Zuckerman’s
(1976) study of adult sensation seekers provides information that might represent the

30

characteristic electrodermal responses of sensation seekers. They selected both female
and male subjects from a normal population with extreme scores on the General
Sensation Seeking Scale (SSS). The results showed that when either a simple visual
stimulus or combination of visual and auditory stimuli was presented, the high
sensation seekers demonstrated a significantly greater SCR to a novel stimulus than
low sensation seekers, but they did not differ on repeated presentations (trials 2-10)
and habituated at the same rate (Neary & Zuckerman, 1976). Unfortunately,
researchers have not used electrodermal measures to determine if the sensory seeking
pattern in children with autism exhibits the same pattern as in sensation seeking
individuals from the normal adult population.

Past Studies Using the Sensory Challenge Protocol
The Sensory Challenge Protocol (SCP) was first developed by Dr. Lucy Miller
and her colleagues as a procedure for measuring electrodermal reactivity (EDR) to
sensory stimulation in children (Miller et al., 1999; Miller et al., 2001). The SCP is a
painless and non-intrusive physiological assessment that is administered in a room
designed like a spaceship, creating an enjoyable atmosphere that encourages children
to actively participate in the experiment. SCP measures five sensory domains: auditory,
visual, tactile, olfactory, and vestibular. (See Chapter 3 for detailed description for the
SCP).
The SCP laboratory paradigm has been used to study sympathetic and
parasympathetic nervous system responses in children with sensory processing

31

disorders to gain insight into the relationship between the function of the autonomic
nervous system and behavioral responsiveness (Miller et al., 1999; Miller et. al., 2005;
McIntosh et al., 1999; Miller et al., 2001; Hagerman et al., 2002; Schaaf et al., 2003).
McIntosh et al. (1999) first used the SCP laboratory paradigm on children who
were clinically identified as having sensory-modulation disorders (SMD). In this study,
19 children with SMD were matched by age and gender to 19 control children. The
results revealed that four children with SMD were non-responders who had no
responses greater than 0.05 µS on any of the trials. While the nonresponders were
excluded from the analysis, the children with SMD showed a larger log magnitude
responses and slower habituation than the controls. These children with atypical EDR
corresponded to those who were reported by parents in the Sensory Profile as showing
abnormal sensory behavior (McIntosh et al., 1999).
Using the same SCP paradigm, Schaaf, Miller, Seawell, and O’Keefe (2003)
studied parasympathetic responses of children with sensory processing disorders. The
study included 9 children with disturbances in sensory processing and 6 typically-
developing children. The children with sensory processing disturbance had a
statistically significantly lower cardiac vagal tone and lower heart period than the
typically-developing children. These results suggested that low parasympathetic
function is a possible factor for behavioral adaptation to sensory stimuli (Schaaf et al.,
2003).
Miller et al. (2005) examined the relations among core symptoms of ASD and
physiological variables. Thirty-eight children, who were diagnosed with high

32

functioning autism or Asperger’s Syndrome, ages 5-15, were recruited. The Autism
Diagnostic Observation Schedule (ADOS) was used to measure the core symptom
domains of social relatedness, communication, and restricted activities. The results
revealed that in the autistic group there was a positive relationship between the
magnitude of response to the siren and the tone and the symptoms in the social domain,
and between the magnitude of the responses to the siren and the symptoms in the
communication domain. That is, physiologic reactivity to the sensory stimuli increases
significantly as the social and communication symptoms increase. The authors also
noted that 53% of the subjects were non-habituators who responded to tones in all 8
trials (Miller et al., 2005), suggesting that over-responsiveness characterized about
half of the children with autism in their study.

Summary
This study was designed to discover whether sensory responsiveness can be
represented by both autonomic and behavioral measures in a sample of high
functioning children with autistic disorder. Behavioral responses to auditory
stimulation are thought to be accompanied by individual differences in autonomic
nervous system (ANS) responsivity. Overall, the research reviewed in this chapter
supports the existence of an over-responsive group and possibly an under-responsive
group among children with autism. A sensory seeking group may also exist although
the physiological literature has not addressed this possibility.

33

CHAPTER 3: METHODOLOGY

Overview
This chapter describes the recruitment method and eligibility criteria for
enrollment of the participants, the instruments, the procedures for data collection, and
the data analysis. Originally, the study plan was to gather data on 60 children with
autism and 20 typically-developing children, in order to conduct cluster analyses of
electrodermal and behavioral variables. However, due to unforeseen difficulties in
recruiting eligible children with autism and a high incompletion rate during the
laboratory experiment, it was decided to conclude this pilot study with 22 children
with autism and 20 typically-developing children.

Recruitment and Procedures
This study was approved by the University of Southern California Health
Sciences Campus Institutional Review Board prior to subject recruitment and data
collection. Signed consent forms and assent forms were obtained from all participants
prior to the data collection. Before posting the recruitment flyers, the researcher first
obtained permission to do so from the directors of several private clinics offering
occupational therapy services as well as several state-funded family resource centers,
which serve children with disabilities and their families. The study flyers were also
mailed or e-mailed to several associations providing support for families of children
with autism (e.g. TACA [Talk About Curing Autism], Autism Speaks) and to online

34

support groups formed by parents of children with disabilities. Parents interested in
possible participation contacted the researcher by phone or via e-mail.
Once the parent expressed interest in having his or her child participate, they
received a package of materials describing the purpose of the study and the laboratory
procedures, the Social Communication Questionnaire (SCQ), the Sensory Processing
Measure (SPM) Home Form, a sheet containing four questions on auditory processing
(to be explained later in this chapter), and a Consent Form. After the parents had filled
out the forms, the researcher next checked the SCQ scores as well as the medication
list on the demographic form to determine if the child with autism met the inclusion
criteria. If a child was taking a medication that was not listed on the flyer, the
researcher would obtain information on the side effects of the medication as reported
in the Physicians’ Desk Reference (2008). If the medication potentially affected
autonomic nervous system functioning, then the child ineligible. In addition, if a child
did not meet the inclusion criteria of the SCQ (SCQ > 15), the child was excluded
from the study, and the researcher provided an hour-long consultation to answer any
questions the parents had regarding why his or her child could not be enrolled. If the
child met the criteria on the SCQ, the researcher scheduled a 2-hour appointment with
the child and his/her parent in the lab. Prior to administering the lab protocol, the
researcher reviewed the Consent Form, answered questions, obtain signed informed
consent from the parents and the signed assent form from the children with autism.
The typically-developing children were recruited from the families of personal
friends of the researcher, from the typically-developing siblings of participants with

35

autism, or from the broader community. To recruit the latter group, recruitment flyers
were posted on bulletin boards in other community locations. Interested parents who
contacted the researcher received a research packet which included a description of the
purpose of the study, the Sensory Processing Measure Home Form, a sheet containing
four questions on auditory processing, and a Consent Form. Once the parents filled out
the forms and returned them to the investigator, the researcher calculated the scores on
the SPM, and those who received scores in the Typical range (below the cutpoint of 1
standard deviation above the population mean) on the Hearing Scale as well as on the
Total score of SPM Home Form were scheduled for a lab visit. Prior to administering
the lab protocol, the researcher reviewed the Consent Form, answered any questions
the parents had, obtained signed informed consent from the parents, and the signed
assent form from the children. For those who were not eligible to participate, the
researcher provided an hour-long consultation to answer any questions the parents had.

Subjects
The number of participants for this study was decided based a report from
Schaaf et al. (2003), who used a modified Sensory Challenge Protocol in their study.
They studied parasympathetic responses of children with sensory processing disorders
compared to typically-developing children using the Sensory Challenge Protocol used
in the present study (Schaaf, 2003). They reported that a sample size of 20 children in
each group was needed to detect an effect size of 0.9 with an alpha set at 0.01.
Therefore, a total of 40 children were considered sufficient for this study.

36

Children with Autism
Parents of 36 high-functioning children with autism, age 5-12 years old, who
were able to communicate verbally and who had previously been diagnosed by
medical and psychological professionals using the DSM-IV, volunteered to participate.
To be included in the autism sample, the child was required to score 15 or
higher on the Social Communication Questionnaire (SCQ), Lifetime Form, which was
used to validate the diagnosis of autism spectrum disorder. The form was used to
insure that the child had communication abilities that were adequate for participation
in the laboratory procedures. Children with autism were excluded if they had a
medical condition or a genetic syndrome known to affect neurological development,
such as a severe vision or hearing impairment, a seizure disorder, or Fragile X
syndrome, or were taking medications that may affect electrodermal or cardiac activity,
such as the Adderall, beta-blockers, Ditropan, SSRIs, or Ritalin.
Fourteen of the 36 recruited children with autism were excluded from the final
analysis. Four children did not obtain scores of 15 or higher on the SCQ, indicating
that their social communication problems were not severe enough to confirm a
diagnosis of autism spectrum disorder. Six children did not complete the Sensory
Challenge Protocol (4 refused to allow the electrodes to be applied, and 2 asked to
discontinue participation during the administration of sensory stimuli). Data for two
children were not included due to movement artifacts. Data for one child were
discarded because the parent was in the lab and talked to the subject during the
administration of the auditory stimuli. Data for one child were discarded because the

37

child was later found to be taking Clonidine and Abilify, which may affect
electrodermal activity. Data from the remaining 22 children with autism were included
in the data analysis.
Of the 22 children with autism whose data were analyzed, the mean score for
the Social Communication Questionnaire (SCQ) was 23.4, with a standard deviation
of 6.6. Table 3 depicts the clinical services that these children with autism were
receiving at the time of the study. Eighteen children with autism (82%) were receiving
occupational therapy, and eight of these 22 (36%) were also receiving physical therapy.
Five (23%) children also received alternative treatments, such as Floor Time (also
known as Relationship Development Intervention or RDI). A high percentage of these
children also received home-based behavioral support (68%), such as applied
behavioral analysis (ABA) or discrete trial training (DTT). Additionally, more than
half of these children also received school-based services, such as a one-on-one
behavioral aid (64%) or were assigned to a specialized class (59%).

38

Table 3
Services Received at the Time of the Recruitment in Children with Autism

Services Received (n=22) N (percent)
1. Occupational therapy 18 (82%)
2. Physical therapy 8 (36%)
3. School-based one-on-one behavioral aids 14 (64%)
4. Specialized classes 13 (59%)

5. Home-based behavioral support 15 (68%)

6. Psychological consulting 3 (14%)

7. Alternative treatments 5 (23%)

Typically-Developing Children
Twenty-six typically-developing children, ages 5-12 years old, were also
recruited. Five of these typically-developing children had a sibling diagnosed with
autism. None of the typically-developing participants had a history of sensory
processing problems, and none had received occupational therapy or another
intervention. In order to be included as a typically developing child in this study, a
child was required to have a T score no higher than 59 for both the Hearing Scale and
the Total score of the Sensory Processing Measure (SPM) Home Form. Scores higher
than 60 (i.e., one standard deviation or more above the population mean) indicated the
presence of sensory modulation difficulties. Four children who were recruited for the
typically-developing group were excluded prior to participating in laboratory data

39

collection because they received T scores above 60 on the SPM Hearing Scale. One of
these excluded children also received a Total SPM T-score above 60.
The data of two more children recruited into the typically-developing group
were excluded after laboratory data collection was completed. One record was
removed from the final data set as its validity was considered doubtful due to
movement artifacts. An additional child was later diagnosed with attention deficit
disorder and was therefore removed from the final dataset. The data from the
remaining 20 typically-developing children were included in the data analysis.
In summary, data from 22 children with autism and 20 typically-developing
children were included in the analysis. Table 4 depicts demographic information of
these children. Of the 22 children with autistic disorder (AD group), 20 were boys,
whereas in the typically-developing (TD group), the number in each gender was equal.
The children with autism were younger, on average, than the typically-developing
children by a little over one year, but the difference in age was not significant. Each
study group was also sub-divided into two age groups: 5 to 7 years and 11 months as
well as 8 years to 11 years and 11 months, in order to examine age effect later in the
analysis. There were also no significant differences found between AD and TD groups
in age groups (χ
2
= 1.53, p = 0.22). There were more boys in the AD group than in the
TD group, and more Asian subjects in the TD group than in the AD group (see Table
4).

40

Table 4
Demographic Information by Study Group

AD group
n=22
TD group
n=20

P-value

Age, Mean (SD) 7.9 ± 2.4 9 ± 2.3 0.14

Age stratification, Mean (SD)
5 to 7 yrs 11 mos 6.3 (1.0), n=13 6.6 (1.0), n=8 0.22
8 to 11 yrs 11 mos 10.4 (1.5), n=9 10.6 (1.2), n=12

Gender, n(%)
Girls 2 (9%) 10 (50%) <0.01
Boys 20 (91%) 10 (50%)

Ethnicity, n(%)
Asian 5 (22.7%) 15 (75%) <0.01
Caucasian 17 (77.3%) 5 (25%)

Instruments
Social Communication Questionnaire, Lifetime Form

The Social Communication Questionnaire (SCQ) was used in this study to
evaluate communication and social interaction skills in children with autism and to
verify the diagnosis of autism spectrum disorder. The SCQ is a 40-item, parent-report
screening measure that is tailored to be sensitive to the symptomatology associated
with autism spectrum disorder (Rutter, Bailey, & Lord, 2003). These 40 behavioral-
based items were derived from the Autism Diagnostic Interview-Revised (ADI-R;
Lord, Rutter, & Le Couteur, 1994), which is based on the ICD-10 (World Health
Organization, 1992) and DSM-IV (American Psychiatric Association, 1994)

41

diagnostic criteria for autism which include communication and restricted, repetitive
stereotyped patterns of behavior. Each question is scored 1 for the presence of
abnormal behavior and 0 for its absence (Yes or No on the answer sheet). The total
score ranges from 0 to 39. The standardization data for individuals ages 4 to 40 years
were collected from several studies (Berument et al., 1999; Bolton et al., 1994;
Gilchrist et al., 2001; Lord 1995), and the results showed that a score of 15 is the
cutoff point distinguishing children with and without autism characteristics. Unlike the
ADI-R, which can only be administered by trained evaluators, the SCQ can be easily
administered without specialized training and uses lay language readily understood by
parents (Rutter, Bailey, & Lord, 2003). The form takes under 5 minutes to complete.
Sensory Processing Measure (SPM) Home Form
To evaluate parental reports on childrens’ sensory behaviors in a natural
environment, the Sensory Processing Measure (SPM) Home Form (Parham & Ecker,
2007), a norm-referenced assessment of sensory integration, was used in this study.
This instrument is a sensory history parent questionnaire designed to identify specific
sensory processing problems in children aged 5-12. It was developed through a series
of rigorous examinations by students and faculty at the Division of Occupational
Science and Occupational Therapy, University of Southern California, Los Angeles
(LaCroix, 1993; Johnson-Ecker, & Parham, 2000; VerMaas Lee, 1999; Chang, 1999).
The SPM Home Form is based on the Evaluation of Sensory Processing (ESP).
The first study undertaken in the development of the ESP was conducted by LaCroix
(1993) who combed the literature as well as expert opinions to compile a large array of

42

sensory history questionnaire items that clinicians had found to be useful. From the
resulting bank of 679 items, 200 items with high content validity were selected for
inclusion in the instrument, based on quantitative analysis by a panel of experts in
sensory integration (LaCroix, 1993).
Johnson-Ecker and Parham (2000) then refined those items through interviews
with several parents. The process led to improvements in wording and deletion of
certain items that were deemed too technical for parents to understand. The resulting
questionnaire of 192 items was then used to identify which items significantly
distinguished between children with and without sensory processing problems,
matched for age, sex, and SES. Results indicated that 84 items significantly
differentiated between the matched groups (N=30 in each group) (Johnson-Ecker &
Parham, 2000).
Subsequent research indicated acceptable reliability and validity of the ESP
(Chang, 1999; VerMaas Lee, 1999; Su & Parham, in press). Inter-rater reliability was
examined in mother-father agreement for 15 children with sensory integration
dysfunction (SID) and mother-father agreement for 20 typically-developing children
(Chang, 1999). The results showed that the percentages of agreement of the auditory
items for the SID group and the typically-developing group were 79.1% and 88.6%,
respectively. Overall, the mean percentage of agreement for the Total score on the
ESP Research Version 3 for the SID group was 79.97%, and 83.95% for the typically-
developing group. The intraclass coefficient (ICC) was greater than 0.75 for most of
the items, indicating that the ESP possessed adequate reliability (Chang, 1999).

43

Based upon the aforementioned studies, the Sensory Processing Measure (SPM)
was standardized on a sample of 1,051 typically-developing children ages 5-12 years
recruited nationwide (Parham, Ecker, Miller, Henry, & Glennon, 2007). Overall, the
median internal consistency was 0.85, and the median test-retest was 0.97. Both
confirmatory factor analysis, which was used to investigate children with sensory
integration problems using the ESP (Su & Parham, in press), and exploratory factor
analysis, which was used to study typically-developing children with the SPM, yielded
strong evidence of the validity of the scoring scales (Parham & Ecker, 2007). The
internal consistency of the Hearing Scale is high (Cronbach’s Alpha= 0.86), and the
test-retest reliability indicating temporal stability is excellent (r=0.95) (Parham &
Ecker, 2007).
The 75-item SPM Home Form questionnaire includes 8 domains: social
participation, vision, hearing, touch, body awareness, balance and motion, taste and
smell, as well as planning and ideas. Parents are asked to rate each item using a 4-
point Likert-type scale (Always=4, Frequently=3, Occasionally=2, Never=1; Parham
& Ecker, 2007). The higher the score a parent reports, the higher the possibility that a
child has a sensory problem. In order to compare the parental report scores to the
normative data, the subtotal raw scores for each sensory domain were converted to a
T-score, which is an indication of how likely a child’s sensory behavior is to differ
from that of a typical child. A T-score between 40 and 59 is in the Typical range,
indicating that a child’s behavioral and sensory functioning is similar to that of a
typically-developing child. A T-score between 60 and 69, which is in the Some

44

Problems range, means that a child has mild to moderate difficulties in behavioral or
sensory functioning. A T-score above 70, the Definite Dysfunction range, indicates a
child has significant difficulty engaging daily activities (Parham, Ecker, Miller, Henry,
& Glennon, 2007).
According to the SPM manual, the questions in the Hearing Scale were
categorized as measuring over-responsiveness (6 items), under-responsiveness (1
item), and sensory seeking (1 item) (for details please see Appendix B). As the
Hearing Scale only includes one question that measures under-responsiveness and one
for sensory seeking, two additional items thought to measure under-responsiveness
and one that measures two to measure sensory seeking were added for the purpose of
this study (See Appendix C). These four newly-added questions had the same response
categories (4-point Likert-type scale) as in the SPM Home Form. One out of the 4
questions was derived from the Evaluation of Sensory Processing VR3, an earlier
version of the SPM and had demonstrated reliability and validity (Chang, 1999;
VerMaas Lee, 1999). Two questions measuring sensory seeking behavior and one
question measuring under-responsiveness behavior were created based on past clinical
observations. These four items were then reviewed by two experts in sensory
integration who agreed that the content matched the targeted pattern. The items were
then added to the under-responsiveness and sensory seeking items, respectively. The
resulting composite raw score for each pattern ranged from 3 to 12. The raw score for
the over-responsiveness pattern, which included six items, ranges from 6 to 24. In
addition, these 4 new questions were added to the raw scores of the Hearing Scale, and

45

this new raw score was labeled “Hear4.” Along with the three composite raw scores,
the Hear4 and t-scores from the Hearing Scale as well as from the Total scores of the
SPM Home Form were included in the data analysis
Psychophysiological Measures
Sensory Challenge Protocol (SCP).
Electrodermal and vagal tone measures were collected during Sensory
Challenge Protocol (SCP) procedures. The Sensory Challenge Protocol is a non-
invasive laboratory procedure that is used to collect electrodermal and cardiac data
from children (Mangeot et al., 2001; McIntosh, Miller, Shyu, & Hagerman, 1999;
Miller et al., 1999; Miller et al., 2001; Miller et al., 2005). Cardiac data were collected
as part of a larger collaborative research project investigating vagal tone, but were not
analyzed in the present study, which does not address vagal tone. During the
administration of the Sensory Challenge Protocol, a customized computer program,
PSYLAB, was used to automatically trigger auditory, visual, and vestibular stimuli
and to transform and record a child’s electrodermal and cardiac activity. The PSYLAB
program also served to cue the researcher to administer the tactile and olfactory
stimuli at precise time intervals. More details about the Sensory Challenge Protocol
are provided in the following section on Procedures. In the present study, only the
EDA data collected during the resting periods (baseline and recovery) and periods
following auditory stimuli during the Sensory Challenge Protocol were used in the
analysis. Responses to two auditory stimuli administered during the protocol were
analyzed: Tone and siren.

46

Autonomic Variables.
The following autonomic variables were recorded by PSYLAB during the
administration of the Sensory Challenge Protocol (SCP). The variables previously
demonstrated test-retest reliability as measures of general sympathetic arousal level
and attention to external stimuli (Schell et al., 2002) and differentiated stabile and
labile subgroups of physiological responders (Schell, Dawson, & Filion, 1988). The
variables are listed below in alphabetical order, according to the codes that were used
in the analyses and presented in Chapter 4 of this dissertation.
1. AMP: Amplitude of skin conductance responses to either tone or siren,
recorded as the average square root of response amplitudes ( SCR amplitude )
that were greater than 0.05 µS, and occurred between 0.8 and 4 seconds after
the auditory stimulus. An amplitude of less than 0.05 µS was considered zero,
indicating no response, and therefore was not included in the calculation of the
average amplitude for a participant. If a subject did not respond to any of the 8
trials for a stimulus, i.e., received an amplitude score of zero on every trial,
then the subject was excluded from the analysis of group differences in
amplitude for that auditory stimulus.
2. FREQ: Frequency of response. This was coded as the number of skin
conductance responses to an auditory stimulus (tone or siren) where the
amplitude was greater than 0.05 µS across the 8 trials of the stimulus.

47

3. HABIT: Habituation. Habituation is the expected decrement in skin
conductance response with the repetition of an identical stimulus. In this study,
habituation was recorded separately for the tone and siren. Habituation was
operationally defined as 2 consecutive non-responses to a repeated stimulus. If
a subject responded to the first trial, i.e., demonstrated an orienting response as
indicated by a skin conductance elevation with a valid amplitude, but did not
respond to the 2
nd
and 3
rd
trials, then the subject was assigned a code of 2 for
habituation, as this subject started to habituate at the 2
nd
trial. If a subject did
not respond to any of the 8 trials of a stimulus, then the subject was assigned a
zero for habituation. If a subject responded to all 8 trials of the stimulus,
habituation was coded as 8.
4. MAG: Magnitude of skin conductance responses to either tone or siren,
recorded as the average square root of the magnitudes ( SCR magnitude ) of
skin conductance responses that occurred between 0.8 and 4 seconds after the
auditory stimulus on all trials, including trials with zero amplitude. If a subject
did not respond to any of the 8 trials of a particular stimulus (tone or siren),
then this subject’s magnitude of skin conductance response for that stimulus
was recorded as zero.
5. NSR base: Non-specific skin conductance responses during baseline. This
was recorded as the average number of skin conductance responses (amplitude

48

greater than 0.05 µS) per minute during the 3-minute initial baseline phase of
the SCP, prior to the administration of sensory stimuli.
6. NSR rec: Non-specific skin conductance responses during recovery. This
was recorded as the average number of skin conductance responses (amplitude
greater than 0.05 µS) per minute during the 3-minute recovery phase that
followed administration of all sensory stimuli during the SCP.
7. ONLAT: Onset latency of response. This is a measure of the time interval
from the onset of the auditory stimulus to the onset of skin conductance
response. It was recorded for each participant as the average time (in seconds)
between the onset of the stimulus and the initiation of the skin conductance
response, across as many of the 8 trials of a stimulus that elicited a response. If
a participant received an amplitude score of zero on every trial of a stimulus,
then the subject was excluded from the analysis of group differences in onset
of latency for that auditory stimulus, as the subject did not demonstrate any
response to the stimulus.
8. PKLAT: Response Peak Latency. This is a measure of the rise time of a skin
conductance response, i.e., the time interval from the onset of response to the
peak of the response. In this study, this was recorded as the average time (in
seconds) from the onset of response to the peak, across as many of the 8 trials
of an auditory stimulus (tone or siren) that elicited a response.

49

9. SCL base: Skin conductance level during baseline. This tonic measure was
computed as the average of 18 log-transformed values during the initial
baseline resting period of the SCP, prior to administration of sensory stimuli.
This SCL value was generated by the PSYLAB computer program for every
10- second block during the 3-minute baseline.
10. SCL rec: Skin conductance level during recovery. After administration of all
the sensory stimuli delivered in the SCP. This tonic measure was computed as
the average of 18 log-transformed values during the recovering resting period
of the SCP. An SCL value was generated by the PSYLAB computer program
for every 10- second block during the 3-minute recovery phase.
Previous research has demonstrated adequate reliability of electrodermal data
gathered using the SCP. Miller et al. (2005) examined 14 children with high
functioning Autism and Asperger’s Syndrome ages 5-15 to study the test-retest
reliability of the SCP. Overall, the results showed moderate test-retest reliability.
Correlations for the average log magnitude of the SCR-OR were r=0.83 for tones and
r=0.16 for sirens. Correlations for latency were r=0.56 (p < .05) for both stimuli.
Overall, the tone stimulus obtained the highest reliability. The non-specific response
(NSRs) rates during the interstimulus interval had a test-retest correlation of 0.71 for
tones and 0.64 for sirens. The log magnitude for tone was 0.83 and for siren was 0.16.
Moreover, electrodermal measures were significantly correlated across stimulus types
(e.g., SCR magnitude to the tone stimulus was correlated with magnitude to the sirens,
etc.) (Miller et al., 2005).

50

Laboratory Procedures
The Sensory Challenge Protocol was administered in a laboratory setting. The
room is temperature-controlled light-and sound-attenuated and decorated to resemble a
spaceship. A sturdy commander’s armchair that resembles an astronaut’s space chair
is located in the center of the room. When the chair is activated during administration
of the protocol, vestibular stimulation is provided with an automated 30-degree tilt
backwards. A wooden control panel with a TV screen, speakers, and strobe light,
which provided auditory and visual stimuli at specific times during the protocol, was
presented approximately 60 centimeters in front of the chair. Electrodes were applied
to the children’s palms and ribcages in order to measure their skin conductance and
heart rate.
At the beginning of a test session, parents and children were invited to visit the
lab at which time the experimenter explained the protocol to them prior to obtaining
informed consent from parents as well as informed assent from children. The
experimenter then told the children that they should pretend to be going on a trip to
outer space where they would experience different sounds, sights, and smells. They
were also told that they needed to wear the Band-Aid-like electrodes that are similar to
those that astronauts wear. After the experimenter had explained the protocol, and
when the child appeared comfortable and ready to participate, the parents left the room
and the children were redirected to the restroom to wash their hands. The parents were
permitted to watch the procedure inconspicuously in a room adjacent to the lab via a
one-way mirror. In the meantime, the experimenter started to roll the video recorder.

51

Video taping in this study was essential because it helped with the data cleaning
process, especially for detecting and marking off the artifacts. Upon the child’s return,
he or she was asked to sit in the commander’s chair and was then asked to watch a
video clip of Apollo 13 in which the characters were preparing for the launch of the
spaceship. In the clip, the astronauts showed how electrodes are positioned on them,
and at the same time, the experimenter placed a pair of electrodes on the thenar and
hypothenar on the palm side of each child’s right hand. This was intended to help the
children to be comfortable with the application of the electrodes. The children were
asked to sit still and not move their hands as they went on their trip.
This protocol was originally developed by Miller et al. (1999) and McIntosh et
al. (1999). In this study, an adaptation of this protocol by Schaaf (2006) was used. The
total protocol took approximately 45 minutes to one and a half hour to complete
including preparation. It included 3 phases: baseline, sensory challenge, and recovery.
Baseline data were recorded for 3 minutes without any stimulation. Next, the 6
stimulus types in the sensory challenge protocol were administered: tonal (84 decibels),
visual (strobe light), auditory (siren at 78 decibels), olfactory (wintergreen-scented oil),
tactile (feather) and vestibular (chair tilt). There were 8 contiguous trials for each
sensory domain, and each stimulus lasted 3 seconds with a pseudo-random interval of
12-17 seconds pause in between each stimulus. There was also a 15-second pause
before each new sensory stimulation domain was initiated. At the end, a 3-minute
silent recovery period was provided. An additional stimulus, which was a 2-minute
long emergency broadcasting signal created from Schaaf’s protocol (2006), at 75db

52

and 853~900 Hz, was added at the end after the recovery phase to provide data
specifically for analysis of vagal tone. These data from the final auditory stimulus of
the end of the recovery phase were not analyzed in this study as they will be used in
subsequent analyses to study parasympathetic responses, which was beyond the scope
of this study (See Figure 2 for the depiction of the SCP).

Data Analysis
Electrodermal data collected during the Sensory Challenge Protocol for two
different auditory stimuli, a tone and a siren, were analyzed. The data were stored in
PSYLAB, a software program which was also used for data reduction by running a
customized macro program for each subject. Graphs of the two data sets for the stimuli
BASELINE
1. Tonal
RECOVERY
NUMBER OF TRIALS
Total (mins)=
Time (seconds)
0
180 15 15 15
12-
17
8.6
Sensory Challenge Protocol
8 8 8 8
3
0 3 5.8 13.2 18.8 = 23.8
2. Visual
7. ER alert
signal
3. Auditory
4. Olfactory
5. Tactile
6. Vestibular
DURATION PER
STIMULI
3 3 3
8
3
8 1
120 3
15 15 15
INTERSTIMULUS INTERVAL
[Psuedo-Random Interval]
12-
17
12-
17
12-
17
12-
17
12-
17
180
21.8 16 11.4
120
Figure 2. The Sensory Challenge Protocol

53

were saved separately as picture files (.jpg). The picture files along with the
videotapes were reviewed at the same time in order to check for the consistency
between the graph and raw data as well as to delete the artifacts.
Baseline skin conductance level was measured prior to the sensory stimulation
presentation. The electrodermal responses to stimuli were counted when the amplitude
was greater than or equal to 0.05 µS and latency was between 0.8 and 4 seconds after
each stimulus was delivered (McIntosh et al., 1999). If the responses were below 0.05
µS, they were not considered valid, based on the recommendations of Boucsein (1992)
and Dawson, Schell, and Filion (2007). When a response occurred 0.8 seconds before
the onset of each stimulus or 4 seconds after it, it was believed to be unrelated to the
stimulus; therefore, the response was counted as a non-specific skin conductance
response (NSR). More details regarding the electrodermal measures are explained in
Chapter 2.
According to Dawson, Schell, and Filion (2007), tonic skin conductance at
baseline (SCL) and the skin conductance response to the stimuli (SCR) must be
transformed, as these variables are frequently found to be positively skewed.
Therefore, for each record of each participant, the SCL was logarithmically
transformed ( log (SCL)), and the SCR amplitude and magnitude were calculated
as SCR amplitude and SCR magnitude for each participant. The SCL was
recorded every 10 seconds, therefore, there are 18 records during the 3 minute resting
period for baseline and recovery phases. Each record was first log transformed before

54

calculating the mean value of SCL at baseline as well as recovery phase for each
subject. A similar process for the amplitude and magnitude in which each response
was first square-root transformed before the mean calculations.
After the data reduction and data cleaning processing, the author found that the
readings in non-specific responses (NSR) and habituation provided by the customized
computer scoring program were incorrect. Due to inconsistencies between the
computer-generated scores and hand calculations, NSRs were deleted from the final
analysis. This issue is further explored in Chapter 5. The assigned scores for
habituation were incorrect in that for those who responded to all trials, the assigned
code should have been 8 rather than zero, whereas for those who did not respond to
any trials, the assigned code should have been zero. Therefore to ensure accuracy,
frequency of responses to auditory stimulation, as well as habituation, were hand
calculated and coded.
T-tests were then applied to the EDA autonomic variables between the group
of children with autism (the AD group) and the typically-developing children (the TD
group). The variables that showed significant differences between the two groups
(p< .05) were further analyzed to test whether age, gender, or ethnicity could be
confounders of the t-test results. Age was next subdivided into 2 groups: 5 to 7 years
and 11 months and 8 to 11 years and 11 months. Ethnicity was categorized as Asian
and Caucasian. The Analysis of Variance (ANOVA) procedure was used to test the
interactions between the study groups (AD and TD) and the characteristics of age,

55

gender, and ethnicity. Pearson correlation coefficients were then computed to
investigate the relations among these previously selected variables.
Next, using the AutoScore Form of the Sensory Processing Measure (SPM)
Home Form (see Appendix L), the T scores for the Hearing scale and Total scores
were computed. T scores between 40 and 59 represent typical behavior (based on the
data collected from the children in the normative sample), whereas those between 60-
69 (+1.0 to +2.0 standard deviations above the normative sample mean) represent mild
to moderate problems (“Some Problems”), and those above 70 (> +2.0 standard
deviations) represent severe problems in sensory functioning (“Definite Problems”).
T-tests were again used to compare the differences in previously-selected EDA
variables between children with autism who received scores in the Some Problems
range and those in the Definite Problems range.
Subsequently, in order to create three composite scores for over-
responsiveness (6 items), under-responsiveness (3 items), and sensory seeking (3
items), the Likert-type scale data from the Sensory Processing Measure (SPM) Home
Form Hearing scale were converted into numeric scores from 1-4 for never,
occasionally, frequently, and always, respectively; this coding was also used for the 4
new items. The hearing scale of the SPM Home Form, which included 8 questions,
yielded a possible range of raw scores from 8 to 32 points (Appendix L). For the
purposes of this study, the 8 questions from the SPM Home Form were combined with
the 4 additional items, shown in Appendix C, to create a “HEAR4” score ranging from
12 to 48 points. Pearson correlation coefficients were then computed to detect the

56

inter-relationship to all the SPM-related variables including the HEAR4, the 3
composite scores, the SPM Home Form Total T scores, and the Hearing scale T scores.
Finally, Pearson correlation coefficient analyses were then computed again
between the selected EDA variables and the SPM-related variables for each study
group. Results were used to examine relationships between these autonomic and
behavioral responses in order to determine if they followed the same trajectory.
Statistical Analysis Software (SAS) version 9.1 was used with alpha set at 0.05.

57

CHAPTER 4: RESULTS

Overview
This chapter presents the results of the statistical analysis of the data from the
22 children with autism (the AD group) and 20 typically-developing children (the TD
group). First, results from the analyses of electrodermal activity (EDA) variables are
presented, including analyses that address the potentially confounding effects of age,
gender, and ethnicity. This is followed by analyses of the behavioral variables.
Associations between the electrodermal and behavioral variables are reported at the
end of this chapter, which concludes with a summary of the study results.

Comparisons of Electrodermal Activity (EDA) Measures between Children with
Autism (AD) and Typically-Developing Children (TD)
Initially, the distributions of EDA variables were examined for normality, after
being transformed. The skin conductance level (SCL) variables at rest were log
transformed, and the skin conductance responses to auditory stimuli, measured as
amplitudes and magnitudes, were square root transformed (see autonomic variables
section in Chapter 3). These specific transformations were done in accord with the
recommendations of Dawson, Schell, and Fillion (2007) regarding the normalization
of these kinds of variables. Compared to the TD group, the AD group demonstrated
wider ranges of responses, but the two groups showed similar degrees of skew.

58

Appendix C presents the detailed data on EDA distributions and skew. In general,
skew was not significant for these dependent variables in either group.
Next, t-tests were used to determine which EDA variables differentiated the
AD and TD groups. As depicted in Table 5, six of fourteen EDA variables
demonstrated significant differences between the two groups. As noted in Chapter 3,
the tonic measures included skin conductance level (SCL) during the baseline (base)
and recovery (rec) phase, and the phasic measures included the amplitude (AMP),
magnitude (MAG), habituation (Habit), number of responses (FREQ), latency
(ONLAT), and rise time (PKLAT) measurement for the tone and for the siren.
Table 5 shows that all tonic EDA measures differed significantly between the
AD and TD groups. Specifically, the AD group demonstrated significantly higher skin
conductance levels (SCL) at baseline and at recovery compared to the TD group.
Regarding the phasic measures for tone stimulation, out of six variables, only
amplitude to tone (tone AMP) showed a significant difference between the study
groups, indicating that the AD group responded with significantly higher amplitudes
to tones across 8 trials when compared to the TD group.
For the phasic responses to siren stimulation, three out of six variables were
significantly different between the two study groups. Specifically, compared to the TD
group, the AD group had greater amplitudes (AMP) and magnitudes (MAG) as well as
higher number of responses (FREQ) to siren.

59

Due to the multiple tests of significance that were performed, Rom adjustment,
a sequentially rejective test procedure (Rom, 1990), was applied to control for family-
wise error rate. After the Rom corrections, SCL at baseline, tone AMP, and siren
MAG remained significant (see Table 5).
It is worth noting that there were 3 children with autism (14%) who did not
respond to any of the 8 trials of the tone, and 2 typically-developing children (10%)
who did not respond to any of the 8 trials of the siren. In this study, these participants
are considered to be non-responders. They were excluded from the amplitude analysis
based on the operational definition of amplitude, which includes only none-zero
responses, and from the latency and rise time analyses.
Some children did not respond to the first presentation of a stimulus, but
responded at least once to a later presentation of the same stimulus. In this study, these
participants are considered to be delayed responders. Four children with autism (18%)
and 3 typically-developing children (15%) were delayed responders to the tone,
whereas 2 children with autism (9%) and 4 typically-developing children (20%) were
delayed responders to the siren.

60

Table 5
Comparisons of EDA Measures for Children with Autism (AD) and Typically-
Developing Children (TD)

AD TD
Variable n Mean (SD) n Mean (SD) t-value p-value

Tonic Measures
SCL base 22 2.20 (0.51) 20 1.80 (0.47)
2.65
0.01*
SCL rec 22 2.38 (0.48) 20 2.10 (0.39)
2.11
0.04

Tone
AMP 19 0.95 (0.28) 20 0.70 (0.21)
3.14
0.003*
MAG 22 0.55 (0.37) 20 0.38 (0.23)
1.72
0.10
FREQ 22 4.41 (2.38) 20 4.15 (1.90)
0.39
0.70
Habit 22 5.41 (2.87) 20 4.75 (2.47)
0.39
0.43
ONLAT 19 1.66 (0.33) 20 1.63 (0.22)
0.79
0.69
PKLAT 19 3.34 (0.51) 20 3.68 (0.98)
-1.34
0.19

Siren
AMP 22 0.97 (0.39) 18 0.77 (0.21)
2.03
0.05
MAG 22 0.64 (0.37) 20 0.37 (0.29)
2.53
0.02*
FREQ 22 5.18 (2.42) 20 3.75 (2.07)
2.05
0.05
Habit 22 5.45 (2.70) 20 4.20 (2.78)
1.48
0.15
ONLAT 22 1.65 (0.33) 18 1.78 (0.43)
-1.12
0.27
PKLAT 22 3.57 (1.09) 18 3.59 (0.58)
-0.07
0.95
Note. Bold numbers indicate significant differences (p < .05)
* Significant after ROM adjustments.

Confounding Effect of Age, Gender, and Ethnicity
Due to the differences in gender distribution, age, and ethnicity between the
AD and TD groups, a series of analyses was then performed in order to examine
whether or not gender, age, or ethnicity affected the EDA variables in such a way as to
create spurious differences between the two groups.

61

Gender
In the AD group, there were not enough girls to determine a gender effect.
However, in the TD group, there were equal numbers of each gender. Therefore, t-
tests were used to investigate gender differences of typical-developing children for the
six EDA variables that were previously found to differentiate between the AD and TD
groups. Results shown in Table 6 indicate that no significant gender differences were
found. Girls were consistently more responsive to tones and sirens; however, the
difference was minimal and not significant. These results suggest that if gender had
confounded the findings on EDA group differences, the group with more girls would
have had higher reactivity. As discussed earlier and shown in the Table 6, this was not
the case. The AD group had higher reactivity but significantly fewer girls, suggesting
that gender differences did not account for the EDA differences that were detected.

Table 6
Comparisons of EDA Measures between Genders in the TD group

Variable
Boys Girls
t-value P-value

n Mean (SD) n Mean (SD)

Tonic EDA
SCL base 10 1.70 (0.50) 10 1.89 (0.43) 0.92 0.37
SCL rec 10 2.00 (0.46) 10 2.20 (0.29) 1.18 0.25

Phasic EDA
Tone AMP 10 0.65 (0.23) 10 0.76 (0.19) 1.11 0.28
Siren AMP 9 0.71 (0.17) 9 0.84 (0.24) 1.34 0.20
Siren MAG 10 0.32 (0.17) 10 0.43 (0.37) 0.87 0.40
Siren FREQ 10 3.70 (1.89) 10 3.80 (2.35) 0.10 0.92

62

To further examine gender as a possible confounder, t-tests were applied for
boys only. The preceding analysis showed that there was no difference in EDA
variables between boys and girls in the TD group. To build on these results, girls were
excluded in order to examine whether differences between the study groups remained
when data were analyzed for boys only.
Results are shown in Table 7. All of the tested EDA variables were
significantly different except for siren FREQ. Even though the group difference for
response frequencies to the siren (Siren FREQ) were not significant, it was in the same
direction as for the other EDA variables, with the AD group having higher response
frequencies than the TD group. After the ROM adjustments with alpha sequentially
reset to 0.025 and 0.017, all EDA measures remained significant with two exceptions
of SCL at recovery (SCL rec) and response frequencies to siren (siren FREQ). Taken
together, the results of these gender analyses indicate that although gender imbalance
may have affected results somewhat, it is not likely that gender bias accounted for the
AD and TD group differences in EDA, as detected by t-tests and shown in Table 3.

63

Table 7
Comparisons of EDA Measures between the AD and TD Groups for the Boys Only

Variable
AD group TD group
t-value P-value

n Mean (SD) n Mean (SD)

Tonic
EDA
SCL base 20 2.18 (0.48) 10 1.70 (0.50) 2.55 0.02*
SCL rec 20 2.36 (0.49) 10 2.00 (0.46) 1.97 0.05

Phasic
EDA
Tone AMP 17 0.94 (0.29) 10 0.65 (0.23) 2.67 0.01*
Siren AMP 20 0.97 (0.41) 9 0.71 (0.17) 2.46 0.02*
Siren MAG 20 0.62 (0.38) 10 0.32 (0.17) 3.02 0.01*
Siren FREQ 20 5.00 (2.45) 10 3.70 (1.89) 1.47 0.15
Note. Bold numbers indicate significant differences (p < .05)
* Significant after Rom adjustments.

Age
In addition to gender, the imbalances of age and ethnicity between the AD and
TD groups were of concern. Analyses of variance with least square means were used
due to the imbalanced cell counts. To examine the effect of age, subjects were
grouped into younger (5 to 7 years and 11 months) and older (8 to 11 years and 11
months) groups and an age group x study group ANOVA was performed for each
EDA variable in which significant between-group differences (depicted in Table 5)
had been identified. Results are shown in Table 8. Although no interaction between
the study group and age group was significant, two trends were suggested. First,
younger children tended to have higher arousal and to be more reactive than older
children. Second, for the same age groups, between the two study groups, children

64

with autism showed higher tonic and phasic EDA than those of typically-developing
children. Even with the effects of age separately identified, half of the EDA variables
still significantly differed between the two study groups, and the other half approached
significance, indicating that the children with autism in this study tended to be more
aroused and reactive than the typically-developing children with the variance due to
age isolated. None of the interactions between age and study group approached
significance. Adjusting for study group and for age x study group interaction, analyses
revealed no age group differences. In the other words, any differences found between
the two study groups are not likely to be the result of age differences.
.

65

Table 8
ANOVA between the Age Groups and Study Groups

AD Group, Mean (SD) TD Group, Mean (SD) P-value
LSM
a

Younger Older Younger Older Study Age
n= 13 n = 9 n = 8 n = 12 F (df) Model Group Group Interaction

Tonic
EDA
SCL base 2.30 (0.52) 2.05 (0.49) 1.87 (0.62) 1.75 (0.36) 2.87 (3, 38) 0.05 0.02 0.24 0.69
SCL rec 2.40 (0.49) 2.35 (0.49) 2.18 (0.52) 2.04 (0.29) 1.59 (3, 38) 0.21 0.07 0.50 0.73

Phasic
EDA

Tone AMP 0.92 (0.32) 1.00 (0.20) 0.66 (0.15) 0.74 (0.24) 3.49 (3, 35) 0.03 0.003 0.35 0.99
Siren AMP 0.99 (0.37) 0.94 (0.43) 0.84 (0.26) 0.73 (0.17) 1.37 (3, 36) 0.27 0.10 0.47 0.79
Siren MAG 0.65 (0.31) 0.61 (0.46) 0.50 (0.40) 0.29 (0.15) 2.82 (3, 38) 0.05 0.03 0.24 0.40
Siren FREQ 5.46 (2.50) 4.78 (2.39) 4.63 (2.62) 3.17 (1.47) 2.25 (3, 38) 0.09 0.09 0.14 0.59
Note. Younger groups were between 5 to 7 years and 11 months old. Older groups were 8 to 11 years and 11 months old
a
Least square means adjustment for multiple comparisons.
65

66

Ethnicity
Next, an analysis was conducted to examine the effect of ethnicity on the
EDA results. Specifically, ANOVA was applied to determine if ethnicity differences
(Asian versus Caucasian) between the study groups might explain the group
differences (Table 9). For both the AD and the TD groups, the Caucasian children
had higher levels for all tonic variables than the Asian children and were more
reactive on three out of the four measures of responses to the siren. Neither the effect
of ethnic group, nor the interaction between ethnic group and study group was
significant. However, a significant effect for the study group was found for the two
EDA measures. These results indicate that the preponderance of Caucasian children
in the AD group may have contributed to the larger number of study group
differences seen in the t-tests, which were reported in Table 5. In other words, the
presence of more Caucasians in the AD group may have magnified the differences
that were attributable to children with autism versus typically-developing children
found on the t-tests. In adjusting for ethnicity and the interaction, only tone
amplitude (tone AMP) remained significant between the two study groups.
Nevertheless, for both tonic EDA variables, in both Asian and Caucasian groups,
children with autism showed greater arousal levels than typically-developing
children. Less consistency was found for the EDA phasic variables, suggesting that
ethnicity is more likely to have confounded results for these variables.
Table 9
ANOVA between the Ethnicity Groups and Study Groups

AD Group, Mean (SD) TD Group, Mean (SD) P-value
LSM
a

Caucasian Asian Caucasian Asian Study Ethnicity
n= 17 n = 5 n = 5 n = 15 F (df) Model Group Group
Interaction

Tonic
EDA
SCL base 2.24 (0.58) 2.06 (0.10) 1.90 (0.57) 1.76 (0.45) 2.53 (3, 38) 0.07 0.09 0.39 0.94
SCL rec 2.41 (0.53) 2.28 (0.26) 2.30 (0.36) 2.03 (0.39) 2.03 (3, 38) 0.13 0.26 0.22 0.74

Phasic
EDA
Tone AMP 1.03 (0.27) 0.73 (0.17) 0.68 (0.21) 0.71 (0.22) 5.85 (3, 35) 0.002 0.04 0.11 0.06
Siren AMP 0.95 (0.35) 1.03 (0.55) 0.95 (0.19) 0.70 (0.17) 2.04 (3, 36) 0.13 0.18 0.46 0.17
Siren MAG 0.64 (0.37) 0.61 (0.41) 0.67 (0.41) 0.27 (0.15) 4.32 (3, 38) 0.01 0.20 0.07 0.12
Siren FREQ 5.24 (2.49) 5.00 (2.45) 5.40 (2.41) 3.20 (1.70) 2.70 (3, 38) 0.06 0.32 0.14 0.23
a
Least square means adjustment for multiple comparisons.
67

68

Correlations among the EDA variables
Table 10 shows the correlation matrix for EDA variables that t-tests indicated
were different for the AD and TD groups. (See Appendix D for a table of
correlations among all EDA variables.) Correlations in Table 10 are presented
separately for the AD and TD groups. In general, in both study groups, the measures
that reflect tonic arousal (SCL) between the baseline and recovery phase as well as
that reflect reactivity to siren (between magnitude and amplitude, between magnitude
and frequency responses) are highly correlated. It is also worth noting that the tone
amplitude has very weak correlations with the siren variables.
The correlations between the measures of tonic arousal and measures of
responsivity are different in the two groups. In the AD group, SCL at baseline is
highly correlated with all phasic measures, whereas SCL at recovery is only
correlated with the magnitude and frequency responses to the siren. In the TD group,
both SCL at baseline and recovery are correlated with the magnitude and frequency
of responses to the siren.

69

Table 10
Intercorrelations among Six EDA Variables for the AD and TD Groups

TD group
AD group
SCL
base
SCL
rec
Tone
AMP
Siren
AMP
Siren
MAG
Siren
FREQ

SCL base
- 0.69* 0.40 -0.05 0.41 0.50

SCL rec
0.78* - 0.12 0.09 0.43 0.48

Tone AMP
0.46 0.27 - -0.12 0.13 0.11

Siren AMP
0.45 0.26 0.25 - 0.69* 0.30

Siren MAG
0.48 0.64* 0.19 0.60* - 0.89*

Siren FREQ
0.40 0.62* -0.01 0.15 0.81* -
Note. The lower left half of the matrix depicts findings for the AD group and the upper right half with
underlined numbers represents the TD group. Bold numbers indicate significant correlations (p < .05)
* Significant after Rom adjustments.

Summary of the EDA Findings
In summary, the study found that compared to typically-developing children,
children with autism tended to have higher skin conductance levels (SCL) at baseline
and recovery phases and greater reactivity to tones and sirens. After Rom
adjustments, only the SCL at baseline, amplitude to tone, and magnitude to siren
remained significant. When possible confounding effects were examined, the results
demonstrated that the differences between the two study groups were unlikely to be
confounded by gender and age. However, ethnicity may have been a confounder,
particularly in responding to phasic measures.

70

These findings correspond to the 1
st
and 2
nd
hypotheses that children with
autism had higher arousal levels at rest and higher levels of reactivity to auditory
stimulation than the typically-developing children. However, contrary to the 3
rd

hypothesis, children with autism did not habituate to auditory stimulation at a
different rate than the typically-developing children.

Analysis for the Sensory Processing Measure (SPM) Home Form
Table 11 shows the results of the analysis of the Sensory Processing Measure
(SPM) Home Form scores, along with the four additional auditory questions added
for this study (described in Chapter 3). For the SPM Hearing Scale T scores, the
majority of the children with autism fell in the Some Problems range (68%) followed
by the Definite Dysfunction range (22.7%), while two children with autism were
within the Typical range. A similar result was seen for the SPM Total T score, except
that one child who was in the Typical range on the Hearing Scale fell into the Some
Problems range for the Total T score. Even though 1 child had a Total T score in the
Typical range, in examining other sensory domains that were not in the Typical range,
all of the 22 children with autism had scores in the problem ranges for more than 2
domains.

71

Table 11
Sensory Processing Measure (SPM) Home Form Interpretive Ranges for the Study
Groups

n (%)
AD Group TD Group
n=22 n=20

Hearing Scale interpretive range
-Typical range 2 (9.1%) 20 (100%)
-Some Problems range 15 (68.2%)
-Definite Dysfunction range 5 (22.7%)

Total scores interpretive range
-Typical range 1 (4.5%) 20 (100%)
-Some Problems range 16 (72.7%)
-Definite Dysfunction range 5 (22.7%)

Due to the study criteria, SPM Hearing Scale T scores and the SPM Total T
scores of the typically-developing children fell below a T score of 59, and therefore,
the t-tests between the groups indicate significant differences on the Hearing Scale T
scores and the SPM Total T Scores, as shown in Table 12. After raw scores on the
Hearing Scale were summed with the four new auditory questions created for this
study, the group difference remained significant, indicating that the four additional
questions did not change the significance of differences between the two study
groups.

72

Table 12
Sensory Processing Measure (SPM) Home Form Scores for the Study Groups

Mean (SD)
AD Group TD Group

t-value P-value
n=22 n=20

SPM Total T-scores 66.72 (5.13) 45.95 (6.60)
11.45
<.0001

SPM Hearing Scale T-scores 66.36 (7.25) 47.30 (5.76)
9.37
<.0001

Hear4
a
25.23 (5.73) 13.35 (1.53) 9.36 <.0001

Patterns of Responsiveness to Hearing

-Over-responsiveness 12.95 (4.12) 6.60 (0.88)
7.05
<.0001
-Under-responsiveness 5.50 (1.47) 3.30 (0.57)
6.49
<.0001
-Sensory Seeking 6.81 (2.15) 3.45 (0.69)
6.96
<.0001
Note. Bold numbers indicate significant differences (p < .05)
a
SPM Hearing Scale raw scores summed with 4 new questions
As explained in Chapter 3, the aforementioned four additional auditory
questions were added in the study in order to increase the number of questions
reflecting each sensory pattern (over-responsiveness, under-responsiveness, and
sensory seeking). Thus, based on the total of 12 auditory questions, three composite
scores were created. They are over-responsiveness (6 questions, possible score range
6 to 24), under-responsiveness (3 questions, possible score range 3 to 12), and
sensory seeking (3 questions, possible score range 3 to 12). Table 12 indicates
significant differences between study groups for each of the three new composite
scores.
The correlation matrix in Table 13 includes all SPM-related variables used in
this study, and presents correlations for the AD and TD groups separately. Results

73

for the children with autism show that the Hearing Scale scores are significantly
correlated with all SPM variables except the sensory seeking composite score, which
approaches significance (r = 0.39, p=0.061). Moreover, over-responsiveness
composite scores are significantly correlated with under-responsiveness composite
scores (r=0.55, p=0.008).
Table 13
Intercorrelations among the SPM Variables for the AD and TD groups

TD group
AD group
Hearing
T score
Total
T score
Hear4
Over-
Resp
Under-
Resp
Sensory
Seeking

Hearing T score - 0.37 0.81* 0.97* 0.37 0.26

Total T score 0.50 - 0.66* 0.31 0.44 0.70*

Hear4 0.89* 0.65* - 0.73* 0.72* 0.69*

Over-Resp 0.88* 0.55 0.92* - 0.25 0.14

Under-Resp 0.53 0.59 0.63 0.55 - 0.44

Sensory Seeking 0.39 0.34 0.53 0.25 -0.06 -
Note. The lower left half of the matrix depicts findings for the AD group and the upper right half with
underlined numbers represents the TD group. Bold numbers indicate significant correlations (p < .05)
* Significant after Rom adjustments.

Comparisons of EDA measures between Some Problems Range and Definite
Dysfunction Range in Children with Autism
Next, t-tests were performed to examine the EDA differences between the
children with autism who scored in the Some Problems range on the SPM Hearing

74

scale, and those who scored in the Definite Dysfunction range. Table 14 presents t-
test results for the selected EDA variables that were found earlier to differentiate
between the study groups (See Appendix E for a table of t-tests for all EDA
variables). As shown in Table 14, even though only tone amplitude and SCL at
baseline approach significance, the trend is clear that children in the Definite
Dysfunction range have higher skin conductance levels and greater responses to tone
and siren than those children in the Some Problems range. Differences are in the
expected direction, where EDA measures are consistently higher for children with
more severe sensory-based behavioral problems.

Table 14
T-tests for the Selected EDA Measures between Some Problems Range and Definite
Dysfunction Range in Children with Autism

Variable
Some
Problems
Definite
Dysfunction
t-value P-Value

n Mean (SD) n Mean (SD)

Tonic EDA
SCL base 15 2.08 (0.54) 5 2.57 (0.33) -1.87 0.08
SCL rec 15 2.35 (0.53) 5 2.48 (0.44) -0.47 0.64

Phasic EDA
Tone AMP 12 0.88 (0.27) 5 1.17 (0.25) -2.00 0.06
Siren AMP 15 0.94 (0.42) 5 1.07 (0.25) -0.63 0.54
Siren MAG 15 0.60 (0.38) 5 0.71 (0.31) -0.59 0.56
Siren FREQ 15 4.93 (2.55) 5 5.80 (2.49) -0.66 0.52

75

Correlations among the SPM variables and the EDA variables

Table 15 depicts intercorrelations among the SPM and EDA variables for the
AD and TD groups separately. In this table, the only EDA variables that are included
are those that were found to significantly differentiate between study groups in the
earlier t-tests of EDA variables. Correlations among all EDA variables and SPM-
related variables can be found in Appendix F.
As shown in Table 15, for children in the AD group, amplitude of response to
tone (tone AMP) is significantly positively correlated with all but two SPM scores.
In examining the composite scores for the patterns of behavioral responses, in the
AD group the over-responsivity composite score is significantly correlated with tone
amplitude, whereas in the TD group, the under-responsivity composite and sensory
seeking scores are significantly correlated with siren amplitude. Interestingly, most
correlations for the TD group are non-significant and close to zero, with two
exceptions: a moderate positive association between the under-responsive composite
and amplitude of response to siren, and a moderate negative association between the
sensory seeking composite score and amplitude of response to siren.

76

Table 15
Intercorrelations between the SPM Variables and the EDA Variables for the AD and
TD Groups

AD group
TD group
Hearing
T-scores
Total
T-scores
Hear4
Over-
Resp
Under-
Resp
Sensory
Seeking

SCL Base 0.28 0.45 0.36 0.39 0.33 0.06
0.04 0.01 0.01 0.09 -0.24 0.10

SCL Rec 0.07 0.13 0.01 0.13 -0.12 -0.07
0.32 0.03 0.18 0.26 -0.01 0.09

Tone AMP 0.41 0.42 0.50* 0.56* 0.35 0.08
0.04 -0.40 -0.04 0.07 -0.10 -0.09

Siren AMP 0.04 0.10 0.22 0.22 -0.04 0.24
0.02 -0.17 -0.02 0.04 0.48 -0.44

Siren MAG -0.12 -0.14 0.02 0.11 -0.24 0.11
0.18 -0.27 -0.07 0.23 -0.09 -0.38

Siren FREQ -0.02 -0.10 0.04 0.12 -0.23 0.13
0.14 -0.24 -0.14 0.20 -0.33 -0.29
Note. Bold numbers indicating significantly correlated (P < .05).
* Significant after Rom adjustments.

Summary of Results
These results showed that the AD group generally had higher arousal and
greater EDA responsivity to tones and sirens compared to the TD group. Specifically,
compared to the TD group, the AD group obtained higher skin conductance levels
(SCL) during the baseline and recovery phases, higher amplitudes of responses to

77

tones and sirens, and greater magnitudes of responses to sirens as well as higher
numbers of responses to sirens. ANOVA was conducted to determine whether EDA
differences were affected by gender, age, and ethnicity imbalances across groups, but
results showed that neither gender nor age accounted for all of the significant group
differences on EDA measures. However, ethnicity may be attributed to the found
differences between the two study groups due to the preponderance of Caucasian in
the children with autism group.
Results from analyses of behavioral data from the Sensory Processing
Measure (SPM) Home Form showed that the majority of children with autism had
auditory modulation difficulties, with 68% of the AD children falling in the Some
Problems range and 23% in the Definite Dysfunction range on the Hearing scale.
When the EDA measures of the children in these two ranges were compared, it
appeared that the higher the T scores a child obtained on the SPM, the more tonic
and phasic electrodermal activity a child demonstrated. Overall, these results suggest
that more severe auditory modulation behaviors of children with autism are
associated with higher levels of resting arousal and stronger autonomic responses to
sound.

78

CHAPTER 5: DISCUSSION

This chapter discusses the findings of this study. Specifically, it compares the
present findings with those of others and makes suggestions for future research.

Summary of the Results
This study investigated whether the electrodermal activity (EDA) of children
with autism differs from that of the typically-developing children, and whether their
autonomic responses to auditory stimuli in a controlled laboratory setting correspond
to parental reports of behavioral difficulties with auditory stimuli in natural
environments. Results showed that, compared to typically-developing children, the
children with autism in this study had significantly higher tonic arousal as indicated
by higher baseline skin conductance levels at baseline and recovery. The children
with autism also were more reactive to auditory stimuli than the typically-developing
children. However, children with autism did not habituate to the auditory stimuli at a
different rate compared to the typically-developing children.
Results also showed that EDA responses were linked to the degree of
behavioral difficulties. In the group of children with autism, those who had more
severe behavioral problems in response to naturally-occurring auditory stimuli, as
measured by T scores for the Hearing scale of the Sensory Processing Measure

79

(SPM) Home Form, demonstrated higher arousal and more reactivity than those who
had less severe behavioral difficulties with sounds.

Influence of Gender, Age, and Ethnicity on EDA Findings
Despite imbalances in gender, age, and ethnicity across the study groups,
evidence of EDA differences between the children with autism and typically-
developing children still remained after variances in gender, age, and ethnicity were
separately extracted. Although the findings of this study determined that differences
in gender, age, or ethnicity did not account for EDA differences between the AD and
TD groups, some trends suggested that age, ethnicity, and gender should be carefully
considered when interpreting data using electrodermal measures. Specifically, in this
study, the younger subgroups of children tended to have higher skin conductance
levels (SCL) and non-specific responses (NSR) rates than the older subgroups of
children; the girls tended to displayed higher SCLs, but lower NSR rates, and were
more reactive to auditory stimuli than boys; and Caucasian children had higher SCLs
and NSR rates than Asian children.
Venables and Mitchell (1996) examined the EDA of 640 Mauritian subjects,
ranging in age from 5 to 25 years. As in the present study, there were no significant
effects on skin conductance levels (SCLs) for age, gender, or the interaction thereof
(Venables & Mitchell, 1996). Boucsein (1992), after reviewing publications about
gender differences in the adult population, concluded that female subjects generally

80

show higher SCLs than males, while males tend to show greater reactivity under
conditions of stimulation. Boucsein (1992) attributed to the differences in SCL in
woman compared to men to hormonal effect. Thus, in this present study, since all
participants were younger than 12 and had not yet reached adolescence, the lack of
differences found in all EDA variables between genders in the typically-developing
children seem to be in accordance with previous study findings.
Similar results were found by Gao, Raine, Dawson, Venables, and Mednick
(2007) using a latent growth curve model in a longitudinal study. They also
discovered that boys and girls do not exhibit different developmental trajectories.
They studied the EDA of 200 Mauritian children when they were ages 3, 4, 5, 6, and
8 years old. Six non-signal 75-db tone stimuli were used to elicit orienting responses.
They found that the shape of developmental trajectory was similar between girls and
boys in terms of the skin conductance orienting response (Gao et al., 2007).
No data regarding possible ethnicity or race differences were found in the
literature on EDA in children, at the time of this writing. The present study found
that Caucasian children showed higher SCLs and NSR rates as well as greater
responses to auditory stimuli than did Asian children, although the differences were
not statistically significant.
Boucsein (1992) suggested that the differences in EDA among different
ethnicities or races may be due to density of active sweat glands, which decreases as
the darkness of the skin increases. That is to say, ethnicity or race may affect the skin

81

conductance level because of differences in skin color. Korol and Kane (1978)
studied 75 subjects (26 Caucasians, 25 African-Americans, and 25 American Indians)
and discovered that the skin conductance levels in American Indians were midway
between those in the Caucasians and African-Americans. This demonstrated that
even though American Indians are viewed as being anthropologically Caucasians,
darkness of skin color rather than race or ethnicity has an influence on skin
conductance levels (Korol & Kane, 1978; Boucsein, 1992). Numerous researchers
have reported that African-Americans have lower skin conductance levels than
Caucasians (Bernstein, 1973; Boucsein, 1992; Fisher & Kotses, 1973; Johnson &
Corah, 1963). Given the trends in EDA data for age, gender, and ethnicity subgroups
in the present data, as well as evidence of the significant effects of gender and
ethnicity among adults, future research on children with autism should strive for a
balance of these variables across diagnostic groups.

Consistency of EDA Findings with Previous Research
In the present study, findings regarding the EDA differences between
children with autism and typically-developing children are consistent with results of
several studies published more than a decade ago. Such findings are that the children
with autism displayed significantly greater skin conductance levels (Palkovitz &
Wiesenfeld, 1980; Steven & Gruzelier, 1984; Barry & James, 1988) and higher NSR
rates at rest (Palkovitz & Wiesenfeld, 1980), and were more reactive to a variety of

82

auditory stimuli (Palkovitz & Wiesenfeld, 1980; James & Barry, 1984; Barry &
James, 1988; van Engeland, 1984) than the controls. Most findings suggest that
children with autism generally are more aroused and more responsive than typically-
developing children. However, there were also some suggestions that were a
subgroup of children who were under-responsive (Steven & Gruzelier, 1984; van
Engeland, 1984).
Nevertheless, our finding contrast with those by Miller et al. (2001), who also
used the Sensory Challenge Protocol. These researchers calculated average responses
across all sensory modalities for each trial and found that children with autism
showed a lower magnitude of EDR compared to typically-developing children
(Miller et al., 2001). The present study examined only responsiveness to auditory
stimuli. Perhaps it could be account for the differences in the results between the two
studies. Both studies suggest a possibility that there may be a group of children with
autism who are under-responsive.
Rates of non-response to the first tone or siren in the series were different
between the two study groups in this study (18% for the tone and 9% for the siren for
the children with autism, 15% and 20% for the typically-developing children). Non-
responders have been reported in groups of children with autism in the past. Van
Engeland (1984) revealed that approximately 16% of children with autism did not
respond to the first trial of auditory stimuli as opposed to 7% of the children in
Gruzelier and Venables’s (1973) sample. In addition, Schoen, Miller, Brett-Green,

83

and Hepburn (2007) discovered that in their sample of high-functioning children
with autism or Asperger’s Syndrome aged 5-15 yrs old, 29% were non-responders to
the first trial in the overall Sensory Challenge Protocol (SCP).
In recent research, approximately 10-25% of a group of adult controls were
reported to be non-responders (Dawson, Schell, & Filion, 2007). In the present study,
two typically-developing children (10%) did not respond to the sirens across 8 trials.
Nevertheless, because the typically-developing children in the present study all had
SPM Home Form scores in the typical range, it may be that the occasional absence
of response to a stimulus is a normal occurrence. We cannot conclude, therefore, that
the occasional occurrence of non-responding among the children with autism (14%)
in this study is indicative of sensory under-responsiveness.
Previous investigators have also demonstrated lower habituation rates in
children with autism than typically-developing controls. In the present study,
children with autism required more trials to habituate (5.41 to tones, and 5.45 to
sirens) than did typical controls (4.75 to tones, 4.20 to sirens), although these
differences were not significant. These findings were consistent with previous
research on habituation rates of children with autism, in which these children showed
little evidence of reduction in amplitude or magnitude over trials (Barry & James,
1988; James & Barry, 1984; Van Engeland, 1984; Steven Gruzelier, 1984). This
finding suggests that the development of response reduction to novel stimuli may

84

take a longer time for children with autism to demonstrate response reaction than for
typically-developing children.

Relationship of Electrodermal Activity (EDA) to Behavioral Reports
In this study, the children with autism (AD) who had more severe sensory
behavioral problems as indicated by the SPM (scores in the Definite Dysfunction
range) displayed higher resting arousal and auditory reactivity on some EDA
measures than those with milder behavioral problems (SPM scores in the Some
Problems range). In the AD group, the behavioral reports (SPM-related variables)
are positively correlated with the tonic EDA (SCL base, NSR base, and NSR rec) as
well as with tone amplitude responses. These results suggest that the more the
abnormal sensory behaviors that the parents observed, the higher arousal and
reactivity the children with autism displayed.
Interestingly, in both study groups, the siren amplitudes or magnitudes were
not correlated to any of the SPM variables, with the exceptions of siren amplitudes to
the composite scores of under-responsiveness and to sensory seeking in the group of
typically-developing children. This may be because the children in this study lived in
a large urban area where sirens were frequently heard. Additionally, children these
days are more accustomed to noisy environments. Not only do they experience
frequent environmental noises such as from people talking, televisions, and traffic,
but also their learning and playing experiences have been changed by high

85

technology enhancements, such as computers, video games, and iPods. Therefore,
reduced responsiveness to sounds such as sirens may have become more prevalent
among typically-developing children as intense auditory stimulation has become
more common. These changes in daily life may have reduced their autonomic
responses to auditory stimuli. This possibility could also explain the high percentage
of typically-developing children (20%) who did not respond to the first siren. Two of
these typical children (10%) did not even respond to the siren across 8 trials.

Auditory Behavioral Problems in Children with Autism
In this study, a high percentage (95%) of the 22 children with autism had
elevated scores on the Total Score of the SPM Home Form, indicating sensory
modulation difficulties. All 22 of these children had scores in the problem ranges for
multiple domains. Moreover, out of these 22 children, 90% had clinically elevated
scores on the SPM Hearing Scale. Such a high percentage of difficulties in auditory
processing suggests that auditory-related sensory behaviors may be one of the most
observable sensory abnormalities in autism, which was also reported by several
previous researchers (Baranek, Foster, & Berkson, 1997; Gomes et al, 2004;
Greenspan & Wieder, 1997; Volkmar, Cohen, & Paul, 1096).

86

Study Limitations
This pilot study had a number of limitations that need to be considered before
any conclusions can be drawn. First, it was challenging to recruit eligible participants
for this study, especially because of the medication exclusion criteria. Collaborative
studies with other universities or institutes are highly recommended in order to
recruit sufficient participants. In this present study, even though their parents were
interested in participation, several children with autism were not recruited because
they were taking medications that required exclusion from the study. In another
situation, a child was not recruited because the parents declined to skip the
medication for one day (more than 24 hours) for fear it would disrupt their lives.
Another limitation of the study is that the effect of dietary supplements is
unknown. Dietary information was not systematically collected in writing, but
several parents of children with autism informed the researcher that their child was
on a special diet. For example, some were on a gluten- or casein-free diet, while
others were taking heavy doses of supplements per day such as fish oil or Co-Q10. It
is not known whether dietary restrictions or supplements have an effect on EDA.
Participant compliance was another challenge. The Sensory Challenge
Protocol (SCP) is a structured procedure in which the children were asked to remain
still (they were told to be like a “statue”). It was a challenge for the younger children
to sit still for at least 30 minutes without moving. Moreover, some children with
autism who appeared to be sensitive to certain stimuli found a way to avoid them.

87

For instance, while keeping the left hand still (attached to the electrodes), some
children covered their left ear by tilting their head to their left shoulder and used their
right hand to cover the right ear during the auditory stimuli. During the strobe light
stimuli, some children blinked a lot or looked away; and during the tactile stimuli (a
feather stroke under the chin), some children covered their chin to avoid it or rubbed
their chin after the stimulus was given. It is unclear if these behaviors, which may
serve self-regulatory or other adaptive functions, had an effect on the children’s
psychophysiological responses. In the future, in addition to an examiner who focuses
on administering the protocol, a lab assistant is recommended to sit next to a child in
order to guide him/her immediately when unwanted behaviors are occurred.
An additional limitation was that the customized computerized scoring
program was later found to provide erroneous readings in non-specific responses
(NSR) and habituation. The reason for the errors in NSR was that the program was
not able to ignore the movement artifacts, which created spurious numbers of NSRs
that were out of typical range. Due to inconsistencies between the computer-
generated scores and hand calculations, NSRs were deleted from the analysis.
Moreover, the assigned scores for the habituation were incorrect – for those who
responded to all trials, the assigned code should have been 8 rather than zero,
whereas for those who did not respond to any trials, the assigned code should have
been zero. In addition, the program did not provide frequency of responses to
auditory stimulation and half-recovery time. At the time of this writing, habituation

88

and number of responses to auditory stimuli had to be calculated by hand, but NSR
rates and half recovery time were not included in the final analysis. Use of
SCRGAUGE by Peter Kohlisch and SCORIT 1980 (Strayer & Williams, 1982) are
recommended by Dawson, Schell and Filion (2007) to solve scoring problems such
as this.
Overall, generalization of the study findings is limited due to several reasons.
First, as a convenience sample, ethnicity, age, and gender were not balanced between
the two study groups. Second, measurement of behavioral under-responsiveness and
sensory seeking was very limited in this study. Three out of 4 added questions were
not examined for construct validity. Third, this study focused only on autonomic
responses and behaviors related to auditory stimuli; thus, future study is needed to
further investigate other sensory domains, such as tactile, visual, or olfactory.
Finally, over 80% of the children with autism were receiving occupational
therapy, raising the possibility of clinical bias. Perhaps in the geographical area
where the study was conducted, children with autism who are over-responsive to
auditory stimuli tend to be selectively referred to occupational therapists. The sample
in this study, therefore, may not represent population of children with autism, many
of whom may be under-responsive or may not have sensory modulation difficulties.

89

Conclusions
These pilot data provide preliminary evidence that children with autism who
have more severe behavioral problems in response to naturally occurring auditory
stimuli demonstrate higher arousal and increased physiological reactivity to auditory
stimuli than do typically-developing children. As the physiological response to
auditory stimuli relates to behavioral problems, the Sensory Processing Measure
Home Form used in this study can identify such sensory modulation difficulties.
Findings tend to validate the SPM Home Form in that, for children with autism,
scores on the measures were significantly correlated with physiological responses to
auditory stimulation. This helps us understand that in children with autism
behavioral problems in response to certain sounds may be due to the fact that their
autonomic nervous systems are not able to modulate surrounding auditory stimuli.

90

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98

Appendix A
Diagnostic Criteria for Autistic Disorder

99

Autistic disorder*
A. A total of six (or more) items from (1), (2), and (3), with at least two from
(1), and one each from (2) and (3):
(1) qualitative impairment in social interaction, as manifested by at least two
of the following:
(a) marked impairment in the use of multiple nonverbal behaviors, such as
eye-to-eye gaze, facial expression, body postures, and gestures to regulate
social interaction.
(b) failure to develop peer relationships appropriate to developmental
level.
(c) a lack of spontaneous seeking to share enjoyment, interest, or
achievements with other people (e.g., by a lack of showing, bringing, or
pointing out objects of interest)
(d) lack of social or emotional reciprocity
(2) qualitative impairment in communication, as manifested by at least one of
the following:
(a) delay in, or total lack of, the development of spoken language (not
accompanied by an attempt to compensate through alternative modes of
communication such as gesture or mime)
(b) in individuals with adequate speech, marked impairment in the ability
to initiate or sustain a conversation with others
(c) stereotyped and repetitive use of language or idiosyncratic language
(d) lack of varied, spontaneous make-believe play or social imitative play
appropriate to developmental level
(3) restricted, repetitive, and stereotyped patterns of behavior, interested, and
activities as manifested by at least one of the following:
(a) encompassing preoccupation with one or more stereotyped and
restricted patterns of interest that is abnormal either in intensity or focus
(b) apparently inflexible adherence to specific, non-functional routines or
rituals
(c) stereotyped and repetitive motor mannerisms (e.g., hand or finger
flapping
or twisting or complex whole-body movements)
(d) persistent precoccupation with parts of objects
B. Delays or abnormal functioning in at least one of the following areas, with
onset prior to age 3 years: (1) social interaction, (2) language as used in social
communication, or (3) symbolic or imaginative play.
C. The disturbance is not better accounted for by Rett disorder or childhood
disintegrative disorder.
*SOURCE: American Psychiatric Association. Diagnostic and statistical manual
of mental disorders- text revision (DSM-IV-TR
TM
, 2000) Arlington, VA:
American Psychiatric Association, 2000.

100

Appendix B
All Auditory Questions Grouped by Patterns

101

All Auditory Questions Used in this Study

Items for Over-responsiveness:
1. Seem bothered by ordinary household sounds, such as the vacuum cleaner,
hair dryer, or toilet flushing?
2. Respond negatively to loud noises by running away, crying, or holding hands
over ears?
3. Seem disturbed by or intensely interested in sounds not usually noticed by
other people?
4. Seem frightened of sounds that do not usually cause distress to other kids
his/her age?
5. Seem easily distracted by background noises such as a lawn mower outside,
an air conditioner, a refrigerator, or fluorescent lights?
6. Show distress at shrill or brassy sounds, such as whistles, party noisemakers,
flutes, and trumpets?

Items for Under-responsiveness:
1. Appear not to hear certain sounds?
2. Seem to under-react to loud noises?*
3. Ignore you when you call his/her name?*

Items for Sensory Seeking:
1. Like to cause certain sounds to happen over and over again, such as by
repeatedly flushing the toilet?
2. Like to hear certain sounds over and over, such as the sound of certain words
or songs?*
3. Seem to enjoy creating certain sounds using their voice or body?*

*Newly-added questions for the study purpose.

102

Appendix C
Distributions of EDA variables

103

Figure C1
Frequency distribution of mean log skin conductance levels (SCL) of the two study
groups at Baseline A) and Recovery B)

A) SCL at baseline

B) SCL at Recovery

104

Figure C2
Distribution of Mean Amplitude Responses to Tone A) and Siren B)

A) AMP to Tone

B) AMP to Siren

105

Figure C3
Distribution of Mean Magnitude Responses (MAG) to Tone A) and Siren B)

A) MAG to Tone

B) MAG to Siren

106

Figure C5
Distribution of Trials to Habituation (Habit) to Tone A) and Siren B)

A) Habit to Tone

B) Habit to Siren

107

Figure C5
Distribution of Number of Responses (FREQ) to Tone A) and Siren B)

A) FREQ to Tone

A) FREQ to Siren

108

Figure C6
Distribution of Latency (ONLAT) to Tone A) and Siren B)

A) ONLAT to Tone

B) ONLAT to Siren

109

Figure C7
Distribution of Rise Time (PKLAT) to Tone A) and Siren B)

A) PKLAT to Tone

A) PKLAT to Siren

110

Appendix D
Intercorrelations among all EDA Variables
Table 16
Correlation Matrix for All EDA variables*

SCL Tone Siren
Variable Base Rec AMP MAG Habit FREQ ONLAT PKLAT AMP MAG Habit FREQ ONLAT PKLAT
SCL Base 1.00 0.69 0.40 0.51 0.47 0.53 0.11 -0.48 -0.05 0.41 0.39 0.50 -0.04 -0.54
Rec 0.78 1.00 0.12 0.24 0.31 0.29 -0.21 -0.37 0.09 0.43 0.37 0.48 -0.07 -0.25
Tone AMP 0.46 0.27 1.00 0.69 0.34 0.37 -0.03 -0.10 -0.12 0.13 -0.01 0.11 -0.18 -0.53
MAG 0.58 0.33 0.83 1.00 0.77 0.91 -0.24 -0.39 -0.26 0.23 0.19 0.37 -0.18 -0.54
Habit 0.55 0.44 0.29 0.80 1.00 0.88 -0.41 -0.54 -0.30 0.31 0.47 0.54 -0.09 -0.47
FREQ 0.52 0.33 0.43 0.89 0.95 1.00 -0.29 -0.51 -0.32 0.28 0.36 0.50 -0.14 -0.47
ONLAT 0.15 -0.07 -0.23 -0.02 -0.01 0.08 1.00 0.25 0.12 0.00 -0.15 -0.04 0.51 0.44
PKLAT -0.05 -0.13 -0.27 -0.18 -0.33 -0.14 0.68 1.00 0.08 -0.35 -0.45 -0.48 -0.09 0.39
Siren AMP 0.45 0.26 0.25 0.30 0.31 0.22 0.00 -0.27 1.00 0.69 0.18 0.30 -0.18 0.15
MAG 0.48 0.64 0.19 0.32 0.43 0.32 -0.24 -0.37 0.60 1.00 0.73 0.89 -0.28 -0.22
Habit 0.45 0.68 0.14 0.30 0.36 0.29 -0.16 -0.02 0.21 0.79 1.00 0.85 -0.47 -0.44
FREQ 0.40 0.62 -0.01 0.32 0.45 0.42 -0.26 -0.12 0.15 0.81 0.88 1.00 -0.24 -0.32
ONLAT -0.15 0.04 -0.12 -0.36 -0.40 -0.41 -0.09 0.18 -0.13 -0.35 -0.30 -0.34 1.00 0.65
PKLAT -0.62 -0.55 -0.29 -0.56 -0.60 -0.63 -0.19 0.09 -0.08 -0.42 -0.41 -0.53 0.37 1.00
Note. The lower left half of the matrix depicts findings for the AD group and the upper right half of matrix with underlined numbers represents the TD group.
Bold numbers indicate significant correlations (p < .05).

111

112

Appendix E
T-tests Results for all EDA Measures between Some Problems Range and
Definite Dysfunction Range in Children with Autism

113

Table 17
T-tests Results for all EDA Measures between Some Problems Range and
Definite Dysfunction Range in Children with Autism

Some Problems

Definite
Dysfunction

Variable n Mean (SD) n Mean (SD) t-value P-value

Tonic
EDA
SCL base 15 2.08 (0.54) 5 2.57 (0.33) -1.87 0.08
SCL rec 15 2.35 (0.53) 5 2.48 (0.44) -0.47 0.64

Tone
AMP 12 0.88 (0.27) 5 1.17 (0.25) -2.00 0.06
MAG 15 0.40 (0.29) 5 1.00 (0.25) -4.10 <.01
Habit 15 4.47 (2.90) 5 8.00 (0.00) -4.72 <.01
FREQ 15 3.53 (2.20) 5 6.80 (0.84) -3.20 <.01
ONLAT 12 1.59 (0.33) 5 1.18 (0.36) -1.24 0.23
PKLAT 12 3.29 (0.48) 5 3.34 (0.68) -0.19 0.85

Siren
AMP 15 0.94 (0.42) 5 1.07 (0.25) -0.63 0.54
MAG 15 0.60 (0.38) 5 0.71 (0.31) -0.59 0.56
Habit 15 5.20 (2.83) 5 6.00 (2.74) -0.55 0.59
FREQ 15 4.93 (2.55) 5 5.80 (2.49) -0.66 0.52
ONLAT 15 1.66 (0.37) 5 1.57 (0.22) 0.50 0.62
PKLAT 15 3.74 (1.27) 5 3.06 (0.40) 1.83 0.08
Note. Bold numbers indicating significant correlation (p < .05)

114

Appendix F
Intercorrelations between the SPM Variables and all EDA Variables

115

Table 18
Correlation Table for SPM-related Variables with all EDA variables for AD group

Variable
Hearing
T-score
Total
T-score
Hear4
Over-
Resp
Under-
Resp
Sensory
Seeking

SCL

Base

0.28

0.45

0.36

0.39

0.33

0.06
Rec 0.07 0.13 0.01 0.13 -0.12 -0.07

Tone

AMP

0.41

0.42

0.50

0.56

0.35

0.08
MAG 0.46 0.33 0.62 0.68 0.42 0.15
Habit 0.30 0.08 0.41 0.47 0.22 0.13
FREQ 0.33 0.16 0.47 0.52 0.32 0.12
ONLAT -0.08 0.21 0.07 -0.06 0.24 0.08
PKLAT -0.16 0.21 -0.07 -0.25 0.01 0.23

Siren

AMP

0.04

0.10

0.22

0.22

-0.04

0.24
MAG -0.12 -0.14 0.02 0.11 -0.24 0.11
Habit -0.03 -0.17 0.01 0.13 -0.29 0.06
FREQ -0.02 -0.10 0.04 0.12 -0.23 0.13
ONLAT -0.13 0.14 -0.33 -0.18 -0.18 -0.40
PKLAT -0.04 -0.19 -0.12 -0.16 -0.20 0.01
Note. Bold numbers indicating significant correlation (p < .05)

116

Table 19
Correlation Table for SPM-related Variables with all EDA variables for TD group

Variable
Hearing
T-score
Total
T-score
Hear4
Over-
Resp
Under-
Resp
Sensory
Seeking

SCL

Base

0.04

0.00

0.01

0.09

-0.24

0.10
Rec 0.32 0.03 0.18 0.26 -0.01 0.09

Tone

AMP

0.04

-0.40

-0.04

0.07

-0.10

-0.09
MAG -0.16 -0.31 -0.21 -0.12 -0.27 -0.09
Habit -0.22 -0.38 -0.25 -0.19 -0.35 -0.02
FREQ -0.17 -0.19 -0.20 -0.12 -0.33 -0.01
ONLAT -0.10 0.22 -0.15 0.00 -0.26 -0.13
PKLAT 0.11 0.11 0.12 0.09 0.09 0.08

Siren

AMP

0.02

-0.17

-0.02

0.04

0.48

-0.44
MAG 0.18 -0.27 -0.07 0.23 -0.09 -0.38
Habit 0.17 -0.29 -0.10 0.25 -0.24 -0.35
FREQ 0.14 -0.24 -0.14 0.20 -0.33 -0.29
ONLAT -0.28 0.44 -0.05 -0.30 -0.04 0.38
PKLAT -0.03 0.42 0.10 -0.05 0.22 0.13
Note. Bold numbers indicating significant correlation (p < .05)

117

118

Appendix G
Glossary

119

Glossary

Abbreviation Descriptions
AD group : comprised of 22 children with autism whose data were
included in the data analysis.

AMP : amplitude response; average of square root of amplitude
that is greater than 0.05 uS and only measurable
responses (non-zero) included.

ANOVA : analysis of variance.

base : indicating baseline phase of Sensory Challenge Protocol
(SCP) in this study.

EDA : electrodermal activity.

FREQ : number of responses that the amplitude is greater than
0.05 uS to auditory stimuli across 8 trials.

Habit : habituation; defined as 2 consecutive non-responses to
tone or siren stimuli.

Hear4 : comprised of raw scores from the Hearing Scale of SPM
Home Form summed with 4 additional auditory
questions.

MAG : magnitude response; which is average of square root of
magnitude that is greater than 0.05 uS and zero response
(no response occurred) on trials.

NSR : non-specific responses; average number of skin
conductance responses per minute during baseline phase
(NSR base) and recovery phase (NSR rec).

NSR base : see NSR.

NSR rec : see NSR.

120

Abbreviation Descriptions
ONLAT : latency; average of time (in seconds) between the time of
the stimulus and the initiation of the response across 8
trials.

Over-resp : over-responsiveness; refers to a state in which “the
individual is disturbed by ordinary sensory input and
reacts defensively to it,” (Parham & Mailloux, 2005, p.
410).

Phasic EDA : reflects a phasic response elicited by a given stimulus.
Phase measures include AMP, MAG, FREQ, Habit,
ONLAT, and PKLAT.

PKLAT : rise time; average of time (in seconds) between the
onsets of response to the peak across 8 trials.

rec : indicating recovery phase of Sensory Challenge Protocol
(SCP) in this study

SCL : skin conductance level; average of 18 log-transformed
skin conductance values. In this study, it was measured
during the baseline phase (SCL base) and recovery phase
(SCL rec).

SCL base : see SCL

SCL rec : see SCL.

SCP : Sensory Challenge Protocol (SCP); a standard laboratory
procedure to measure autonomic nervous response.

SCQ Lifetime Form : Social Communication Questionnaire (SCQ) Lifetime
Form.

SD : standard deviation.

SMD : sensory modulation difficulties.

SPM (SPM) Home Form : Sensory Processing Measure (SPM) Home Form.

121

Abbreviation Descriptions
sensory seeking : describes a person who “actively seeks out particular
kinds of sensations at higher frequencies or intensities
than is typical” (Parham & Mailloux, 2005, p. 410).

TD group : comprised of 20 typically-developing children whose
data were included in the data analysis.

Tonic EDA : reflects a person’s tonic sympathetic activation in any
situation, including at rest without orienting response.
Tonic measures include SCL & NSR.

Under-resp : under-responsiveness; describes a condition in which
“the individual tends to ignore or be relatively unaffected
by sensory stimuli to which most people respond”
(Parham & Mailloux, 2005, p. 410).

122

Appendix H
Subject Recruitment Flyer

123

124

125

Appendix I
Parental Consent and Child Assent Forms

126

INFORMED CONSENT

TITLE: PATTERNS OF SENSORY RESPONSIVENESS TO AUDITORY
STIMULATION IN CHILDREN WITH AUTISM

PRINCIPAL INVESTIGATOR: CHIA-CHEN MEGAN CHANG

DEPARTMENT: DIVISION OF OCCUPATIONAL SCIENCE AND
OCCUPATIONAL THERAPY

24-HOUR TELEPHONE NUMBER: 626-363-3600

WHY IS THIS STUDY BEING DONE?

We invite your child to take part in a research study. This study is about
understanding the ways in which children with autism respond to sensations,
especially sounds. We hope to learn how strongly and how often a child’s nervous
system pays attention to repeated sounds, and whether these patterns of response are
related to their behavior when responding to sounds in everyday life. The study will
evaluate both autistic children and non-autistic children. Your child is being invited
as a possible participant because he or she is 5-12 years old, and either is a typically-
developing child (a child without autism), or has been diagnosed with autism. The
typically developing children will be recruited among the families of personal friends
or siblings (brother or sister) of children with autism. About 80 children will take
part in this study.

WHAT IS INVOLVED IN THE STUDY?
If you decide to have your child take part, this is what will happen:

If your child is typically-developing, an occupational therapist first will ask you to
complete the Sensory Processing Measure (SPM) Home Form, a questionnaire that
asks about your child’s behavior in everyday life, including responses to sounds and
other types of sensory experiences such as touch, vision, and movement. If your
child has autism, in addition to the SPM Home Form, the therapist will ask you to fill
out the Social Communication Questionnaire (SCQ), which is a screening
assessment. If your child scores within a certain range on the assessment(s), then
your child will be asked to participate in the “space lab” procedure.

IRB Approval: HS-07-00337
Version Date: 12/10/07

127

During the space lab procedures (which takes about an hour), your child will be
asked to imagine that he or she is an astronaut in a pretend spaceship which provides
sounds, sights, smells, textures, and movements. The researcher will then ask you
move to the adjoining observation room from which you can observe your child and
fill out the questionnaires. You may observe the lab procedures from this room for as
long as you wish.
Next, the researcher will ask your child to watch a short film clip from the movie
Apollo 13 (a movie about astronauts), while the researcher attaches 2 band-aid-like
electrodes (similar to the ones being put on the astronauts in the movie) to your
child’s right hand and 3 band-aide-like electrodes to his or her ribcage. This will give
us information about the amount of sweat being produced on your child’s hand, as
well as breathing and heart rate, before and during the sensory experiences. Six
different sensory experiences will be presented to your child (a tone, a strobe light, a
siren, a touch with a feather, a smell, and the chair tilting backward for a few
seconds). Each one of these sensations will be given 8 times, followed by a rest
period. You or your child can stop any of the study activities at any time.

Our equipment if very sensitive to a child’s movements, which create signals (false
data reading) that can be misinterpreted when analyzing the data; therefore, we need
to videotape the lab process in order to review the videotapes and recode the data
collected from your child. Reviewing the videotape to recode the data is part of the
data cleaning process.

WHAT ARE THE POSSIBLE RISKS AND DISCOMFORTS?

Potential risks and discomforts your child could experience during this study include:

Electrodes: The electrodes may cause minor discomfort: If your child is
uncomfortable with the electrodes, he or she can easily remove them and stop the
activity at any time.

Psychological risks: Possible psychological risks for children may include mild
anxiety or discomfort, or claustrophobia (fear of enclosed spaces), and our therapists
are trained to respond to any difficulties a child may experience.

Questionnaire: As a parent, you might feel minor embarrassment answering the
questionnaires. You may also refuse to answer any questions you don’t want to
answer and still have your child remain in the study.

IRB Approval: HS-07-00337
Version Date: 12/10/07

128

WHAT ARE THE POSSIBLE BENEFITS OF TAKING PART IN THIS
STUDY?

Your child will not benefit from taking part in this study. However, your child’s
participation in this study may help us learn more about autism.

WHAT OTHER OPTIONS ARE THERE?

An alternative would be to not to have your child take part in this study.

WILL YOUR CHILD’S INFORMATION BE KEPT PRIVATE?

The investigator and the Institutional Review Board (IRB) will keep your child’s
records for this study private as far as the law allows. We may publish the
information from this study in journals or present it at meetings. If we do, we will
not use your child’s name.

WHAT HAPPENS IF YOUR CHILD GETS INJURED OR NEEDS
EMERGENCY CARE?

In the very unlikely event that your child will experience an injury or medical
emergency while participating in study procedures, will assist you will in contacting
the most convenient medical facility for care. The cost incurred for this care will be
your responsibility.

UNDER WHAT CIRCUMSTANCES CAN YOUR CHILD’S
PARTICIPATION BE TERMINATED?

The investigator may withdraw your child from this study if circumstances arise
which warrant doing so.

WHAT ARE YOUR RIGHTS AS A PARTICIPANT, AND WHAT WILL
HAPPEN IF YOU DECIDE NOT TO PARTICIPATE?

Your child’s participation in this study is voluntary. Your decision whether or not to
have your child take part will not affect your child’s current or future care at this
institution. You are not waiving any legal claims or rights. If you do decide to have
your child take part in this study, you are free to change your mind and stop your
child from being in the study at any time. You may withdraw your child at any time
without consequences of any kind.
IRB Approval: HS-07-00337
Version Date: 12/10/07

129

WHOM DO YOU CALL IF YOU HAVE QUESTIONS OR CONCERNS?

You may contact Megan Chang at 626-363-3600 with any questions or concerns
about your participation in this study. If you feel you have been hurt by taking part in
this study, please contact Megan Chang at 626-363-3600. If you have any questions
about your rights as a study subject, please contact the Institutional Review Board
Office at LAC+USC Medical Center, IRD Building, 2020 Zonal Avenue, Suite 425,
Los Angeles, CA 90033. (Telephone number: 323-223-2340). You will get a copy of
this consent form.

AGREEMENT:

I have read (or someone has read to me) the information provided above. I have been
given a chance to ask questions. All my questions were answered. I have decided to
sign this form in order for my child take part in this study.

Name of Parent/Legal Guardian Signature Date Signed

Name of Witness Signature Date Signed

Print Name of Child

I have personally explained the research to the parent/legal guardian and
answered all questions. I believe that he/she understands the information
described and freely consents to participate.

Name of Investigator/Person
Obtaining Informed Consent
Signature Date Signed
Form Valid For Enrollment From
7/4/2008 To 7/3/2009
Institutional Review Board
HS-07-00337
IRB Approval: HS-07-00337
Version Date: 12/10/07

130

UNIVERSITY OF SOUTHERN CALIFORNIA
Division of Occupational Science and Occupational Therapy

ASSENT TO BE IN RESEARCH

PATTERNS OF SENSORY RESPONSIVENESS TO AUDITORY
STIMULATION IN CHILDREN WITH AUTISM

1. My name is Megan Chang.

2. We are asking you to take part in a research study because we are trying to learn
more about how your body responds to sound, smell, light, touch, and movement.

3. If you decide to be in this study, you will be asked to sit still for about an hour
and pretend you are in a spaceship like in the movie Apollo 13. Just like the
astronauts in the movie, we will attach two band-aid-like electrodes on your hand
and two band-aid-like electrodes on your chest. We will also videotape you like
the astronauts. If you are not comfortable or get scared during the experiment,
you can stop at any time you want.

4. Sometimes things happen in research studies. Some of the bad things that could
happen are: you may not like certain sound, light, smell, touch, or movement.
Some of these things might happen to you or they might not. Or things might
happen that we don’t know about yet.

5. This study may help us better understand how to help children with autism.

6. Please talk this over with your parents before you decide whether or not to take
part in this study. We will also ask your parents to give their permission for you
to take part in this study. But even if your parents say “yes” you can still decide
not to do this.

7. If you don’t want to be in this study, you don’t have to. You may stop being in
this study any time. Remember, being in this study is up to you and no one will
be upset if you don’t want to take part in this study or even if you change your
mind later and want to stop.

8. You can ask any questions that you have about the study. If you have a question
later that you didn’t think of now, you can call me 626-363-3600 or ask me next
time.

IRB Approval: HS-07-00337
Version Date: 12/10/07

131

9. Putting your name at the bottom means that you have decided to be in this study.
You and your parents will be given a copy of this form after you have signed it.

______________________________________________
Name of Subject (please put your name here ↑) Date

______________________ ___________________________ __________
Name of Person Obtaining Assent Signature of Person Obtaining Assent Date

Form Valid For Enrollment From
7/4/2008 To 7/3/2009
Institutional Review Board
HS-07-00337
IRB Approval: HS-07-00337
Version Date: 12/10/07

132

Appendix J
Demographic Information Form

133

Sensory Challenge Lab Demographic Form

1. What is your child’s gender?
 Male
 Female

2. What is your child’s date of birth? _________/_____/______
Month Day Year

3. Please describe your child’s ethnicity:
 1) Asian
 2) Black, Non-Hispanic
 3) Hispanic
 4) Native American
 5) White, Non-Hispanic
 6) Other: ____________________________

4. Is your child currently taking any medication?
 Yes, If yes, please list in the 4a.
 No
4a. If yes, please list below:
Name Dose Time of Last Dose
1)
2)
3)
4)
5)
6)
7)

5. Does your child have any official diagnoses?
 Yes. If yes, please select from 5a.
 No
5a. If yes, please select below:
 1) Autistic disorder
 2) Asperger’s Syndrome
 3) Autism Spectrum Disorders
 4) Generalized Anxiety Disorder
Subject ID:_______

134

 5) Cognitive Delay/Mental Retardation
 6) Fragile X Syndrome
 7) Genetic Disorder
 8) Hearing Impairment
 9) Learning Disorder
 10) Major Depressive Disorder (Depression)
 11) Neurological Disorder
 12) Pervasive Developmental Delay
 13) Sensory Processing Disorder, Sensory Integration Dysfunction, or
Sensory Modulation Dysfunction.
 14) Visual impairment
 15) Other (please specify):_______________________________

6. Please indicate the results of testing if your child has received:

 Autism Diagnostic Observation Schedule (ADOS):
Date tested:____________________
Scores/Results:__________________________________________
Score for Module 3: _____________________________________
- Communication:__________________________

 Social Communication Scale (SCQ):
Date tested:____________________
Scores/Results:____________________________________________

 Sensory Processing Measure, Home Form (SPM):
Date tested:____________________
Total Scores:___________________
- Hearing Scores:__________

7. Currently, what treatment(s) does your child receive?
 A. Occupational Therapy
 A1. Private/clinic with focus on sensory integration,
Date started/Ended__________
 A2. School-based
Date started/Ended__________
 B. Physical Therapy
Date started/Ended__________
 C. School-based behavioral aid (one-on-one)
Date started/Ended__________

135

 D. Home-base behavioral support
 ABA, Date started/Ended__________
 Other: ____________________________________________
Date started/Ended__________
 E. Specialized classroom
Date started/Ended__________
 F. Psychologist/Psychiatrist
Date started/Ended__________
 G. Alternative Treatment: Please specify________________________
Date started/Ended__________

8. Please describe the pregnancy:
 Full-term, no complications
 Full-term with complications, please describe below:
__________________________________________________________

9. Please describe the birth:
 No complications
 No complications, Cesarean section
 Complications, please describe below:
__________________________________________________________

10. Have we tested any siblings of this child?
 Yes
 No
10a. If no, would you be willing to have your other child to participate in this
study?
 Yes. If yes, please inform your therapist or lab experimenter to obtain
pertinent package
 No

THANK YOU VERY MUCH FOR ANSWERING THE QUESTIONS. WE WILL NOT
SHARE ANY INFORMATION YOU ANSWERED WITH OTHERS. ANY
PUBLICATIONS FROM THIS STUDY WILL NOT REVEAL YOUR IDENTITY. IF
YOU WOULD LIKE TO KNOW ABOUT THIS STUDY RESULT, PLEASE LEAVE
YOUR NAME AND ADDRESS TO THE LAB EXPERIMENTER, AND WE WILL
INFORM YOU ONCE THE STUDY IS COMPLETED.

136

Appendix K
Social Communication Questionnaire, Lifetime Form

137

138

139

Appendix L
Sensory Processing Measure (SPM) Home Form

140

141

142

143

Appendix M
Questionnaire of the Four Additional Auditory Questions

144

Additional Hearing Questions for the Sensory Processing Measure
(SPM) Home Form (used for the purpose of this study only).

1. Seem to under-react to loud noises?
1) Never
2) Occasionally
3) Frequently
4) Always

2. Ignore you when you call his/her name?
1) Never
2) Occasionally
3) Frequently
4) Always

3. Like to hear certain sounds over and over, such as the sound of certain words
or songs?
1) Never
2) Occasionally
3) Frequently
4) Always

4. Seem to enjoy creating certain sounds using their voice or body?
1) Never
2) Occasionally
3) Frequently
4) Always

Abstract (if available)

Abstract This study investigated the relationship between autonomic reactivity and behavioral responses to auditory stimulation in 22 high-functioning children with autism (AD) and twenty typically-developing children (TD). A primary purpose was to examine whether the AD and TD groups differed with respect to autonomic activity at rest and following auditory stimulation. An additional purpose was to investigate whether the severity of behavioral difficulties with auditory stimuli in everyday life, as reported by parents, was associated with electrodermal responses to auditory stimuli presented in a controlled laboratory setting. Electrodermal activity (EDA) was measured at rest and in response to two auditory stimuli, a tone and a siren, using the Sensory Challenge Protocol. Behavioral difficulties were measured with the Sensory Processing Measure (SPM) Home Form. T-tests were applied to EDA variables to detect differences between the two study groups. Confounding effects of gender, age, and ethnicity on EDA findings were also analyzed. Associations between EDA measures and SPM scores were determined using Pearson correlation procedures.

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Creator Chang, Chia-Chen Megan (author)

Core Title Autonomic and behavioral responses of children with autism to auditory stimulation

School School of Dentistry

Degree Doctor of Philosophy

Degree Program Occupational Science

Publication Date 05/18/2010

Defense Date 02/19/2009

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

Tag auditory stimulation,children with autism,electrodermal activity,OAI-PMH Harvest

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Clark, Florence A. (committee chair), Parham, L. Diane (committee chair), Blanche, Erna (committee member), Chou, Chih-Ping (committee member), Dawson, Michael E. (committee member), Schell, Anne M. (committee member)

Creator Email chiachec@usc.edu,megan.osot@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-m2277

Unique identifier UC1286776

Identifier etd-Chang-2849 (filename),usctheses-m40 (legacy collection record id),usctheses-c127-240796 (legacy record id),usctheses-m2277 (legacy record id)

Legacy Identifier etd-Chang-2849.pdf

Dmrecord 240796

Document Type Dissertation

Rights Chang, Chia-Chen Megan

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Repository Name Libraries, University of Southern California

Repository Location Los Angeles, California

Repository Email cisadmin@lib.usc.edu