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`Dyslexia
By Carsh Wilturner, Ph.D.
Green River Community College
Auburn, WA
- (This update is provided courtesy of APA's Community College Working Group. It is based on the work of: Shaywitz, S. (1996). Dyslexia. Scientific American, November, 98-104.)
In this article, Sally Shaywitz, co-director at the Yale Center for the Study of Hearing and Attention, presents the phonological model of dyslexia. This model contrasts with older models of dyslexia that emphasize visual system deficits. This article is quite engaging and easily understandable by introductory psychology students who are familiar with cognition, language, and biological chapters in an introductory text. It is a good demonstration of how current research eclectically synthesizes from various specialty areas in psychology to explain behavior. It is thus a good antidote for the necessary but often frustrating segmentation of topical coverage usually pursued in most introductory psychology texts.
The article begins with a short engaging case study of a medical student who is both intellectually gifted and dyslexic. Shaywitz presents the phonological model of dyslexia. In brief, this model views the language system as composed of a number of modules, each devoted to a particular language processing task. The phonological module is a lower level module devoted to processing the phonemes (basic language sounds) that comprise language. Shaywitz presents evidence that this module is probably biologically located in the interior frontal gyrus (lower part of the left frontal lobe) for most people, though there are some gender differences. The phonological module is essentially a processor which allows the brain to segment and assemble phonemes into words which can then be further processed and decoded into meanings.
In dyslexia, according to this model, the phonological module is unable to perform its segmenting task on written words. Because this basic low level module is unable to first segment written language into phonemes, all further processing cannot be brought into play since all higher order processing relies on this basic segmentation process. As Shaywitz says, "...although the language processes involved in comprehension and meaning are intact, they cannot be called into play, because they can be accessed only after a word has been identified." Shaywitz goes on to provide a model of the reading process and to discuss the neural architecture undergoing the reading process.
This article can be utilized in a number of ways including class discussion, written extra-credit report, or with particular structured questions relating the article to research methods (experimentation, correlation, case study), to association cortex functioning, to the Wernicke-Geschwind model, and/or to other language models.
The above article was originally published in the May/June 1997 issue of The Psychology Teacher Network. The article is reprinted here with the permission of the Education Directorate of the APA. Further publication of the article is not permitted without the express written consent of the Education Directorate.
