The goal of this study is to examine the central executive of working memory in normal aging, specifically focusing on its capacities to manipulate or modify the format of the to-be-recalled material. The central executive was measured with the alphabetical span procedure, during which subjects were asked to recall a random series of words in their alphabetical order. The storage demand was equalized across subjects by adjusting the list lengths according to individual span. Experiments 1, 2, and 3 showed that elderly subjects were not impaired in manipulating information, relative to young controls, even when the difficulty of the task was increased. In Experiment 4, validity was tested by asking young subjects to perform the task under the conditions of full or divided attention. Alphabetical recall was more impaired than direct recall during the divided attention condition, which suggests a larger involvement of the central executive component in the former. These results are discussed in relation to the hypothesis of a central executive impairment being associated with normal aging.Working memory (WM) is a short-term memory system involved in tasks that require concurrent retention and processing (Baddeley, 1986;Baddeley & Hitch, 1974, 1994Salthouse, 1994). In Baddeley's theoretical framework, WM is a tripartite system composed of two specialized slave systems-the phonological loop and the visuo spatial sketchpad-and a central executive. The phonological loop contributes to the retention ofverbal information and is subdivided into a passive phonological store and a rehearsal procedure. The visuospatial sketchpad holds images and spatial information. The central executive is an attentional component involved in the control and distribution oflimited resources (Baddeley, 1986(Baddeley, , 1992Baddeley & Hitch, 1974). This study focuses on the manipulation capacities of the central executive in normal aging. Manipulation is defined as the process of actively and consciously modifying the format of the information to be recalled. Within a WM framework, manipulation would require involvement of the central executive component.This work was supported by a grant from the Medical Research Council of Canada (MRC; PG-28) and from Ie Fond de la Recherche en Sante du Quebec (FRSQ) to S,8., by a chercheur-boursier fellowship from the FRSQ to S.8., and by a scholarship from the FCAR to N.R. and N,C. The authors thank Laurent Mottron, Francois Crepeau, Geoffrey R. Loftus, Frank Bellezza, and Leah Light for their helpful comments on an earlier version of the text Thanks to Michel Lamoureux and Jean-Francois Angers for statistical advice, as well as to Fanny Guerin, Sherif Karama, and Sonia Litalien for testing assistance. Special thanks to Rodolphe Sauvage for conducting Experiment 3. Finally, the authors gratefully acknowledge Ronald Dixon for his comments and for editing the text. Correspondence concerning this article should be addressed to Sylvie Belleville, Centre de Recherche de l'Institut Universitaire de Geriatric de...
