Abstract: Twenty-four old-age subjects (mean age at 65) and 24 young subjec-ts (mean age at 24) were chosen to perform the short-term memory searchtask according to Sternberg's procedure. The heart rate (HR), finger pulsevolume (FPV), and electrodermal response (EDR) were recorded bothduring their performance on the search task and at the rest period.The results indicated that the search time of all subjects increased withthe searching items, and the aged showed significantly longer RT than theyoung subjects. In performing search tasks, the aged group showed gene-rally lower reactivity in HR, FPV, and EDR than the young group. Theseresults tended to support the hypothesis that the aged were underaro-usal rather than overarousal in performing cognitive tasks. There weresignificant correlations between the reactivity in autonomic nervous sys-tem (FPV and EDR) and the search time, which might be explained bytwo possibilities: (1) the longer search time among the aged was the re-sult of the lower arousal level; (2) both long search time and low arousallevel were caused by changes in the central nervous system of the agingpeople.

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