Think back to your first day at primary school.
For many of us, it's one of our clearest childhood memories.
Oh, that's me, waving goodbye to my proud mum.
But the fact is, we really can't trust our childhood memories
because for these early memories,
gaps appear and our brains fill in the details.
Before long, memories can become a mishmash
of your memory, those of your friends and family,
and photos or home videos.
So what you think happened can be quite different from the reality
you actually lived through.
To understand why you can't trust your memories,
we need to ask: what a memory actually is.
So people often think that memories are sort
of these physical structures that live in the brain,
almost like something in a computer, like a file that you can go
and open and find.
Instead the memories actually live as networks distributed across the brain
and so when you're especially reliving a memory of your life,
you are accessing often lots of different parts of your brain,
which all lead you to be able to have a full complex representation
of what happened.
So some of the brain cells that were activated during my actual experience,
are reactivated when I remember it.
Clusters of brain cells that form a memory are linked up
and each time we remember, these links become stronger.
But strong doesn't always mean stable.
For a long time people thought that if you stored
something in your long-term memory,
it was pretty much there permanently.
But that pretty much got shattered when it became clear that
there wasn't very good evidence for the permanence
of memory in the first place.
Four years of piano lessons!
Yeah, it looks pretty faded.
You know what? Save Chopsticks and Heart and Soul
and get rid of the rest.
So, our memories aren't fixed or permanent
and, in fact, they're always changing.
We're essentially reconstructing our narrative rather than reliving it.
This we referred to as reconsolidation
and we refer to it as pulling up this memory network,
accessing it and actually laying it down again
and every time you reconcile it,
every time you put this network back down,
you're actually able to change it.
And this tendency for memories to change,
is hugely important and it's totally natural.
It happens to everyone.
But it's possible to manipulate this process.
You can supply people with misinformation
that can change their memory.
You can ask them leading or suggestive questions,
that insinuate that there were details present
that there weren't out there in the real world,
people are exposed to media coverage where they get ideas,
about an event, maybe a high publicity event,
that they themselves are witness.
This was the largest audience to ever witness an inauguration. Period.
All of these are ways in which new information
can enter somebody's memory
and cause a transformation and alteration,
a contamination in that original person's memory.
Those aren't your memories, they're somebody else's.
Using these insights, researchers wanted to see
if they could go one step further.
What you can do is that you can get people to come in
to the lab, you can tell them that they experienced
something that never actually happened ...
When you were 14-years-old you initiated a physical fight
and the police called your parents.
That's ... I ... I .. I don't ... I feel like I've ...
I don't think I've ever been in a fight.
I'm so confused.
Over the course of three interviews, you get them to repeatedly imagine
what could have happened and what could
have happened starts to turn into what would have happened,
which turns into what did happen.
I remember like a verbal fight and maybe I ...
Seems so unlike me but maybe I pushed or something?
– Good, OK.
And so what you're doing is, you're activating your imagination
and you're activating real fragments of memories,
of things that they can remember
like their best friends, their family members
and in the end, what you've done is
you've created a whole fictional representation,
a whole memory of something that never actually happened.
You can see how this can have major consequences.
It doesn't really matter what happened
on my first day of school.
No one is really interested, except me.
But if memory is this unstable, can it be relied upon
when it's really needed?
Like in a court of law.
We are going to be able to prove to you in this case
things the public didn't know, things the police didn't know,
were provided by a young man who was at the scene.
As someone who has been a memory expert in courtrooms,
it's a fascinating thing to watch how slippery and unreliable
memories can be and how really the criminal justice system
is deeply affected by police interviews, by therapists.
Come on buddy. Let's get this out, OK?
Take us through it. It's the video in your head.
Play it for us.
And so it's really important that people who are
evaluating this evidence, understand all the different things
that can go wrong.
Advanced DNA testing showing that Mr Halsey,
despite his conviction in the late 80s,
did not brutally murder two young children.
Over 70% of DNA exonerations in the US,
have been shown to involve inaccurate eyewitness testimony,
which highlights just how much is at stake
when it comes to justice and memory.
But it's not all dark.
False memories can help people as well.
Understanding false memories allows us to also therapeutically intervene
when someone has experienced something or is remembering something
that is negatively influencing their lives.
Both in terms of just regular talk therapy,
but also in terms of of deeper medical approaches
to making those memories more flexible,
being able to change them and ultimately improve people's lives.
These kinds of insights into the nature of memory
are a great tool for therapists
treating depression or tackling phobias
like fear of flying or spiders,
all the way up to dealing with the conditions like PTSD.
So we know that memories are a huge part of who we are
but we also know that they are constantly changing, updating
and reshaping to fit our needs.
Sometimes they are completely false.
When you look at this process, what you're seeing is creativity,
you're seeing imagination,
you're seeing problem-solving, you're seeing intelligence.
I mean what you're really seeing when you look at the capability
of creating false memories,
is we see the capability to be human,
and so I think that false memories in and of themselves
are part of the human experience
and we just need to better understand them,
rather than to be afraid of them.
Thanks for watching.
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