What is Selective Mutism

Child Characteristics

Selective Mutism (SM) is a childhood social communication disorder in which children consistently fail to speak in select situations, despite the ability to understand and to use language. Children with SM usually speak to family members at home, but do not speak at kindergarten or school. The speech patterns of each SM child vary along a continuum of severity – from children who speak to everyone outside school, and select peers in school, through children who fail to speak to everyone in school, peers and staff. Some will not speak to anyone outside their home, or to only certain family members inside their home, and a rare few do not speak to family members inside the home.

When another condition exists which accounts for the failure to speak, such as PDD, retardation, psychosis or a lack of language skills, then the child does not have SM.

There are many comorbid constellations of traits that have been found in research to be associated with SM, again, each child has a unique set of characteristics. Research has found that 90% of children with SM suffer from social anxiety, and 30 – 40% has some language or speech impairment. Other comorbid conditions could include: shyness and hypersensitivity, oppositional behavior, stubbornness and perfectionism, nuero-developmental delay (often auditory processing delay), and learning disabilities.

There is often a genetic component of shyness or a history of SM in one of the parents or siblings, bilingualism, or disconnectedness from the cultural milieu of the outside society.

Often there is a marked contrast between the outgoing and communicative child at home, and the inhibited, introverted functioning at school. No link has been found between intelligence and SM and no link has been found in the large research studies between traumatic events and SM. (For a sensitive, anxious child, seemingly everyday events may be experienced as traumatic – such as being shouted at by a teacher, being embarrassed in front of a class, or being mocked by peers for a mispronunciation.)

Most research has found that the incidence of SM is around 0.07% that is seven children in every 1,000, and it is 3 times that number in children from bilingual homes. It is most prevalent between the ages of 4 and 8; onset usually occurs when the child first enters an educational framework in which speech is expected, but sometimes onset is gradual – the child decreases speech output until he eventually stops speaking.

The DSM –IV states that SM can be diagnosed after one month during which the child fails to speak, not including the first month at school during which his initial reticence is not necessarily the forbearer of SM.

Table 1: DSM IV Diagnostic Criteria

Selective Mutism (formerly Elective 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.

B. The disturbance interferes with educational or occupational achievement or with social communication.

C. The duration of the disturbance is at least 1 month (not limited to the first month of school).

D. The failure to speak is not due to a lack of knowledge of, or comfort with, the spoken language required in the social situation.

E. The disturbance is not better accounted for by a Communication Disorder (e.g., Stuttering) and does not occur exclusively during the course of a Pervasive Developmental Disorder, Schizophrenia, or other Psychotic Disorder.


Selective mutism is caused by the interaction between the nature of the child and external factors – nature and nurture. One can conceptualize this as various factors fitting into one of three groups – predisposing factors, precipitating factors, and maintaining factors:

Predisposing factors could include: Anxiety of child, shyness, timidity, hyper-sensitivity. Family history of shyness, anxiety or selective mutism –can include anxious parents, anxious behavior modeling by parents. Speech impairment of child – usually expressive language. Bilingualism, negative self image related to speech (e.g. doesn’t like sound of voice), neuro-developmental delay, often sensory processing disorder.

Precipitating factors (triggers) could include: School or kindergarten admission, frequent geographical moves, family belonging to linguistic minority, negative reactions to child talking – bullying, shouting etc.

Maintaining factors could include: Social Isolation of families, misdiagnosis (that is, the child is wrongly diagnosed as having oppositional behavior, autism, retardation etc.), lack of early and appropriate intervention. Lack of understanding by teachers, families, psychologists, reinforcement of the mutism by increased attention or affection, heightened anxiety levels caused by pressure to speak, ability to convey messages non verbally, over acceptance of mutism.

When there is a combination of predisposing factors, that heighten the child's vulnerability to SM, and triggers – events such as nursery school admission or a geographical move, the scales could tip and bring about the onset of SM. Predisposing factors include elements of the child's psychological and physiological make up which make him more vulnerable to selective mutism; this could includes an anxious or shy nature, a family history of shyness, and stubbornness and perfectionism. Many children with SM have some type of speech difficulty, including bilingualism. Maintaining factors facilitate the continuation of the condition – marring the child's chances of overcoming selective mutism.