Converging evidence for phonological and surface subtypes of reading disability.

Abstract

Using regression-based procedures introduced by A. Castles and M. Coltheart (1993), the authors identified 17 phonological and 15 surface dyslexics from a sample of 68 readingdisabled 3rd-grade children by comparing them to chronological-age (CA) controls on exception word and pseudoword reading. However, when Ihe dyslexic subtypes were defined by reference to reading-level (RL) controls, 17 phonological dyslexics were defined but only 1 surface dyslexic. When the CA-defined subtypes were compared to RL controls, the phonological dyslexics displayed superior exception word reading but displayed deficits in pseudoword naming, phonological sensitivity, working memory, and syntactic processing. The surface dyslexics, in contrast, displayed a cognitive profile remarkably similar to that of the RL controls.There is considerable face validity to the idea that reading disabled individuals differ among themselves in the way that they have become poor readers and in the cognitive underpinnings of their disability. Yet the field has made very little progress toward defining separable groups of disabled readers. For example, the idea that separate subgroups of poor readers could be defined based on aptitudeachievement discrepancies has not proven fruitful for the reading disabilities field (

Reliability and prevalence of an atypical development of phonological skills in French-speaking dyslexics

“…In contrast to the classical method, the regression method points to a relative deficit, either in the orthographic skills of dyslexics relative to their phonological reading skills, or in their phonological reading skills relative to their orthographic skills. Stanovich et al (1997) characterized the subtypes defined in this manner as 'soft', as opposed to the 'hard' subtypes defined using the classical method. Soft subtypes are defined by plotting pseudoword performance against irregular-word performance (and vice versa) and then examining the 90% (or 95%) confidence intervals around the regression lines determined from the control group.…”

“…More recently, five multiple-case studies were carried out, three with English-speaking dyslexics (Castles & Coltheart, 1993;Manis, Seidenberg, Doi, McBride-Chang, & Peterson, 1996;Stanovich, Siegel, & Gottardo, 1997) 1 and two with French-speaking dyslexics (Génard, Mousty, Content, Alegria, Leybaert, & Morais, 1998;Sprenger-Charolles et al, 2000). Two methods were used to analyze the results: the classical method and the regression method.…”

“…Indeed, in some studies phonological dyslexics alone were found to suffer from phonological deficits (e.g. in English: Manis et al, 1996;Stanovich et al, 1997), but not in other studies (e.g. in English: Zabell & Everatt, 2002;in Spanish: Jimenez-Gonzalez, & Ramirez-Santana, 2002;in French: Sprenger-Charolles et al, 2000).…”

Varieties of developmental dyslexia in Greek children

“…The rest of the children (N=32 cases) were impaired in both processes but still they were more impaired in one of the two. Manis et al (1996) carried out a similar study to that of Castles and Coltheart with 51 dyslexics, as did Stanovich, Siegel, and Gottardo (1997). In both these studies when reading age control children were considered the number of surface dyslexic children was reduced in contrast to the phonological dyslexics.…”

Auditory word identification in dyslexic and normally achieving readers

“…Two critical dimensions that may be important are the degree of phonological deficit and the degree of language impairment (Gallagher, Frith, & Snowling, 2000;Griffiths & Snowling, 2002;Joanisse et al, 2000;Manis, Seidenberg, Doi, McBride-Chang, & Petersen, 1996;Stanovich, Siegel, & Gottardo, 1997). According to the phonological representations hypothesis, the degree of phonological impairment should be the primary variable affecting gating task performance.…”