Selective MutismM M Nieves, F Mesa, and D C Beidel, University of Central Florida, Orlando, FL, USA

ã 2012 Elsevier Inc. All rights reserved.

GlossaryContingency management Behavioral intervention that

involves the structured provision of rewards for certain

behaviors. The value of performing each behavior is clearly

specified in advance.

Exposure Exposure is a procedure used in behavior therapy

than involves, under therapist-controlled conditions,

placing individuals in contact with an object, event, or

situation that they fear.

Selective mutism A consistent failure to speak in specific

social situations (in which there is an expectation for

speaking, e.g., at school) despite speaking in other

situations.

Shaping Shaping is a process by which an individual’s

behavior is reinforced to achieve a predetermined status.

Systematic desensitization A form of behavior therapy that

combines the use of gradual exposure and relaxation skills to

approach more anxiety-provoking situations.

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The term selective mutism (SM) used to describe the failure to

speak in social settings has undergone an evolution over the

past 130 years. The condition was first described by Adolf

Kussmaul in 1877, who labeled it aphasia voluntaria. The use

of this term conceptualized this disorder as one in which

children voluntarily withheld speech. This label was later

changed (in 1934), when the term elective mutism was pro-

posed by Swiss child psychiatrist Moritz Tramer. Still, the

term implied that children with SM elected or chose to remain

quiet in social settings. Whereas the current International Clas-

sification of Diseases – Tenth Edition has retained the term elec-

tive mutism, other diagnostic schemas such as the Diagnostic

and Statistical Manual of Mental Disorders – Fourth Edition

Text Revision (DSM-IV-TR) changed the term from elective to

selective in an effort to avoid previous conceptualizations of the

behavior as inherently volitional (i.e., the child actively refus-

ing to talk). Thus, whereas the ICD-10 continues to conceptu-

alize SM as a withholding of speech in social settings, the

change in wording from ‘elective’ (voluntarily deciding not to

speak) to ‘selective’ was an effort to remove the connotation

that children with this disorder were deliberately oppositional

and replace it with the connotation that it was the situation,

and not the child, that was responsible for the lack of speech.

Despite the change in term in the DSM, the controversy regard-

ing the presence of oppositional behavior in at least a subgroup

of children with SM remains.

Diagnosis

According to the DSM-IV-TR, SM is defined “as consistent

failure to speak in specific social situations (in which speech

is expected, e.g., at school) despite speaking in other situa-

tions” (p. 125). The most common presentation of SM is a

child who speaks freely (and often loudly) when at home in

the company of parents or siblings. However, when other

individuals (often including grandparents) come to the home,

the child ‘clams up’ refusing to speak, often refusing tomake eye

contact and sometimes hiding in another part of the house.

Similarly, a child with SM who speaks at home will refuse to

speak in any environment outside of the home, even if in the

presence of parents, if there are other people who might over-

hear the conversation. At these times, parents often report per-

sonal frustration or embarrassment because adults are speaking

to their child and the child stares back but does not respond.

Parents fear that this refusal to speak will be perceived as ‘rude’

by other adults and parents quickly respond for the child.

Although this negates parental distress, it also allows children

to escape from what is perceived to be an uncomfortable situa-

tion, and perhaps sets up a pattern of continued avoidance of

verbal communication (see section ‘Etiology’). In school, when

parents might not be available, children will often turn to a

classmate to verbally communicate their needs to a teacher.

The use of the phrase ‘verbal communication’ in the above

paragraph is a deliberate choice on our part. Often, nonmental

health professionals interpret a ‘failure to speak’ as a failure

to communicate. In fact, children with SM are often able to

communicate quite effectively through nonverbal means. Ges-

tures, pointing, nodding, writing, and even using email are

some the means that children with SM use to communicate

their needs. Therefore, these children can express themselves

even without the use of verbal communication.

Simple failure to speak in situations where speech is

accepted is not sufficient for a diagnosis of SM. This failure to

speak must interfere with educational/academic achievement

or with social communication. In many instances, children

with SM do have difficulty in school. Although most children

with SM appear to learn, it is often difficult for teachers to

determine the child’s academic achievement. Children refuse

to read aloud making it difficult to assess their reading skill.

Similarly, because they refuse to speak, they do not answer

questions in class or ask the teacher for help, leading to distress

on the part of the child and frustration on the part of school

personnel.

In addition to the need for SM to result in distress or

functional impairment, the diagnostic criteria require that the

duration of the disturbance must be at least 1month and not

limited to the first month of school. Indeed, social reticence in

novel situations is common and often occurs, even among

children who do not have SM. Therefore, it is important to

allow children to become familiar and comfortable in new

situations before raising concern about limited speech in

Selective Mutism 303

these settings. Even if children remain in the same school, the

start of a new school year, with a new teacher, a new classroom,

new school subjects, and perhaps even new classmates, may

create sufficient novelty and elicit temporary distress. Thus,

there is a need to allow any child to adjust to new surroundings

prior to determining the existence of SM.

Interestingly, the refusal to speak does not always

interfere with the children’s ability to establish friendships.

Following the diagnostic subgrouping used for social phobia,

Cunningham, McHolm, and Boyle examined the social skills

and social relationships of children with either specific SM

(e.g., did not speak to teachers but spoke to friends at school)

or generalized SM (e.g., spoke only to parents at home). Despite

their subtype designation, children with SM had similar scores

on parent-rated measures of social phobia, generalized anxiety,

and obsessive–compulsive disorder (OCD) symptoms. Fur-

thermore, parental and teacher reports revealed that children

in both SM groups had significantly poorer verbal and nonver-

bal social skills when compared to controls. Despite this, chil-

dren with SM did not see themselves as less accepted by peers.

Therefore, even though adults perceive significant psychopa-

thology among children with SM, this condition may not

always seriously impact children’s ability to interact with peers.

The diagnostic criteria require that the failure to speak is not

due to a lack of knowledge of, or comfort with, the spoken

language required in the social situation. Therefore, a diagnosis

of SMmust be cautiously applied when evaluating children who

have recentlymoved fromanother country, and/or forwhomthe

language spoken at school (or in other settings) is not their first

language. In such cases, it is important to determine if the same

pattern of behavior existed prior to the move to a new country

or culture. Similarly, SM is not diagnosed if the lack of speech is

part of a larger communication disorder such as stuttering or

only occurs as part of other disorders such as pervasive develop-

mental disorder, schizophrenia, or another psychotic disorder.

Epidemiology

SM typically begins between 3 and 5 years of age. Yet, even

though refusal to speak occurs at such a young age, the determi-

nation that the child has a psychological disorder does not

necessarily occur until the child enters situations where failure

to speak is problematic – such as formal schooling. Since chil-

dren speak at home, parents may not initially view the behavior

as problematic. Thus, there is often a considerable lag between

initial failure to speak and referral to a mental health specialist.

The delay from onset to identification and diagnosis holds out

the possibility of entrenchment of the mutism behavior and has

implications for treatment and service delivery. Specifically,

intervention for children with SM is intensive and extensive.

Therefore, earlier identification could lead to earlier interven-

tion thereby shortening intervention length and perhaps pre-

venting or limiting functional impairment.

Relationship to Social Anxiety Disorder and Shyness

Although it is possible that SM could exist in conjunction with

many other disorders, children with SM most often exhibit an

anxious affect, show social avoidance, and are very often

comorbid with social phobia, with rates ranging from 61 to

97% of children with SM also meeting criteria for social pho-

bia, depending on the particular characteristics of the sample,

leading some researchers to propose that SM may not be a

separate disorder but a severe and developmentally appropri-

ate variant of social phobia.

By conceptualizing failure to speak as a behavioral avoid-

ance strategy designed to eliminate distress, it is possible to

examine the idea that SM represents a developmentally appro-

priate and/or severe variant of social phobia. To date, most of

the research has addressed the issue of severity and has com-

pared children with SM and comorbid social phobia to chil-

dren with social phobia alone. In the following review, we will

refer to children with SM and comorbid social phobia simply

as children with SM. In one of the initial investigations, Man-

assis and her colleagues found that children with social phobia

and children with SM scored similarly on a number of stan-

dardized measures of general anxiety and social anxiety. In our

research clinic, children with SM were rated by parents and

observers as more socially distressed than children with social

phobia alone. However, in our clinic, the groups were indistin-

guishable in terms of self-report measures assessing social anx-

iety, trait anxiety, and general fears.

Furthermore, research data suggests that children with SM

are not anxious in general. Rather, their anxiety is restricted

to social situations and social conversation. For example, chil-

dren with SM self-reported significantly higher social anxiety

than children with other anxiety disorders and controls.

However, children with other anxiety disorders reported

greater overall anxiety than children with SM and controls.

Thus, children with SM are not just overly anxious – rather

their anxiety appears to be specific to social situations. Overall,

the data suggest that there may be a special relationship

between social phobia and SM, although not all researchers

are in full agreement. Alternatively, it may be that as a result

of their behavioral avoidance, children with SM may underre-

port anxiety symptoms.

Oppositionality

As noted above, a number of children with severe social phobia

symptoms do respond to verbal communication by others. In

an effort to identify factors that might differentiate children

with SM from other children who have social phobia, a num-

ber of clinicians have pointed to refusal to speak as evidence of

an oppositional behavior style. Overall, there is minimal evi-

dence for the presence of significant externalizing disorders,

such as conduct disorder or oppositional defiant disorder in

children with SM although they sometimes display opposi-

tional symptoms/behaviors. However, this type of behavior

(e.g., refusing to engage with an anxious object, situation, or

event) also exists among children, and even adults, with other

types of anxiety disorders. Thus, the presence of oppositional

behavior, whether it is refusal to leave a parent (as in the case of

separation anxiety disorder) or refusal to speak (as in the case

of SM), may indicate the presence of severe anxiety and not

oppositional defiant disorder. The distinction between the pres-

ence of oppositional behaviors and oppositional defiant

304 Selective Mutism

disorder is important to emphasize, as many parents often hear

the work ‘oppositional’ and conclude that the therapist is

labeling their child as being deliberately oppositional rather

than understanding anxious emotionality as the probable basis

for the behavior.

Etiology

There is no single identified etiology for SM. As with many

other conditions, it is likely that biological, psychological, and

environmental factors play a role either singularly or in various

combinations. There is a strong family history of social phobia,

avoidant personality disorder, taciturnicity (minimal speech),

shyness, and SM among the first-degree relatives of children

with SM. These results, further supported by numerous clinical

observations, indicate that a genetic predisposition must be

considered. However, it is important to note that when disor-

ders ‘run in families,’ mechanisms such as vicarious condition-

ing and information transfer may be as important as genetics.

A number of investigations have examined the presence

of neurological deficits, neurodevelopmental delays, language

abilities, and auditory processing deficits among children with

SM. In many instances, research data suggest a significantly

higher presence of speech/language abnormalities among chil-

dren with SM when compared to children with no disorder.

There are two important caveats to keep in mind. First, even

though much of the research finds a significantly higher rate

of speech/language deficits among children with SM, the rates

of abnormalities do not exceed 50% of the sample, suggesting

that the deficits that might exist do not account for a substan-

tial number of cases of SM. Second, there are different abnorm-

alities reported in different studies and the findings are not

consistent, discounting the idea that there is a consistent

abnormality that accounts for a substantial number of cases

of SM.

Traumatic experiences have been suggested as an etiological

factor, but data from controlled empirical trials do not support

this hypothesis. However, as noted above, parents may be

deliberately or inadvertently contributing to the onset and/or

maintenance of this disorder in one of two ways. First, as noted

above, a number of parents of children with SM also have

social phobia, avoidant personality disorder, SM or exhibit

minimal speech in social encounters. Thus, these parents may

model anxious behaviors and/or limited speech in social

encounters and children may learn to imitate this pattern of

behavior.

Parents and teachers, among others, often reinforce nonre-

sponse to social overtures by (1) continuously asking the child

to ‘please answer,’ setting up a contest of wills (which the

child will always win) or (2) answering for the child. Behaviors

such as these often have the opposite effect on children with

SM. That is, parental attention to ‘not talking’ often strengthens

the child’s lack of speech. For example, clinically, it has been

our experience that when the child will not answer an adult,

the child is encouraged to whisper the response to the parent,

who will respond for the child. This strategy allows the child

to get what he or she might need but also the attention that

the child receives sets up a pattern of reinforcement for

not speaking. Teachers and classmates often participate in

reinforcing silent behavior. In particular, classmates are often

used by the child to request permission to go to the bathroom,

ask a question, etc. In such cases, there is little motivation for

the child to speak, as there are alternative ways of getting what

the child needs/desires. In order for therapy to be efficacious,

all relevant parties must be trained to discontinue reinforce-

ment of nonspeaking and reinforce the child for any attempts

at speaking (see section ‘Treatment’).

Assessment

Exemplary assessment of SM requires that clinicians draw

information from various sources. Given the clinical sympto-

mology of the disorder, the child is often unable to provide an

adequate description of their experiences. Therefore, informa-

tion shared by the parent is essential to the assessment of SM.

The Anxiety Disorders Interview Schedule for Children and

Parents is a semistructured clinical interview that gathers infor-

mation pertaining to SM, as well as other anxiety and psychiat-

ric disorders. Items of the ADIS-C/P assess DSM-IV diagnostic

criteria as well as vital features such as symptom history, age of

onset, and situations in which the child displays mutism.

Furthermore, the ADIS-C/P allows for severity ratings to be

assigned to each diagnosis. Although it is unlikely that children

will verbally respond to the interview questions, we have found

that oftentimes, they respond in nonverbal fashion, giving a

‘thumbs up or thumbs down’ for ‘yes’ or ‘no’ and using the

feelings thermometer included in the ADIS-C/P to allow chil-

dren to point to their estimated level of distress.

Another method through which a parent may relay infor-

mation is the SM Questionnaire (SMQ), a 17-item parent

report measure. The SMQ consists of items that assess for

speaking behavior in three general situations: at school, at

home or with family, and in public. Parents rate each behavior

on a 4-point Likert-type scale that ranges from 0 (never) to 3

(always); thus, lower scores on the SMQ represent fewer

instances of speech from the child. The SMQ has demonstrated

excellent internal reliability and consistency and convergent

validity with the ADIS-C/P clinical severity ratings. Additional

studies replicate the strong psychometric properties of the

SMQ and support its incremental validity when used with

other measures of child anxiety.

Although it is difficult to interact directly due to the mut-

ism, behavioral observation remains a useful approach to

examining first-hand the nature of impairment (i.e., whether

or not the child engages in nonverbal communication). More-

over, examining the specific situations, people, and events that

are associated with each child’s specific refusal/inability to

speak will allow parents and therapists to identify characteris-

tics that elicit or maintain the lack of speech in certain settings.

The developmental history is a critical consideration when

evaluating SM. Potential neurological deficits should be con-

sidered to rule out other conditions that may better explain

language difficulties and delay. Additionally, a thorough

speech and language assessment could identify potential

speech problems that may be contributing to SM. This may

be particularly important if parents report articulation or flu-

ency difficulties that are observed when the child is at home.

Audio-taped samples of ‘normal’ speech with family members

Selective Mutism 305

may be used to determine fluency, semantics, phonetics, and

expressive syntax. By identifying potential difficulties in the

child’s speech, assessors may begin to ascertain and address

the factors influencing mutism across other situations.

Because schoolteachers typically have extensive interactions

with their students, they are important sources of information

in the assessment of SM. Schoolteachers may provide descrip-

tions of verbal and other communicative behaviors in school

settings. They furthermore may identify peers/classmates to

whom the child speaks and who may assist at later points of

the intervention. Schoolteachers may also provide descriptions

of the situations in which the child is most or least likely to

verbalize and may report on the success of previous interven-

tion attempts.

Treatment

Within the past 15 years, several reviews have summarized

the efficacy of psychosocial and pharmacological interven-

tions to treat SM. The treatment literature for SM is relatively

small, with many studies having methodological weaknesses

(i.e., lack of comparison groups). Currently, most investiga-

tions consist of single case studies. Thus, the need for larger

randomized controlled trials is evident but may be limited

by the relatively rare nature of this disorder. The literature on

treatment includes a broad range of modalities, including play

therapy, family therapy, behavior therapy, cognitive-behavior

therapy (CBT), and multimodal interventions. However, critical

reviews of the extant literature conclude that behavioral inter-

ventions offer the most robust evidence for efficacy. Newer CBT

approaches also have support for their effectiveness, including

a web-based CBT program for children with SM.

Behavioral interventions for SM include exposure-based

practices such as systematic desensitization, shaping and stim-

ulus fading, self-modeling, social skills training, and parent-

based contingency management. Systematic desensitization

traditionally involves the use of gradual exposure and relaxa-

tion skills to approach more anxiety-provoking situations. The

therapist also assists the child in developing a fear hierarchy

so that the feared speaking situations are targeted in order

of difficulty. There is evidence that systematic desensitization

is effective in increasing speech with peers and teachers and

reducing anxiety related to speaking. However, systematic

desensitization and relaxation techniques may work better for

older youth, with younger children benefitting more from

in vivo exposure, due to difficulty with imaginal exercises.

Similarly, cognitive techniques used in CBT (i.e., cognitive

restructuring, coping plans) may be more effective for older

youth with SM relative to younger children.

Contingency management techniques involve positive

reinforcement for nonverbal communication (i.e., pointing,

nodding) and eventually verbal communication through shap-

ing, where approximations of the target behavior (i.e., mouth-

ing words, whispering) are reinforced. Once contingency

management is implemented successfully, stimulus fading

interventions can be used by rewarding speech after gradually

increasing (i.e., fading in) the number of people and places to

which the child is exposed. It can be helpful to begin shaping

and fading procedures with a friend or family member to

whom the child already speaks before adding unfamiliar peo-

ple to the group. With parent-focused techniques, therapists

can also train parents to continue with contingency manage-

ment in scenarios encountered regularly (i.e., restaurants).

Although there is support in the literature for both contingency

management and stimulus fading, follow-up studies are

needed to confirm if gains made in treatment are sustained

after the reinforcement is ceased.

Self-modeling is an effective and convenient technique to

increase speech. Self-modeling involves creating and playing

video and/or audiotapes repeatedly of the child speaking. It is

expected that the child habituates to hearing their voice in

settings where they previously remained silent. It is important

to note that sometimes children refuse to record their own

voices. In addition, if not done correctly, listening to a record-

ing of their voice could make the child’s anxiety worse. Thus,

this procedure should be done under the guidance of a mental

health clinician.

Since children with SM may begin to avoid social interac-

tion with peers at an early age, positive interactions may be

thwarted by the lack of appropriate skills to initiate and main-

tain friendships. Social skills training may be used to facilitate

speech in instances when the child has anxiety related to peer

interaction. In a randomized trial comparing children with

social phobia (without SM) who received fluoxetine alone

and those who received a combination of medication and

social skills training, deficits in social skill remained for chil-

dren who received the medication alone, despite reporting a

decrease in anxiety related to social situations. Because chil-

dren with SM most likely suffer from social phobia, these data

suggest that children with SM may have similar positive out-

comes with the inclusion of social skill training.

Many approaches in treating youth with SM combine behav-

ioral procedures, thus limiting the ability to identify the efficacy

of any one treatment component. When exposure-based prac-

tices and parental contingencymanagement practices were com-

pared, exposure-based practices were superior at increasing

words spoken audibly and daily in public situations. Empirical

support for differential effects of behavioral techniquesmay lead

to increased gains and cost-effectiveness in treatment.

For more than a decade, researchers have been concerned

about the considerable gap existing between the frequency

with which physicians prescribe pharmacological treatments

to children with SM and the limited empirical data supporting

the prescribed medications. Currently, the majority of studies

examining the efficacy of medication are single case studies,

which limit the external validity of the findings. A review of the

literature has examined the effectiveness of selective serotonin

reuptake inhibitors (SSRIs), monoamine oxidase inhibitors,

and depressants (i.e., nitrous oxide). Although there is some

support for all three forms of medications mentioned, SSRIs

(i.e., fluoxetine, paroxetine, sertraline, fluvoxamine, citalo-

pram) appear most promising for youth diagnosed with SM.

Medication is recommended only for those children who have

a chronic condition and are unresponsive to other forms of

treatment (i.e., psychosocial and behavioral). Researchers also

note that youth treated with fluoxetine remain highly symp-

tomatic once treatment ends and that side effects are common.

Since the United States Food and Drug Administration placed

‘black box’ warnings on these medications to alert consumers

306 Selective Mutism

of the risk of suicidal thoughts or self-harm, clinicians and

physicians must carefully monitor youth on SSRIs. Future

research is needed to assess how youth with SM function

once medication is discontinued.

Since SM may otherwise have an extensive treatment

course, increasing awareness of SM to target school teachers,

physicians, and parents, may increase the early identification

and possibly improve treatment outcome. Since maintenance

of the disorder may be highly influenced by the child’s envi-

ronment, a collaboration of efforts with parents, teachers, and

the child’s friends proves promising in reducing the cycle of

reinforcement the child receives for not speaking. Overall,

much more research is needed in many areas (i.e., longitudinal

studies) to better conceptualize SM and identify the best modes

of treatment.

See also: Anxiety Disorders; Social Anxiety Disorder.

Further Reading

Anstendig KD (1999) Is selective mutism an anxiety disorder? Rethinking its DSM-IVclassification. Journal of Anxiety Disorders 13: 417–434.

Beidel DC and Turner SM (2005) Childhood Anxiety Disorders: A Guide to Researchand Treatment. New York, NY: Taylor & Francis Group.

Beidel DC, Turner SM, Sallee FR, Ammerman RT, Crosby LA, andPathak S (2007) SET-C versus fluoxetine in the treatment of childhood socialphobia. Journal of the American Academy of Child and Adolescent Psychiatry46: 1622–1632.

Bergman RL, Keller ML, Piacentini J, and Bergman AJ (2008) The development andpsychometric properties of the Selective Mutism Questionnaire. Journal of ClinicalChild and Adolescent Psychology 37: 456–464.

Carlson J, Mitchell A, and Segool N (2008) The current state of empirical supportfor the pharmacological treatment of selective mutism. School Psychology Quarterly23(3): 354–372.

Cline T and Baldwin S (2004) Selective Mutism in Children, 2nd edn. London, UK:Whurr.

Cohan SL, Chavira DA, and Stein MB (2006) Practitioner review: Psychosocialinterventions for children with selective mutism: A critical evaluation of theliterature from 1990–2005. Journal of Child Psychology and Psychiatry47: 1085–1097.

Cunningham CE, McHolm AE, and Boyle MH (2006) Social phobia, anxiety,oppositional behavior, social skills, and self-concept in children with specificselective mutism, generalized selective mutism, and community controls. EuropeanChild & Adolescent Psychiatry 15: 245–255.

Garcia AM, Freeman JB, Francis G, Miller LM, and Leonard HL (2004) Selectivemutism. In: Ollendick TH and March JS (eds.) Phobic and Anxiety Disorders inChildren and Adolescents: A Clinician’s Guide to Effective Psychosocial andPharmacological Interventions, pp. 433–455. New York, NY: OxfordUniversity Press.

Manassis K, Fung D, Tannock R, Sloman L, Fiksenbaum L, and McInnes A (2003)Characterizing selective mutism: Is it more than social anxiety? Depression andAnxiety 18: 153–161.

Schwartz RH and Shipon-Blum E (2005) ‘Shy’ child? Don’t overlook selective mutism.Contemporary Pediatrics 22: 30–34.

Silverman WK and Albano AM (1996) The Anxiety Disorders Interview Schedule forChildren for DSM-IV (Child and Parent Versions). San Antonio, TX: PsychologicalCorporation.

Vecchio J and Kearney C (2009) Treating youths with selective mutism with analternating design of exposure-based practice and contingency management.Behavior Therapy 40(4): 380–392.

Viana A, Beidel D, and Rabian B (2009) Selective mutism: A review and integration ofthe last 15 years. Clinical Psychology Review 29(1): 57–67.