Danes with ties to the World War II Danish resistance movement have far more vivid, detailed and accurate memories of occupation and liberation than their countrymen who were unaffiliated with the resistance movement, according to a study in the May Journal of Experimental Psychology: General (Vol. 134, No. 2).
Furthermore, the memories of most of the study's participants were far more accurate than results of studies of short-range flashbulb memory would have predicted, according to lead researcher Dorthe Berntsen, PhD, of the University of Aarhus in Denmark.
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.
To see if having a personal stake would boost flashbulb memory accuracy, Berntsen and her Aarhus colleague Dorthe K. Thomsen, PhD, had 145 Danes ages 72 to 89, including 66 who had ties to the resistance movement, fill out a questionnaire asking for detailed descriptions of their memories of four different war-related events--the German invasion, the liberation, their most positive personal memory and their most negative personal memory.
To test the accuracy of participants' recall, Berntsen and Thomsen had both the older participants and a control group of younger participants, ages 20 to 60, fill out a questionnaire on factual details that could be corroborated against historical data, such as the weather, day of the week or the time of the day that the radio announced the liberation.
Danes who had lived through World War II performed five times better than the control group in recalling events related to the invasion and liberation. Moreover, the Danes affiliated with the resistance movement had significantly higher scores than the unaffiliated Danes on all areas of recall, which the authors say suggests that their strong recollections are due to a combination of "permastore"--a long period of stable retention after the initial memory decline--and an effect of social identity on personal memory.
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.
However, Berntsen notes that even flashbulb memories have flaws.
"The participants still made mistakes," she says. "But their memories were far more accurate than we would expect."
Berntsen plans to expand the study's methodology to further study flashbulb memories for remote historical events.