Abstract
The Digit Symbol test and a copying test with identical graphomotor requirements but no visual search, memory, or coding demands were given to 108 normal volunteers and neurologically screened physical rehabilitation patients age 20 to 90 yr. The ratio of coding to copying scores did not change over age, and the high correlations between them were similar across age groups. Little variance was unaccounted for; gross lapses in non-motoric functions such as memory or attention may prevent Digit Symbol's use with some patients, but subtler decrements need not be invoked to explain age effects. Tentative norms provided here allow evaluation of individual deviations in coding/copying ratios or exploratory use of the copying test to monitor the course of disease or drug titration with patients whose linguistic or perceptual deficits invalidate Digit Symbol or Trail Making tests. If discrepant ratios characterize some groups of patients, the ratios may become useful diagnostic indices. If coding and copying are as closely related for patients with cerebral dysfunction as for normals, the copying test may become a useful alternative to Digit Symbol with patients unable to comply reliably with its requirements.
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