The False Memory Archive: Did that really happen?

We think our recollections are reliable, but research shows that all of us are susceptible to false memories. Kate Hilpern discovers what can happen when we rewrite the past

Picturing the past: our recollections of events from years gone by are added to every time we remember them, influenced by subsequent knowledge, photographs or cultural beliefs

"I have a strong memory of being a boy in a car driving along a country road in Suffolk," recalls a man who I will call Adam. "Rounding a corner near home, we swerved, narrowly avoiding a milk float. The milk float ended up on its side, covering the road in milk. I can still picture the road, a large oak tree and the milk sloshing about, despite the fact that the boy in the car was my father. I have never lived in Suffolk."

Oscar Wilde described memory as "the diary we all carry about". But nothing could be further from the truth. Research shows that even when our recollections of the past are held with great confidence, clarity and emotion, they can be inexact and often wrong. In fact, the latest studies show that the higher the level of detail, the less likely it is that your memory is accurate.

Adam's false memory is among hundreds of anonymous ones being collected by the False Memory Archive, as part of a Wellcome Trust-funded exhibition by artist AR Hopwood on the topic. Those who think – or know – they have a false memory simply go to the Archive's website and type in their experience. But plenty of people in the public eye get caught out, too. Mitt Romney's memory of the golden jubilee of the automotive industry in Michigan, which he said happened when he was four years old, was very precise and full of convincing details. But the golden jubilee took place on 1 June 1946, nine months before he was born.

In a study published last week in the Journal of Experimental Psychology, researchers found that the details of childhood memories – colours, the weather or the time of an event – cannot be accurately recalled, so our brains fill in the gaps with fabricated details. Cara Laney, professor of psychology at Reed College in Portland, Oregon, explains: "The problem is that most people think memories are merely something we store in our brains, like books in a library, that we then go and look up when we want them. But, in fact, they are recreated every single time we remember them." In most cases, there are some traces of the original experience. But post-event information will be added on, she explains – things we've learned about the event since, some conclusions about how this particular type of event normally happens, cultural beliefs, some mistaken bits that actually belonged to other events, possibly some photos and so on.

"The metaphor I use is a wall of many-coloured Lego blocks. You have a bunch of individual blocks and you use some of them to build up a wall then tear it down. It will never be exactly the same wall twice even if you try to make it the same."

The good news is that memory reconstruction usually works in our favour. "Memory has a 'superiority complex'," explains Elizabeth Loftus, the distinguished professor of psychology and social behaviour at the University of California, "with studies showing that we remember we got better grades than we did, that we voted in elections we didn't vote in, that we gave more money to charity than we did, that our kids walked and talked earlier than they really did, It's not that we're lying – it's just something that happens naturally to allow us to feel a bit better about ourselves."

Interestingly, the one group who are less likely to have this prestige-enhancing memory distortion are those suffering from depression. "You could argue, as one researcher in the area, has, that they are 'sadder, but wiser'," says Loftus. It's not just the individual who can alter their memories – other people play a part, too. Indeed, Loftus's first experiments, back in the 1970s, involved interviewing people who'd seen a car accident. "In one study, I asked people how fast the cars were going when they hit each other. But when I substituted the word 'smashed' for 'hit', people estimated that the cars were going faster. In fact, the leading 'smashed' question also made people more likely to remember seeing broken glass when there was no broken glass at all."

Building on her interest in just how much other people can affect a person's memory, Loftus carried out a study in the 1990s in which participants were asked to talk about a number of events that happened to them as children. Through several suggestive interviews, people were led to believe that when they were children, they had been lost in a shopping mall for an extended time, that they were frightened, crying and ultimately rescued by an elderly person. "By the time we were done, about a quarter of our subjects fell sway to the suggestion and even began to remember the made-up event," she says.

The finding was both clear and groundbreaking – you can plant entirely false memories in a person's mind. Perhaps not surprisingly, scientists from around the world wanted to test just how far you could go. "You were attacked by a vicious animal. You nearly drowned as a child and had to be rescued by a lifeguard. You witnessed demonic possession. Your hand was caught in a mousetrap and you had to go to hospital. These are just some of the things planted in the minds of adults and, in the last case, children. In every case, significant numbers of people weren't just susceptible to the actual memory, but they gave confident, detailed and often emotional accounts about these experiences that never happened," says Loftus.

Among the most worrying consequences of manufactured memories came to light in the 1990s, when people were going into therapy with one kind of problem, such as depression or anxiety, and leaving with another – a "memory" of abuse, often perpetrated by loved ones. "Virtually all these problem cases claimed they had completely repressed these horrific memories until the therapy made them aware of them. But there is no credible scientific support for this kind of massive unsubstantiated repressed memory," says Loftus.

While such cases no longer make headlines, The British False Memory Society says it's an ongoing problem. "We're not talking about people who have snippets of memories of abuse or a feeling that something was wrong in the past, then remember more during therapy. This is about people who spontaneously produce a memory that's completely out of the blue and completely out of character," says the society's director, Madeline Greenhalgh.

Indeed, over the past 20 years, a large number of studies have modelled some of the most common techniques used by such therapists – including journaling, hypnosis, group counselling, picture cueing and guided imagination – and shown that they can indeed lead to false memories, points out Laney.

A very similar argument applies in the case of eyewitness testimony, she says. "Some well-meaning investigator or co-witness gives a witness some information and that information gets melded with the witness's memory for what happened," she explains (think of Loftus's car accident example). "This can be even more problematic when the witness is also the perpetrator. People can come to believe they committed terrible crimes that they didn't actually commit when their memories are messed with in this way," says Laney.

But it's not just the reliability of memory – the honest mistakes an eyewitness makes – that pose a problem in the court system, says Amina Memon, professor of psychology at Royal Holloway University of London. "Believability about a memory is also a concern." Indeed, juries tend to believe a memory that's full of detail is probably genuine, whereas in fact the opposite is true. "While genuine memories have a certain core content, we won't remember all the details. Reconstructed memory will fill those details in," explains Memon.

Juries are also swayed by people who are confident and emotional in their recollection. "But again we know that people can be very confident and emotional about something that never happened," she says.

Good news in the US is that psychologists are increasingly asked to appear as court witnesses to explain how memory really works, and the Supreme Court in the State of New Jersey has now issued guidelines about how eyewitness evidence needs to be evaluated. "It was a bold decision that finally recognises the scientific work we've been doing and indicates the world is finally waking up to the fact that faulty memories are responsible for many travesties of human justice," says Loftus.

In the UK, judicial acceptance is slower. "Judges are resistant to calling in eyewitnesses to explain the science of memory," says Christopher French, professor of psychology at Goldsmiths, University of London. "They say everyone knows how memory works, but actually there is this huge gap between the public misunderstanding and the reality."

Consequences of distorted and false memories aren't all bad. "When we planted a warm childhood memory about eating asparagus, we found that people said they liked asparagus more and wanted to eat it more," says Loftus. "Why this is exciting is that it takes us beyond the mere demonstration that memory is malleable and shows that memory distortions can affect people's behaviours long after the distortion has taken hold. I'm now wondering whether we could utilise this to help beat issues such as obesity. There are ethical dilemmas because therapists can't ethically manipulate a patient's memory, even for a happier, healthier life, but there's nothing to stop a parent doing it to help prevent a child at risk. When I first suggested this, it prompted an outcry from critics, but which would you rather have: a kid with all the problems of obesity – diabetes, heart trouble, shortened lifespan – or a kid with one extra little bit of false memory? I know which I'd go for."

To find out more about the False Memory Archive and the accompanying touring exhibition, visit falsememoryarchive.com