What information is retained in a memory over time, and which parts get lost? These questions have led to many scientific theories over the years, and now a team of researchers at the Universities of Glasgow and Birmingham have been able to provide some answers.
Their new study, which is published today in Nature Communications, demonstrates that our memories become less vibrant and detailed over time, with only the central gist eventually preserved. Moreover, this ‘gistification’ of our memories is boosted when we frequently recall our recent experiences.
The work could have implications in a number of areas, including the nature of memories in post-traumatic stress disorder, the repeated questioning of eye-witness testimonies and even in best practice for exam studying.
While memories are not exact carbon copies of the past — remembering is understood to be a highly reconstructive process — experts have suggested that the contents of a memory could change each time we bring it back to mind.
However, exactly how our memories differ from the original experiences, and how they are transformed over time, has until now proven difficult to measure in laboratory settings.
For this study, the researchers developed a simple computerised task that measures how fast people can recover certain characteristics of visual memories when prompted to do so. Participants learned word-image pairs and were later required to recollect different elements of the image when cued with the word. For example, participants were asked to indicate, as fast as possible, if the image was coloured or greyscale (a perceptual detail), or whether it showed an animate or inanimate object (a semantic element).