Pasco, G. & Tohill, C. (2011). Predicting progress in Picture Exchange Communication System (PECS) use by children with autism.

International Journal of Language and Communication Disorders, 46, 120-125.
Abstract:Background:The Picture Exchange Communication System(PECS) is a widely used communication intervention for non-verbal children with autism spectrum disorder. Findings for the benefits of PECS have almost universally been positive, although there is very limited information about the characteristics of PECS users that determine the amount of progress that they are likely to make. Lee Mas...