However, they're able to speak freely to close family and friends when nobody else is listening – for example, when they're at home.
It's important to understand that when the mutism happens, the child is not voluntarily refusing to speak but is literally unable to speak, feeling frozen. In time, they learn to anticipate the situations that provoke mutism and do all they can to avoid them.
Experts believe SM is a phobia of talking.
Most children will work their way through SM with sympathetic support, although they may remain reserved and anxious in social situations.
Which children are affected?
SM is relatively rare, affecting one in 150 children. Most primary schools will know of at least one child with SM.
It's more common in girls and children of ethnic minority populations, or in those who have recently migrated from their country of birth.
When does it start?
SM usually occurs in early childhood and is first noticed when the child begins to interact outside the family circle – for example, when they start nursery or school. It can last a few months but, if left untreated, can continue into adulthood.
What are the signs?
Children with SM often have other fears and social anxieties and may have additional speech and language difficulties.
They may not be able to give you eye contact and may seem: nervous uneasy and socially awkward clingy excessively shy and withdrawn, dreading that they will be expected to speak serious stubborn or aggressive, having temper tantrums when they get home from school frozen and expressionless during periods they cannot talk
Children with SM may communicate using gestures – for example, nodding or shaking their head to get their message across. They may manage to respond with a word or two, or speak in an altered voice, such as a whisper.
Some children