Elective mutism was defined as a refusal to speak in almost all social situations (despite normal ability to do so), while selective mutism is considered to be a failure to speak in specific situations and is strongly associated with social anxiety disorder. In contrast to selective mutism, someone who is electively mute may not speak in any situation, as is usually shown in books and movies. Elective mutism is often attributed to defiance or the effect of trauma.
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:
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", mental retardation, and trauma. Elective mutism in the third edition revised (DSM III-R) is described similarly as in the third edition except for specifying that the disorder is not related to social anxiety disorder.
In 1994, the fourth edition of the DSM reflected the name change to selective mutism and redefined the disorder.