This case study describes a selective mute Mexican-American boy who, at initial referral, had never spoken to peers or teachers while in school. The treatment procedure employed shaping and reinforcement of speech in therapy sessions. These sessions involved the psychologist alone, the classroom teacher and psychologist, the boy's best friend and the psychologist, a small assertiveness skills group, and a small group for reading instruction. Results indicated that the subject first whispered one word and then gradually expanded his vocalizations from one-word answers to complete sentences over a 3-year period. By the end of the treatment, he answered questions in a normal tone of voice but rarely asked questions. Through the use of shaping, positive reinforcement, and stimulus fading, the treatment was successful in helping the boy to speak in several settings.
Selective mutism (SM; formerly elective mutism) is a rare disorder characterized by refusal to speak when a person is capable of speech and speech is normally understood. Diagnosis according to DSM-IF' requires refusal to speak in specific social situations, including school (American Psychiatric Association, 1994). Onset generally occurs during preschool years (American Psychiatric Association, 1994; Wright, Miller, Cook, & Littman, 1985). Data on the frequency of this disorder in the general population are not clear. Past research indicates that 0.4% to 1% of guidance clinic referrals have the disorder (Labbe & Williamson, 1984). Fundudis, Kolvin, and Garside (1979) found that 2 out of 3,300 children were reported to have elective mutism at the age of 7 years; and Brown and Lloyd (1975) discovered that 42 of 6,072 kindergarten children were not speaking after 8 weeks of school.
Although there are several reports of higher incidence of SM among children of minority cultures, statistical significance is seldom demonstrated (Hesselman, 1983). One exception (Bradley & Sloman, 1975) showed an elevated incidence among immigrant children in Canada. This positive trend was found again in a British sample, but the difference was not significant (Cline & Kysel, 1987/1988).
A review of behavioral interventions in the treatment of elective mutism was completed by Labbe and Williamson (1984). Most of the studies reviewed were based on contingency management using positive reinforcement and stimulus fading. Labbe and Williamson presented a scheme for assessment and treatment planning based on subtypes. Assessment of an elective mute client may involve differentiating between several categories of manifestation that call for different intervention strategies. Intervention strategies involve careful description of the environments in which the client will speak. For example, if the client speaks to only one person in most test environments, the Requests for reprints should be sent to