Effects of item cohort on memory across the adult life span
Popular stereotypes of aging give the impression that memory processes deteriorate gradually as a person ages. Research on memory for world events across the life span is limited, however, and the results are variable. Several confounds exist in many studies of world knowledge memory and aging, which further complicates study. This study acknowledges the existence of the confounds present in reserch on memory and aging, and represents an initial attempt to deal with the problem in the only way possible, by studying the covariation effects of age of the subject at learning, at test, and age of the world knowledge items in the memory store. By simultaneously varying subject age and item age, this study examines two issues: memory decline due to chronological aging, and memory decline due to the length of time an item has been held in memory. There is a limited set of performance outcomes that will support the inference of a stable chronological age at which memory begins to decline. There is also a set of alternative data configurations supporting the conclusion of a decline in memory due to the length of time an item is held in storage. To examine these two issues, world knowledge items from three time periods (5, 15 and 25 years old) were generated fitting three categories (entertainment, books-literature, and history-political). Items from each category were equally represented in each time period. Four groups of 15 female subjects with average ages of 45, 55, 65 and 75 were tested for recall and recognition of all items. 1. Results indicated no consistent memory decline due to chronological aging. 2. Some decline in recall was noted with increasing subject age, but recognition performance remained constant. 3. Interactions were observed between subject and item age for both recall and recognition scores. 4. Differences in feeling-of-knowing judgements were observed between all subject age groups. This study's results suggest that there are no consistent declines in memory performance due to chronological aging or item age (time-in-storage). Two models are proposed to explain the results. One: the size of the memory store increases as chronological age increases. The larger the set of data held in storage, the greater the chances for errors in tagging, storage and retrieval. Two: results obtained in this study suggest that the use of meta-memorial processes change as a person ages. Older persons may use metamemorial processes differently than do younger subjects, to compensate for changes in the size of the store, physiological declines, and changes in the social and intellectual demands placed on the memory system as people age.