Independence of age-related influences on cognitive abilities across the life span.

Age-related increases in childhood and age-related decreases in adulthood have been reported for a wide variety of cognitive variables, but relatively little research has addressed the question of the independence of these influences. In this project, cross-sectional life span data (age 5 to 94 years) from the nationally representative sample used to establish the norms for the Woodcock-Johnson Psycho-Educational Battery (R. W. Woodcock & M. B. Johnson, 1989, 1990) were subjected to several types of analyses. The results indicated that the majority of age-related differences appear to be shared across different cognitive variables and are well predicted by individual differences in higher order factors. These findings suggest that the role of task-specific interpretations of developmental differences in cognition needs to be reevaluated to take into consideration the lack of independence of age-related influences on a variety of cognitive variables.