The term "flashbulb memory" describes the vivid recall of time, place and other personal contextual information during a stressful, emotional and often historical event, like 9/11 or the German occupation and subsequent liberation of Denmark.

Past studies have traditionally tested short-range flashbulb memory, assessing participants immediately after a monumental event and then retested them after various time periods, such as one year. Most such studies have found that memory distorts emotions, personal involvement and external details, like the weather, quickly over time.

The findings suggest that one's emotional intensity at the time of the event and subsequent rehearsal are critical to recalling the memory accurately, says Berntsen, adding that the results also imply that studies using relatively short test delays do not predict performance after several decades.