Scientists Implant and Then Reverse False Memories in People

Researchers have demonstrated just how easy it is to trick the mind into remembering something that didn’t happen. They also used two very simple techniques to reverse those false memories, in a feat that paves the way for a deeper understanding of how memory works.

Our brains are far from perfectly functioning recorders of our life events.

The human memory system is fallible and malleable, so much so that it is possible—and even quite common—for people to possess false memories. Memory glitches can lead to all sorts of wider social implications, especially in the legal and forensic field. But now, for the first time ever, scientists have evidence showing they can reverse false memories, according to a study published in the journal Proceedings of the National Academy of Sciences.

“The same way that you can suggest false memories, you can reverse them by giving people a different framing,” the lead researcher of the paper, Aileen Oeberst, head of the Department of Media Psychology at the University of Hagen, told Gizmodo. “It’s interesting, scary even.”

Short-term memory allows us to be present in the moment, while long-term memory helps piece together our identity through the recollection of our past experiences, among other things. Yet, especially the farther back we go, the more our recollection gets murky. For example, when you think back to your childhood, you are reconstructing your past while also being affected by the current circumstances: who is asking, why, and how, Oeberst explained.

“As the field of memory research has developed, it’s become very clear that our memories are not ‘recordings’ of the past that can be played back but rather are reconstructions, closer to imaginings informed by seeds of true experiences,” Christopher Madan, a memory researcher at the University of Nottingham who was not involved in the new study, told Gizmodo.

“When people describe a memory, they will say that they are ‘absolutely certain’ of it. But this certainty can be an illusion. We suffer from the illusion of believing that our memories are accurate and pure,” Lisa Son, professor of Psychology at Barnard College of Columbia University, told Gizmodo. “This is despite the fact that we, in fact, forget all the time.”

Indeed, our minds are able to fabricate memories of entire events just by piecing together bits of stories, photographs, and anecdotes somebody else shares. These so-called false memories have been a hot topic of research for a while now, and there’s growing evidence that they could be a widespread phenomenon, according to a 2016 analysis of the field.

Building off of that, Oeberst’s lab recently implanted false memories in 52 people by using suggestive interviewing techniques. First, they had the participants’ parents privately answer a questionnaire and come up with some real childhood memories and two plausible, but fake, ones—all negative in nature, such as how their pet died or when they lost their toy. Then they had researchers ask the participants to recall these made-up events in a detailed manner, including specifics about what happened. For example, “Your parents told us that when you were 12 years old during a holiday in Italy with your family you got lost. Can you tell me more about it?”

The test subjects met their interviewer three times, once every two weeks, and by the third session most participants believed these anecdotes were true, and over half (56%) developed and recollected actual false memories—a significantly higher percentage than most studies in this area of research.

These findings reveal the depth of false memory and fit closely with prior research in the field, according to Robert Nash, a psychologist at Aston University who was not involved in the study. “Such as the fact that some of the false memories arose almost immediately, even in the first interview, the fact that they increased in richness and frequency with each successive interview, and the fact that more suggestive techniques led to much higher levels of false remembering and believing,” Nash told Gizmodo.

According to Henry Otgaar, a false memory researcher at Maastricht University who was a reviewer of this study, there’s been an increase in people thinking that it’s difficult to implant false memories. This work is important in showing the relative ease by which people can form such false memories, he told Gizmodo.

“Actually, what we see in lab experiments is highly likely underestimation of what we see in real-world cases, in which, for example, a police officer or a therapist, suggestively is dredging for people’s memories that perhaps are not there for weeks, for months, in a highly suggestive fashion,” he said, suggesting this is what happens in some cases of false confessions.

But researchers, to some extent, already knew how easy it is to trick our memories. Oeberst’s study is innovative in suggesting that it’s equally as easy to reverse those false memories. And knowing the base truth about what actually happened isn’t even necessary to revert the fake recollections.

In the experiment, Oeberst had another interviewer ask participants to identify whether any of their memories could be false, by simply thinking critically about them. The scientists used two “sensitization” techniques: One, source sensitization, where they asked participants to recall the exact source of the memory (what is leading you to remember this; what specific recollection do you, yourself, have?). And two, false memory sensitization, where they explained to the subjects that sometimes being pressured to recall something can elicit false memories.

“And they worked, they worked!” Oeberst said, adding that of course not every single participant was persuaded that their memory was false.

Particularly with the false memory sensitization strategy, participants seemed to regain their trust in their initial gut feeling of what they did and didn’t remember, as if empowered to trust their own recollection more. “I don’t recollect this and maybe it’s not my fault, maybe it’s actually my parents who made something up or they were wrong,” Oeberst said, mimicking the participants’ thought process. “Basically, it’s a different solution to the same riddle.” According to Oeberst, the technique by which false memories are implanted is the same used to reverse them, “just from a different angle, the opposite angle.”

The memories didn’t completely vanish for everybody; 15% to 25% of the participants still believed their false memories were real, and this is roughly the same amount of people who accepted false memories right after the first interview. A year later, 74% of all participants still recognized which were false memories or didn’t remember them at all.

“Up until now, we didn’t have any way to reject or reverse false memory formation,” said Otgaar, who has published over 100 studies on false memory. “But it’s very simple, and with such a simple manipulation that this can already lead to quite strong effects. That’s really interesting.”

The researchers also suggest reframing thinking about false memories in terms of “false remembering,” an action determined by information and context, rather than “false memories,” as if memories were stable files in a computer.

“This is especially important, I think, insofar that remembering is always contextual. It’s less helpful for us to think about whether or not people ‘have’ a false memory and more helpful to think of the circumstances in which people are more or less likely to believe they are remembering,” said Nash.

Although remembering whether you actually did get lost in Italy as a teen might not be so consequential, not all memories are just yours to keep.

For example, in forensic settings, the system draws often draws on eyewitness recollection, and sometimes people falsely remember events or details, which can potentially result in a wrongly conviction. Similar cases take place during clinical psychological therapy, where a therapist may try to elicit a so-called repressed memory, which, according to Oeberst, is actually a lot less common than many therapists suggest. The therapist may end up implanting a false memory in their patient’s mind instead.

Some caution of the generalizability of this study to everyday life is necessary, Madan pointed out; it’s still just a lab experiment. And there’s still little understanding of how effective these techniques might be at “reversing” a false recollection that a person has believed for a very long time, not just for a couple of weeks, Nash said. But the takeaway is that “every memory is a meta-memory, or an interpretation of a past time, one that can be impurified or purified by suggestions from the social environment,” Son said, “and the simple awareness of this fact is crucial.”

So while Oeberst’s study might leave you in a bit of an identity crisis, it actually offers some hope. “Our study adds some kind of optimistic hints,” Oeberst said. “Maybe not all is lost. Once you have suggestive interviewing, maybe it’s still possible to get some kind of actual truth, even if there has been some false influence.”

Sofia Quaglia is an Italian journalist based in New York City. She covers all things science, from public health systems to the latest discoveries in marine biology. Her work has appeared in Inverse.com, Psychology Today, Quartz, and more. As a News Analyst for NewsGuard Technologies, she fact checks and debunks fake health and science news.