How shared are age-related influences on cognitive and noncognitive variables?
Several theories have suggested that age-related declines in cognitive processing are due to a pervasive unitary mechanism, such as a decline in processing speed. Structural equation model tests have shown some support for such common factor explanations. These results, however, may not be as conclusive as previously claimed. A further analysis of 4 cross-sectional data sets described in Salthouse, Hambrick, and McGuthry (1998) and Salthouse and Czaja (2000) found that although the best fitting model included a common factor in 3 of the data sets, additional direct age paths were significant, indicating the presence of specific age effects. For the remaining data set, a factor-specific model fit at least as well as the best fitting common factor model. Three simulated data sets with known structure were then tested with a sequence of structural equation models. Common factor models could not always be falsified--even when they were false. In contrast, factor-specific models were more easily falsified when the true model included a unitary common factor. These results suggest that it is premature to conclude that all age-related cognitive declines are due to a single mechanism. Common factor models may be particularly difficult to falsify with current analytic procedures.
Allen
P A
PA
Department of Psychology, The University of Akron, Ohio 44325-4301, USA. paallen@uakron.edu
Hall
R J
RJ
Druley
J A
JA
Smith
A F
AF
Sanders
R E
RE
Murphy
M D
MD
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics; D012015:Reference Standards; D015203:Reproducibility of Results