When I first met LC, she was 25. She had a beautiful memory, I was told, and beautiful memories are my research hobby. LC could remember her life as a rich, flowing narrative: the colours of her clothes, her exact conversations, the minutiae of her daily routine. But there was a glitch. Her beautiful memory spanned only between the ages of 9 and 14, and it only covered events related to her devout Catholic faith. During those times, she could remember everything, but the rest was as scattered and vague as it is for any of us.


LC’s case may seem peculiar, but she was just doing an extreme version of what we all do every day: building a story of our past. We all need a personal history in order to give us a sense of who we are in the present, but the past we remember is not always a truthful representation of what happened. LC’s late adolescence had been marred by psychological problems, and now she was unwittingly building a personal history – some of it real, some of it not – that could explain her sufferings.

Dying isn't as bad as you think © Scott Balmer

Indeed, research has shown that we are all constantly picking and choosing memories, based on our current needs and goals. This is carried out without our awareness, by a psychological mechanism called the ‘monitoring system’. Think of the last time a particular sight, smell or sound brought an image or concept to mind – psychologists call these ‘involuntary memories’. Your monitoring system tells you whether this recollection ‘feels’ like a memory (how detailed and emotional it is), and whether it fits into your current idea of yourself (how ‘plausible’ it is). If it fits, it becomes part of your story; if it doesn’t, it’s neglected – for the time being.

LC’s memories covered 500 pages, maybe more. “I remember it so well,” she used to say, “that day when I was riding a bicycle in my violet and pink skirt and my pink hairband, and I fell off and scratched my leg.” It’s impossible to know how many of LC’s memories actually happened, but our assessments showed that she was making many of them up. LC wasn’t lying, though. We all have apparent recollections of events that never happened.

More like this
Bacteria controls the weather © Scott Balmer

For his entire life, the eminent neurologist Oliver Sacks had a vivid memory of the London Blitz… but he wasn’t even in London at the time. In a 2010 study at the University of Hull, we found that 20 per cent of participants had at least one memory that they no longer believe happened to them. These false memories are the result of our brains’ ability to imagine possible (and impossible) scenarios – perhaps based on something that actually happened to us, or just invented entirely. The vividness of the mental images, and their emotional intensity, trick the monitoring system into labelling the image as a real memory.

So the past we remember is not entirely truthful. But this is no bad thing. Memory is there to provide a consistent, plausible sense of self that helps us negotiate the ups and downs of life. A not-so-truthful past achieves this goal. Problems arise only when there’s an extreme discrepancy between the personal narrative and reality, as in LC’s case. Most of us live extremely well with our selective memories. Our identities might be fabricated, but we’d be lost without them.

This is an extract from issue 330 of BBC Focus magazine.

Subscribe and get the full article delivered to your door, or download the BBC Focus app to read it on your smartphone or tablet. Find out more


Follow Science Focus on Twitter, Facebook, Instagram and Flipboard