Recall can improve for events that seemed forgettable but later gained significance
"What makes for a long-lasting memory? Research has shown that emotional or important events take root deeply, whereas neutral or mundane happenings create weak impressions that easily fade. But what about an experience that initially seemed forgettable but was later shown to be important? Animal research suggested that these types of older memories could be strengthened, but scientists had not been able to replicate this finding in humans—until now. New evidence suggests that our initially weak memories are maintained by the brain for a period, during which they can be enhanced."