The authors examined the question of whether a decrease in the efficiency of inhibitory processing with aging is a general phenomenon. Thirty elderly and 32 young adults performed a series of tasks from which the authors could extract measures of inhibitory function. The tasks and task components included response compatibility, negative priming, stopping, spatial precuing, Wisconsin Card Sorting Test (WCST), and the Cognitive Failures Questionnaire (CFQ). Only limited evidence for age-related differences in inhibitory function was obtained. Old adults had more difficulty than young adults in stopping an overt response and adopting new rules in a categorization task. However, elderly and young adults produced equivalent negative priming effects, response compatibility effects, spatial precuing effects, and self-reported cognitive failures. The findings are discussed in terms of the relationship between aging, inhibitory processes, and neuroanatomical and physiological function.A dominant view in the aging literature is that cognitive decline in later life is the result of a progressive and generalized slowing of information-processing activities (Birren, 1974;Cerella, 1990;Salthouse, 1992). Much of the evidence for such a view has been provided through reanalyses of existing data sets (Cerella, 1985b;Myerson, Hale, Wagstaff, Poon, & Smith, 1991;Salthouse, 1985). Examination oflarge numbers of tasks has suggested that reaction times (RTs) of elderly subjects can be described as simple linear or nonlinear functions of young subjects' RTs, without reference to the specific nature of the tasks. Although this generalized-slowing view provides a good account of RT data in a multitude of studies (but see Baron & Mattila, 1989;Fisk, Fisher, & Rogers, 1992), such a view has, for the most part, been descriptive rather than theoretical in nature (but see Cerella, 1990).An important question is what processes or mechanisms are responsible for this generalized slowing that occurs during aging? One relatively recent proposal that could provide the theoretical basis for generalized slowing concerns inhibitory function. Hasher and Zacks (1988; see also Zacks & Hasher, in press) suggested that age-related processing deficits in a variety of cog- We are indebted to Susan Gass for assistance in data collection, with special thanks to Heather Pringle for her invaluable assistance in data management and project organization. We express our appreciation to Tram Neill and Joan McDowd for their helpful comments on a draft of this article.Correspondence concerning this article should be addressed to Arthur F. Kramer, Beckman Institute, University of Illinois, 405 North Mathews Avenue, Urbana, Illinois 61801. nitive skills could be accounted for by a decrease in the efficiency of inhibitory processing during aging. More specifically, inefficient inhibition could result in ineffective selective attention, which could, in turn, result in the intrusion of task irrelevant information into working memory. The consequences of the entrance of...

The authors examined the ability of younger and older adults to search for targets defined by single features (feature search), conjunctions of 2 features (conjunction search), and conjunctions of 3 features (triple-conjunction search). Feature search was relatively age-invariant, with both older and younger adults displaying shallow search slopes. However, older adults did show reduced search rates for many conjunction targets. Interestingly, both older and younger adults benefited equivalently when an extra feature was available to define the conjunction target. That is, the relative amount of improvement in search performance was similar for younger and older adults when the triple-conjunction search was compared to the conjunction search. These results are discussed in terms of age-related differences in the effectiveness of bottom-up and top-down mechanisms that support visual search.

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We investigated the influence of extended wakefulness on automatic and nonautomatic processes in memory and visual search tasks. Subjects were trained in consistently mapped and variably mapped versions of each task, attaining automatic performance in the consistently mapped versions. We then recorded performance measures and event-related brain potentials for a 14-h period that began during the evening of the last day of training. Overall performance declined with extended wakefulness, but the benefits of consistently mapped training were retained throughout the night. Performance decrements consisted of an increase in nonresponses, increased response latencies, and decreased accuracies. P300 latencies increased, and P300 amplitudes decreased with extended wakefulness. When viewed together, reaction time and event-related brain potentials measures suggest that the locus of extended wakefulness effects was during early perceptual processes.

The main goal of the present study was to examine the feasibility of employing event-related brain potentials to measure dynamic changes in mental workload. Subjects performed two tasks, monitoring and mental arithmetic, both separately and together. Following an analysis of the performance, subjective workload ratings, and average ERP data in the single- and dual-task conditions, two different conditions from each of the tasks were selected for further analysis. A bootstrapping approach was employed to determine the amount of ERP data required to discriminate between these conditions. The results of these analyses indicated that (a) 90% correct discrimination could be achieved with from 1 to 11 s of ERP data, (b) the best ERP measures varied across tasks and subjects, and (c) the inclusion of temporal and spatial aspects of the ERP data improved the ability to discriminate among workload levels. The data is discussed with respect to real-time assessment of mental workload.