A study of cognitive changes over time : as reflected by the Wechsler Intelligence Scales, in a learning disabled population
Date
1988
Authors
McQuaid, Monica Mary
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Abstract
Data from learning disabled subjects who had been given the WISC as children (mean age = 10 years) and the WAIS-Ras adults (mean age= 25 years) were studied in an attempt to discover cognitive changes that may have occurred during the course of development.
Other longitudinal studies report variability in the development of the learning disabled population. For example, Spreen (1987) reporte~ a less favorable future outcome (in terms of achievement and adjustment) for those learning disabled subjects with greater neurological impairment, while those without neurological impairment tended to have a more favorable outcome as adults. In contrast, Sarazin & Spreen (1986) found the neuropsychological test scores of the non-neurologically involved group to be the least stable over a 15 year interval, as compared to the scores of those with neurological deficits. Further, as a result of tracing cluster-analyzed subtypes of learning disabled subjects from childhood to adulthood, Spreen & Haaf (1986) found that many subjects were in different subtypes as adults. Changes occurred within the learning disabled population, as defined by neurological and cluster analyzed classifications.
In the present investigation, cognitive changes in subjects from both of these classification schemas were measured by differences between WISC and WAIS-R composite IQ scores, subtest scaled scores, and Verbal-Comprehension, Perceptual-Organization, and Freedom from Distractibility factor scores (as defined by Cohen, 1952, 1957, 1959; Kaufman, 1975; Parker, 1983). In general, results suggest that subjects with no neurological impairment changed on the greatest number of Wechsler measures and showed the largest differences from childhood to adulthood. The results of the analyses involving the subtypes were ambiguous due to the small sample size, but they suggest that those with minimal impairment, as well as those with a reading disability or visuo-perceptual disorder, changed the most over a 15 year time period. In both classification schemas, scores tended to decline with time; the decline was in both the verbal and performance realms. Implications of these findings are discussed.