Age-Related Deficits in Component Processes of Working Memory Adam Gazzaley University of California, San Francisco, and University of California, Berkeley Margaret A. Sheridan, Jeffrey W. Cooney, and Mark D’Esposito University of California, Berkeley Working memory deficits in normal aging have been well documented, and studies suggest that high memory load plus the presence of distraction negatively impacts successful memory performance to a greater degree in older individuals. However, characterization of the component processes that are impaired by these task manipulations is not clear. In this behavioral study, younger and older subjects were tested with a delayed-recognition and recall task in which the encoding and delay period were both manipulated. During the encoding period, the subjects were presented with either a single letter or multiple letters at their predetermined forward letter span, and the delay period was either uninterrupted or interrupted with a visual distraction. There was an age-related impairment of working memory recognition accuracy only in the combination of high memory load and distraction. These results suggest that when working memory maintenance systems are taxed, faulty recognition processes may underlie cognitive aging deficits in healthy older individuals. Keywords: aging, distractor, working memory, delayed-recall task, delayed-recognition task Memory loss is a frequent complaint in older adults, and it involves not only difficulty remembering recent events but also impairments in holding information “in mind” over short periods of time. The latter cognitive process is referred to as working memory (WM), and age-related deficits in WM have been dem- onstrated in many studies (Belleville, Peretz, & Malenfant, 1996; Dobbs & Rule, 1989; Foos & Wright, 1992; Salthouse, Babcock, & Shaw, 1991; Wingfield, Stine, Lahar, & Aberdeen, 1988). WM refers to the temporary representation of information that was just experienced or just retrieved from long-term memory but is no longer accessible in the external environment (Baddeley, 1986). These internal representations are short lived but can be maintained for longer periods of time through active rehearsal or maintenance strategies, and they can be subjected to various op- erations that manipulate the information in such a way that makes it useful for goal-directed behavior. To maintain and manipulate relevant information that is not accessible in the environment, the brain needs a storage process as well as rehearsal or maintenance processes that can prevent the contents of the storage system from decaying (see, for example, D’Esposito & Postle, 1999). Although not completely dissociable, these component pro- cesses of WM can be studied with some degree of isolation with the help of different task designs. Storage capacity is often as- sessed by a span test, in which a series of letters, digits, words, or images are presented to subjects for immediate recall. WM main- tenance processes are often assessed with delay tasks, which require subjects to hold information in mind over an interval of time. In general, storage processes, as assessed by span tasks, are not affected by normal aging (see, for example, Wingfield et al., 1988). In contrast, WM maintenance processes, as assessed by delay tasks, have been found to be impaired in normal aging (Anders, Fozard, & Lillyquist, 1972; Byrd, 1986; Craik & Rabi- nowitz, 1985; Nielsen-Bohlman & Knight, 1995). However, not all studies that have assessed WM maintenance processes have found age-related impairments (e.g., Boaz & Denney, 1993). Moreover, in those studies that have found deficits, the precise nature of the deficit is not clear. There are several possible explanations for the discrepant findings in the cognitive aging literature. First, in stud- ies that have not found age-related impairment on delay tasks it is possible that WM maintenance processes were not sufficiently taxed. For example, older individuals were not impaired on delay tasks that required the maintenance of only a single item (Chao & Knight, 1997; Della-Maggiore et al., 2000). In these studies, im- pairments may have been observed if more demands had been placed on WM maintenance processes by increasing the memory load. Even in studies that have found an age-related impairment on delay tasks, it is still plausible that deficits in other processes, rather than WM maintenance processes, contributed to impairment on the task. For example, some delay tasks require free recall, whereas others test by recognition (e.g., Crook & Larrabee, 1992; Crook & West, 1990). Although both types of delay tasks tap WM maintenance processes, they differ in the types of cognitive pro- cesses that are necessary for retrieving information that is being actively maintained. Thus, impairment in retrieval-related pro- cesses, rather than maintenance processes, could account for the age-related impairments that were observed. Adam Gazzaley, Department of Neurology and Physiology, University of California, San Francisco, and Helen Wills Neuroscience Institute and Department of Psychology, University of California, Berkeley; Margaret A. Sheridan, Jeffrey W. Cooney, and Mark D’Esposito, Helen Wills Neuroscience Institute and Department of Psychology, University of Cal- ifornia, Berkeley. This work was supported by National Institutes of Health Grants AG025221, MH63901, AG15793, and NS40813; the National Research Service Award; the American Federation for Aging Research; and the Veterans Administration Research Service. We thank Marcia Johnson and Karen Mitchell for helpful comments on the article. Correspondence concerning this article should be addressed to Adam Gazzaley, University of California, San Francisco, 1700 4th Street, Byers Hall, Room 102C, San Francisco, CA 94143-2522. E-mail: adam.gazzaley@ucsf.edu Neuropsychology Copyright 2007 by the American Psychological Association 2007, Vol. 21, No. 5, 532–539 0894-4105/07/$12.00 DOI: 10.1037/0894-4105.21.5.532 532