How reliable is your memory? Can you remember what you were doing on this day ten years ago? Or do you struggle to remember what you ate for lunch yesterday? Regardless of how well you think you remember things, all of our brains are full of memories of events that never happened – so-called false memories. And that, according to science, isn't necessarily something to worry about.
To explain this strange phenomenon and much more, we talked to Dr Julia Shaw, a research associate at University College London and expert on criminal psychology.
How are memories stored in the brain?
Memories are essentially networks of neurons. And autobiographical memories – memories of our lives – involve connecting different parts of the brain. These memories don't just live in one little piece.
In fact, when you feel like you're reliving an experience – the smells, the sights, the sounds, the tastes – all of the parts of the brain that are responsible for different sensations are recruited as part of this really big and complicated network.
How common are false memories?
Everybody has false memories all the time – even if they think that they have the world's best memory.
Scientists have tested people who are called HSAMs (people with Highly Superior Autobiographical Memory), who have the best autobiographical memories in the world. They're the kinds of people who you can ask what they did on 2 November 1972 and they'll tell you most of what they did that day.
Even these people, when you carry out false memory experiments, create false memories at about the same rate as everybody else. Just because you're amazing at remembering things doesn't mean you aren't also prone to the same kinds of distortions and confabulations as everyone else.
It seems to be a core aspect of how the brain works. That's because the networks of the brain aren't meant to be static. The brain works as a dynamic and fluid organ, which has to constantly accommodate new information. That's why our memories are able to change.
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Do false memories also change over time? How can we spot them?
False memories grow over time because they have to – you're creating something that didn't happen, and your brain is adding details.
While it's possible that one could create a false memory that's a whole story right away, out of the blue, that's not really what happens. That's more likely to be a lie. But, if we're talking about memories, things that we actually believe happen to us, that usually requires more of a process and a bit more time.
When you form a false memory you start with a detail and then you begin wondering about other things that might have happened. And it embellishes over time. You often start with what-ifs.
For instance, imagine thinking 'maybe I fell down the stairs when I was six'. You might think about how they could have happened. Then the next time you're thinking about it you already have this image in your head of yourself falling down the stairs. Then you start to edit it, adding parts – I fell down the stairs and I hit my head and so on.
It feels more like you're accessing a memory because you are accessing a memory of the last time you thought about it. You've got this growth where you're adding details over time.
In essence, false memories grow over time, whereas true memories typically either stay the same, or, especially over long periods of time, disintegrate. It’s much more common that we forget details of things that did happen, and that a real memory gets less rich. But false memories tend to get more rich.
How can we avoid the traps of false memories?
You can write things down, take pictures, take videos. If something is important, assume you're going to forget it. That's the main thing.
Another thing I advise is that you can be very mindful. The bigger you make a memory trace in the first instance, the more likely you are to find it later.
Memory champions, people who competitively remember the order of two shuffled decks of cards in an hour, do this all the time. They use memory aids that help them to make bigger memory fragments.
For autobiographical memories, you can describe what you're experiencing right now (and what you're seeing) almost like you're a storyteller, telling the story to someone else.
Let’s say you're somewhere where you literally can't record the memory independently – you’re underwater perhaps. You have to really pay attention to every detail in the scene that you want to remember.
You describe the specific blue of the water, what the fish look like, the fins on each fish's back. You think about how you feel, about the interactions that are happening in front of you. You really paint a richly detailed picture.
What you’re doing when you do that is creating a much bigger memory fragment that's connecting more parts of your brain and so is more likely to be found later.
Can false memories ever be a good thing?
False memories sound like defects, but I think that they are a core part of being human. The fact that we have false memories is a testament to the brain's creativity and its ability to constantly, creatively recombine information.
Usually in the false memories I see in my research, people are using real people, real places – things that they've heard, things they've seen, maybe in movies or elsewhere. But they're all real bits of information.
A false memory is just combining all of that into a narrative that didn't actually happen to you. That is an incredible ability. It’s probably one of the things that really defines us as a species, and I think it's a beautiful thing.
If we were to get rid of false memories – let's say we suddenly have perfect memories – I think we’d get rid of lots of other things that we value. It’s more than being the perfect archivist of our own personal past. It's a good thing. We like our false memories.
This conversation has been edited for clarity and length. The full interview, which featured in the BBC Science Focus podcast series Instant Genius, is available here.
About our expert, Dr Julia Shaw
Julia is a research associate at University College London. She is an expert on criminal psychology, and the author of three books, Bi: The Hidden Culture, History, and Science of Bisexuality, Making Evil: The Science Behind Humanity’s Dark Side and The Memory Illusion: Remembering, Forgetting and The Science of False Memory.
Her research has been published in the Journal of Police and Criminal Psychology, Psychiatry, Psychology and Law and Psychological Science.
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