Age-related changes in the efficiency of cognitive processing across the life span.

The global-speed and the specific-gain/loss hypotheses have been dominant theoretical frameworks in the recent literature on cognitive development and aging. Few attempts have been made to explicitly assess the predictive power of the two frameworks against each other. We evaluated the extent to which age changes in performance in executive function tasks (involving response selection, response suppression, working memory, and adaptive control) depend on age-related changes in global information-processing speed. Our sample consisted of children, adolescents, adults and seniors. Analysis of covariance and structural equation modeling revealed a mixed pattern of results. Controlling for global speed removed the child vs. adult differences in the speed of responding on the executive function tasks but the senior vs. adult differences remained. This mixed pattern of findings was interpreted to suggest that the effects of advancing age on the speed of responding are mediated by a global mechanism during childhood but during senescence the efficiency of executive functioning seems particularly vulnerable to the effects of age.