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How many days hath September, April, June or November? Maybe it’s 30 or 31... I’ve lost my phone – now where’s it gone?
Memory is strange: sometimes crystal clear on people and places we came across years ago, often much more cloudy on things that happened just last week. Which is why scientists at the Memory Lab have taken up the challenge: to find out what memory is, how it works and why it is so fundamental to how we make sense of the world.
Why is it that we can remember the lyrics to that song from 10 years ago – but not where we put the car keys? Memory is strange: we forget important things, remember insignificant details, recall in vivid detail things that happened many years ago, but can’t remember why we came upstairs.
So just what is memory? For an easy-to-remember definition, says Jon Simons, Professor of Cognitive Neuroscience and Head of the School of Biological Sciences, you can’t beat Cicero’s assertion that “memory is the treasure house of all things”. It influences… well, everything.
“Everything we’re conscious of and everything we know is shaped by our previous experiences of the world and the way it works,” says Simons. “Our personality and behaviour all develop in ways that reflect things that have happened to us in the past.”
Of course, we now know far more about our treasure house – that it’s not just one place, for example.
“I’m looking at people’s stories of their memories: how people talked about them, the key features they thought were important to include, how they described their emotions in their memories..."
Since the advent of functional brain imaging research, we now know that many regions of the brain play a part in memory, from the hippocampus to the parietal lobe regions, which sit just behind our ears.
“It’s a big network,” says Simons. “Regions contribute in different ways depending on the kind of memory task you’re performing, the kinds of information you’re trying to remember, and whether you’re learning new information or retrieving older information.”
But while we have a very good understanding of, for example, the bits of our brains involved in remembering a shopping list, we understand far less about the subjective experience of memory – how it feels when we remember something. Think back to a vivid experience and you may well be able to remember it in rich detail: the sights, the smells, the sounds. You might feel that you are back there having that experience again.
“And that’s what I’m really fascinated by,” says Simons. “Basically: how do we do that? What are the brain systems and networks that enable us to mentally travel back in time and relive a previous experience as if it is playing out in front of us again?"
This is tough stuff to investigate, because, as he points out, “You’re basically trying to get inside someone’s head.”
So Simons has turned to the people who are in fact very good at doing just that: his colleagues in the arts and humanities. The project, When Memories Come Alive, brings together researchers in fields ranging from neuroscience to literature and history to find new ways of thinking and talking about memory.
Dr Martha McGill, a research associate on the project, is an expert on supernatural beliefs in Britain in the early modern period (1500-1800).
She’s using 17th-century journals – which tend to focus on the author’s spiritual journey – to better understand how the subjective experience of remembering changes according to the cultural context in which it is embedded.
“I’m looking at people’s stories of their memories: how people talked about them, the key features they thought were important to include, how they described their emotions in their memories, how they described sensory input in their memories, and how they thought about or framed the figure of their own self within those memories,” she says.
"Improving our memory can enhance everyone’s quality of life. It could help us perform better, and discover more effective ways to learn and retain information"
In this framework, human memory is seen as corrupted: the last people to have perfect recall were Adam and Eve before the ‘Fall’.
Our unruly animal spirits – semi-corporeal vapours made from rarified blood which travel around our bodies communicating instructions from the soul – provoke memories and can be easily influenced by angels and demons. But we don’t need to worry too much about misremembering: if we are very devout and trust the Holy Spirit to guide us, we will remember perfectly.
“The Holy Spirit is essentially taking over: guiding people’s thoughts and purifying the functions of memory so that things come out in a reliable way,” says McGill. “Most of the diaries we have were written by Protestants, but we have some Catholic writing too. One of those, Mary Xaveria, has the apparition of Saint Francis Xavier to help her.
He comes back in a ghostly form and helps her memory function. She writes that she remembers nothing when she takes up her pen, but then he comes along and the memories flow out.”
This ‘vividness’ – the visual qualities of memory provoked by Saint Francis Xavier – is a key area of interest for Will Duckett, PhD student at the Department of Psychology.
But he is interested in those who don’t have it. “Typically, most people will say that they can remember things by ‘seeing’ a picture of them in their head,” says Duckett. “But around six per cent of people have aphantasia: they don’t picture things in their heads when they remember them.”
“Two people standing close to each other will remember an event differently, simply because we bring so much of ourselves and our previous experience, expectation, knowledge, bias and thinking to bear on the way we encode that experience.”
And when asked to recount what happened, we bring all these things back into our reconstruction of the event.
Aphantasics demonstrate just how much more we still have to learn about memory. One might imagine, for example, that people who can’t remember things visually will have worse memories. Not so, according to research.
“There is a mismatch between how vivid imagery is in people’s minds and their memory,” says Duckett. “Whether you have a strong image in your mind or if you picture nothing at all, people appear to remember equally well across the board. “For example, if I showed a person an object with three pictures beneath it and asked which of the three pictures represents the object when it is rotated 90 degrees, most people would imagine it rotating in their heads to answer. Aphantasics don’t – but they can still do that task. They do it a little slower, but aren’t significantly less accurate, and even identify subtle difference better.”
Interestingly, Duckett points out, it’s estimated that 20 per cent of people in scientific or mathematical careers are aphantasic – while those who have vivid visual recall are over-represented in the arts. It all suggests that experiencing no mental imagery may be beneficial in some careers. The experiences of aphantasics demonstrates the importance of recognising that memory is subjective, says Duckett. Research has shown that the brain patterns of aphantasics and non-aphantasics are similar. “That’s an objective measurement, but their subjective experience is different. It’s not ‘wrong’.”
Delving further into this subjective experience is likely to have a direct impact on many memory related conditions. Gates Scholar and Second Year PhD student Julia Maybury is interested in episodic memory – memories about events in our lives that tend to involve specific details.
To better understand how we recall such events, she’s investigating memory precision, or how well we can remember specific details of retrieved memory representations at different times of day, and the role sleep might play. “There are pretty big age differences in terms of peak memory performance during the day,” she says.
“Older adults tend to perform better on memory tasks in the morning, while younger adults perform better in the afternoon and evening.” There are also differences in terms of ageing and sleep, too. Older adults tend to sleep less, says Maybury, and experience a reduction in deep sleep. This decline is important because deep sleep plays a key role in memory consolidation and storage, the process by which memories are transferred from short-term storage in the hippocampus to another brain region – the neocortex – which is associated with long-term storage.
However, we might not need to sleep deeply for this to happen, says Maybury. “I’m beginning to explore the potential benefits of short periods of wakeful rest on the memory. In my study, participants study information and are then asked to sit still in a darkened room with their eyes closed for 15 minutes. Then their memory for the learned information is tested. I am interested in whether this period of quiet rest could be as beneficial as a full night of overnight sleep.” A deeper understanding of the relationship between memory and sleep will help us design improved ways to remember as we age, she says.
So memory is functional: it enables us to do stuff. But it also makes us who we are: self might influence memory, but memory also influences self, says Simons. “Two people standing close to each other will remember an event differently, simply because we bring so much of ourselves and our previous experience, expectation, knowledge, bias and thinking to bear on the way we encode that experience.”
And when we’re asked to recount what happened, we bring all these things, again, into reconstructing the event. “And the other side is that our memories therefore influence the things we remember about ourselves – our interactions with the world, our place in the world, the way that we might be perceived by others, our sense of who we are, and our competencies and perhaps lack of competencies,” he says. Now, where did I put those keys?
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