«DOCUMENT RESUME ED 363 732 CE 064 960 AUTHOR Fowler, Anne E.; Scarborough, Hollis S. TITLE Should Reading-Disabled Adults Be Distinguished from Other ...»
4. TtiE SEOUENa OF DEVELOPMENT The preceding sections presented material that might suggest a necessary sequence of development. It was argued that phoneme awareness is necessary for decoding, that decoding is necessary for accurate and efficient word recognition, and that skilled word recognition is essential for good reading comprehension. Despite these contingencies, it is important to note that there is little evidence that these steps are, or should be, acquired in such an ordered fashion. In fact, a number of studies have indicated just the opposite. That is, while decoding entails phoneme awareness, the very exposure to orthography and decoding aids the acquisition of phoneme awareness (Bowey & Francis, 1991; Perfetti et al., 1987). While phonological recoding is argued to be an important step in word recognition, so, too, does sight word recognition proceed alongside and even aid phonological decoding skill (Ehri, 1992; Byrne, 1992). While greater practice in word recognition yields automaticity, initial evidence of automaticity in decoding is observed between first and second TECHNICAL REPORT T193374 grade and continues to develop throughout adulthood (Horn & Manis, 1987). As efficient word recognition aids in comprehension, so, too, does comprehension aid the beginning reader in recognizing unknown words (Stanovich, 1980).
Studies show that in terms of instructional implications, listening comprehension should proceed alongside decoding, that word recognition may lay the foundation for decoding, and that decoding has effects on phoneme awareness. Recent research emphasizes strongly the interplay of these various components of reading and is very conservative in granting absolute developmental priority.
To understand the nature and causes of reading disabilities, it is necessary to examine how the process of learning to read goes awry in some individuals. In particular, a great deal of research has addressed the questions of which components of reading are most difficult for dyslexic children to master and what kinds of cognitive and linguistic weaknesses may underlie their difficulties in reading acquisition.
L CliARACTERISTICS ASSOCIATED WM SPECIFIC READING DISABIUTYAs stated earlier, specific reading disability, or dyslexia, entails unexpectedly poor reading in relation to aptitude. From an educational standpoint, this state of affairs is usually only apparent after the child has received several years of formal instruction yet has not acquired age-appropriate word recognition skills by the second or third grade. Because these children are otherwise bright and competent, earlier signs of difficulty are generally unnoticed or disregarded by teachers and parents, and indeed some dyslexic children manage to conceal their problems for a considerable time. Once most classmates have reached greater levels of skill, however, including those who are less intelligent or from more disadvantaged backgrounds, the child's specific deficiency can no longer be dismissed as a transient phenomenon. The child's record to this point reveals a consistent profile of underachievement in primary grade reading.
The first clue to the underlying basis of reading disability, therefore, is that the dyslexic child's problems exist from the beginning of the school years. Because curricula and assessments during the early grades typically emphasize word recognition much more strongly than text comprehension, the early onset of reading disability suggests that the locus of the problem lies at a relatively low level, and decades of research have indeed borne this out. As noted earlier, identifying printed words involves letter recognition, sight recognition of memorized words, and decoding through the application of letter-sound correspondences. To some extent, all of these subskills are typically weak in young dyslexic children. Over the past 20 years, however, a programmatic body of research, employing sophisticated methodologies and well-defined ift, LT LITERACY
NATIONAL CENTER ON 31samples, has provided persuasive evidence that the most serious deficiency is in decoding itself. In particular, it has been shown that even after they are able to identify printed letters sufficiently well, reading-disabled children are less able to sound out pseudowords (i.e., apply letter-sound correspondence rules in the absence of word-specific memories and contextual cues) than other students, including younger, normally developing children whose overall word recognition and comprehension skills are at the same level (i.e., reading level matcbed controls). This kind of comparison is strong evidence that a decoding problem is not a result of generally poor word recognition skills (stemming, for example, from a visual memory deficit), but rather may be causally related to an inability to identify printed words. In short, there is a great deal of evidence that cracking the alphabetic code is the main obstacle that impedes progress in learning to read for these children.
The link between alphabetic literacy and oral phonological processing in the normal course of reading acquisition is well established. Research on reading disability has also demonstrated that weaknesses in phonemic awareness are very apparent in dyslexic children, as would be expected given their decoding problems. Several studies have shown that compared to reading level matched controls, disabled readers are less proficient in segmenting spoken words, in categorizing words according to phonemic similarity, and in performing other tasks requiring the awareness and manipulation of the sounds of oral language (Bradley & Bryant, 1978; Fowler, 1990). This link between poor phoneme awareness and poor decoding has also been shown to be a reliable basis for predicting reading acquisition differences in longitudinal studies. Of the many differences among children in the late preschool years, variability in metaphonological skill has consistently been found to predict later reading achievement more successfully than such potentially important factors as visual processing abilities, nonverbal cognitive skills, and even verbal intelligence (Blachman, 1984; Bradley & Bryant, 1983; Lundberg, Frost, & Petersen, 1988; Mann & Liberman, 1984). In sum, even before formal reading instruction begins, children who will turn out to have specific reading disability are likely to differ from their peers in their sensitivity to the phonological structure of spoken language, and this relative weakness in phonological processing persists in tandem with decoding difficulties during the course of reading acquisition.
Several other difficulties have also been observed in young pre readers who become disabled readers. These include limitations in TECHNICAL ItEPORT TIt93-7 verbal short-term memory, despite adequate recall of nonverbal material (Share, Jorm, Maclean, & Matthews, 1984; Wagner et al.,
1987) and slowness and inaccuracy in retrieving the names of symbols or pictures (Denckla & Rudel, 1976; Wolf, 1991). While at first glance these abilities may appear to have little in common, it has been hypothesized that the limiting factor in each task is facility with some aspect of phonological processing. That is, to retain a stimulus list in working memory or to repeat back a pseudoword, one ordinarily creates and stores a phonological representation of the items that were heard, and uses that stored information as the basis for recall. Inadequate phonological processing of stimuli could thus result in an insufficient memory representation, and hence in less accurate recall. Similarly, rapid retrieval of stimulus names is thought to depend on the accessibility and precision of phonological representations of words in memory, so weak phonological traces would impede performance on rapid naming tasks. Moreover, these associated weaknesses could individually affect reading acquisition and reading performance directly. For instance, learning to identify printed letters, recognizing exception words and familiar words by sight, and analyzing the syntactic and semantic relations among words in connected text, all depend heavily on the adequacy of verbal memory representations. Thus, while phonological processing abilities appear to be the most fundamental source of difficulty that disrupts the learning of letter-sound correspondences, weaknesses in other aspects of word recognition and in reading comprehension may indirectly result from memory limitations that also stem from more basic phonological impairments.
So much research and thinking in recent years has been devoted to exploring the clear and important relationships between phonological weaknesses and reading disabilities that there has been a tendency to neglect some other characteristics that may also contribute to reading problems. In particular, other aspects of oral language processing, aside from phonological abilities, are also relatively weak in children who have specific reading problems (Lovett, 1987; Morice & Slaghuis, 1985; Siegel & Ryan, 1984; Vogel, 1974; Whitehouse, 1983). To some extent, the poor syntactic, semantic, and lexical abilities of dyslexic schoolchildren may be consequences of early reading failure or Matthew effects. This cannot be the whole story, however, because these linguistic deficits also appear to precede the emergence of these children's reading problems. Several longitudinal studies have found that lexical and syntactic, as well as phonological, differences among 4- to 6-year-olds, for instance, are predictive of
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later differences in reading achievement (Butler, Marsh, Sheppard & Sheppard, 1985; Scarborough, 1989; Share et al., 1984; Stanovich, Cunningham & Feeman, 1984). Dyslexic children have also been shown to have weaknesses in their metalinguistic ability to segment and analyze language into component words, morphemes, phrases, and sentences, suggesting that phonological awareness may be but one manifestation of a broader pattern of difficulty in conscious linguistic processing (Siegel & Ryan, 1984; Fowler, 1988; Tunmer, Nesdale & Wright, 1987). Furthermore, in one recent study that focused on the early development of children at risk for reading disability because of a family history of dyslexia, children who subsequently became disabled readers were found to have weaker language abilities than children who became good readers (Scarborough, 1991). These differences were particularly evident in the syntactic domain and emerged at a very young age (2.5 years).
These results suggest that although phonological difficulties may pose the most immediate obstacle to cracking the alphabetic code, children with weak phonological skills may also be characterized by a wider array of language processing difficulties that could impede the process of learning to read.
As reading acquisition continues, the dyslexic child is likely to improve in both reading and oral skills. The initial failure in learning to decode, however, prevents most children with specific reading disability from catching up to their peers with respect to the accuracy and speed of word recognition. This lack of ageappropriate skill and automaticity, in turn, imposes a bottleneck in processing, as discussed earlier, so that the child's superior listening comprehension abilities cannot be as readily applied to the task of comprehending what is read. Consequently, performance on tests of reading comprehension is likely to be severely limited by decoding skills, as is generally characteristic of unskilled readers.
In sum, a consistent profile of reading disability has emerged that fits quite well with what has been learned about normal reading acquisition. It seems that the child with a specific reading disability suffers from subtle linguistic deficits that affect his or her ability to reflect on the phonological and syntactic structures of oral language, to decode printed words into their oral counterparts, to access lexical information rapidly, to retain phonological information in memory, to acquire a sight vocabulary, and to discover meaningful relations among strings of words that have been identified. The cognitive and linguistic problems of dyslexic children are not associated with similar difficulties in processing nonverbal material, just as the reading 3,9 TECHNICAL REPORT T193-7 problems need not be accompanied by math deficiencies. It should be emphasized also ilizt this set of problems is associated with reading disability not just at the outset, but throughout the grade school yeais (and even beyond). These problems do not necessarily make it impossible for dyslexic children to acquire any reading skill at all but primarily compromise the efficiency and accuracy of word recognition.