Using differential reinforcement to treat functional hypophonia in a paediatric rehabilitation patient

Behaviour analysis studies have demonstrated the use of operant procedures for treating symptoms of psychiatric disorders. These symptoms are usually caused or maintained by a variety of variables including specific organic mechanisms, yet most can be modified by environmental social contingencies. In this case study, data is presented on a 16 year-old male admitted to a rehabilitation hospital following the onset of polymyositis. This patient also presented with functional hypophonia and met the DSM-IV diagnostic criterion for a conversion disorder. In conjunction with the medical team and a speech pathologist, a behavioural programme was developed and implemented to shape and differentially reinforce increasingly complex vocalizations. Results were evaluated using a moving treatment, multiple baseline across responses design. Differential reinforcement in the form of written and verbal feedback was effective in shaping normal speech. The protocol was applied comprehensively across staff and settings. Results are discussed in terms of basic behavioural research on 'learned non-use'.