Clinical Implications of the Double DeficitModel for Adolescents with DyslexiaAllyson HarrisonQueen’s Universityharrisna@queensu.caPresently, there is considerable support forboth the phonological core deficit model ofDyslexia as well as evidence to support namingspeed deficits as primarily contributing tothis disability. Wolf and Bower (1993; 1999)proposed that many students with Dyslexiamight also be impaired in both underlyingprocesses, calling this the Double Deficit model.This study investigated whether 137 Canadianadolescent Dyslexics could be categorizedinto subtypes according to the presence orabsence of phonological deficts alone, namingspeed deficits alone, or a combination ofthe two. 137 Dyslexic subjects aged 11-14were seen for updated psychoeducationalassessments in a program designed to assiststudents with Dyslexia in making the transitionfrom elementary to secondary school. All hadprevious diagnoses of Dyslexia.Tests administered included the ComprehensiveTest of Phonological Processing, WechslerIntelligence Scale for Children-Fourth Edition,Wechsler Individual Achievement Test-SecondEdition, the Wide Range Assessment of Memoryand Learning – Second Edition, the Test of WordReading Efficiency, and the Processing Speedmeasures from the Woodcock Johnson –III.Results support the existence of both single anddouble deficit groups, and confirm that thosewith both deficits are the most severely impairedacross multiple measures.Contrary to previous research, most adolescentswere classified as either naming speed only orDouble Deficit, and about a third of the grouphad deficits in naming speed deficit with intactphonological skills. This may suggest that whileearly phonological deficits are amenable toremediation, identification of language symbolsfails to become automatized in children withDyslexia and may require more targetedintervention.
