Improving Eye-Witness testimony by undoing false memories

Diana, Princess of Wales

Diana ten years before a certain false memory started spreading.

Do you remember August 31st, 15 years ago? Diana, Princess of Wales, died in a car crash in Paris along with her partner Dodi Fayed and others. Do you remember seeing the video of the crash? If so, you share that memory with 44% of the participants James Ost and colleagues recruited in 2002 in Britain.

This memory is false.
There is no such video. False memories are not a fringe problem, they are more widespread than one likes to think. Less than three months after the 9/11 attacks in 2001 in New York then US president George W. Bush claimed to have seen the first plane hit one of the Twin Towers. Afterwards, he claimed, he had entered a class room and had eventually been told about the second plane.
And I was sitting outside the classroom waiting to go in, and I saw an airplane hit the tower—the TV was obviously on, and I use[d] to fly myself, and I said, ‘There’s one terrible pilot.’
George W. Bush as quoted in Greenberg, 2004, p. 363
TV channels are usually not very good in predicting terrorist attacks and September 11th was no exception. The first plane hitting the World Trade Center was not shown on live television. The person who was preparing for war as a response to the attacks apparently had a false memory of them.
Marvin Anderson

Marvin Anderson was found guilty of rape due to a false memory. He spent 15 years in prison. Read his story: here.

If these examples are a chilling reminder of just how bad human memory is, consider that in 72% of wrongful convictions – which are later overturned by DNA evidence – eyewitness misidentification was a factor (Innocence Project). The unreliability of eye-witness memory is a widespread problem. New research coming out of Germany and Britain by Aileen Oeberst and Hartmut Blank (article in press) offers a way of overcoming false memories.
Their participants were shown a film of a car chase and heard a short summary of the action. The summary changed two small details but was otherwise correct. When asked in a subsequent questionnaire about the film these changed details were more likely to be misrembered than unchanged details which the summary of the film correctly represented. This finding is called the misinformation effect – a false memory is created through information received after a piece of information has been memorised. This is likely what happened to George W. Bush: the first plane hitting the World Trade Center was indeed shown on TV but only much later. A later viewing changed his memory of an earlier event.
After completing the questionnaire participants were told about the true purpose of the experiment, that details were changed between film and summary, and that they should fill in the questionnaire again. Now, the misinformation effect could no longer be found. Further experiments suggest that people no longer tried to remember a single detail (‘What happened to the car?’) but instead engaged in a more elaborate task of retrieving one or two memories from different sources (‘What happened to the car in the film rather than the summary?’).
Still, usually memories need to be retained for longer than 15 minutes. How do the findings change with a five week gap between implanting the false memory and trying to abolish it? The misinformation effect could still be reduced simply by telling people five weeks after getting film and summary that the two did not entirely match. Introducing a more elaborate questionnaire further improved memory. It leads to better performance because people are told in detail which manipulated details to consider carefully and it asks where they have a piece of information from.
The authors hesitantly suggest these changes to eye-witness testimony: 1) remind them that ‘they might have encountered additional information relevant to a witnessed event from various post-event sources (e.g. other witnesses, the media, etc.) and that some of this information may have been inconsistent with their own perceptions and memories.’ 2) ‘ask people not only for event details but also for (possibly contradictory) post-event information, and also […] explicitly ask for the source of every remembered detail.’ By making the remembering process more elaborate than a simple ‘Tell me what you know’ one can help people remember correctly.
The implications for what we mean by ‘memory’ are intriguing. Depending on what task you set people, they remember things differently. Apparently, constructing a memory from bits and pieces scattered in the mind is highly dependent on the situation we are in. The reason why we are not aware of this is because the brain plays a trick on us: a memory always feels somehow real, genuine, and personal. Even that of Diana’s crash video.

Greenberg, D.L. (2004). President Bush’s False ‘Flashbulb’ Memory of 9/11/01 Applied Cognitive Psychology, 18, 363-370 DOI: 10.1002/acp.1016

Oeberst, A., & Blank, H. (2012). Undoing suggestive influence on memory: The reversibility of the eyewitness misinformation effect Cognition DOI: 10.1016/j.cognition.2012.07.009

Ost, J., Vrij, A., Costall, A., & Bull, R. (2002). Crashing Memories and Reality Monitoring: Distinguishing between Perceptions, Imaginations and ‘False Memories’ Applied Cognitive Psychology, 16, 125-134 DOI: 10.1002/acp.779



1) By Rick (Princess Diana, Bristol 1987) [CC-BY-2.0 (, via Wikimedia Commons

2) via Innocence Project:


  1. hey! just now I came across your summary of our studies – great job! it’s great that you mind!

    all the best, aileen

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