The Role of Parent Verbal Contingencies in the Lidcombe Program of Early Stuttering Intervention

Abstract

Stuttering is a speech disorder affecting 1- 2% of the population. The cause of stuttering remains unknown, yet its negative impact is evident across the lifespan. Stuttering treatment becomes less effective once a child reaches school age; therefore early intervention is indicated. The most efficacious early stuttering treatment is the Lidcombe Program. In the Lidcombe Program, parents respond to their child’s stutter-free and stuttered speech in treatment conversations. These responses - verbal contingencies - reflect operant conditioning techniques based on positive reinforcement and punishment. Developers of the treatment have believed verbal contingencies to be the core therapeutic agent of the Lidcombe Program, but this has never been adequately tested. This thesis reports on two clinical studies seeking to investigate this assumption. In the first study, 33 preschool children who stutter (PCWS) were randomly assigned to one of two treatment groups: standard Lidcombe Program and Lidcombe Program without the verbal contingency request for self-correction. Children were treated until they attained a 50% reduction in stuttering severity. Results from this study displayed no significant differences on outcome measures between the two groups. In the second study, a randomised controlled trial with a non-inferiority design, 72 PCWS were randomised to two groups; standard Lidcombe Program and Lidcombe Program without verbal contingencies. Data was collected over four sites following nine months of treatment. Consistent findings of non-significance were reported across outcome measures, providing evidence that the removal of verbal contingencies does not result in inferior outcomes compared to standard procedures after nine months of treatment. This thesis makes a significant contribution to Lidcombe Program development, illuminating the need to reconsider theoretical underpinnings that lead to a stuttering reduction in the earlier stages of treatment.