The essential feature of Selective Mutism is the persistent failure to speak in specific social situations (e.g., school, with playmates) where speaking is expected, despite speaking in other situations (Criterion A). The disturbance interferes with educational or occupational achievement or with social communication (Criterion B). The disturbance must last for at least one month and is not limited to the first month of school (during which many children may be reluctant to speak) (Criterion C). Selective mutism should not be diagnosed if the individualís failure to speak is due solely to a lack of knowledge of, or comfort with, the spoken language required in the social situation (Criterion D). It is also not diagnosed if the disturbance is better accounted for by embarrassment related to having a Communication Disorder (e.g., Stuttering) or if it occurs exclusively during a Pervasive Development Disorder, Schizophrenia, or other Psychotic Disorder (Criterion E). Instead of communicating by standard verbalization, children with this disorder may communicate by gestures, nodding or shaking the head, or pulling or pushing, or by short utterances, or in an altered voice.
Associated features of Selective Mutism may include excessive shyness, fear of social embarrassment, social isolation and withdrawal, clinging, compulsive traits, negativism, temper tantrums, or controlling or oppositional behavior, particularly at home. There may be impairment in social and school functioning. Although children with this disorder generally have normal language skills, there may occasionally be an associated Communication Disorder (e.g., Phonological Disorder, Expressive Language Disorder, or Mixed Receptive-Expressive Language Disorder) or a general medical condition that causes abnormalities or articulation. Anxiety Disorders (especially Social Phobia), Mental Retardation, hospitalization, or extreme psychosocial stressors may be associated with the disorder.