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
obsessive-compulsive disorder (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depression and being notably withdrawn, usually showing no facial expressions.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
anti-social 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. 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. ==Cultural references==