Age-Related Changes in the Processing of To-be-Ignored Stimuli: Preserved Selective Attention Does Not Prevent Subsequent Allocation of Excessive Processing Resources (IN4-1.004)

Abstract

Objective: To investigate age-related changes in attentional operations involved in the processing of to-be-ignored stimuli. Background A critical mechanism for conserving capacity-limited resources and efficiently carrying out task demands is to limit the allocation of resources to stimuli that are supposed to be ignored. Design/Methods: ERPs were measured in 12 young (mean age 23) and 15 old (mean age 74) well-matched adults during a color-selective attention task. Subjects responded to target letters in a specified color (Attend) while ignoring letters in a different color (Ignore). Results: There were minimal age-associated differences in selective attention (Attend-Ignore), as indexed by the size of the posterior Selection Negativity (SN) and anterior Selection positivity (SP). In stark contrast to their younger counterparts, old subject appropriated a similar amount of resources to targets under the Attend and Ignore conditions for operations involved with orienting and decision-making, as measured by the size of the P3a and P3b components. Old subjects demonstrated a decline of attentional control, as indexed by a smaller anterior N2 to target-like stimuli under Ignore. Old subjects also exhibited prolonged latencies of the SP, SN, P3a, and P3b components, suggestive of delays in carrying out pertinent operations. Prolongation of SN latency did not correlate with subsequent delays in P3 latency, but did predict larger P3 responses to targets under the Ignore condition. Conclusions: Despite the relative preservation of early selective attention, old subjects appropriated substantially more controlled processing resources in response to target-like stimuli under Ignore. Although inefficiencies in selective attention may undermine the quality of information available for subsequent operations, they do not fully account for the strikingly increased allocation of resources in response to to-be-ignored targets. One consequence of this age-related deficit is that older adults are at high risk for running out of processing resources to manage increased task demands. Supported by: R01 AGO17935. Disclosure: Dr. Alperin has nothing to disclose. Dr. Haring has nothing to disclose. Dr. Zhuravleva has nothing to disclose. Dr. Holcomb has nothing to disclose. Dr. Rentz has received personal compensation for activities with Elan Pharmaceuticals as a consultant. Dr. Daffner has nothing to disclose.