A French team of neuroscientists demonstrates, through brain imaging, the link between collective memory and personal memories.
How, as individuals, do we construct what serves as our memories? How are these shaped, and by what? Are they the result of an exact reconstruction of past events or a fantasized vision of our past?
These questions have plagued many intellectuals for decades. They even made up the bulk of the work of the French sociologist Maurice Halbwachs who, in his book The social frameworks of memory published in 1925, advanced the theory that memories are influenced by their social context.
For the first time, a team of French neuroscientists proves him right. In a study published in the journal Nature Human BehaviorInserm researchers Pierre Gagnepain and Francis Eustache (Inserm/University of Caen-Normandy/Ecole Pratique des Hautes Etudes) show that the memory of individuals is inseparable from the group to which they belong and from the social contexts linked to collective memory.
The same collective representations of history
To understand the notion of collective memory, the researchers analyzed media coverage of the Second World War in order to identify the common collective representations associated with it. In total, 30 years of reports and documentaries from the Second World War, broadcast on French television between 1980 and 2010, have been viewed and transcribed.
Using an algorithm, they then analyzed this corpus and identified groups of words regularly used in discussions of major themes associated with our collective memory of the Second World War, such as the D-Day landings. “Our algorithm automatically identifies central themes and the words associated with them repeatedly, revealing our collective representations of this crucial period in our history,” explains Pierre Gagnepain in a statement.
The second stage of the scientists’ work consisted in understanding the link between these collective representations of war and individual memory. They therefore recruited 24 volunteers to visit the Mémorial de Caen and asked them to observe photos from this period, accompanied by captions.
From the words contained in the captions, the team was able to define the degree of association between the photos and the various themes identified previously. For example, if words associated with D-Day were in the caption, the photo was also considered related to this theme. Thus, the researchers were able to establish a proximity between each of the images: when two photos were linked to the same theme, they were considered to be “close” in the collective memory.
The same mental model
But how are these photos perceived in the memory of individuals? To find out, the researchers gave the volunteers an MRI during which they asked them to recall the images seen at the Memorial the day before. The scientists were particularly interested in the activity of their medial prefrontal cortex, a region of the brain linked to social cognition.
The researchers thus compared the level of closeness between the photos by looking at collective representations of the Second World War in the media and, using brain imaging, by looking at the individual memories that people had of these images after a visit to the Memorial. They then realized that when photo A was considered to be close to photo B – because it was linked in the same way to the same collective theme – it also had a higher probability of triggering brain activity similar to that of photo B in subjects’ brains.
For researchers, this is proof of a link between collective memory and individual memory. “Our data demonstrates that collective memory, which exists beyond the individual level, organizes and shapes personal memory. It constitutes a shared mental model making it possible to link the memories of individuals across time and space”, concludes Pierre Gagnepain.
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