Selective mutism (SM) is an anxiety disorder in which a person who is otherwise capable of speech becomes unable to speak when exposed to specific situations, specific places, or to specific people, one or multiple of which serving as triggers. This is caused by the freeze response. Selective mutism usually co-exists with social anxiety disorder. People with selective mutism stay silent even when the consequences of their silence include shame, social ostracism, or punishment. Signs and symptoms Children and adults with selective mutism are fully capable of speech and understanding language but are completely unable to speak in certain situations, though speech is expected of them. The behaviour may be perceived as shyness or rudeness by others. A child with selective mutism may be completely silent at school for years but speak quite freely or even excessively at home. There is a hierarchical variation among people with this disorder: some people participate fully in activities and appear social but do not speak, others will speak only to peers but not to adults, others will speak to adults when asked questions requiring short answers but never to peers, and still others speak to no one and participate in few, if any, activities presented to them. In a severe form known as "progressive mutism", the disorder progresses until the person with this condition no longer speaks to anyone in any situation, even close family members. To meet DSM-5 criteria for selective mutism, one must exhibit the following: 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. The disturbance interferes with educational or occupational achievement or with social communication. The duration of the disturbance is at least 1 month (not limited to the first month of school). The failure to speak is not due to a lack of knowledge of the spoken language required in the social situation. The disturbance is not better accounted for by a communication disorder (e.g., childhood-onset fluency disorder) and does not occur exclusively in people with autism spectrum disorders or psychotic disorders such as schizophrenia. Selective mutism is strongly associated with other anxiety disorders, particularly social anxiety disorder. In fact, the majority of children diagnosed with selective mutism also have social anxiety disorder (100% of participants in two studies and 97% in another). Some researchers therefore speculate that selective mutism may be an