Memory for events after twenty years

This is a study of one person's memory for events that occurred twenty years earlier. Memory was observed to follow an asymptotic rate of decay. No experience of recovered memories occurred. Factors found to be related to recall were the rarity of the event, its vividness, and the emotional intensity experienced at the time. Factors unrelated or only weakly related were perceived importance of the event, its association with knowledge, and intensities of physical sensations. Pleasant events were recalled a little better than unpleasant. Though less strongly associated with memory than is location, moderate marking of events with date and time was found. The results suggest that personal memory declines as the images of events one by one submerge into the mass of generalized experiences. The more vivid, rare, and emotional experiences are more likely to remain discriminable, and may be sustained by rehearsal.