In this far-ranging chat, psychologist Elizabeth Loftus spoke with MIT neuroscientists Steve Ramirez and Xu Liu about the future of memory manipulation.
Last year, MIT neuroscientists Xu Liu and Steve Ramirez manipulated the memory of a mouse. In a fascinating and mildly troubling breakthrough caused by a laser and the protein channelrhodopsin, they “activated” fear memories in a mouse. The impetus, says Ramirez, was the awful feeling of a break-up, the desire, Eternal Sunshine-style, to erase the bad associations with his ex. Says Ramirez, “I realized, maybe that’s a little bit lofty for now. So what if we could start off by going into the brain of a mouse and just find a single memory to begin with? Could we jump-start that memory back to life, maybe even play with the contents of that memory?”
Well, as psychologist and criminologist Elizabeth Loftus knows, humans already have extremely faulty memories; so what happens when the technology for manipulation on the neural level becomes possible? Could there be a future therapy for people with depression or PTSD — or heartbreak? What might that mean for the courtroom of the future? And do people really want to have their memories manipulated, or do our memories make us who we are?
To tackle these questions, TED asked Loftus, Ramirez, and Liu to join in a phone conversation about the future of memory manipulation. Below is an edited transcript of the conversation.
A question for the group: Why is human memory so malleable?
Elizabeth Loftus: Whatever your theory is, why would Darwin or God or whoever have made us with memories that are so malleable? That must serve some sort of function, and one of the functions that malleable memories can serve is to be able to correct errors that creep in. You can update your memory with accurate information, and that is certainly a benefit.
It’s also thought that sometimes we might be better off with distorted memories. There are spontaneous memory distortions — we remember we gave more to charity than we really did, or we got better grades than we really did, or we voted in elections that we didn’t really vote in. These allow us to feel better about ourselves, and maybe live a little bit of a happier life.
Xu Liu: I think there are probably some protective mechanisms in the brain. Sometimes when very traumatic events happen, people say they kind of black out. Probably that’s one of the ways the brain is trying to protect us from those really traumatic memories by blocking them or sometimes even changing them.
EL: Xu, you’re getting perilously close to a folklore I’ve been fighting for a while. The idea that we repress horrific brutalization and are completely unaware of it is an idea that’s been floating around for a long time. But I have not found any credible scientific support for the idea that you can, for example, be raped for ten years and have absolutely no awareness that this happened, and go into therapy and reliably recover it later. So while I do think that sometimes unpleasant and awful memories can be distorted or changed in a way that allows us to feel a little better, I don’t know about the blockage of repeated brutalization.
Steve Ramirez: I was actually wondering, Elizabeth, if you happened to know: Is it easier to induce false memories in people with depression, whether through suggestibility or hypnosis? Or are they more immune to them?
EL: I’d love to know the answer to that, but we have not knowingly run people with depression through our memory distortion experiments. Recently, we published a paper where we took individuals with extraordinarily good autobiographical memories — they can almost remember every day of their adult life — and we found that even this special group of people was susceptible to memory contamination. We thought if any group were going to be immune, it would be them. They weren’t. It raises the question: Is anybody?
XL: Memory is also connected to the way we imagine the future. We tend to have a more positive bias in our memory, but somehow, studies show, the memories and imaginations of people with depression are probably more realistic than “normal” people.
EL: Yes, I’ve seen some recent articles on the fact that many of the same brain structures are involved when we imagine a future event as when we try to recall a past event — so people are hypothesizing that there’s a connection between those two activities. Maybe this malleable memory system allows us the flexibility to anticipate alternative futures that we can contemplate and then grapple with in advance.
SR: Right. If I remember correctly, there are a handful of studies implicating the same structures involved in forming memories and projecting yourself into the future. People with certain kinds of damage to the memory-forming areas of the brain show profound deficits in being able to project themselves into the future. That’s a really neat interplay.
EL: So where are you going next with the mice?
SR: It’s all over the place. With our first couple of papers, we wanted to provide a tool that could activate discrete memories, or could even tinker with them a little bit to play with the contents of memories. But this team of just Xu and me has blossomed into more than a dozen people asking whether we can do those same kinds of manipulations with recent memories and old memories. And rather than sticking with fear memories, could we also do this with pleasurable memories? So that’s one of the next steps.
One of the reasons I asked you about depression patients is because I’m working on a project now to try to reactivate positive memories in animals with depression. This is to see what the interplay is between a brain that’s in a depressed state and a positive memory that might potentially rescue that depressed state.
EL: That’s fascinating. This may only be tangentially relevant, but we have asked whether it’s easier to distort somebody’s memory in a negative versus a positive direction. We finally have some good evidence that people are more likely to adopt a false memory when it’s a positive memory — and more likely to do so if it also paints you in a more positive light. I don’t know if this is true for people with depression, but it might be a terrific treatment for depressed people. If you can succeed in doing that, it would be enormous.
SR: Yeah. Because there are plenty of treatments for depression, and yet their efficacy is low. We have a pretty good idea of what certain drugs are doing to the brain; I think the goal with this new project would be to do more of a cognitive intervention. We know sometimes they work really well in people. Sometimes they even outperform drug treatments.
But as to how they work mechanistically, the brain has still been a black box with that kind of treatment, so providing an analogous or roughly parallel animal model would be great, because we can actually go in and causally dissect these circuits.
EL: What kinds of criticisms do people throw at you?
XL: One of the first things people ask is, ‘are you sure you are manipulating a memory per se, or are you only manipulating a sensory representation?’ For example, people ask whether you can reactivate the same sensory areas and reactivate a response. That’s a very good question. So far, our answer is that we think we are manipulating memory, but not a sensory representation per se. If it’s purely sensory, then it doesn’t matter whether you activate the same cells a day after the memory or a month after the memory; the response should more or less be the same.
We found that when we activate these cells over a short period of time, we can cause the recall of the memory — but if we reactivate them a month later, they don’t do anything any more. This is consistent with the so-called “systems consolidation” hypothesis: short-term memory involves the hippocampus, but long-term memory is somehow transferred to other areas, like the cortex. Someone else in the lab tried to activate cortical neurons a month later, and indeed we saw that memory gets recalled.
SR: One of the challenges we got in regard to our false memory paper is that we need an operational definition of a false memory. People weren’t necessarily convinced that what we claimed was a false memory truly was one.
The relationship between false memory, like the kind we created by manipulating a mouse, and false memory in humans is at best unclear. We wouldn’t directly try to adopt our animal model as one for human false memories, because it’s slightly different in terms of how these kinds of memories are formed. What we did was to artificially reactivate the memory of a particular environment and then redirected a feeling of aversion to that memory by sending the mouse mild foot shocks, in order to form an artificial association between the two.
So Elizabeth, is it accurate to say that most false memories in humans are not really totally reconstructed? In other words, the false memory doesn’t come out of the blue but recombines elements of previous memories into a memory that’s no longer a bona fide representation of the past? It sounds almost like you’re ungluing elements from certain past experiences and then regluing them onto a particular memory, so that memory becomes updated in a way that is no longer representative of that actual event.
EL: That’s a good description of what often happens with humans when they are developing what we think of as a false memory: They are taking bits and pieces of experience from different times and different places and combining them together to construct what feels to them like a memory.
We too get a question: ‘How do you know that you really have a false memory, as opposed to what we’d call ‘demand characteristics’?’ I don’t know if you have this with mice, but you do get human subjects who want to tell you something because they want to please you, because they figure out what it is you’re looking for and they want to help you.
So we’ve developed a number of ways of deciding — or convincing ourselves — that we’re really dealing with a false memory. One interesting way is to put people into what they think is a completely different experiment at a different time much later and see how they behave. So if we plant a false memory that you got sick eating a particular food and then later on, we put you in another experiment, you’ll think it has a different purpose. Then, if you have a chance to eat that food that made you sick, and you don’t eat it as much, it convinces us that this really is a memory operating.
Another thing psychologists have used to prove to themselves that the subject really believes it’s their memory is, when you put them in a new situation, will they tell someone else that they have this memory? If they do that, when there’s no original experimenter around to please, that also helps convince us.
But I don’t know if there’s anything analogous there for mice. I mean, you obviously can’t ask them.
XL: We have to test that by observing their behavior and by looking into their brains. Something good about working with animals is we can look into the cells and see which areas of the brain are actually activated by this memory. By looking at that, we can more or less tell whether the animal is recalling a traumatic event or not. So that’s one advantage of using animals, but again, that’s just based on observation. We cannot tell exactly what the animals are thinking, unlike with humans.
EL: As we get better at planting false memories and controlling behavior, what are the societal implications? Should we ever be doing this for people? Should we ever ban the use of this mind technology? I don’t really have the answers to that.
SR: By giving TED Talks about memory manipulation, I think the three of us can agree that we are promoting this conversation and this dialogue with everybody, that this is a two-way street of insight that needs to happen so that we can make proper legislation.
When the Human Genome Project was started in the 1980s, everybody thought that this dystopian future and Gattaca and genetically engineered kids would happen in the next couple of decades — and that clearly didn’t come to be. In fact, we started that conversation 20-25 years before the genome was even sequenced, so once it was sequenced, that meant there was a 25-year head start on that conversation. Such that — while not perfect — there was the proper legislation to prevent, for example, certain jobs or certain CEOs from discriminating based on genetic background.
By starting this conversation now about memory manipulation technology and implanting false memories, we can have a head start — on the order of decades — before this kind of technology reaches the realm of humans, so that we’re prepared. My hope would be that if something like this were to reach escape velocity and was somehow applied to humans, it would be in a clinically relevant setting. The same way that doctors don’t give antidepressants to an entire population, they just give them to those patients who are debilitated by depression, maybe this technology would just be made available for the population that’s debilitated by things like PTSD or depression.
EL: That reminds me of memory-dampening drugs, like propranolol. Supposedly, you give propranolol to individuals who have had trauma and it dampens the memory. We did a study not long ago in which we asked people to imagine that they had gone through a trauma, they were beaten up on their way home from work and robbed, then they went to the emergency room and the doctor offered them this drug that would reduce their chances of post-traumatic stress disorder. To my shock, 80 percent of people said they didn’t want the drug.
XL and SR [together]: Oh wow.
EL: Their memories are their identity; they don’t know the side effects; what other memories is it going to take away? We’ve repeated that study several times now, and some people just don’t want to have their memory dampened, even when it’s painful and even when they’re told it will help minimize their risk of getting post-traumatic stress disorder. This has taught me that people cherish their memories even when they’re painful and harmful.
And even when they’re fake!
EL: Even if [the memories] are fake and they believe they’re real, they’re going to want to cling to them. So that’s just going to complicate the policy decision-making in this area.
SR: Interestingly enough, that was raised repeatedly in the comments sections for both of our TED talks. A lot of people were saying that they did learn from the heartache of a break-up, that there are mistakes they would no longer make, and it really threads together and unifies their sense of being emotionally “now.”
EL: I appreciate all the times I’ve had a romantic entanglement and a broken heart, and it’s not too painful to think back on it. But on the other hand I would really like to die of an overdose of morphine. I don’t want the pain and I would frankly rather blot out death. It seems we really are complicated creatures.
This article is published as part of our “Questions Worth Asking” series. This week’s teaser: “Should we redesign humans?” See also a playlist of talks featuring thoughts on this topic from the likes of Juan Enriquez and Anthony Atala — and an admittedly incomplete tour of the history of biomaterials.
Elizabeth Loftus: How reliable is your memory?
Steve Ramirez and Xu Liu: A mouse. A laser beam. A manipulated memory.
Elizabeth Loftus studies false memories. As she describes in her TED Talk, The fiction of memory, she has implanted erroneous memories of childhood trauma into adult study subjects as part of her work. She has pinpointed failures in eyewitness testimonies. She’s found that misinformation can reshape taste preferences. And, she’s found that people in stressful situations might not recall their experience as reliably as they might think.
Elizabeth Loftus: How reliable is your memory?
Loftus’s research is provocative, challenging and as she acknowledges, raises deep ethical questions about when it might actually be right to implant false memories (for instance, what if you want your kids to like asparagus and turn their noses up at fatty foods? Could you, should you embed false memories in their small minds?) She obviously couldn’t compress her 40-plus years of research into an 18-minute talk; here are just some of the recent studies she’s been working on that shed more light on this difficult topic:
“Queasy does it”: False alcohol beliefs and memories lead to diminished alcohol preferences by Seema L. Clifasefi, Daniel M. Bernstein, Antonia Mantonakis, Elizabeth F. Loftus, Acta Psychologica, 2013
This study suggests that specific alcohol preferences can be minimized if subjects are falsely informed that drinking rum or vodka made them sick. It works toward deepening our understanding of how false memories might influence actions of the present and future, and it might hold implications for the development of future alcohol interventions.
False memories of fabricated political events, by Steven J. Frenda, Eric D. Knowles, William Saletan, Elizabeth F. Loftus, Journal of Experimental Social Psychology, 2013
In the largest study of false memory to date, 5,269 participants were asked about their memories of a series of true and false political events. About half of the participants falsely remembered that the fake events had occurred — fascinatingly, there was a strong correlation between political orientation and the formation of false memories. Liberals remembered unfavorable (false) events involving George Bush; conservatives constructed false memories about Barack Obama. This study illustrates that implanted memories “stick” better when they tally with someone’s preexisting thoughts and beliefs.
Individual differences in false memory from misinformation: Personality characteristics and their interactions with cognitive abilities by Bi Zhu, Chuangsheng Chen, Elizabeth Loftus et al., Personality and Individual Differences, 2010
In this investigation, Loftus and her team examined the association between personality characteristics, cognitive abilities and memory falsification. They discovered an interesting phenomenon: those who typically take the lead are more prone to fall victim to false memories. Conversely, those experiencing depression or a fear of negative evaluation were less susceptible to memory modification.
The Consequences of False Memories for Food Preferences and Choices, by Daniel M. Bernstein and Elizabeth F. Loftus, Perspectives on Psychological Science, 2009
As she mentioned in her talk, Loftus successfully manipulated food preferences in subjects by suggesting that a certain food made them ill as a child. This study and two others, Asparagus, a Love Story (2008) and False memories about food can lead to food avoidance (2005) shed further light on her work in this area. The authors describe how they succeeded in creating both food avoidance and food fondness by suggesting positive experiences with asparagus and negative experiences with pickles and eggs.
Photo: James Duncan Davidson
Elizabeth Loftus begins her talk at TEDGlobal 2013 with the tragic story of Steve Titus, who was arrested in 1980 because he sort of matched the physical description of, and drove a similar car to, a man who had raped a woman in his area. Looking at a photo lineup, the victim told police that Titus looked “the closest” to the man who had raped her. But by the time the trial began, the victim had become certain that Titus was the attacker.
Memory scholar Elizabeth Loftus worked on this case, and became fascinated by the question: How did the victim’s memory go from uncertain to certain? The stakes of this shift were unbelievably high. While Titus was eventually exonerated by a journalist who tracked down the real rapist, he lost faith in the justice system, lost his job and fianceé, and became obsessed with what had happened to him. He died of a stress-related heart attack at age 35.
Loftus studies memory, but in an unconventional way. “I don’t study when people forget,” she says. “I study when people remember things that didn’t happen. I study false memories.” It’s an issue that comes up often in courts, which highly value witness testimony. In a survey of 300 cases of wrongful conviction, where a person was later exonerated of a crime, three-quarters of them had been incarcerated due to faulty human memory.
“Many people believe that memory works like recording device,” says Loftus. “But decades of research has shown that’s not the case. Memory is constructed and reconstructed. It’s more like a Wikipedia page — you can go change it, but so can other people.”
Photo: James Duncan Davidson
In one study conducted by Loftus, people were shown a simulated accident and were asked how fast a car was going when it either “hit” or “smashed into” a second vehicle. When the word “smashed” was used, people overestimated how fast the car was going — and reported seeing broken glass at the accident site. More recently, Loftus did a study on members of the military as they were being trained on how to handle interrogations in the event of capture. These subjects underwent a stressful physical interrogation and were later asked to identify the interrogator. If they were fed suggestive info, they would misidentify the interrogator — even if there was no physical resemblance.
“When you feed people misinformation about some experience they had, you can distort or contaminate or change their memory,” says Loftus. It doesn’t have to be done with malintent — it can be inadvertent.
In the early 1990s, Loftus became interested in a kind of story she was seeing more and more in the media. A psychotherapy patient would remember a brutal memory that they had repressed from childhood. When Loftus looked into some cases — including one where a woman had remembered being forced into a satanic ritual, forcibly impregnated, and having her stomach cut — she was struck that the physical evidence just didn’t match up with the memory. She wondered: Were the exercises of psychotherapy actually leading to false memories? She designed a study where suggestion was used to plant a memory of being lost in a mall as a child — and it stuck with a quarter of subjects. Loftus notes that other studies conducted around the globe showed that it was easy to plant traumatic childhood memories, even for highly unlikely events.
As Loftus spoke out on what might be happening in these cases, she says, she was hit with a defamation suit from one anonymous subject. “I became part of a disturbing trend in America where scientists are being sued for speaking out on matters of controversy,” she says.
Photo: James Duncan Davidson
More recently, Loftus drew public fire when she presented the results of a study where a memory was planted that subjects had gotten sick after eating a certain food as a child. When later presented with the food at a picnic, they ate much less of it. The inverse worked for good memories about healthy foods. This made Loftus wonder: Could the malleability of memory be used to help establish healthier behaviors? This, of course, brings up ethical dilemmas.
“When should we use this mind technology? And should we ever ban its use?” she asks. “False memories aren’t necessarily bad or unpleasant. By planting a warm fuzzy memory about a healthy food, like asparagus, we can get people to get asparagus more.”
To a big laugh, she wonders if using these tools on children was any more ethically suspect than encouraging them to believe in Santa Claus. She, however, understands why the topic makes people uncomfortable.
“Most people cherish their memories,” says Loftus. “But I know from my work just how much fiction is already in there.”
Elizabeth Loftus’s talk is now available for viewing. Watch it on TED.com »
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Photo: v u O n g / Flickr CC
How do you keep memories? And how much can you trust those preservations? This week’s TED Radio Hour, “Memory Games,” looks at recollections versus actual experiences, sorts through our tendency to create false memories, and unpacks how we can actually enhance our ability to remember.
Forensic psychologist Scott Fraser starts the hour. He is the guy called upon by attorneys or prosecutors when they have issues with a witness’s statement. Fraser discusses the importance of implanted memories — believing that you remember something that is the result of “post-experience information” — which is akin to what happens when a photograph or a story from our parents lead us to recall an experience that we may not actually remember. These false memories may seem innocent enough, but when on the witness stand of a murder trial, it could lead to wrongful conviction.
Next, Nobel laureate Daniel Kahneman reveals his insights into the space between experience and memory. He has found that, typically, the end of an experience is what is most important. In other words — a beautiful, moving symphony with a screeching sound at the end will not be remembered fondly. Kahneman gives an evolutionary explanation for this phenomenon. And in an unmissable part of the interview, he also shares a remarkable story from his youth — as a 7-year-old Jewish boy in occupied Paris, he remembers being hugged by an SS soldier. His various memories of this moment differ, and always serve to remind him that human nature isn’t always black or white.
To close the show, writer and US Memory Champion Joshua Foer describes how he remembers mundane details, like a group of random numbers, by associating each with an imagined grotesque, creepy, or outlandish act occurring in his various rooms in his childhood home. Think: cookie monster riding a horse in his kitchen. These striking images give him something notable to associate with an ordinary memory. This practice has been used by memory champions as far back as Ancient Greece, and anyone can use this tool. If you want to have good memory, says Foer, all you need to do is practice.
Check your local NPR schedule to find out when the show airs today, or listen via NPR’s website »
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