The Greek philosopher Aristotle once called memory, "the scribe of the soul," meaning that our memories are integral to our sense of self.
But can we actually trust them?
Nothing about memory is simple.
For starters, where are memories stored?
In which part of the brain?
Hundreds of studies have come to the same conclusion—there isn't one.
They're stored, processed, and moved around the brain, creating complex connections across neural networks that we still don't fully understand.
The potential storage capacity of the human brain is vast.
It's not possible to quantify exactly, but estimates put it in the multimillions of gigabytes.
But memory is malleable.
What we remember is not necessarily what happened.
A memory is not a recording.
It's more like a dramatic reconstruction and one that we can keep changing without realizing it.
For any experience to be remembered, it has to be encoded.
This encoding though is not any kind of direct translation.
It's a rich and complex process that creates associations and meanings.
As sensory information is encoded, and also whenever it's retrieved, it's interpreted in a way that can change it, and introduce errors.
Memory is a creative process, because unlike computers, we need to be able to make sense of the information we store.
That means we're never remembering things exactly the way they occurred.
We might be remembering something very similar, but subtly modified and colored by our own sets of associations.
Two people who see the same thing won't necessarily remember the same thing.
And in certain situations that's very problematic.
Psychologist Elizabeth Loftus produced groundbreaking research on eyewitness testimony.
Her work showed that memories can easily be influenced, even after they've been created.
For example, if investigators ask witnesses a leading question about a crime—such as, "what color coat was he wearing?"—their memories may adapt to incorporate the suggestions.
Similarly, if two eyewitnesses confer with each other, their memories of events often change, incorporating what they've heard from the other one but they won't realize this has happened.
And witnesses who are shown an image of a someone after a crime, even if it's one of an innocent person, can sometimes paste it on to their memory of the actual event, a process known as unconscious transference.
The Innocence Project estimates that around 70 percent of wrongful convictions later overturned by DNA evidence, are due to mistaken eyewitness testimony.
In some cases, memories can even be deliberately created and implanted.
The Lost in the Mall experiment took a test group of subjects and talked to them in depth about key childhood memories, while also adding an invented one: the experience of having been lost in a shopping mall.
It was found that between a quarter and a third of subjects not only accepted this new memory as genuine, but enriched it with specific details.
They'd created a new memory indistinguishable from memories of events that had actually happened.
We've all possibly done the same thing.
Most of us have certain key memories of being a very young child.
But research suggests that they're highly unlikely to be actual memories due to the way memory is stored in the infant brain.
In many cases, we probably imagined certain scenes at a later age, when shown photos or told stories about certain events.
The subjective experience of these memories is no different to remembering childhood events that actually happened.
Your precious first memory may well not be a real memory, and we're all perhaps living in our imaginations more than we realise.
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