Working memory decline in normal aging: Memory load and representational demands affect performance

Abstract

Normal aging is associated with numerous changes in cognitive capacities, including an overall decline in working memory performance. Nevertheless, whereas some neuropsychological evaluations have suggested that visuo-spatial working memory may exhibit a greater age-related decline than verbal working memory, other assessments made in real-world tasks, or in tasks with higher memory loads, have suggested that age-related declines in working memory performance may be similar for spatial, visual and verbal information. Here, we tested young (20–30 years) and older (64–73 years) healthy adults in real-world laboratory memory tasks designed to assess the impact of memory load (one, two or three items to remember) on age-related changes in working memory performance for color and allocentric spatial information. We used several measures to characterize working memory performance: the total number of choices to find the goal(s), a measure of overall task performance; the number of correct choices before erring, an estimate of memory capacity; and the number of errorless trials, a measure of perfect memory. All measures revealed: (1) an overall decline of working memory performance with age; (2) a greater age-related decline of working memory performance with higher memory loads, regardless of the type of information; (3) no evidence that spatial working memory was more affected by age than color working memory. We discuss how age-related declines in working memory performance may be most influenced by memory load, the representational demands of the task and its dependence on hippocampal function, and not by the type of information to be remembered.