Controlled and automatic forms of memory and attention: process purity and the uniqueness of age-related influences.

Estimates of controlled and automatic processes hypothesized to underlie performance in a memory task and in an attention task were derived for 115 participants from 18 to 78 years of age using the process-dissociation procedure. Participants also performed speed and neuropsychological tests that were suspected to be negatively related to age. Process estimates showed good reliability (from .76 to .98), and the qualitative distinction between processes was supported by the overall pattern of correlations among measures. However, only estimated automatic processes exhibited unique variance, as they were either weakly related or unrelated both to performance on the other tests and to each other. Estimates of the control processes, in contrast, shared considerable variance with measures from other tests, and there were no unique, or independent, age-related effects on these measures. The results highlight the need to distinguish between process purity and the uniqueness of age-related influences in accounting for age differences in cognition.