Rich false memories of autobiographical events can be planted - and then reversed, a new paper has found.
The study highlights - for the first time - techniques that can correct false recollections without damaging true memories. It is published by researchers from the University of Portsmouth, UK, and the Universities of Hagen and Mainz, Germany.
There is plenty of psychological research which shows that memories are often reconstructed and therefore fallible and malleable. However, this is the first time research has shown that false memories of autobiographical events can be undone.
Studying how memories are created, identified and reversed could be a game changer in police and legal settings, where false memories given as evidence in a courtroom can lead to wrongful convictions.
According to Dr Hartmut Blank, co-author of the research from the University of Portsmouth's Department of Psychology, "believing, or even remembering something that never happened may have severe consequences. In police interrogations or legal proceedings, for instance, it may lead to false confessions or false allegations, and it would be highly desirable, therefore, to reduce the risk of false memories in such settings.
"In this study, we made an important step in this direction by identifying interview techniques that can empower people to retract their false memories."
The researchers recruited 52 participants for a study on 'childhood memories' and with the help of parents, they implanted two false negative memories that definitely didn't happen, but were plausible. For example getting lost, running away or being involved in a car accident.
Along with two true events, which had actually happened, participants were persuaded by their parents that all four events were part of their autobiographical memory.
The participants were then asked to recall each event in multiple interview sessions. By the third session, most believed the false events had happened and - similar to previous research - about 40 per cent had developed actual false memories of them.
The researchers then attempted to undo the false memories by using two strategies.
The first involved reminding participants that memories may not always be based on people's own experience, but also on other sources such as a photograph or a family member's narrative. They were then asked about the source of each of the four events.
The second strategy involved explaining to them that being asked to repeatedly recall something can elicit false memories. They were asked to revisit their event memories with this in mind.
The result, according to Dr Blank, was that "by raising participants' awareness of the possibility of false memories, urging them to critically reflect on their recollections and strengthening their trust in their own perspective, we were able to significantly reduce their false memories. Moreover, and importantly, this did not affect their ability to remember true events.
"We designed our techniques so that they can principally be applied in real-world situations. By empowering people to stay closer to their own truth, rather than rely on other sources, we showed we could help them realise what might be false or misremembered - something that could be very beneficial in forensic settings."
The paper is published in the scientific journal Proceedings of the National Academy of Sciences.