Award Date


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Committee Member

Christopher Kearney

Number of Pages



This was the first study to examine the differential effectiveness of two behavioral interventions for selective mutism while employing a single-case alternating treatments design with documentation of treatment outcomes, calculation of effect size, and measures of treatment integrity. Participants were recruited via press release to the local media and the Clark County School District. Interested participants were initially screened over the telephone. If the screening indicated that a child met diagnostic criteria for selective mutism and did not meet exclusionary criteria, an assessment was scheduled. Each participant was assessed by the Anxiety Disorders Interview Schedule for Children for DSM-IV Child and Parent versions, Child Behavior Checklist, and Teacher Report Form. In addition, daily logs were collected from parents, children, and teachers to evaluate degree of mutism. The present study included nine children age 4-9 years. Five participants started with treatment A (exposure therapy) and followed the ABBABAAB pattern and four participants started with treatment B (contingency management) and followed the BAABABBA pattern. The results indicated that exposure-based therapy and contingency management are effective behavioral interventions for selective mutism. The majority of children (86%) met criteria for treatment success at post-treatment. Rates of speech increased over 600% from baseline to end of treatment. Child ratings of speech indicated a large treatment effect size and parent ratings of speech indicated a moderate treatment effect size. Furthermore, the results indicated that exposure-based therapy was more effective than contingency management. The study provides additional support for the use of behavioral interventions for selective mutism. More specifically, the study provides empirical support for the differential effectiveness of exposure-based therapy. Several clinical implications for identification, assessment, and treatment of selective mutism were presented.


Anxiety; Anxiety; Case; Contingency Management Control; Contingency Management; Design; Exposure Therapy; Intervention; Mutism; Selective Mutism; Treatment

Controlled Subject

Clinical psychology

File Format


File Size

4720.64 KB

Degree Grantor

University of Nevada, Las Vegas




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