Proceedings of the Annual Meeting of the Cognitive Science Society

Central to the rational analysis of m e m o r y is the proposal that memory's sensitivity to statistical structure in the environment enables it to optimally estimate the odds that a m e m o r y trace will be needed n o w (Anderson, 1990). These odds are based on (1) the pattern of prior use of the m e m o r y (e.g., h o w recently it has been needed) and (2) the similarity of the current context to the previous contexts in which it has been needed. W e have analyzed three sources of informational demand in the environment: (1) speech to children; (2) word usage in front page headlines; and (3) the daily distribution of authors of electronic mail. W e found that the factors that govern m e m o r y performance, including recency, also predict the odds that an item (e.g., a word or author) will be encountered now. Here w e tested a basic prediction the theory makes about the independence between context and recency in the environment by extending our previous analysis of recency in the N e w York Times. Though the results of four behavioral experiment were inconsistent with this independence assumption, the combination of the rational and environmental analyses were able to account for 9 4 % of the variance in these experiments.