This possibility is given added credibility by results from a second line of research, that is, regression studies evaluating skills and abilities underlying reading ability (Catts, Hogan, & Fey, 2003; Curtis, 1980; Foorman, Francis, Shaywitz, Shaywitz, & Fletcher, 1997; Hoover & Gough, 1990; Vellutino, Scanlon, Small, & Tanzman, 1991; Vellutino et al., 1994). These studies have shown that there is a developmental asymmetry in the acquisition of skill in comprehending written text such that facility in word identification carries much greater weight as a determinant of reading comprehension in children at the early stages of reading development than in children at later stages, whereas language comprehension processes carry much greater weight as determinants of reading comprehension in children at later stages of reading development than in children at early stages of reading development. After further reading this article it goes on to tell the causes of cognitive deficit theories of dyslexia. Dyslexia has most often been attributed to deficiencies in visual, linguistic, and low-level sensory functions, and we exemplify such theories below. However, dyslexia has also been attributed to deficiencies in general learning abilities that are involved in all learning enterprises and not just learning to read. For example, specific reading disability has been variously attributed to deficiencies in selective attention (Douglas, 1972), associative learning (Brewer, 1967; Gascon & Goodglass, 1970), cross-modal transfer (Birch, 1962), serial-order processing (Bakker, 1972), and both pattern analysis and rule learning (Morrison & Manis, 1982). To better understand the study this is what the article stated to what happened in the study. In studies conducted comparing poor and normal readers across a broad age range (most often grades 2 through 8), few significant differences between these groups were found on measures of visual processing ability when the influence of verbal coding was controlled. For example, in experimental studies evaluating such processes (Vellutino, 1979, 1987; Vellutino & Scanlon, 1982), it was found that memory for visually presented letters and words that were visually similar (such as b, d, was, and saw) was as good in poor readers as it was in normal readers when the task required a written response rather than a naming response, which did differentiate these two groups. Language and language based deficit is a major part of learning when dealing with Dyslexia. Such findings suggest that early reading difficulties in children from this population may not be caused primarily by vocabulary and syntactic deficits and may, more often, be a consequence of prolonged reading problems. These deficits may also be co-morbid, reflecting the co-occurrence of oral language and reading difficulties (e.g., Catts et al., 2003). However, existing data do not preclude the possibility that vocabulary and syntacti