Biomedical subjects

Stephen Joy

Publications and source records attributed to Stephen Joy.

3 recordsLinked to original sources

PubMed2004

Speed and memory in the WAIS-III Digit Symbol--Coding subtest across the adult lifespan.

The primary role of speed in determining Digit Symbol scores is well established. Among the important questions that remain to be resolved are: (1) whether speed accounts for all of the age-related decline in Digit Symbol scores, and (2) whether memory ability makes any significant contribution to Digit Symbol performance, especially after controlling for speed. We analyzed data from the WAIS-III/WMS-III standardization sample to resolve these issues. As expected, speed (Digit Symbol-Copy) correlated very strongly with Digit Symbol--Coding. Memory (Digit Symbol--Incidental Learning or WMS-III index scores) correlated more moderately with Digit Symbol-Coding. Even after controlling for variance in Coding explained by Copying, a statistically significant proportion of the residual variance was explicable in terms of memory functions. The contribution of memory to Digit Symbol--Coding, while relatively small, is real. In addition, a small portion of the age-associated decline in Coding scores cannot be accounted for by Copying scores.

Adolescent↗

PubMed2003

Digit Symbol-Incidental Learning in the WAIS-III: construct validity and clinical significance.

We analyzed WAIS-III/WMS-III standardization data for evidence of the construct validity and clinical utility of the Digit Symbol-Incidental Learning procedures (Pairing and Free Recall). Scores on both tests correlated moderately with WMS-III memory index scores (mean r=.38 for Pairing and .36 for Free Recall). Cutoff scores can be used to identify younger and older adults likely to suffer from memory impairment. In the standardization sample (which excludes neurological patients), these have moderate positive predictive power (averaging .56 if either test yields a positive finding), moderate negative predictive power (.76), and high specificity (.88), but low sensitivity (.35). In a clinical sample, the same cutoff scores were much more sensitive, correctly identifying 88% of a group of patients with Alzheimer's Disease. Examinees who obtain these low scores should receive follow-up memory testing. Very high scores are associated with a reduced risk of memory impairment.

Adolescent↗

PubMed2003

Decoding digit symbol: speed, memory, and visual scanning.

The authors evaluated the relative contributions of speed, memory, and visual scanning to Digit Symbol score in a sample of young adults (N = 87). Speed (Symbol Copy) explained 35% of Digit Symbol variance; only half of this was attributable to graphomotor speed (Name Printing), implying a role for perceptual speed. Visual-scanning tests (e.g., Symbol Scan) explained (on average) 34% of Digit Symbol variance, much of which was independent of perceptual-motor speed, establishing an important role for visual-scanning efficiency in Digit Symbol performance. By contrast, memory tests (on average) explained only 4% to 5% of Digit Symbol variance: statistically significant but clearly subsidiary, although a visual memory composite correlated more strongly with Digit Symbol. The Digit Symbol incidental learning procedures did, however, correlate moderately with other memory measures, suggesting that they are valid memory screening devices.

Adolescent↗