Case Study Review and Discussion of the Double-Deficit Hypothesis

Article: Deeney, T., Wolf, M., & O’Rourke, A.G. (2001). "I like to take my own sweet 
                  time”: Case study of a child with naming-speed deficits and reading 
                  disabilities. Journal of Special Education, 35, 145-155.

According to the Double-Deficit Hypothesis described in this article, the two core deficits in children with developmental dyslexia are phonological processes and naming speed deficits. These two deficits account for three subtypes of dyslexic readers including those with a single phonological deficit, a single naming-speed deficit, and a combination of the two deficits. Children with a single phonological deficit are thought to have problems with word attack and decoding skills; whereas, children with a single naming speed deficit are thought to have difficulties with word identification and orthographic skills. Children who have a combination of the two deficits (phonological and naming speed) have the most widespread and resistant forms of reading troubles. This group has difficulties with a combination of word identification and orthographic skills as well as word attack and decoding skills.

The authors describe the case study reported in this paper as the first published study to follow a child with a single naming speed deficit resulting in a severe reading disability. The study followed a 9-year-old male over the course of 70 hours of intervention aimed at improving his reading abilities. This child was able to decode words by sounding them out, but had difficulties with letter orientation and sight vocabulary. The intervention consisted of participation in the RAVE-O program, a program aimed at addressing problems with processing speed and fluency, plus a combination of phonological analysis and blending work. Post intervention results, using both standardized and non-standardized measures, revealed improvements in the child’s performance IQ and reading. The next article discussed will describe the RAVE-O program in greater detail.

Blogger: Katherine Harder. Katherine is completing her final year in the Masters of Clinical Science program in Communication Disorders at The University of Western Ontario. She is also a research student in the Language and Working Memory Lab studying the effects of increasing cognitive demands on working memory in children with poor language or working memory skills.