Increased reliance on attentional precues in normal aging

Results from studies of normal aging and Alzheimer's disease suggest these individuals have larger attentional cuing effects than younger participants or nondemented controls. However, such studies have tended to use either speeded peripheral detection tasks or speeded discrimination tasks. Such tasks do not permit determinations of the mechanism of the attentional effect. For example, in speeded detection tasks, an attentional effect could be produced by shifts in perceptual sensitivity or response criteria; discrimination tasks, in which accuracy is often near ceiling, could contain hidden speed-accuracy tradeoffs. To address these shortcomings, we tested neurologically normal younger and older participants in a cued discrimination task in which accuracy was measured. We ensured accuracy was below ceiling by following a target digit with a single masking stimulus, a procedure that minimizes the contribution of later decision-level effects on attention (Shiu & Pashler, 1994). We found that the younger participants showed a smaller attentional effect (accuracy difference under "valid" minus under "invalid" cues) than older participants (4.39% versus 9.54 %, p < 0.01). Results support the conclusion that attentional effects are increased in normal aging. This increase could be produced by (a) increased allocation of attentional resources to the precued location in older participants or (b) increased levels of decision-level uncertainty, or noise, in older participants. Ongoing experiments will allow us to distinguish these alternatives, but the present results clearly indicate that older participants are more reliant on attentional precues in an unspeeded discrimination task.