Date of Award


Degree Name

Master of Science


Communication Disorders and Sciences

First Advisor

Bass-Ringdahl, Sandie


Children with developmental disabilities often have complex communication needs that require professional intervention. For children with limited or no functional speech, the first step in treatment programming is choosing an augmentative and alternative communication (AAC) modality that best represents the needs of the child. The availability and diversity of AAC systems are only increasing (Loncke, 2014). Parents and practitioners are faced with a difficult decision and existing literature has yet to come to a consensus on the potential benefits or disadvantages of incorporating specific AAC strategies. The field of applied behavior analysis has empirically demonstrated the utility of AAC modalities as viable manding topographies to reduce problem behavior (Harding et al., 2009; Ringdahl et al., 2009). Despite reliable reductions in problem behavior, there is paucity in research directly comparing mand modalities and the subsequent effects on communication repertoires. Existing studies contain methodological features that make it difficult to draw firm conclusions (Chambers & Rehfeldt, 2003; Gregory, DeLeon, & Richman, 2009; Tincani, 2004). Therefore, the purpose of the current investigation is to expand on existing literature evaluating aided and unaided AAC modalities and contribute to literature on mand training as it relates to topography-based versus selection-based system outcomes. This study compares three popular mand modalities frequently utilized in interventions implemented by speech-language pathologists and behavior analysts: (1) speech only (2) picture card + speech (3) sign + speech. Conditions were compared in an alternating treatments design for two participants to determine differential modality acquisition, problem behavior reduction, communicative gesturing, and speech emergence. Methodological considerations were given to control for the influence of transfer of stimulus control procedures by adopting a graduated time delay prompt fading procedure and, to the greatest degree possible, minimize the influence of response effort variability by employing the lowest response effort possible across all conditions. Results support the “multimodal” conceptual framework and the practice of “total communication” and provide evidence against the opposing “incompatibility hypothesis.” Keywords: augmentative alternative communication (AAC), mand, verbal behavior, multimodal, total communication, incompatibility hypothesis, aided, unaided, topography-based, selection-based




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