美国国家公共电台 NPR Elizabeth Loftus: How Can Our Memories Be Manipulated?（在线收听）

GUY RAZ, HOST:

When most people think of memory, they think of like a hard drive and our brain that just records things and etches it into our brain.

ELIZABETH LOFTUS: Yes.

RAZ: And from time to time, we can recall those events with a fair amount of accuracy. Is that true?

LOFTUS: Well, that metaphor is not a good metaphor. I have learned through my work, through, you know, now decades of studying the malleability of memory that under certain circumstances, it is not reliable. It is easily manipulated.

RAZ: This is Elizabeth Loftus. She's a professor of psychology at UC Irvine. And Elizabeth not only studies how our memories can be flawed but how they can be controlled and altered and manipulated. Elizabeth explains her idea from the TED stage.

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LOFTUS: I'd like to tell you about a legal case that I worked on involving a man named Steve Titus. Titus was a restaurant manager. He was 31 years old, about to be married. She was the love of his life. And one night, the couple went out for a romantic restaurant meal. They were on their way home, and they were pulled over by a police officer. You see, Titus's car sort of resembled a car that was driven earlier in the evening by a man who raped a female hitchhiker. And Titus kind of resembled that rapist.

So the police took a picture of Titus. They put it in a photo lineup. They later showed it to the victim, and she pointed to Titus's photo. She said, that one's the closest. The police and the prosecution proceeded with a trial. And when Steve Titus was put on trial for rape, the rape victim got on the stand and said, I'm absolutely positive that's the man. Titus was convicted. He proclaimed his innocence. His family screamed at the jury. His fiancee collapsed on the floor sobbing. And Titus is taken away to jail.

Titus lost complete faith in the legal system, and yet, he got an idea. He called up the local newspaper. He got the interest of an investigative journalist, and that journalist actually found the real rapist, a man who ultimately confessed to this rape, a man who was thought to have committed 50 rapes in that area. And when this information was given to the judge, the judge set Titus free.

Titus was so bitter, and so he decided to file a lawsuit against the police and others whom he felt were responsible for his suffering. And that's when I really started working on this case, trying to figure out, how did that victim go from that one's the closest to I'm absolutely positive that's the guy? I was asked to work on Titus's case because I'm a psychological scientist. I study memory. I've studied memory for decades.

And if I meet somebody on an airplane, we ask each other, what do you do, what do you do? And I say, I study memory. They usually want to tell me how they have trouble remembering names or they've got a relative who's got Alzheimer's or some kind of memory problem. But I have to tell them, I don't study when people forget. I study the opposite, when they remember things that didn't happen or remember things that were different from the way they really were. I study false memories.

In one project in the United States, information has been gathered on 300 innocent people - 300 defendants who were convicted of crimes they didn't do. They spent 10, 20, 30 years in prison for these crimes. And now DNA testing has proven that they are actually innocent. And when those cases have been analyzed, three-quarters of them are due to faulty memory, faulty eyewitness memory. Well, why?

Like the jurors who convicted those innocent people and the jurors who convicted Titus, many people believe that memory works like a recording device. You just record the information, then you call it up and play it back when you want to answer questions or identify images. But decades of work in psychology has shown that this just isn't true. Our memories are constructive. They're reconstructive. Memory works a little bit more like a Wikipedia page. You can go in there and change it, but so can other people.

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RAZ: It's an amazing story. And I know that you do a lot of this kind of work as a legal expert. But you also do run these kinds of experiments in your lab, right?

LOFTUS: Yes. One of my early experiments involves showing people a simulated accident, where a car goes through an intersection with a stop sign, for example. And by asking a single leading question that suggests it was a yield sign, we can get lots and lots of people to believe and remember they saw a yield sign instead of a stop sign. We then, in later work, went even further and planted entire memories into the minds of people for things that never happened.

So we've made people believe that when they were 5 or 6 years old, they were lost in a shopping mall. Other scientists who work in my field have made people believe that they were attacked by a vicious animal or that they had a serious accident or that they were - even witnessed demonic possession. It's not that hard to get people to believe and remember things that didn't happen.

RAZ: How? How do you do that?

LOFTUS: The way we did our lost-in-the-mall study, our original lost-in-the-mall study, was I want to talk to you about your memories. We've been talking to your mother, and your mother told us some things that happened to you when you were about 5 years old. And so we just want to ask you about these experiences. And then I might present you with three true memories, things your mother told me really did happen to you when you were 5 or 6 years old, and then a made-up scenario about you being lost in the mall, frightened, crying, rescued and brought back together with the family.

And in our original study, about a quarter of these ordinary men and women fell sway to the suggestion and began to remember all or part of this made-up experience about being lost in the mall. So that's one example of how we have used a pretty strong form of suggestion to get people to develop what we're now calling rich false memories.

RAZ: Have you ever realized that you hold false memories?

LOFTUS: Well, personally, I had a kind of an amazing experience. I have to preface this with the fact that when I was 14 years old, my mother drowned in a swimming pool. And, you know, jump ahead decades later. I went to a 90th birthday party of one of my uncles. And one of my relatives told me that I was the one who found my mother's body. And I said, no. No, it didn't happen. And this relative was so positive that I went back from that family reunion and I started thinking about it. And I started maybe visualizing.

And I started to think maybe it really did happen. I started to make sense of other facts that I did remember in light of this news. And then my relative called me up a week later and said, I made a mistake, it wasn't you. And so I thought, oh, my gosh, I just had the experience of my subjects, where someone convincingly tells you and you start to visualize and you start to feel it. And then it wasn't true.

(SOUNDBITE OF TED TALK)

LOFTUS: When you feed people misinformation about some experience that they may have had, you can distort or contaminate or change their memory. Misinformation is everywhere. We get misinformation not only if we're questioned in a leading way. But if we talk to other witnesses who might consciously or inadvertently feed us some erroneous information, or if we see media coverage about some event we might have experienced, all of these provide the opportunity for this kind of contamination of our memory.

RAZ: In just a moment, we're going to hear more from Elizabeth Loftus on the ethics of memory manipulation. I'm Guy Raz, and you're listening to the TED Radio Hour from NPR.

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RAZ: It's the TED Radio Hour from NPR. I'm Guy Raz. And on the show today, ideas about manipulation, how outside forces can alter and control how we view the world, even how we remember it. And just before the break, psychologist Elizabeth Loftus was describing some of the experiments she's conducted on memory manipulation. Here's more from Elizabeth on the TED stage.

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LOFTUS: If I plant a false memory in your mind, does it have repercussions? Does it affect your later thoughts, your later behaviors? Our first study planted a false memory that you got sick as a child eating certain foods - hard-boiled eggs, dill pickles, strawberry ice cream - and we found that once we planted this false memory, people didn't want to eat the foods as much at an outdoor picnic. The false memories aren't necessarily bad or unpleasant. If we planted a warm, fuzzy memory involving a healthy food like asparagus, we could get people to want to eat asparagus more.

And so what these studies are showing is that you can plant false memories, and they have repercussions that affect behavior long after the memories take hold. Well, along with this ability to plant memories and control behavior obviously come some important ethical issues, like when should we use this mind technology, and should we ever ban its use?

RAZ: Just the suggestion (laughter) of doing that, it was, like, making my heart beat faster because it just seems crazy. The opportunity to abuse this technology just seems infinite.

LOFTUS: If I could just give you a counter, you know, example that might make you think about maybe under some circumstances this would be a good idea, there are clinical studies of a drug called propranolol that's being used to dampen or weaken the memories of a traumatic event. It's thought that these weakened memories will be less likely to result in post-traumatic stress disorder. Let's say you were mugged and traumatized and hit, you know, in a park and ended up in an emergency room. You could potentially be offered this drug. It would weaken your memory and reduce the chances you would develop post-traumatic stress disorder.

RAZ: I'm not comfortable with that. I have to be honest with you.

LOFTUS: (Laughter) I know a lot of people aren't.

RAZ: Yeah. I mean, I - I obviously understand the benefits of it, but it seems so dangerous. I mean, it seems like science fiction.

LOFTUS: So then OK, you don't want to do it. Maybe some other people do. Do they get to?

RAZ: I mean, I don't know, right? I mean, that - that's a big ethical question that we have to ask, right?

LOFTUS: It's a huge ethical question.

RAZ: Because our memories tell us who we are, where - we know who we are because of what we believe we have been. Without our memory, we're not - we're just a meat suit, right? We don't have anything else.

LOFTUS: It's interesting. I would agree with you. Memory, you know, is the basis for our identity and tells us who we are. But part of memory may tell us who we want to be. There is scientific evidence that we distort our own memories in a positive or prestige-enhancing direction without anybody else intervening. So people remember that their grades were better than they really were. They remember that they gave more to charity than they really did. They remember that they voted in elections that they didn't vote in. They remember that their kids walked and talked in an earlier age than they really did - all of these prestige-enhancing memories.

Distortions can occur in the minds of people who are otherwise trying to be honest. So what does that say about how memories are our identity? Maybe memories are who we would prefer to be. So what could be the benefits of this malleable memory system? There's no one right answer, but I actually envision a future where we might be really, really effective at designer memories. And then we're going to have to be asking the question when we're really good at this mind technology are we going to ever affirmatively use it to help people or would that be a bad idea?

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RAZ: Elizabeth Loftus - she's a professor of law and psychology at UC, Irvine. You can find her full talk at ted.com.