Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Jonathan Comer

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Jeremy Pettit

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

Katie Hart

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Elizabeth Cramer

Fourth Advisor's Committee Title

Committee Member


selective mutism, child, intensive treatment, group treatment, anxiety, cbt

Date of Defense



Selective mutism (SM), an anxiety disorder most commonly presenting in childhood, is characterized by a failure to speak in certain social situations. Due to its unique presentation (e.g., lack of speech) and low prevalence, expertise in the treatment of SM is scarce, leaving many affected families without access to care. Intensive Group Behavioral Treatment (IGBT) allows families to travel to a specialty clinic to receive a course of treatment in a single week. This study is the first to evaluate IGBT for SM in a randomized controlled trial. 29 children aged 5-9 with SM were randomized to immediate IGBT or to a 4-week waitlist with psychoeducational resources (WLP). Analyses demonstrated high family satisfaction with the program and low barriers to treatment participation. At Week 4, 50% of the immediate IGBT group and 0% of the WLP group were classified as “clinical responders.” There was a significant Time × Group interaction effect on social anxiety severity, verbal behavior in social situations, and global functioning. Time × Group interaction effects were not observed for IE-rated SM severity, verbal behavior at home, or overall anxiety. Structured behavioral observations revealed significant pre-to-post IGBT improvements in child verbal behavior, and parental positive attention, but not in parental provision of opportunities for child to respond to questions. Across the days of the program there were significant positive changes in most domains of observed child verbal behavior. School-year follow-up assessments (conducted 8 weeks into the following school year) revealed improvements in SM severity, social anxiety severity, global functioning, overall anxiety, and verbal behavior in home and social settings. Post-IGBT school year teachers rated less impairment and more verbal behavior relative to teachers in the pre-IGBT school year. Findings provide the first empirical support for the efficacy of IGBT for children with SM. Half of IGBT-treated youth evidence significant treatment response at Week 4, with more significant improvements unfolding into the following academic school year. Further study is needed to examine mechanisms of IGBT response, as well as other innovative treatment methods for children with SM to determine which treatment formats work best for which affected children.



Previously Published In

Cornacchio, D., Furr, J. M., Sanchez, A. L., Hong, N., Feinberg, L. K., Tenenbaum, R., ... & Ollendick, T. H. (2019). Intensive group behavioral treatment (IGBT) for children with selective mutism: A preliminary randomized clinical trial. Journal of Consulting and Clinical Psychology, 87(8), 720.



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