John O'Neill1, Andrew P Blowers1, LaDonna Henson2, Ruth Anne Rehfeldt1. 1. Behavior Analysis and Therapy, Rehabilitation Institute, Southern Illinois University Carbondale, Carbondale, IL 62901-4609 USA. 2. Evaluation and Developmental Center, Rehabilitation Institute, Southern Illinois University Carbondale, Carbondale, IL 62901-4609 USA.