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The brain doesn’t distinguish between false and genuine memories – cognitive psychologist

Our memories help shape who we are. But what if they’re not essentially ours? Can they be false? We talked to Dr. Elizabeth Loftus, a cognitive psychologist and an expert on human memory.

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Sophie Shevardnadze: Dr. Elizabeth Loftus, cognitive psychologist, research expert on human memory, really great to have you with us today. Welcome.

Elizabeth Loftus: Thank you. 

SS: Alright, so you have been researching memory for decades now. And you're quite famous for saying that human memory is unreliable. What does that mean exactly? I mean, I understand perfectly when people just forget things, like, where's my remote, or what year was it when I went to Jamaica, etc. But you mean that even the things that we don't forget, that we know that we know are not necessarily true?

EL: Right. The problems of memory are much more than just not being able to think of something when you want to think about it or forgetting some fact that you're searching for. I study the opposite problem, which is what happens when people remember things that didn't happen or remember things that are different from the way they actually were. So I study false memories. I think I can best explain it by describing some of the experiments that I've been doing over these many decades. So a large percentage of them involve showing people, say, a simulated accident or a simulated crime, and then deliberately trying to distort somebody's memory for some detail of that accident or crime. So I might show somebody an accident where a car goes through a yield sign at the intersection but suggests to the witness that they saw a stop sign instead of a yield sign. And in these experiments, many people will adopt the suggestion, we call it misinformation, and claim it as their own memory. And this phenomenon even has a name now, it's called the misinformation effect. When we're exposed to misleading information about some event that we have experienced, we will sometimes accept that misinformation incorporated into our memory. And of course, it causes errors in memory. So that's one kind of memory distortion that we've been able to produce experiments over and over and over as have many other scientists around the world.

SS: So you describe how you and your colleagues successfully implanted some false memories into your test subjects, which, to my mind, sounded pretty traumatic, like, for instance, making some of them think that they were bitten by a dog as kids, or nearly drowned and had to be rescued. Once you implant a painful memory like this can it be erased just as easily?

EL: Okay, so just backing up a slight step. You know, after we did the studies where we distorted memory for a detail of an event, we then asked the question: just how far can you go with people? Could you plant an entire memory into the mind of someone for something that didn't happen? And our first effort to do that was to plant a false memory that when you were a kid, you were lost in a shopping mall, with particular people, you were crying and frightened and ultimately rescued. Other people planted other kinds of very rich false memories: attack by an animal, nearly drowned and had to be rescued by a lifeguard, committed a crime as a teenager that was serious. And so these studies showed that you can even implant an entire event into people's memories. Now, I think what you're asking about is, you know, would this be traumatic for people? Well, I and others have done these studies. At the end of the experiment, of course, we debrief the subjects, we might have, you know, apologised for having to use deception, we might try to tell them, their behaviour is very normal. We don't want them to feel like a sap. And you know, people are quite fascinated and I've never seen anybody be traumatised by being in one of these experiments. I think if that were a frequent occurrence, then our human subject review committees would not be so willing to allow these studies to go forward.

SS: Sure, but the question really is can you erase a false memory as easily as you can implant it?

EL: It's harder to take away someone's genuine memory than to add something to their memory. But of course, in these studies, what we've added something and then we're trying to let them know that it wasn't really real. And of course, most subjects will accept that. One of the things that we're finding now is down the road, you know, what happens to these people? Do they continue, even though you've told them you made the event up, it didn't happen that way, what are they thinking? What's churning around in there? And what we have found is that there may be a little bit of fiction that still resides in their memory system. But often there are some benefits. Often they show kind of more knowledge about memory. And even in one study, we showed it protects them to some extent against a future attempt to manipulate them. So we see some benefits from having gone through some of these experimental processes.

SS: So does critical thinking and rationality have something to do with it? I mean, those who have enhanced critical thinking do not believe the first thing they're told and there is like always this grain of healthy scepticism with which they consume information in general, – are these people more immune to having their memories contaminated, so to speak?

EL: We've just done one study where we showed a future attempt to manipulate them and they were protected to some extent. Whether it has broader effects on critical thinking, whether it enhances them in some other ways, I think that's a great question. That's for some future researcher to dig into. And that's an empirical question but one that could be investigated.

SS: What about if, like, I'm conscious of the fact that a false memory can be implanted? For instance, after our interview, I know that this actually can be done? Does it help me protect myself from a manipulation, sort of?

EL: Well, there are warning studies, studies where people are warned, ‘Watch out, you're going to hear a version from another witness, it might have some errors in it,’ some kind of warning. And those warnings do help people resist the influence of suggestive information. Unfortunately, they seem to work only in the short term, not in the long term. So when we walk around the world, and when you leave this interview, you might be protected for a little while, the short term, but you're not going to be walking around, you know, for the rest of your life with this warning flashing in the forefront of your consciousness to protect you. So, there's a little bit of good news and then not so good news.

SS: So when someone speaks about a memory, how do you tell that it might be a false one? What are the clues? I mean, choice of words, intonation, body language, or what are the indications?

EL: No, I mean, those aren’t the things to look for. Again, we have asked, for example, maybe people would express more emotion about their genuine memories than false memories that are a product of suggestion. And when that's been explored, it hasn't been found to be true. People can be just as emotional about a false memory as a true one. We've even subjected people to neuroimaging, put them into a functional magnetic resonance imager and done imaging on a true memory versus a false memory, when people are telling you something that really happened versus something they believe happened but didn't. And the brain can't reliably distinguish true and false memories. What you need to know whether you're dealing with a genuine memory or one that is a product of imagination, suggestion or some other processes, you need independent corroboration to know.

SS: Okay. Your findings have been used in court to defend against sexual assault allegations. There are studies such as the famous ‘lost in the mall’ study, or the ‘Bugs Bunny and Disneyland’ where people ended up believing memories that were planted into their heads by researchers. But while the studies show we can make people believe they saw Bugs Bunny and Disneyland, can traumatic memories, like abuse or betrayal, really be implanted? I mean, are these types of memories not too serious for such manipulation?

EL: You know, we have human subjects and ethics committees that review our proposed research. And so we're probably not going to be able to plant a deliberate false memory that your father raped you for 10 years in a satanic cult. We wouldn't be given permission to do something quite that drastic. And so what researchers have done is try to think of an analogue, something you can plant that if it had actually happened, it would have been at least mildly traumatic. And so we have succeeded, we and other investigators in my field, in planting a false memory that you were attacked by a vicious animal, or you were bullied, or you nearly drowned and had to be rescued by a lifeguard, or you witnessed someone being demonically possessed. So these experimental studies have been successful in planting these pretty dramatic memories. And then we have a lot of studies of, you know, actual real-world cases. In this country, there are now hundreds and hundreds of people who have been through highly suggestive therapy, therapy that has led them to believe that they had memories that were extremely traumatic, and they now realise these memories were false. They call themselves retractors, they've retracted their memories after doing a lot of harm and suffering for their family members and others who they accused. You know, it's a pretty interesting phenomenon from the point of view of a memory scientist, many of them have sued their former therapists for planting false memories, some of them getting multimillion-dollar judgments from juries or trial settlements. And the study of these retractors also tell us about the whole process by which false memories are planted in the minds of people, and in these cases, ultimately disavowed.

SS: Dr. Loftus, in one interview you say that people tend to distort some of their own memories to feel better about themselves, like thinking their grades at school were better than they actually were, or giving more money to charity than they actually did. But why do people make up memories that would make them feel bad?

EL: Yeah, you know, I hear that question. Why would anyone want to believe or remember that they were, you know, abused by a family member if it didn't happen? And, you know, because there's a cost to it. You often get estranged from your family, the sibling stop talking to each other, there's a lot of disruption and pain. And my response to that is if there's a cost to it, there must be a really big benefit. So what could be that benefit? And in many of these cases, the individual who succumbs to this suggestive therapy starts to believe and then think they remember these experiences, uncorroborated, denied, sometimes impossible experiences. Why? Well, sometimes they have an explanation for their problems. They’re depressed or anxious, and now they have an answer: it's not that you were crazy, it's not that you're a bad person, you were abused. They often get a lot of empathy or sympathy from others there, they can be bathed in a love bath and get a lot of attention. These are some of what you might call the benefits of having a memory or a false memory of something that's not particularly pleasant.

SS: So your experiments with planting false memories were a way to prove that some people's claims to memories of abuse were false, and the memories were false, obtained during therapy. But if therapists do have the power to plant false memories in their clients’ heads, why would they plant memories of abuse? I mean, why not plant memories of a happy childhood instead?

EL: Well, I don't think they think they're planting false memories. What's happening in many of these scores and scores of cases that I've dug into and analysed, the patient goes to the therapist, ‘I'm depressed, I'm anxious, I have an eating disorder,’ and the therapist has one and only one idea about what the problem is with this patient, the sort of sex abuse answer, and the therapist may start asking leading questions or providing information that is misleading, like, ‘You know, in my experience, 70 or 80% of people with your symptoms were sexually abused, maybe something like that happened to you’. And there begins this process of an interaction that leads this patient to start to imagine and then think they're remembering something that didn't happen. This is not about a therapist sitting down and saying, ‘Boy, what can I plant in the mind of this patient today?’

SS: But just continuing the thought, like, if traumatising bad memories can be planted whatever way, can good ones also be planted? For instance, I read, you did research about planting memories in people to deal with their obesity...

EL: Oh, yes. So, well, at some point, my collaborators and I asked the question, what are the consequences of having a false memory? So if I plant a false memory in you, does it have repercussions? Does it affect you down the road? Does it affect your later thoughts, your later intentions, your later behaviour? And we studied this in a series of studies where we planted a false memory that you got sick on a particular food as a child, so I might get you to believe and remember you got sick on eggs, or you got sick on pickles, you got sick on strawberry ice cream, and then we found people aren't as interested in eating these foods later on. So we then did the opposite. We planted a warm fuzzy memory about a healthy food, like asparagus, and then people wanted to eat more asparagus. So that really got me thinking that you can plant a false memory, control people's preferences, and maybe their nutritional selection, maybe make a dent in the obesity problem in our society, and that might be good for people. 

SS: So I mean, that could work with anything, pretty much like hypnosis, I mean, to quit smoking, or I don't know, quit drinking excessively or anything. Could that be another way to replace hypnosis?

EL: Well, in one of the studies we did plant a false memory that you got sick on a vodka drink and people weren't as interested in drinking a vodka drink. So sure, in principle, this could be done with lots of different things. You know, hypnosis does something different. Hypnosis doesn't get people to tell you, ‘I had a memory for X, Y and Z and here's the details of my experience.’ You know, it works by a different process. But what I'm studying is the creation of memories for things that didn't happen, and what the repercussions might be after you adopt one of these false memories.

SS: So can memory tampering be used by therapists not to induce trauma, but to actually hide it from the patient, to make the patient forget?

EL: Well, in principle, even though it's a little harder to erase a memory, one of the things that we've done is we've substituted a different memory. So in the simple example, I make you believe the car went through a stop sign, instead of a yield sign. So to some extent, I've weakened the yield sign in your memory, the true detail, by substituting another, different detail, and that would be one way that to some extent you could weaken or take away a memory. But I'll tell you, when we learned about this drug propranolol that has been used in clinical trials to erase people's memories for a traumatic experience or weaken their memories, let me put it that way… Well, let's say, you had a traumatic experience, you ended up in the emergency room, so doctor gave you this propranolol, what it's supposed to do is weaken the memory and minimise the chances that you will develop Post Traumatic Stress Disorder, which can be pretty debilitating, and something that people ought to want to avoid. When we ask people, whether they'd be interested in taking such a drug if they were offered it at the emergency room after undergoing a trauma, most people said no, they didn't want that drug. They had all different kinds of reasons. I mean, would it have side effects? Would it take away some other memories? They were scared of it. And that kind of taught me that people cherish their memories, even if the memories are bad for them.

SS: Surely forgetting about pain brings peace, right? I mean, the ancient Greeks knew that, you know, when they told stories about the river of forgetfulness from which the death souls had to drink to forget their lives. So is it ethical for doctors to be erasing memories or supplanting real ones with fake ones even in order to help?

EL: From what I understand, in the therapeutic world, you're not supposed to deceive people or tell them lies even if it's for their own good. And, you know, it's not for me to decide what the rules of life should be for a society, it's for all of us together to decide. But at one point when I suggested, for example, in these food studies, there's nothing to stop a parent from trying something like this out on their overweight or obese teenager or child, sometimes people resisted that suggestion, and they'd say, ‘Oh, my God, there she goes, she's suggesting that parents lie to their children, how awful.’ And my response to that was, hello, Santa Claus. Parents lie to their kids probably often for one reason or another, not to usually hurt them, but for one reason or another. And when you think about it, if you had a child and it were a choice between being obese and having heart troubles with a shortened lifespan and higher risk of diabetes, or having a little bit of fiction, sprinkled into their memory system that might dramatically reduce their obesity, improve their diet and live a healthier life, what would you choose?

SS: Right. But memories from our experiences, they basically make us who we are, right? Is it possible for someone to plant members in such a way to completely change one's personality? Is that possible?

EL: Again, I don't know. That's pretty extreme. That's one of those things, empirical question, to study that you'd have to get very specific. Then, you know, what is it you want to turn a person into? And think about how you would design that study, what it would look like, what results you could anticipate. In principle, you can induce changes in people through the memory distortion process.

SS: All right, Dr. Loftus, it's been really interesting talking to you. Thanks a lot.

EL: Thank you for your questions. I see you've been reading a lot. You've really done your homework here. So it's a pleasure talking to you too.

SS: Thank you so much. Good luck with everything. Have a great day.

EL: Okay, bye-bye.

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