Abstract
Previous studies show that Alzheimer's disease (AD) patients are more impaired by misleading (invalid) spatial cues than are nondemented controls, suggesting that AD patients may have fewer attentional “resources” with which to monitor unattended locations. However, these studies have generally used speeded detection or discrimination tasks, which do not readily permit attentional effects to be isolated. To overcome the limitations of speeded tasks, AD patients and controls performed an unspeeded spatial cuing task requiring them to discriminate targets preceded by valid and invalid cues (Experiment 1) or valid, neutral, or invalid cues (Experiment 2). Ten patients with mild AD, 20 neurologically-normal older controls, and 20 neurologically-normal younger controls participated in each experiment. If AD patients show reduced attentional resources compared to control groups, the AD patients should show larger cuing effects (valid vs. invalid accuracy) in Experiment 1 and an attentional benefit (valid vs. neutral accuracy) in Experiment 2. In Experiment 1, AD patients showed attentional effects similar to those of older controls, although both groups showed larger attentional effects than the younger controls (ps < .05). Moreover, none of the groups showed attentional benefits in Experiment 2, a result inconsistent with resource allocation. Our results indicate that AD patients do not show larger attentional effects when tested in unspeeded tasks, suggesting that these patients may not have impaired attentional “resources.” AD patients appear to have relatively intact perceptual-level attention and can orient attention to peripheral cues to reduce the uncertainty associated with briefly presented targets.
NIH N515071-04, NIH AG 17177-03