A controlled single-case treatment of severe long-term selective mutism in a child with mental retardation.

The aim of the present study was to demonstrate the efficacy of combining two operant learning procedures--shaping and fading--for treating selective mutism. The participant was a 12-year-old boy with mental retardation presenting a severe long-term selective mutism. The treatment was aimed at increasing the loudness of his vocalizations in an increasingly social milieu.