You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Elective mutism and explain in detail?
Elective mutism is a now outdated term which was defined as a refusal to speak in almost all social situations (despite normal ability to do so), while selective mutism was considered to be a failure to speak in specific situations and is strongly associated with social anxiety disorder.  In contrast to selective mutism, it was thought someone who was electively mute may not speak in any situation, as is usually shown in books and films.  Elective mutism was often attributed to defiance or the effect of trauma. Those who are able to speak freely in some situations but not in others are now better described by selective mutism.

History
In 1877, a German physician named the disorder aphasia voluntaria to describe children who were able to speak normally but often "refused" to.In 1980, a study by Torey Hayden identified four "subtypes" of Elective Mutism:
Symbiotic mutism: the most common of the forms, caused by a vocal and dominating mother and absent father (very rarely the other way around) and characterized by the use of mutism as controlling behavior around other adults.
Speech phobic mutism: the least common, in which the child showed distinct fear at hearing a recording of their voice.  This also involved ritualistic behaviors, which may reflect OCD, and was thought to be caused by the child having been told to keep a family secret.
Reactive mutism: a reaction to trauma and/or abuse, with all children showing symptoms of depression and being notably withdrawn, usually showing no facial expressions.  Notably, Hayden admits that some children put in this category had no apparent incident to react to, but they were included because of their symptoms.
Passive-aggressive mutism: silence is used as a display of hostility, connected to antisocial behavior.  Some of the children in her study had reportedly not been mute until age 9–12.The Diagnostic and Statistical Manual of Mental Disorders (DSM), first published in 1952, first included Elective Mutism in its third edition, published in 1980.  Elective mutism was described as "a continuous refusal to speak in almost all social situations" despite normal ability to speak.  While "excessive shyness" and other anxiety-related traits were listed as associated features, predisposing factors included "maternal overprotection", intellectual disability, and trauma