Aging, Divided Attention, and Processing Capacity

Abstract

The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.

Effect of normal aging on the manipulation of information in working memory

“…The fact that divided attention dramatically di- The observation of normal manipulation capacities in aging is in disagreement with a number ofprevious studies. Other experiments have reported adult age differences on tasks that have also involved a manipulation of the information retained in WM (Craik, 1986;Dobbs & Rule, 1989;Foos, 1989;Tun etal., 1991;Wright, 1981). This was thought to reflect the impairment experienced by aged individuals in novel and demanding situations, or in conditions requiring active processes, and was explained by a central executive defect.…”

“…Impaired levels of performance have been observed in elderly subjects on divided attention paradigms (Inglis & Caird, 1963;McDowd & Craik, 1988;Salthouse, Rogan, & Prill, 1984;Tun et aI., 1991;Wright, 1981). However, many studies have also failed to observe age differences in divided attention (e.g., Baddeley, Logie, Bressi, Della Sala, & Spinnler, 1986;Belleville, Malenfant, et aI., 1992;Somberg & Salthouse, 1982;Wickens, Braune, & Stokes, 1987).…”

“…For example, aged individuals are impaired when the syntactic complexity of the to-be-verified sentences on the sentence span procedure is increased (Gick et aI., 1988;Morris et aI., 1988;Wright, 1981). Although this has been interpreted as arising from a deficit in the active process of working memory, it may also relate to a specific impairment in syntactic processing.…”

“…A number of studies have observed that elderly people are impaired in tasks that require the manipulation of the Copyright 1998 Psychonomic Society, Inc.information retained in WM (Craik, 1986;Dobbs & Rule, 1989;Foos, 1989;Tun, Wingfield, & Stine, 1991;Wright, 1981). One interesting example of a manipulation task is provided by Craik (1986).…”

What we know about acquisition of adult literacy

“…At least four separate studies (Hines and Posner 1976;Lindholm and Parkinson 1983;Poon, and others 1976;Wright 1981) have found that the difference between name identity and physical identity decisions is greater for older adults than for young adults. These results therefore imply that with increased age more time is needed to access information from long−term memory.…”