What is the Causal Relation Between Verbal STM Problems and Dyslexia?
Bruce F. Pennington University of Denver
Guy Van Orden Arizona State University
Donald Kirson University of Denver
Marshall Haith University of Denver
To begin this chapter, I want first to acknowledge the enormous contribution of the work of Isabelle Liberman, her colleagues and students to my own work on defining the linguistic phenotype in familial dyslexia. I hope it is within the compass of my role as a grateful intellectual offspring to offer some friendly scrutiny of the possible relation between verbal STM and reading skill that has been developed in several recent publications by Susan, Don, and colleagues, including the Brady chapter in this volume ( Brady, 1986; Brady, Mann, & Schmidt, 1987; Mann & Brady, 1988; Shankweiler, Crain, Brady, & Macaruso, in press). In Brady's chapter in this volume, she reviews evidence supporting the important role of verbal working memory in the reading process, presents evidence that phonological processing efficiency affects verbal memory capacity, and considers evidence on the possible relations among different phonological processing skills. She concludes that we do not yet know whether deficits in verbal working memory are causal or contributory in dyslexia or what the relation is among different phonological processing skills.
In this chapter, I focus on two issues: (1) What is the causal relation between problems in verbal STM, including problems in phonological coding