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Information Processing and Reading Achievement in the Deaf Population: Implications for Learning and Hemispheric Lateralization
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Information Processing and Reading Achievement in the Deaf Population: Implications for Learning and Hemispheric Lateralization Carol A. Kusche At least two important factors have been found to be significantly related to good reading comprehension: (a) processing speed, which includes retrieval from semantic memory, scanning speed of working memory contents, linguistic understanding, and past language experience; and (b) short-term memory, which for hearing individuals seems to involve phonetic encoding (Golinkoff & Rosinski, 1976; Guttentag & Haith, 1978; Hess & Radtke, 1981). Automatic or unconscious processing of written material appears to be acquired with relative ease by most hearing children because they learn to transfer the patterns of spoken language, which have become habitual due to years of linguistic stimulation and practice, onto the secondary media of reading and writing (Fries, 1962; Wolff, 1973). Reading, then, appears to be a language-based skill that ultimately depends upon automatic processing and unconscious linguistic awareness (Mattingly, 1972). The early language deprivation experienced by most deaf children, however, results in deficiencies in the primary linguistic knowledge available in long-term memory storage; because deaf children are generally weak in their automatic processing of the patterns, rules, and strategies for linguistic performance, they lack the repertoire necessary for easy transference to a new language-based skill. Furthermore, research has indicated that deaf individuals also show deficits in short-term memory functioning. The following conclusions seem to emerge from the large body of available data. 1. Deaf children and adults tend to do poorly on memory-span tests or on tasks in which the order of information is important. 2. Encoding strategies differ between deaf and hearing subjects at all developmental levels studied. 3. Deaf subjects do not generally utilize phonetic encoding strategies. 4. There appears to be much variability among deaf subjects in types of encoding strategies that are utilized. Cross-sectional pilot data collected by this author indicated that shortterm memory development appears to show little improvement after the age of 9% (strikingly reminiscent of the asymptote generally reported for reading comprehension scores). Twelve-year-old deaf children demonstrated memory abilities that were relatively retarded as compared to norms for hearing children of the same age. It was suggested that total communication comprehension skills may also be compromised by poor memory abilities, but this is an area in need of further research. The complete version of this paper is available in microfiche or hard copy from ERIC Document Reproduction Service. Ask for Document No. ED 247 719. 115 Issues in Reading and Reading Methodology Significant correlations between reading skills and short-term memory capacities have been reported for both deaf and hearing children (Blair, 1957; Carey & Blake, 1974; Hartung, 1970). It has been suggested that internal speech (i.e., phonetic encoding) is necessary for good reading achievement (Conrad, 1979). The data indicate, however, that it may be the kinesthetic or proprioceptive recoding associated with phonetic encoding that is actually the important factor (Hintzman, 1967). Hardyck and Petrinovich (1970) have suggested that an auditory-proprioceptive stimulus complex may be used as a stable mediator during the early process of learning to read. This stimulus complex allows for the development of neural analogues. Once developed, these neural analogues ultimately replace the auditoryproprioceptive process and render it unnecessary; automatic processing is then possible. Deficiencies in linguistic knowledge (automaticity for language processing , memory capacities, reading achievement, etc.) suggest that another factor may be related that may ultimately prove to be of crucial importance, and that is left hemispheric specialization and lateralization for verbal memory and language-related functions. More specifically, research currently available suggests that early language deprivation may result in less than efficient myelinization and dendritic differentiation (i.e., an increase in the number of branches of neuronal dendrites and the synaptic interconnections between them) in the brain, which may be reflected in relatively weak hemispheric specialization and concomitant deficiencies in linguistic and memory-related functioning (see Rodda et al., pp. 94-99). The human brain is asymmetrical and the left hemisphere appears to be specialized for language functions for most of the hearing population (Geschwind, 1979; Geschwind & Levitsky, 1968; Witelson & Paille, 1973). Asymmetrical differences between the two cerebral hemispheres are apparent even in human fetuses, which suggests that the left hemisphere's propensity toward developing superior language competence may have a solid anatomical base (Geschwind, 1979). More specifically, Broca's Area (in the frontal lobe above the Sylvian Fissure) appears to control expressive language and the muscles used in speaking, while Wernicke's Area (in the temporal lobe below the Sylvian...