«DOCUMENT RESUME ED 363 732 CE 064 960 AUTHOR Fowler, Anne E.; Scarborough, Hollis S. TITLE Should Reading-Disabled Adults Be Distinguished from Other ...»
Whereas studies of reading-disabled adults consistently show deficiencies in word recognition measures, reading comprehension performance is more variable. Earlier, a description was given about how reading comprehension in children depends jointly on word recognition and listening comprehension; further, it is suggested that the same two components influence reading comprehension in adults as well (Sticht, et al., 1974; Sticht & James, 1984). Even if listening comprehension abilities are intact, the persisting inefficiency of word recognition is likely to create a bottleneck in processing that would impede extraction of meaning, as is seen for unskilled reading. in childhood. Indeed, many adults also have difficulties with reading comprehension despite apparently good verbal intelligence.
On the other hand, one might expect adults to have had much more practice in trying to overcome their reading difficulties and to have developed more sophisticated strategies for circumventing them. There is evidence that some disabled adult readers, more so than unskilled children, can use contextual cues very effectively to improve comprehension. For example, Blalock (1981) observed that her sample was amazingly adept at using contextual cues, such that they could read many words in context that they could not decode in isolation (on the basis of spelling sound TECHNICAL REPORT TR937 correspondences alone). More systematic studies have supported Blalock's observation that comprehension levels may exceed isolated word recognition skill. For example, Pennington et al., (1990) found such a pattern in two different groups of dyslexics, each with a self-reported history of reading and spelling difficulty plus a current significant discrepancy between aptitude and reading level. One group was identified through the family study;
the other was recruited from a reading clinic at the local community college. When compared to eighth-grade schoolchildren matched on word recognition, dyslexic subjects were significantly behind on pseudoword reading and spelling but ahead on reading comprehension, performing almost at the grade level of chronological age controls (dyslexics, 11.0; age-matched controls, 12.8; reading level controls, 10.5). In this sample, it seems there were many dyslexics whose reading comprehension skills were within the normal range, despite deficient decoding skills.
A similar pattern was also observed by Bruck (1990), using the sample described earlier; despite childhood histories of dyslexia and persistent decoding deficits, her subjects had managed to achieve eleventh-grade reading comprehension scores and were progressing through college. How did they comprehend as well as they did? In a systematic comparison of words read in isolation and in meaningful context, Bruck found that context aided the dyslexics in both accuracy and speed; the error rate of the dyslexics dropped from 9% to 2% and reaction time dropped by 136 milliseconds. In contrast, the sixth grade reading-level controls did not show any contextual facilitation (they apparently did mit fully appreciate the content of the passage), and the facilitation shown by normal adult readers was very small though significant (22.6 milliseconds). It should be pointed out, however, that even when reading words in context, the reaction times for the dyslexic group were significantly slower than the times obtained for sixth graders reading the words in isolation (681 vs. 598 milliseconds).
In her attempts to understand processes of reading comprehension, Bruck further divided her group of college dyslexics into good comprehenders (50th percentile, n - 7) and poor comprehenders (25th percentile, n - 8). The two groups did not differ significantly on word recognition (accuracy, speed, or error pattern), spelling, or nonverbal intelligence. Rather, only listening comprehension (assessed through verbal intelligence measures) discriminated good and poor comprehenders. These findings are consistent with the view that reading comprehension depends crucially on listening comprehension and that listening comprehension may operate independently of word recognition,
NATIONAL CENTER ON ADULT LITERACY 53
as outlined in the reading comprehension model presented earlier (Sticht, 1974; Hoover & Gough, 1990).
Also consistent with this model is the possibility of adults whose decoding skills are intact but whose reading comprehension is limited by poor listening comprehension skills. Although this pattern has not been found in pure form among reading-disabled individuals, work by Sticht suggests that such individuals exist. For example, using parallel measures for listening and reading comprehension, Sticht (1972) found that poor readers among 100 army recruits had listening comprehension skills equivalent to reading comprehension level. From this he concluded that poor readers are also poor language understanders. There are two ways to interpret these findings in light of the data on reading-disabled adults. It could be argued that the army recruits would not qualify as reading disabled exactly because reading is not significantly below general intelligence (which correlates highly with listening comprehension). Alternatively, it may be that these recruits would have shown decoding deficits as well if measures of automaticity and speed had been employed. Although it may turn out that the association between listening comprehension may be a crucially important distinction between the reading-disabled adult and the one who is functionally illiterate, our suspicion is that the only way to accurately identify (and treat) the sources of reading difficulty is to test both to see whether listening comprehension is at a high level and whether decoding skills are accurate and automatic. On the one hand, the very fact that intelligence exceeds reading comprehension in the reading-disabled sample suggests that these subjects are still in the early stages of acquisition prior to achieving what Sticht refers to as mature reading, typically achieved in seventh or eighth grade, and that decoding skills have not been mastered. On the other hand, it cannot be denied that language comprehension plays an important and separate role in reading comprehension and that training in oral listening and in content areas will serve to improve reading comprehension (Sticht et al., 1974).
Finally, the traditional notion that only spelling remains unimpaired in reading-disabled individuals can be understood in relation to recent research on adults. That is, spelling requires very similar skills to those needed for word recognition: for regular words, a grasp of letter-sound correspondences; for irregular words, familiarity with memorized word-specific letter sequences. In view of this, it is not surprising that many researchers have confirmed that poor adult readers indeed are also typically poor spellers (Aaron & Scott, 1986; Blalock, 1981; Bruck, 1990; Bruck & Waters, TECHNICAL REPORT TR93,g,, SE 1990; Miles, 1986; Pennington et al., 1990; Scarborough, 1984). For many disabled readers, their spelling difficulties are simply more tangible and self-evident, perhaps leading to the misapprehension that only spelling remains a problem.
4. THE COGNITIVE LINGUISTIC PROFILE OF ME READING-DISABLED ADULTThe evidence discussed thus far suggests that those aspects of reading which proved most difficult for reading-disabled children also constitute obstacles to skilled reading in adulthood. But one might hypothesize that the underlying causes of reading difficulty may have ameliorated over the years. The focus is on the three
areas most commonly implicated in childhood reading disability:
phoneme awareness, speed and accuracy of lexical access, and verbal memory. As will be seen, whereas phoneme awareness and lexical access are fully implicated in adulthood, the story regarding phonological memory is more complicated.
In adults, as in children, phoneme awareness measures are strong predictors of phonological recoding skill and word recognition knowledge. This is true both for nonspecific learningdisabled adults (Pratt & Brady, 1988; Read & Ruyter, 1985) and for adults in family studies who, on the basis of measures on standardized tests, appear to have ( 3mpensated for the reading problems (Pennington et al., 1990). In every sample of reading disabled adults that has been tested for it, phoneme awareness problems have been apparent (Blalock, 1981; Byrne & Ledez, 1983;
Liberman, Rubin, Duques & Carlisle, 1985; Perin, 1983). These deficits are upheld when comparisons are made with normal reading controls matched on age, social class and nonverbal IQ (Pratt & Brady, 1988), matched on (or co-varying for) verbal IQ (Felton et al., 1990), or when the dyslexic adults were compared to developing children of equivalent reading status (Read & Ruyter, 1985). Phoneme awareness problems are evident in adults with reading disabilities, but not in adults who have pure math disabilities or who are not affected (Siegel, 1992). Although limited access to orthographic strategies might plausibly explain the poor performance of subjects on some phoneme tasks such as speaking in pig Latin, segmenting spoken words into phonemes, or deleting phonemes from words, evidence for more global phonological deficits suggests that the problem is deeper than that. For example, syllable counting generally develops prior to reading instruction and is a good kindergarten predictor of later reading success (Liberman et al., 1974; Mann & Liberman, 1984); however, Blalock (1981) noted that only 11 out of 36 learning disabled could count the syllares in words ranging from 2 to 5 syllables. Blalock also noted that 16 of 26 subjects had problems with rhyming tasks, and
NATIONAL CENTER ON ADULT LITERACY 55the subject in Temple's (1988) case study could not reliably distinguish rhyming from non-rhyming words (e.g., load/cold), and was limited in his ability to produce rhymes. In short, deficits in phonological sensitivity appear to be robust and potentially even causal.
Reading-disabled adults also show a reliable decrement in speed when compared to normal reading controls (Decker, 1989;
Felton et al., 1990; Miles, 1986; Wolff, Michel & Ovmt, 1990). Decker (1989), for example, found that when IQ was controlled for, only the measures of speed of lexical access (naming letters) and speed of pseudoword decoding distinguished dyslexic adults from normal reading adults; the groups did not differ on spatial or mathematical measures. Felton et al., (1990) obtained similar results; within a large battery of measures, only rapid naming proved as important as pseudoword reading and phonological awareness as indicators of a childhood history of reading disability, once differences in intelligence and social class status had been controlled for. Other evidence for impoverished performance on a rapid naming task was found by Wolff et al., (1990) in a study of 90 middle-class adolescents and adults with specific developmental dyslexia. When compared to other learning disabled controls without reading problems, but matched for age, sex, social class, and normal IQ, the dyslexics made more errors and had slower speeds in producing labels for colors and pictures of common objects. These data suggest that naming speed acts as a rate-limiting factor on reading fluency in adolescents and adults.
In a particularly interesting demonstration of problems with speed, Miles (1986) compared college students with reading disabilities with other normal-reading college students in their response to 28 days of practice in identifying briefly displayed sets of digits, letters, and Russian letters. With practice, the normal readers improved dramatically over the month (from 700 milliseconds to less than 10), but only moderate reductions were attained by the dyslexic students (from 1500 to 525 milliseconds).
The poorer readers also pointed more slowly to orally or visually labeled parts of a video figure (hand, mouth, eye, etc.) and were much slower at verifying statements such as "the star is to the left of the cross" in response to visual arrays of symbols.
The full story on lexical access, however, is not yet clear.
Pennington et al., (1990), for example, used a discrete trial lexical naming task and found that although dyslexic adults were slower than age-matched control subjects, they were no slower than children of equivalent reading ability. Furthermore, even in studies
TECHNICAL REPORT T193-7Si
that have found differences between reading-level matched groups, speeded naming scores have not usually been correlated in any systematic way with individual differences in reading skills. Clearly, there is a need for further work on this issue.
The third area of phonological processing implicated in childhood reading disability and in anecdotal reports of adult poor readers is verbal short-term memory (Brady, 1991). Verbal memory refers to the identification, retention, and recall of verbally encodable stimuli, whether orally or visually presented;
there is considerable evidence that this store is phonological at base. As in the body of research on childhood reading problems, systematic experiments on adults have yielded more variable results than have been obtained for phoneme awareness. For instance, Pennington et al., (1990) found that clinic-referred dyslexics, but not familial pure dyslexics (from a sample studied from a behavior genetics vantage point), had shorter digit spans than nondisabled adult readers. Interestingly, there seems to be a trend toward greater weaknesses in verbal memory among adults with nonspecific reading problems (i.e., with accompanying math deficits and/or low IQ) than among adults with specific reading disability. For example, Siegel (1992) found that adults with specific reading disability (with normal math skills and normal IQ) and those with specific math disabilities (with normal reading skills and normal IQ) did not have verbal memory deficits; whereas adults with low achievement in both math and reading (and with somewhat lower average IQs) did show weaknesses in memory skill.
Likewise, Read and Ruyter (1985), whose sample was functioning in the low-normal IQ range, found that memory deficits were related to weaknesses in decoding and phoneme awareness. Similarly, learning-disabled adults who were referred through vocational rehabilitation agencies and who presented broad and severe academic problems were described as having specific deficits in verbal (but not nonverbal) memory (Minskoff, Hawks, Steidle, & Hoffman, 1989; McCue, Shelley, & Goldstein, 1986).