Contingency Manipulation in Discrete-trial Interventions for Children with Autism
Research funded by National Institute on Deafness and Other Communication Disorders: 1R21DC011498-01A1.
Co-Investigator: William V. Dube
A significant deficit in functional communication is one of the defining features of people diagnosed with autism, and applied behavior analysis (ABA), with a technology rooted in basic and applied research, is one of the most effective evidence-based approaches for teaching communication skills. Discrete-trial training (DTT) techniques are a mainstay of ABA. When these techniques are applied to address a person’s communication deficits, symbolic matching-to-sample (MTS) tasks are often used to teach symbolic relations between spoken words, text, and/or symbols, and their two- or three-dimensional referents. Despite the research literature describing various laboratory-derived procedures for teaching MTS (e.g., stimulus fading, stimulus shaping, delayed prompting), these procedures have not been widely adopted in special education classrooms because they are either procedurally complex, are impractical for specific teaching tasks, and/or are contraindicated when students have a history of prompt dependency. Consequently, table-top methods involving mainly trial-and-error learning are most often employed, and that situation seems likely to continue for the foreseeable future. Unfortunately, only a few published studies have examined how the efficacy of this basic method can be enhanced by manipulating the consequences arranged for correct responses and errors, but these studies suggest significant potential for improvement. The present research addresses this knowledge gap. It involves a component analysis of the error- and preference-correction procedures that have supplemented trial-and-error training on MTS tasks with a view to identifying the behavioral processes underlying their effectiveness. Three laboratory studies will each use children with Autism and compare their rates of learning the intended stimulus associations across MTS procedures that differ with respect to an isolated and exaggerated feature of some correction technique. The independent measures of conditional stimulus-control and response bias offered in recent quantitative models of MTS performance will be used to monitor changes in participants' performance with increasing exposure to the procedures, and the procedures will be arranged in an alternating-treatments design. These experiments will determine: (1) whether error-correction trials serve a punitive or a practice function by comparing the efficacy of immediate correction with delayed correction, (2) whether the remedial effects of the standard error-correction procedure accrue from preventing the development of stimulus or position biases by controlling relevant distributions of reinforcers, (3) whether explicitly increasing the opportunities for errors to extinguish, and/or increasing stimulus observing requirements, on error-correction trials enhances their efficacy. A fourth study, conducted in a classroom using special-education teachers and educationally-relevant stimuli, will assess the social validity of an effective correction procedure from the lab studies. An anticipated outcome of this research is the design and empirical validation of procedures that can either stand alone or supplement others (including those aiming to train in an "errorless" manner) to speed the learning of MTS tasks in people with moderate to severe autism.