Available online at www.sciencedirect.com
Behavior Therapy 40 (2009) 380 – 392
www.elsevier.com/locate/bt
Treating Youths With Selective Mutism With an Alternating Design
of Exposure-Based Practice and Contingency Management
Jennifer Vecchio
Christopher A. Kearney
University of Nevada, Las Vegas
Selective mutism is a severe childhood disorder involving
failure to speak in public situations in which speaking is
expected. The present study examined 9 youths with
selective mutism treated with child-focused, exposurebased practices and parent-focused contingency management via an alternating treatments design. Broadband
measures of functioning were employed, but particular
focus was made on behavioral assessment of words spoken
audibly and daily in public situations. Treatment ranged
from 8 to 32 sessions and resulted in positive end-state
functioning for 8 of 9 participants. Broader analyses
indicated greater effectiveness for exposure-based practice
than contingency management. The results support recent
case reports of behavioral treatment for this population but
in more rigorous fashion. Clinical and research challenges
are discussed, including caveats about length and intensity
of treatment for this population and need to develop
standardized daily measures.
SELECTIVE MUTISM IS A persistent and potentially
debilitating condition in which a child fails to speak
in public situations in which speaking is expected.
Youths with selective mutism generally speak well
in familiar situations such as home but fail to speak
to people in situations such as school, restaurants,
shopping centers, and parks and other recreational
areas. Failure to speak must last at least 1 month. A
diagnosis of selective mutism does not generally
Address correspondence to Christopher A. Kearney, Ph.D.,
Professor and Director of Clinical Training, University of Nevada,
Las Vegas, Department of Psychology, 4505 Maryland Parkway,
Las Vegas, NV 89154-5030; e-mail: chris.kearney@unlv.edu.
0005-7894/08/380–392/$1.00/0
© 2008 Association for Behavioral and Cognitive Therapies. Published by
Elsevier Ltd. All rights reserved.
apply to youths with a communication disorder
such as stuttering or to youths who lack knowledge
or comfort with the primary language spoken in
public situations (American Psychiatric Association, 2000). As such, selective mutism in the United
States does not typically apply to new immigrants
or to youths whose parents are non-English speakers (Krysanski, 2003; Vecchio & Kearney, 2007).
Selective mutism affects 0.2 to 2.0% of children,
impacts boys and girls equally, and begins typically
during preschool and early school-age years (Bergman, Piacentini, & McCracken, 2002; Chavira,
Stein, Bailey, & Stein, 2004; Elizur & Perednik,
2003; Garcia, Freeman, Francis, Miller, & Leonard, 2004; Kumpulainen, 2002). Treatment for
many cases of selective mutism is delayed several
years, however, because these children are simply
considered shy by parents or because the children
often speak well at home (Andersson & Thomsen,
1998; Ford, Sladeczek, Carlson, & Kratochwill,
1998; Schwartz et al., 2006). As the disorder
progresses, children may experience debilitating
problems such as peer rejection, few friendships,
incomplete verbal academic tasks or standardized
tests, or inadequate language or social skills
(Cunningham, McHolm, & Boyle, 2006; Kumpulainen, Rasanen, Raaska, & Somppi, 1998).
Selective mutism has a chronic course in some but
not all cases, though additional longitudinal data
are sorely needed (Cohan, Price, & Stein, 2006;
Remschmidt, Poller, Herpertz-Dahlmann, Hennighausen, & Gutenbrunner, 2001; Steinhausen,
Wachter, Laimbock, & Metzke, 2006).
Research regarding selective mutism has burgeoned in recent years to better conceptualize and
treat this often shadowy problem. Children with
selective mutism have been historically described as
shy, timid, socially withdrawn, inhibited, and
selective mutism
reticent (Kopp & Gillberg, 1997; Kristensen, 2001;
Lesser-Katz, 1986; Steinhausen & Juzi, 1996). In
more recent years, researchers have employed
standardized measures with this population to
discover a very high prevalence of comorbid social
anxiety disorder (Sharp, Sherman, & Gross, 2007;
Vecchio & Kearney, 2005; Yeganeh, Beidel, Turner,
Pina, & Silverman, 2003). Researchers have also
found many youths with selective mutism to have a
developmental disorder or delay (Kristensen,
2000). Some have claimed as well that language
and auditory processing impairments, memory
problems, and oppositional behavior exist in
selective mutism, raising the possible need for
subtyping in this population (Arie et al., 2007;
Kristensen & Oerbeck, 2006; Manassis et al., 2003;
Yeganeh, Beidel, & Turner, 2006).
Treatment for youths with selective mutism has
generally gravitated toward procedures that target
anxiety-and oppositional-based components of the
disorder. Cohan, Chavira, and Stein (2006) conducted a comprehensive review of the treatment
literature for selective mutism and found that
researchers primarily used behavioral strategies to
reduce anxiety, boost appropriate verbalizations,
and reduce oppositional or inappropriate attentionseeking behavior. Key behavioral strategies for
youths with selective mutism include exposurebased practices such as systematic desensitization,
social skills training and modeling, self-modeling,
shaping and stimulus fading, and parent-based
contingency management. A number of other
strategies have also been used, including family
systems, psychodynamic, and multimodal
approaches, but the authors concluded that behavioral interventions were primarily supported.
Other recent studies have also supported the use
of behavioral strategies for cases of selective mutism
(Baskind, 2007; Fisak, Oliveros, & Ehrenreich,
2006; Vecchio & Kearney, 2007).
Cohan, Chavira, and Stein (2006) also found
substantial drawbacks with the extant treatment
literature for youths with selective mutism. First,
the use of wide-ranging, standardized, or systematic
assessment techniques has been relatively uncommon, especially for key outcome variables. Second,
many intervention studies were based on record
review or individual cases with no control. Third,
standardized treatments with measures of treatment integrity are virtually nonexistent. Fourth,
very little information is available as to which
specific treatment strategies are most useful for
children with selective mutism. Dismantling studies
are necessary to determine which treatment components are most active for promoting behavior
change for this population. In particular, research-
381
ers have called for graphic display of treatment
outcomes as well as effect size calculations to help
make this determination (Pionek Stone, Kratochwill, Sladezcek, & Serlin, 2002).
To partly address these concerns, we conducted a
controlled outcome study using standardized and
systematic assessments and a single-participantbased alternating treatments design. The design
allowed us to examine the specific impact of
exposure-based practice and contingency management in 9 youths with selective mutism. We chose
exposure-based practice and contingency management for several reasons. First, these techniques
have been used historically to increase a child's
audible speech in public places via anxiety reduction (exposure) and modification of inappropriate
attention-seeking or compensatory behaviors such
as pointing (contingency management). Second, we
wished to keep the study circumscribed to make a
clearer determination about which technique was
more effective for reducing selective mutism. Third,
child-based exposure and parent-based contingency
management allowed the therapist to clearly
delineate treatment phases. Based on limited
literature that exposure-based practices and contingency management are effective for reducing
selective mutism, we hypothesized that the treatment techniques would be equally effective.
Method
participants
Nine children aged 4 to 9 years and their parents
voluntarily participated in this study. Children were
mostly female (7), had a mean age of 6.6 years (SD =
1.9), and were European-American (4), biracial (2),
Asian-American (2), or Hispanic (1). Most families
(7) had two parents, and mean annual family
income was $67,889. Participants were recruited
from public and private schools (7), a preschool (1),
and from a general press release to the community
(1). All children met diagnostic criteria for primary
selective mutism. Secondary diagnoses included
social phobia (9), separation anxiety disorder (2),
specific phobia (2), attention-deficit/hyperactivity
disorder (1), enuresis (1), generalized anxiety
disorder (1), and oppositional-defiant disorder (1).
Participants were excluded if (a) failure to speak
was due to lack of knowledge or comfort with
spoken language required in a social situation, (b)
failure to speak was better accounted for by a communication disorder such as stuttering, (c) mutism
occurred exclusively during the course of a pervasive
developmental or psychotic disorder, (d) a child was
currently receiving pharmacological or other treatment for selective mutism, (e) a child had non-
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vecchio & kearney
English-speaking parents and/or English was not the
primary language spoken in the home, (f) a child had
deaf parents, (g) a child had been absent for more
than 20% of school days in their current academic
year, (h) a child had a developmental disorder, (i) a
child was less than age 4 years or greater than age 10
years, or (j) a child had comorbid diagnoses rated as
more severe than selective mutism. Children with
comorbid diagnoses equal in severity to selective
mutism were eligible for the study.
measures
Given the furtive and fluid nature of selective
mutism symptoms, a daily behavioral assessment
approach was emphasized for this study. In addition, given the great difficulty in collecting daily
data from young children with selective mutism and
their parents, participants were asked to primarily
complete two uncomplicated daily measures. However, data were collected from multiple sources,
including children, parents, teachers, and clinicians.
Child measures. Children completed two daily
measures. First, children completed a one-item
Daily Rating of Anxiety Scale. A 0-to-10 scale
was used (0 = none, 5 = some, and 10 = extreme
anxiety). Youths provided one rating per day.
Second, children completed a Daily Rating of
Behavior Scale to monitor speaking patterns.
Children recorded number of words they mouthed,
whispered, or spoke in school or other public
settings. If applicable, children also rated how
audible their spoken words were on a 0-to-10 scale
(0 = not at all audible and 10 = completely audible).
Children were asked to tell us how many words
they spoke (or whispered or mouthed) at school or
in public that day. We contacted the children at
night and collected this information via telephone
or parents asked their children in the evening and
provided us with a number. Children were asked
how many words they said in school and outside of
school (public settings) but not at home. Some
children told us of the phrases they said at school
and we counted the words, and other children
counted how many words occurred in stories they
read in class. Other children were instructed to say
certain phrases to their teachers or others, and these
words were counted as well. The two youngest
children (ages 4 and 6 years) did not provide child
data, but we found no difficulty with the other
children with respect to counting.
Parent measures. Parents completed a demographic information sheet as well as the Child
Behavior Checklist and two daily rating scales. The
Child Behavior Checklist (CBCL) (Achenbach &
Rescorla, 2001) is a 118-item broadband instrument that yields parent rating scores for internaliz-
ing, externalizing, and mixed behavior problems. T
scores were used for this study. The CBCL is one of
the most widely used standardized measures for
assessing emotional and behavioral problems in
children and has demonstrated excellent test-retest
(r = .90) and interrater (r = .76) reliability as well as
construct and criterion-related validity.
The Daily Rating of Child Anxiety Scale was a
one-item instrument rated on a 0-to-10 scale (0 =
none, 5 = some, and 10 = extreme anxiety). Parents
rated their perceived level of child anxiety on a daily
basis. In addition, the Daily Rating of Child
Behavior Scale was completed by parents daily to
monitor their child's speaking patterns. Parents
recorded number of words their child mouthed,
whispered, or spoke in school or other public
settings. If parents conducted an exposure in the
school and took their child to the school (and thus
observed their child speak to the teacher or others),
then they counted the words spoken. Parents only
recorded words they actually heard their child
speak. If applicable, they also rated the audibility of
their child's words on a 0-to-10 scale (0 = not at all
audible and 10 = completely audible).
Teacher measures. Primary teachers for seven
participants completed the Teacher Report Form
(TRF; Achenbach & Rescorla, 2001) and primary
teachers for six participants completed two daily
rating scales, though only three teachers provided
posttreatment TRF data. The TRF is a 118-item
broadband instrument that yields teacher rating
scores for internalizing, externalizing, and mixed
behavior problems. T scores were used for this
study. The TRF is one of the most widely used
standardized measures for assessing emotional and
behavioral problems in children and has demonstrated excellent test-retest (r = .90) and interrater
(r = .60) reliability as well as construct and
criterion-related validity. TRF data were obtained
for seven participants at pretreatment (2–7 and 9),
for three participants at posttreatment (4, 6, 7), and
for four participants at follow-up (4, 5, 8, 9).
The Daily Rating of Student Anxiety Scale was a
one-item instrument rated on a 0-to-10 scale (0 =
none, 5 = some, and 10 = extreme anxiety).
Teachers rated their perceived level of student
anxiety on a daily basis. In addition, the Daily
Rating of Student Behavior was completed by
teachers daily to monitor their student's speaking
patterns. Teachers recorded number of words their
student mouthed, whispered, or spoke in school. If
applicable, they also rated the audibility of their
student's words on a 0-to-10 scale (0 = not at all
audible and 10 = completely audible).
Clinician measure. Clinicians administered the
Anxiety Disorders Interview Schedule for DSM-IV:
selective mutism
Child and Parent Versions (ADIS-C/P; Silverman &
Albano, 1996). This semistructured diagnostic
interview is widely used to assess anxiety-related
disorders in youths, including selective mutism. The
interview consists of individual sections on various
mental disorders as well as yes/no items to assess
symptoms and symptom severity, frequency, and
duration. The interview accommodates young or
mute children by allowing for nonverbal responses
to items and via visual rating scales. The interviews
have demonstrated good kappa reliability coefficients for major diagnostic categories based on
composite information (.62–1.00) and parent
information only (.65–1.00) (Silverman, Saavedra,
& Pina, 2001). The interviews have also demonstrated good convergence with anxiety scale scores
in an examination of concurrent validity (Wood,
Piacentini, Bergman, McCracken, & Barrios,
2002).
Children aged 9 years (n = 3) and parents were
interviewed separately and data were later combined to derive composite diagnoses (see Silverman
& Albano, 1996, for specific procedures). Children in the study less than age 9 years did not
participate in the diagnostic interview process, so
diagnoses in these cases were derived solely from
parent report. The interviews were administered by
an advanced graduate student in clinical psychology trained in the use of the measures. Clinical
severity ratings of diagnoses were assigned on a 0to-8 scale to derive primary and comorbid
diagnoses. Comorbid diagnoses were those with
less severe clinical severity ratings but which also
applied to a given child.
assessment and consultation
procedure
Initial participant screening. Interested parents
contacted the researchers and participated in an
initial telephone screening. Parents were asked to
identify their child's primary behavior problem and
to stipulate whether their child met general criteria
for selective mutism. In addition, the screener
interviewed the parents regarding each exclusionary criterion mentioned earlier. If the initial screening indicated a child met diagnostic criteria for
selective mutism and did not meet any exclusionary
criteria, then a formal assessment session was
scheduled. Thirty-seven sets of parents were
screened in this fashion. Twenty were excluded
because they met one or more of the exclusionary
criteria: 10 were excluded because English was not
the primary language or the child was not knowledgeable or comfortable with spoken language used
in most public situations, 4 were excluded for
currently receiving treatment for selective mutism, 4
383
were excluded for age constraints, and 2 were
excluded for having deaf parents. In addition, one
child refused to participate in the study. Of the 21
children excluded during initial screening, 14 were
male and 7 were female.
Formal assessment and consultation. Sixteen
formal assessments and/or initial treatment were
thus conducted. Parents were given the option to
have the formal assessment conducted at the child's
school, in their home, or at a specialized university
clinic. Seven assessments were conducted at the
clinic setting, and two were conducted at the
participant's home. Parents provided written consent, and children provided nonverbal assent prior
to data collection. Parents also completed the
diagnostic interview, CBCL, and a demographic
information form. Parents provided consent to
contact their child's teacher to derive TRF and
other data.
Seven children were excluded from the study
during this formal assessment/early intervention
process: 1 child failed to meet diagnostic criteria
for selective mutism, 1 child had a non-Englishspeaking parent, 2 children met criteria for
selective mutism but their parents decided not to
participate in the study, and 3 children met criteria
for selective mutism but dropped out of the study
within 3 sessions. Children excluded from the
study during the formal assessment/early treatment
process were referred for treatment, received
treatment from the researchers separate from the
study, or were provided with contact information
for other mental health providers in the community. Of these 7 children, 5 were male and 2 were
female. The remaining 9 children who completed
formal assessment and who remained in the study
did so for 8 to 32 sessions designed to be
administered twice per week (therapy time range,
2 to 5 months).
Eligible families were then scheduled for a
consultation session to review assessment results
and learn more about the treatment study. Families
were informed of the time commitment involved,
including two formal treatment sessions per week
(scheduled at least 3 days apart) and daily rating
scales. The basic principles and goals of each
treatment component were described. Parents then
provided additional consent for the treatment phase
of the study, and the first formal session was
scheduled. An additional release of information
form was completed to allow the therapist to
coordinate treatment with each child's teacher.
The initial assessment and consultation session
constituted the baseline period of this study. Daily
ratings of anxiety and speech were then collected
from baseline to posttreatment.
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vecchio & kearney
treatment procedure
A single-participant alternating treatment design
was employed for this study. Treatment A involved
child-focused, exposure-based practice and Treatment B involved parent-focused contingency management. The order in which treatments were
provided was randomized and counterbalanced.
Five children began with Treatment A and followed
an ABBABAAB pattern. Four children began with
Treatment B and followed a BAABABBA pattern.
Between sessions, the alternating treatment was not
used. When a child received Treatment A, parents
were instructed not to employ treatment B until the
next Treatment B session. The therapist provided
reminders of this requirement after each treatment
session. Regular parent-therapist discussions
regarding the order, progress, and assignment of
treatment revealed no instances in which parents or
children reported difficulty setting aside one set of
techniques (e.g., A) to implement the other set of
techniques (e.g., B). Treatments A and B were not
employed concurrently.
Treatment A. Treatment A consisted of childfocused, exposure-based practices that involved
shaping, modeling, prompting, and in vivo exposure along an established hierarchy of key situations. Shaping included the production of
vocalizations with mouth closed, vocalizations
with mouth open, mouthed words without verbalization, whispered single words, whispered sentences, and sentences with progressively increased
audibility until normal spontaneous communication was achieved. Modeling and prompting were
used by the therapist to promote target responses.
Youths were required to achieve adequate speech in
this manner in a progressively more difficult series
of settings: home, clinic setting, community settings
such as restaurants or shopping centers, and school.
Examples of initial tasks for a child along a
hierarchy included playing games with verbal input,
reading aloud, giving short reports, asking and
answering questions, practicing short conversations, and ordering food. Examples of later tasks
at school included speaking and reading to the
therapist in an empty classroom, speaking and
reading with a teacher present in the classroom,
speaking and reading with a few classmates in the
classroom, reading to a teacher or peers in a small
reading group, and speaking in class when expected
to speak, such as being called on to answer a
question. Homework assignments were also provided to youths to practice what had been
accomplished during the past treatment session.
Treatment A thus involved a proactive, therapistdirected introduction to a speaking situation with
concurrent anxiety-reduction techniques such as
breathing retraining. Youths were required to, and
did, enter arranged exposure situations to engage in
a formal anxiety extinction process. Expectations
and prescribed opportunities for speaking in these
situations were high. Exposure situations were
highly anxiety-provoking and exposures were
conducted in situations other than settings common
to a child's everyday life. During exposure-based
homework assignments between sessions, parents
were permitted to contact the therapist for assistance. No formal rewards were provided for
speaking during exposures.
Treatment B. Treatment B consisted of parentfocused contingency management that involved
establishing a consequence system for speaking and
failure to speak. Parents were asked to reward
youths for appropriate speech in public places and
punish youths for failure to speak in public places
during situations the child was expected to speak.
Punishment involved loss of privileges such as early
bedtime or loss of toys or television time based on
parent observations or teacher reports of failure to
speak during the day in public settings. Youths were
asked by parents as appropriate to speak audibly to
others in a preestablished way. Consequences were
established for successfully or unsuccessfully engaging in and practicing therapeutic homework assignments. Initial tangible reinforcers for speech were
later replaced with greater social reinforcement.
Routines were also established so a child would
have increased opportunities to speak in public;
examples include accepting a call from the therapist
or family members, asking a child to greet someone
in public, or taking a child to recreational activities
that require some social interaction. Parents were
also encouraged as well, even during end stages of
treatment, to continue placing their child in
interactive settings and restrict accommodations
for unwillingness to speak. Parents were also taught
to engage in short, specific commands to their
children and to ignore inappropriate compensatory
behaviors, especially as treatment progressed.
Teachers were instructed as well to engage in
appropriate contingency management procedures
during and following treatment.
Treatment B thus involved a reactive, largely
parent-directed response to a child's actions in
everyday speaking situations without concurrent
anxiety reduction techniques such as breathing
retraining. Youths were not required to enter an
arranged exposure situation to engage in a formal
anxiety extinction process. Instead, a child's speech or
lack of speech was linked to incentives or disincentives, respectively, in situations common to his or
her everyday life such as school. During contingencymanagement-based homework assignments between
selective mutism
sessions, parents did not contact the therapist for
assistance. A full description of the treatment protocols is available from the first author.
treatment integrity and reaction
One therapist conducted all assessment and treatment sessions. Integrity raters attended 76% of
treatment sessions to observe the therapist and
provide yes/no answers to key questions. Integrity
raters were four undergraduate and two graduate
psychology students who read and reviewed each
treatment protocol (A and B) and who were taught
the different techniques in each treatment protocol.
Raters were given a copy of the treatment protocols
and the treatment integrity form for evaluating the
sessions.
For Treatment A, raters answered the following
questions: If necessary, were shaping, modeling,
and prompting used? Was the hierarchy mentioned
and discussed? Did the in vivo exposures follow the
hierarchy? Were homework assignments pertaining
to the exposure given? Did the session focus solely
on Treatment A? For Treatment B, raters answered
the following questions: Was the treatment session
held only with the parents? Were the concepts of
contingencies, reinforcement, and shaping discussed? Were consequences, rewards, and target
behaviors clearly identified? Were homework
assignments pertaining to the plan given to the
parents? Did the session focus only on Treatment B?
Treatment reaction questions were presented to
parents at the end of the study. Parents were asked
to rate two questions on a 0-to-10 scale (0 =
completely not due to the treatment approach and
10 = completely due to the treatment approach).
The following questions were posed: How would
FIGURE 1
385
you attribute the changes in your child's behavior to
the exposure-based treatment approach? How
would you attribute the changes in your child's
behavior to the contingency management-based
treatment approach?
posttreatment and 3-month
follow-up
Treatment continued until criteria were met for
positive end-state functioning, when parents withdrew from the study after at least three treatment
sessions, or following 6 months of treatment,
whichever came first. Positive end-state functioning
was defined as speaking in school when expected to
speak, speaking in a free manner, and speaking at an
audible level to teachers and peers and in all
mandated social settings such as restaurants, recreational areas/playgrounds, and school. Participants
received 8 to 32 treatment sessions split equally
across Treatment A and Treatment B (M = 18.1,
SD = 7.7).
Diagnostic interviews and broadband measures
of behavior (CBCL, TRF) were readministered at
posttreatment. Participants were contacted as well
3 months following posttreatment. Formal posttreatment data were unavailable for two families
and follow-up data were unavailable for three
families due to moving or failure to respond to
therapist requests for information.
Results
interrater reliability of interview
and daily measures
An additional graduate student attended 67% of
ADIS-C/P interviews, and 100% interrater diag-
Words spoken per day in public by Participant 1.
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vecchio & kearney
FIGURE 2
Words spoken per day in public by Participant 2.
nostic agreement was obtained. Regarding daily
measures, interrater reliability for ratings of number of words spoken was initially calculated across
all three data sources: children, parents, and
teachers. Interrater reliability was .86. Interrater
reliability for daily ratings of number of words
spoken was also calculated for only children and
parents: .92. Child and parent ratings of child
anxiety and mouthing and whispering of words
were largely zero across all cases at all points, so
these variables were not included in interrater
reliability, individual, or collective analyses.
individual participant data
Participants improved greatly during treatment.
Individual participant data regarding words spoken per day in public are presented graphically in
Figures 1 through 9. At posttreatment and 3-
FIGURE 3
month follow-up, eight of nine participants met
criteria for positive end-state functioning. One
participant (#6) met criteria for selective mutism at
posttreatment and 3-month follow-up based on
parent but not child report. However, this
participant's parent indicated her daughter was
speaking more often in public and with greater
ease in several social situations at follow-up
compared to pretreatment. Her clinical interference rating for selective mutism also declined from
8 at pretreatment to 4 at post-treatment. The
family terminated treatment after 16 sessions due
to a family emergency.
treatment effect size
Cohen's d was calculated to measure treatment
effect size based on child, parent, and teacher
reports. Effects of Treatment A (exposure-based
Words spoken per day in public by Participant 3.
selective mutism
FIGURE 4
Words spoken per day in public by Participant 4.
practice) and Treatment B (contingency management) were compared by pooling data across
participants (Table 1). Three paired-sample t-tests
were computed comparing Treatment A and Treatment B means per participant for mean number of
words spoken per day. Children displayed significantly greater speech during Treatment A than
Treatment B based on child (t = 4.96, pb .01),
parent (t = 3.70, p b .01), and teacher (t = 2.82, p b
.05) reports. Dunlap and colleagues (1996) presented a formula for calculating effect size across
data points. This formula accounts for the correlation between measures so effect size is not overestimated. Cohen's d was thus computed from the
paired-sample t-tests with consideration of the
correlation between Treatments A and B. Results
indicated a large effect size based on child report
FIGURE 5
387
(0.83), a moderate effect size based on parent report
(0.41), and a small effect size based on teacher
report (0.25).
associated symptomatology
Data from broadband measures were not subjected to formal analysis due to limited sample
size. However, participants generally showed
improvement from pretreatment to posttreatment
and 3-month follow-up. CBCL internalizing,
externalizing, and total T scores decreased for
seven participants from pretreatment (66.7/49.3/
56.7) to posttreatment (62.7/47.5/53.2) and
remained stable at 3-month follow-up (61.3/48.8/
53.7). TRF internalizing, externalizing, and total T
scores for three participants decreased from
pretreatment (66.3/51.0/58.0) to posttreatment
Words spoken per day in public by Participant 5.
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vecchio & kearney
FIGURE 6
Words spoken per day in public by Participant 6.
(63.3/43.0/54.0). TRF internalizing, externalizing,
and total T scores for three different participants
remained stable from pretreatment (60.3/47.0/
53.7) to 3-month follow-up (62.0/50.0/55.0).
treatment integrity and reaction
Treatment integrity was determined by raters to be
100%. The therapist in all observed sessions
maintained strict adherence to the appropriate
treatment and did not introduce aspects of the
opposing treatment. Treatment reaction ratings
were obtained from seven participants. Treatment
A (child-focused, exposure-based practice) received
a mean rating of 9.5 on a 0-to-10 scale (range 7–10,
SD = 1.1). Treatment B (parent-focused contin-
FIGURE 7
gency management) received a mean rating of 7.9
on a 0-to-10 scale (range 5–10, SD = 2.0).
Discussion
This study is one of the first to employ systematic
assessment and treatment procedures in a controlled investigation of outcome utilizing exposurebased practices and contingency management for
selective mutism. Results indicated that both treatment approaches may be effective for increasing
audible speech in this population, though exposurebased practices may be significantly more effective.
Results of the study match those of several
previously published case reports, but do so in
more rigorous fashion (Baskind, 2007; Fisak et al.,
Words spoken per day in public by Participant 7.
selective mutism
FIGURE 8
Words spoken per day in public by Participant 8.
2006; Vecchio & Kearney, 2007). The results also
provide further empirical evidence for earlier claims
that behavioral procedures for selective mutism
produce positive end-state functioning (Cohan,
Chavira, & Stein, 2006).
Results of the present study suggest that exposure-based practices may be more effective than
contingency management, though both procedure
sets were helpful. This may provide some preliminary support for conceptualizing selective mutism as
an anxiety disorder because exposure-based practices are commonly and effectively used for
problems such as panic disorder, social phobia,
and generalized anxiety disorder (Compton et al.,
2004; James, Soler, & Weatherall, 2005; In-Albon
& Schneider, 2007). In addition, the most common
comorbid diagnoses in the present study were
anxiety-based, particularly social phobia. This
FIGURE 9
389
finding replicates prior diagnostic studies in this
area (Sharp et al., 2007; Vecchio & Kearney, 2005;
Yeganeh et al., 2003). Parents also found exposurebased practices to be somewhat more useful than
contingency management practices.
Some researchers, however, claim that elements
other than anxiety contribute to selective mutism
(Arie et al., 2007; Kristensen & Oerbeck, 2006;
Manassis et al., 2003; Yeganeh et al., 2006), and
two key findings from the present study may
provide some support for these claims. First, the
utility of contingency management, though not as
powerful as exposure-based practices, may illustrate an oppositional or other component of
selective mutism that requires external consequences for behavior change. In the case of one
participant who continued to meet criteria for
selective mutism, she reported at follow-up that she
Words spoken per day in public by Participant 9.
390
vecchio & kearney
Table 1
Means and standard deviations for number of words spoken
across informants for Treatments A and B
Report
Treatment A
Treatment B
Child
Parent
Teacher
62.8 (17.3)
62.1 (18.6)
28.0 (30.9)
44.2 (22.1)
45.0 (30.0)
19.6 (27.2)
Note. Treatment A = child-focused, exposure-based practice;
Treatment B = parent-focused contingency management.
simply chose not to speak in certain situations and
was not fearful.
Second, daily anxiety ratings and rates of
mouthing and whispering for all participants were
extremely low, to the point that formal analyses of
these variables were rendered moot. One possibility
is that participants felt the comprehensive rating
system was cumbersome and thus concentrated on
the most important variable: audible words spoken
in public. In addition, anxiety ratings were not
necessarily specific to speaking situations. Still, the
low ratings may provide evidence of limited daily
distress for this sample. Parents provided anecdotal
reports, even after education about anxiety components and endorsement of social anxiety symptoms,
that they believed their children to be more shy than
anxious in social situations. Further research is
needed to explore potential discrepancies between
assignments of anxiety-based diagnoses and relatively low daily ratings of anxiety in this population. Some speculate that selective mutism affects
self-reported anxiety because a child chooses not to
answer others or to place herself in many anxietyprovoking situations during the day (Beidel &
Turner, 2005; Yeganeh et al., 2003).
Clinicians who address youths with selective
mutism may have several daunting challenges
before them. First, developing collaborative efforts
with children, parents, and teachers is likely
imperative for generalizing treatment gains, especially in cases involving school-based mutism.
Second, intense clinical efforts are generally necessary for this population, including frequent sessions, an extended treatment time line, exposurebased practices in community and school settings,
and frequent conversations with parents and
consulting professionals. Third, use of daily behavioral assessment measures, especially with respect
to words audibly spoken, will likely provide more
information about treatment effectiveness than
global measures of functioning.
Researchers who address youths with selective
mutism also have several daunting challenges before
them. Because selective mutism is a particularly fluid
and furtive problem, developing standardized, daily,
and sensitive measures for this population remains a
priority. Larger-scale investigations of behavioral
and nonbehavioral treatments for youths with
selective mutism remain necessary as well. Of
particular value would be interventions designed
to fit the demands of everyday clinical practice, or
eliminating time-consuming techniques that have
less efficacy and that limit family choices regarding
treatment providers. As mentioned earlier, longitudinal data and longer-term follow-up data
regarding this population are also needed. Finally,
early screening for selective mutism in an era when
many children attend day care or preschool would
seem to be a useful practice.
Limitations of the current study should be
considered when interpreting results. First, teacher
compliance to daily measures regarding selective
mutism was spotty, and these measures may have
been too taxing in some cases. Second, the scope of
the daily dependent measures may have been a bit
ambitious for children and parents, though compliance was generally good. Still, children and
parents may have eschewed attention to lesser
variables such as daily anxiety or mouthing of
words in favor of more obvious and relevant
variables such as words audibly spoken. Multiple
ratings throughout the day may have been preferable as well. Third, as with any alternating
treatments design, the possibility of carryover
effects must be considered. Finally, various specific
techniques were included under the broad rubrics of
child-focused, exposure-based practice and parentfocused contingency management. Research is
needed to further dismantle these techniques to
identify individual effectiveness.
Despite these limitations, the present study does
provide new though preliminary evidence regarding
differential effectiveness of child-and parent-based
treatments for youths with selective mutism. The
study provides some evidence that exposure-based
practices could remain a priority when addressing
this population, but that contingency management
practices may be a useful adjunct. Parent-based
approaches for selective mutism could be particularly important in cases involving high rates of
compensatory behavior, language differences
between home and school, or when young children
depend on frequent exposures established by
parents. As with many childhood behavior disorders, including children and parents in the
treatment process is likely preferable than either
party alone.
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R E C E I V E D : January 14, 2008
A C C E P T E D : October 12, 2008
Available online 3 November 2008