SPEED MEDIATION OF ADULT AGE-DIFFERENCES IN COGNITION

Previous research has established that a large proportion of the adult age-related variance in various measures of fluid cr process cognition is reduced when statistical control procedures such as hierarchical regression are used to eliminate variation in measures of perceptual speed. This finding was confirmed in the present study and was extended to include paired-associate and free-recall measures of memory in addition to measures of reasoning and spatial abilities. Most of the speed mediation was associated with speed measures requiring cognitive operations such as comparison or substitution instead of merely motor responses such as copying symbols or drawing lines. These results suggest that the rate of performing elementary cognitive operations is an important proximal mediator of the adult age differences in several types of cognitive tasks.