Science TED Talks

Elizabeth Loftus on embedding false memories in U.S. soldiers

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Photo: Thinkstock

Photo: Thinkstock

“We can’t reliably distinguish true memories from false memories,” declares psychologist Elizabeth Loftus in today’s talk. She’s spent the past forty years studying the memory, and has reached some mind-blowing conclusions about what we know, and what we think we know. Here, she shares more detail about her work, and suggests further reading for anyone interested in finding out more about the topic. 

Elizabeth Loftus: How reliable is your memory? Elizabeth Loftus: How reliable is your memory? There is a lay belief that when something traumatic happens, it leaves a kind imprint in the mind. In one large survey of potential jurors in the U.S., one question asked whether the jurors agreed or disagreed with this statement: “The act of remembering a traumatic event is like a video recording in which one can recall details as if they had been imprinted or burned into one’s brain.”

Over half of the jurors (52%) either agreed that this was true or did not know. We hear of crime victims saying things like “I was so frightened, I’ll never forget that face as long as I live.” But is this really true?

As I describe in my talk, my collaborators and I tried to answer this question by conducting a study that involved a very unusual stressful experience. The subjects in our study were members of the U.S. military who were enrolled in Survival School training, a program that prepares them for the possibility of being captured as a prisoner of war. During this training, the soldiers must try to evade capture by the enemy, but they fail. They are sent to a prisoner of war camp where they are hooded and stripped of their identities and thrown in extremely uncomfortable cells. As part of the training, they are interrogated for a half hour in a hostile, aggressive manner. The interrogation is physically abusive, involving facial slaps and abdominal punches, and being slammed into the wall.

Eventually the soldiers are rescued and their memory is tested. They try to identify the person who conducted the interrogation, and answer other questions about their experience. This experience is just as it might happen after a real experience of capture by enemies during war.

Psychiatrist Charles Morgan and his collaborators have been studying the effects of Survival School for a number of years. We worked together to conduct a study with the soldiers who’d gone through the training in which some would be fed erroneous information. Some have been exposed to misinformation about the “perpetrator” who conducted the hostile interview. They were showed a photograph of a man who was identified as the one conducting the interrogation, and were asked questions such as, “Did your interrogator give you anything to eat? Did he give you a blanket?” The trick was that the photograph was of a completely different person. When the soldiers were fed this misinformation, 84% of them later on went ahead and identified the person whose photograph was shown. All of them were, of course, mistaken.

The soldiers’ memories for other details could also be affected by misinformation. For example, some of them were fed misinformation about a weapon that was supposedly present during the interrogation. Later on, 27% claimed to have seen the nonexistent weapon. Others were fed misinformation about a telephone that was in the interrogation room. Later on, over 90% of them claimed to have seen that non-existent telephone.

These findings show that even when an event is stressful, people can be led to make memory mistakes when fed misinformation. Moreover, this happened to a high degree even though the soldiers were highly trained individuals.

I must admit that I did have some concerns when we were ready to think about publishing these findings. Were we going to be publishing a recipe for how bad people can do horrible things to others and then contaminate the memories of their victims for what had happened to them? In the end, we decided that it was important to get the findings out so that people could understand what could happen to memory, and perhaps then figure out some ways to defend against it.

Our findings appeared in the International Journal of Law and Psychiatry in early 2013. Hopefully our paper will help dispel some beliefs about the workings of memory to which many lay people mistakenly cling. I was surprised to see that in another nationwide survey in the United States, people were asked whether they agreed or disagreed with this statement: “Once you have experienced an event and formed a memory of it, that memory does not change.” Nearly 48% agreed. In now hundreds of studies, involving tens of thousands of subjects, other psychologists and myself have shown that this is simply not true. And now we know it’s not true even when people are well trained and when they’ve undergone an enormously stressful experience.