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.
Joy
Stephen
S
Albertus Magnus College, 700 Prospect Street, New Haven, CT 06511, USA. joy@laurel.albertus.edu
Kaplan
Edith
E
Fein
Deborah
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D001288:Attention; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008570:Memory, Short-Term; D008875:Middle Aged; D011594:Psychometrics / Q000706:statistics & numerical data; D011597:Psychomotor Performance; D011930:Reaction Time; D012016:Reference Values; D015203:Reproducibility of Results; D013223:Statistics as Topic; D014888:Wechsler Scales / Q000706:statistics & numerical data*