Working memory and vigilance: Evidence from normal aging and Alzheimer's disease

Both single unit recording and neuroradiological studies suggest that front al and executive processes are necessary for visual maintenance rehearsal. This observation is linked to the classic vigilance literature by the propo sal that vigilance decrement is found when the subject is required to maint ain a representation over a brief delay. Vigilance performance was therefor e studied in a sample of elderly subjects who were tested over a 40-min per iod involving perceptual or memory-based tasks which were matched for initi al level of performance. There was a significant interaction between task a nd delay, with only the memory-based task showing decrement. A second study used the same two tasks to investigate vigilance performance in patients s uffering from probable Alzheimer's Disease. Over a 15-min delay period, an equivalent interaction effect occurred, again indicating substantially grea ter decrement for the memory-based task. The results are interpreted as con sistent with a role for the executive processes of working memory in both v isual rehearsal and vigilance performance, (C) 1999 Academic Press.