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There has been general consensus in dyslexia research that phonological processing deficits underlie dyslexic readers' failure to acquire adequate word recognition skills (Blachman, 1997; Bradley & Bryant, 1983; Brady & Shankweiler, 1991; Bruck & Treiman, 1990; Catts, 1996; Shankweiler & Liberman, 1972; Foorman, Francis, Shaywitz, Shaywitz, & Fletcher, in press; Kamhi & Catts,1989; Lyon,1995; Stanovich,1986,1988,1992; Torgesen, Wagner, Rashotte, Burgess, & Hecht, 1997; Tunmer, 1995; Vellutino & Scanlon, 1987; Wagner & Torgesen, 1987). The assumption of a phonological-core deficit-that difficulty representing the sound structure of words impedes a child's ability to learn decoding principles-has guided diagnostic and intervention efforts in reading disabilities and has been a fundamental tenet in the work to be described here.
Despite the considerable progress made in phonology-based research, certain aspects of dyslexia continue to elude the best theoretical explanations and interventions based on this single core-deficit perspective. As Rudel (1985) cautioned more than a decade ago, there are poor readers who slip through our diagnostic batteries because they have adequate to good phonological decoding skills. And, as stated by Blachman (1994) and by Torgesen, Wagner, and Rashotte (1994), there are unexpected "treatment resisters" who do not respond to our well-constructed, phonological-based interventions.
The work to be presented in this special issue of JLD is heavily influenced by the phonological-core deficit perspective and by the psycholinguistic tradition underlying it. Over the last years, however, the authors represented here have begun to diverge from a strict version of the phonologicalbased view as they have attempted to explain the consistent presence of naming-speed deficits in severely impaired readers and the relationship of naming speed to reading failure. Although most current conceptualizations of naming speed subsume it under phonological processes (Torgesen et al., 1997), the authors in this issue are investigating whether namingspeed deficits represent a second core deficit in dyslexia that is largely independent of phonology and, thus, not subsumable under it (Bowers & Wolf, 1993; McBride-Chang & Manis, 1996; Lovett, 1995; Wolf & Bowers, 1999).
The focus on naming speed stems from work in the neurosciences begun by Geschwind (1965) and tested and developed by Denckla (1972) and Denckla and Rudel (1974, 1976a, 1976b). Denckla and Rudel created a series of continuous naming-speed tasks, called Rapid Automatized Naming (RAN) tests, that have been...