Contents
About the Book
About the Author
Title Page
Dedication
Epigraph
Introduction: You-ness, and clay with consequences – Why identity and memory are inherently linked
1. I remember being born: Infant mobiles, tea with Prince Charles, and Bugs Bunny – Why some of our childhood memories are impossible
2. Dirty memories: #thedress, time travellers, and the good old days – Why to remember is to perceive
3. Dancing with bees: Roofies, sea slugs, and laser beams – Why brain physiology can lead our memories astray
4. Memory wizards: HSAMs, braincams, and islands of genius – Why no one has infallible memory
5. Subliminal memories: Baby learning, psycho-phones, and brainwashing – Why we need to pay attention in order to form memories
6. Defective detective: Superiority, identity crisis, and making monsters – Why we are overconfident in our memory
7. Where were you when 9/11 happened?: Flashbulbs, memory hacking, and traumatic events – Why our memory for emotional events is flawed
8. Social me-dia: Media multitasking, groupiness, and digital amnesia – Why media moulds our memory
9. Tooky pulled my pants down: Satan, sex, and science – Why we can falsely remember traumatic events
10. Mind games: Secret agents, memory palaces, and magical realism – Why we should embrace our faulty memory
Acknowledgements
Endnotes
Index
Copyright
Dr Julia Shaw is a senior lecturer and researcher in the Department of Law and Social Sciences at London South Bank University, and is one of only a handful of experts in the world who conduct research on complex memory errors related to emotional personal events – so-called ‘rich false memories’.
Dr Shaw has published research articles in various international academic journals, has written textbook chapters, is a regular contributor to the popular science magazine Scientific American, and gives guest lectures and conference presentations around the world. She also teaches classes at undergraduate and graduate level, for which she has won two teaching excellence awards.
Besides her teaching and research, she has delivered general business and police-training workshops, has evaluated offender diversion programs, and works with the UK police to advise on historical sexual and physical abuse cases. She has also been featured as an expert on TV, radio, and in UK and international newspapers.
Think you have a good memory? Think again.
Memories are our most cherished possessions. We rely on them every day of our lives. They make us who we are. And yet the truth is they are far from being the accurate record of the past we like to think they are. True, we can all admit to having suffered occasional memory lapses, such as entering a room and immediately forgetting why, or suddenly being unable to recall the name of someone we’ve met dozens of times. But what if our minds have the potential for more profound errors, that enable the manipulation or even outright fabrication of our memories?
In The Memory Illusion, forensic psychologist and memory expert Dr Julia Shaw uses the latest research to show the astonishing variety of ways in which our brains can indeed be led astray. She shows why we can sometimes misappropriate other people’s memories, subsequently believing them to be our own. She explains how police officers can imprison an innocent man for life on the basis of many denials and just one confession. She demonstrates the way radically false memories can be deliberately implanted, leading people to believe they had tea with Prince Charles, or committed crimes that never happened. And she reveals how, in spite of all this, we can improve our memory through simple awareness of its fallibility.
Fascinating and unnerving in equal measure, The Memory Illusion offers a unique insight into the human brain, challenging you to question how much you can ever truly know about yourself.
To Fred.
‘Our memories are constructive. They’re reconstructive. Memory works … like a Wikipedia page: you can go in there and change it, but so can other people.’
– Professor Elizabeth Loftus
Nobel Laureates, on receiving their prize, get the equivalent of a Twitter post explaining what the award is for. Since I learned this, I have spent what is probably far too much time reviewing these 140-characters-or-fewer statements written to describe the profound impact laureates have had on the world.
One of my all-time favourites summarises the work of Seamus Heaney, who won the 1995 Nobel Prize in literature. It explains that he received the award ‘for creating works of lyrical beauty and ethical depth, which exalt everyday miracles and the living past’. What an incredible statement. Beauty, ethics and history, drenched with a sense of wonder and captured in just a few words. Every time I read that phrase I smile.
I write these laureate summaries on the little whiteboard I have on my desk as inspiration. I also use them in my lectures, and I try to weave them into my writing. They represent the notion that even humanity’s greatest achievements can be explained in plain English. This is an idea that has been echoed by many of history’s greats; that for our work to carry significance, we must be able to explain it simply.
I live by this philosophy of explanatory parsimony myself, though of course it does sometimes come at the cost of explanatory adequacy. In other words, when I explain concepts by using analogies, stories or simplifications, I always risk losing some of the nuances of the inherently complex issues under discussion. The subjects I will be examining here, memory and identity, are both incredibly complex, and in a single book I can only hope to scratch the surface of the incredible research being done at the intersection of those areas. But while I cannot promise to capture the whole scientific picture, I do hope to begin a questioning process, one which addresses fundamental queries that have likely been nagging at most of us ever since we first began to utilise the gift of introspection.
Like many others, I first noticed my ability to introspect when I was a child. I remember lying awake for hours as a little girl, unable to fall asleep because I was so engrossed in thought. Lying on the top bunk of my bed I would press the soles of my feet against the white ceiling of my room and reflect on the meaning of life. Who am I? What am I? What is real? While I did not know it at the time, this was when I began to become a psychologist. Those questions are about the core aspects of what it means to be human. As a little girl I had no idea that I was in such good company when I could not figure out the answers.
While I no longer have the bunk bed, I do still have the questions. Instead of philosophising to my ceiling I now conduct research. Instead of discussing who I am with my musical bear, I get to discuss it with fellow scientists, students, and others who are curious like me. So, let us start our adventure through the world of memory at the beginning of all beginnings, where re-search is me-search. Let’s ask: What makes you, you?
When we define ourselves we may think about our gender, ethnicity, age, occupation and the markers of adulthood we have achieved, such as completing our education, buying a house, getting married, having children or reaching retirement. We may also think about personality characteristics – whether we tend to be optimistic or pessimistic, funny or serious, selfish or selfless. On top of this we likely think about how we compare to others, often directly monitoring how our Facebook friends and LinkedIn connections are doing to see whether we are keeping up. However, while all of these descriptors may be more or less appropriate ways of defining who you are, the true root of your ‘you-ness’ almost certainly lies in your personal memories.
Our personal memories help us understand our life trajectories. It is only through my personal memories that I can recall the chats I had with one of my most inspiring undergraduate professors, Dr Barry Beyerstein, who taught me critical thinking and often shared lemon poppy-seed loaves with me. Or the talks after lectures with Dr Stephen Hart, who was the first person in my life to encourage me to go to graduate school. Or my mom’s serious car accident a few years back, which taught me the importance of expressing my emotions to the people I love. Such milestone interactions carry tremendous significant for us, and help us organise our personal narrative. More generally, memories form the bedrock of our identities. They shape what we think we have experienced and, as such, what we believe we are capable of in the future. Because of all this, if we begin to call our memory into question we are also forced to question the very foundations of who we are.
Take this thought experiment as an example: What if you awoke one morning and could not remember anything that you have ever done, or thought, or learned? Would this person still be you? In thinking about this scenario, we may instinctively react with a feeling of fear. We may have the immediate sense that everything we are could be taken away from us just by taking our memory, leaving us a shell of our former selves. If our memory is gone, what do we have left? We could easily picture it as the premise of a terrifying science fiction movie: ‘And then they awoke, none of them knowing who they were.’ Alternatively we may look on the prospect with a sense of relief that we would no longer be confined by our past and could start our lives anew, with our basic mental capacities and personality still intact. Or perhaps we find ourselves uncertain, vacillating somewhere between the two viewpoints.
While that kind of dramatic memory loss is thankfully rare in real life, at the same time our memories are subject to an enormous array of errors, distortions and modifications. I hope to shed light on some of them in this book. Armed with science and genuine curiosity, and sprinkling in little bits of my own escapades, I want to repeatedly challenge us to consider the many ways our memory can go awry. But how do we really begin to talk about the complex phenomenon of memory? Let us begin by looking at two of the key terms in memory research.
Semantic memory, also called generic memory, refers to the memory of meanings, concepts and facts. Individuals are often better at remembering certain types of semantic information than others. For example, someone who is great at remembering the dates of historic events might be terrible at remembering people’s names; another person might experience the opposite – being great with names but terrible at important dates. Although both of these are types of semantic memory, performance in such tasks can vary considerably between individuals.
Semantic memory works alongside episodic memory, or autobiographical memory. When you remember your first day of university, your first kiss, or the vacation you took to Cancún in 2013, you are accessing your episodic memory. This term refers to our collection of past experiences. It is our personal memory scrapbook; our mind’s diary; our internal Facebook timeline. Episodic memory is the mechanism that keeps track of memories that occurred at a particular time and place. Accessing these kinds of memories can be like reliving multisensory experiences. We can feel our toes in the sand, the sun against our skin, the breeze in our hair. We can picture the venue, the music, the people. These are the memories we cherish. It is this particular memory bank that defines who we are, rather than just the facts we know about the world.
Yet, this episodic memory that we all rely on so much is something many of us woefully misunderstand. If we can get a better picture of how it actually works, we will also gain a better understanding of the circus that is our perceived reality.
Once we begin to question our memories, and the memories of others, it seems less surprising that we can often disagree with friends and family about the details of important past events. Even the precious memories of our childhood can actually be shaped and reshaped like a ball of clay. And memory errors are not isolated to those who we may perceive as vulnerable – those suffering from Alzheimer’s, brain damage or any other notable impairment. Instead, memory errors can be considered the norm, not the exception. We will explore this potential discord between reality and memory in more depth later.
Similarly, false memories – recollections that feel like memories but which are not based on any real occurrence – are experienced all the time. And the consequences of such false memories can be very real. Believing inherently fictitious representations of reality can affect anything in our lives, potentially causing real joy, real upset, and even real trauma. Understanding our faulty memory processes may therefore help us establish a sense of how we can – and cannot – evaluate the information contained in our memories, and how to use them appropriately to define who we are. This has certainly been my experience.
Over the course of my years of research on memory, I have come to realise that we see the world in deeply imperfect ways. In turn this has given me a great respect for the scientific method and collaborative research – the collective enterprise of science. They offer the best hope of seeing through the veil of our imperfect perceptions to understand the workings of memory. However, even with the wind of decades of memory research in my sails, I must admit that there will likely always be some doubt as to whether any memory is entirely accurate. We can merely collect independent corroborating evidence that suggests that a memory is a more or less accurate mental representation of something that actually happened. Any event, no matter how important, emotional or traumatic it may seem, can be forgotten, misremembered, or even be entirely fictitious.
I now dedicate my life to researching how memory errors can occur, with a particular focus on how it is possible to shape our memories, and the memories of others, moulding actual past experiences to create a fictitious perceived past. What sets me apart from most of the other researchers doing similar work is the nature of the memories I generate. Over the course of just a few friendly interviews I can use my understanding of memory processes to severely distort the memories of my participants. I have convinced people they have committed crimes that never occurred, suffered from a physical injury they never had, or were attacked by a dog when no such attack ever took place. This may sound impossible, but it is simply a carefully planned application of memory science. And while it perhaps sounds a little sinister, I do it in order to help discover how severe memory distortions can come about, an issue which is particularly important for criminal justice settings where we heavily rely on the memories of eyewitnesses, victims and suspects. By creating complex false memories of crime that look and feel real in the lab, I highlight the distinct challenges our faulty memory processes pose for the law.
When I tell people this, they immediately want to know exactly how I do it. I’ll be explaining that later in this book but for now let me assure you that it involves no sinister brainwashing, torture or hypnosis. Due to our psychological and physiological configuration all of us can come to confidently and vividly remember entire events that never actually took place.
The Memory Illusion will explain the fundamental principles of our memories, diving into the biological reasons we forget and remember. It will explain how our social environments play a pivotal role in the way we experience and remember the world. It will explain how self-concept shapes, and is shaped by, our memories. It will even explain the role of the media and education in our (mis)understanding of the things we think memory is capable of. And it will look in detail at some of the most fascinating, sometimes almost unbelievable, errors, alterations and misapprehensions our memories can be subject to. While this is by no means an exhaustive study, I hope that it will nonetheless give you a solid enough grounding in the science involved. And perhaps it will leave you wondering just how much you truly know about the world, and even about yourself …
‘I REMEMBER BEING born’ – 62 million hits on Google. ‘I remember being a baby’ – 154 million hits. ‘I remember being in the womb’ – 9 million hits. People show a huge amount of interest for early childhood and even pre-childhood memories. We all want to grasp for our earliest memories and understand the impact they may have had on us. And perhaps we also want to know just what our memories are capable of during our infancy. Some people, like Ruth who responded to a Guardian online question on this topic, are keen to share their earliest recollections:
I was in a dark, warm place and I felt very secure. I could hear a steady, rhythmic blip blip blip sound (mother’s heartbeat) and I was comforted by it. Suddenly something terrible happened and it frightened me (mother’s screams, I’m sure). Then the blip blip sound returned and I thought everything was OK. Again the terrible thing happened and this time I knew it would happen again and again. I was terrified! My body was being painfully pulled and squeezed, mother was screaming and I thought something terrible, horrible and awful was happening! Then I came out and the doctor said something to me that was friendly and welcoming. I didn’t know the words but I got his message! … If my mother were still alive I would ask her if there was a large window in front of us with the sun shining brightly through it and if the doctor had a black moustache and was short and fat.1
Ruth is one of countless people who claim they can recall their birth. It is also common for people to claim to have memories from when they were babies, apparently remembering what their nursery or crib looked like, or recalling specific events. Over the course of my career I have heard many examples of this. ‘I remember all the little airplanes on the mobile above my bed.’ ‘I remember getting stuck in my crib and being scared because I was caught in the latch!’ ‘I remember that my favourite toy was a blue musical bear – I would pull the string and it would help me go to sleep. And how could I possibly know that, if not from memory, since we got rid of the bear when I was two?’
When you stop and think about it, it actually is pretty incredible. How could those people possibly remember any of those things at such a young age?
Well, they couldn’t.
Everyone has an earliest memory – clearly one of our memories must be the oldest. And, barring a belief in past lives, this memory must be of an event that happened within a knowable time frame – some time between now and when our minds first came into existence. But how can we discern whether the earliest memory we think we have is an accurate representation of something that happened?
When people claim to be able to remember the mobile that hung above their beds when they were a baby, or the hospital room in which they were born, or the warmth they felt inside their mother’s womb, they are recalling what psychologists refer to as impossible memories. Research has long established that as adults we cannot accurately retrieve memories from our infancy and early childhood. To put it simply, the brains of babies are not yet physiologically capable of forming and storing long-term memories. And yet many people seem to have such memories anyway, and are often convinced that they are accurate because they can see no other plausible origin for these recollections.
But actually, it does not take much to think of a few alternative explanations. Is there really no other way we could know what our mobile or crib looked like, or that we got caught in the latch of our crib, or that we had a musical bear? Surely there could be external sources for this information: perhaps old photographs or a parent’s retelling of events. We might even have memories of objects of personal importance because they were still around much later in our lives.
So we know that at least some of the necessary raw material to build a convincing picture of our earlier childhood can be found elsewhere. When we then place this information into seemingly appropriate contexts, such as a retelling of an early life event, we can unintentionally fill in our memory gaps, and make up details. Our brains piece together information fragments in ways that make sense to us and which can therefore feel like real memories. This is not a conscious decision by the ‘rememberer’, rather something that happens automatically. Two of the main processes during which this occurs are known as confabulation and source confusion.
As Louis Nahum and his cognitive neuroscience colleagues at the University of Geneva put it, ‘Confabulation denotes the emergence of memories of experiences and events which never took place.’2 This single word describes a complex phenomenon that affects many of our memories, particularly early ones. Of course, in the case of early childhood memories, this definition can fall a bit short: the event may have actually taken place, it is just impossible that our brains were able to store this information at such a young age and present it back to us in a single meaningful memory later on.
Alternatively, the belief that we have early childhood memories of events like birth may be simply due to misidentifying the sources of information. This is known as source confusion – forgetting the source of information and misattributing it to our own memory or experience. Wanting to remember our lovely childhoods, we may mistake our mother’s stories for our memories. Or we may meld into our personal narratives recollections told to us by our siblings and friends. Or we may mistake our imagination of what our childhood could have been like for a real memory of what it was like. Of course, memory errors can also be due to confabulation and source confusion working in tandem.
One of the first experiments which demonstrated that we can fiddle with our memories of childhood was conducted by memory scientists Ira Hyman and Joel Pentland at Western Washington University in 1995.3 Their 65 adult participants were told that they were taking part in an experiment investigating how well people could remember early childhood experiences. They were told they would be questioned about a number of events which they had experienced before the age of six, details of which had already been provided by their parents through a questionnaire. Finally, they were told that accuracy of recall was paramount.
But of course this was no regular childhood memory study. The researchers did not just want to see how well the participants remembered true events – they wanted to see how well they remembered events that had never actually happened. Among the true accounts obtained from the participant’s parents they had hidden a false account they had made up themselves: ‘When you were five you were at the wedding reception of some friends of the family and you were running around with some other kids, when you bumped into the table holding the punchbowl and spilled the punchbowl on the parents of the bride.’ Appropriately, the study is frequently known simply as the ‘spilling the punchbowl’ experiment.
It is easy to picture this event – it’s both emotional and plausible. We all know what weddings look like in our particular cultures and countries. We all know what a punchbowl looks like, or at least what it might look like. We all know that weddings are generally formal events, so we likely picture the parents of the bride as an older couple dressed up for the occasion. It is easy to picture ourselves running around in this situation at the age of five. And, as it turns out, it is even easier to picture all this if we imagine the event happening for a few minutes.
Each participant was asked first about two true events which the researchers had learned about from the participants’ parents, and then they were asked about the fake punchbowl incident. After giving participants basic information for each memory, the researchers asked them to try to form a vivid mental image of the event in order to access the memory. They asked them to close their eyes and imagine the event, including trying to picture what the objects, people and locations looked like. The researchers had the participants come back three times, each visit a week apart, and repeat the process.
What they found will astonish you. Just by repeatedly imagining the event happening, and saying out loud what they were picturing, 25 per cent of participants ended up being classified as having clear false memories of the event. A further 12.5 per cent could elaborate on the information that the experimenters provided, but claimed that they could not remember actually spilling the punch, and were therefore classified as partial rememberers. This means that a large number of people who pictured the event happening thought that it actually did happen after just three short imagination exercises, and that they could remember exactly how it happened. This demonstrates that we can misattribute the source of our childhood memories, thinking that something we imagined actually happened, internalising information that someone suggested to us and spinning it into a part of our personal past. It is an extreme form of confabulation that can be induced by someone else by engaging your imagination.
As an aside, besides being an amazing researcher who has contributed greatly to our understanding of false memories, Ira Hyman is a complex character, and instantly likeable. While we are talking about him, here is a quick multiple-choice quiz. Complete the sentence: Ira Hyman …
wrote his first academic publication about the Beatles.
has danced in a ballet.
hates pickles.
All of the above.
Of course, the answer is ‘all of the above’. And we love him for it.
Let’s back up and talk about the neuroscience of memory and exactly why early childhood memories are so prone to distortion in a physiological sense. When scientists talk about memory maturation – how our memories change as we age – they typically talk about changes in short-term memory and long-term memory separately. Short-term memory is a system in the brain that can hold small amounts of information for short periods of time. Really short periods of time – only about 30 seconds or so. For example, when we go to remember a phone number and repeat it to ourselves over and over until we dial it, in what is known as the phonological loop, we are using our short-term memories.
This system cannot carry much of a memory load. Since a seminal paper published in 1956 by George Miller from Princeton University,4 which also happens to be one of the most cited psychology papers of all time, the number of items we are said to be able to hold in working memory at once is seven plus or minus two. In other words, depending on our unique memory abilities and our mental state at the time, our capacity can be diminished to only holding five pieces of information or increased to holding nine. This variability is sometimes noticeable: when we get really tired many of us will find our short-term memory seems to all but disappear.
While Miller’s magic number, seven, has been questioned – according to a 2001 paper by Nelson Cohen from the University of Missouri5 the number of items we are able to hold may really be just four – the same principles remain; we can only keep a few things in short-term memory at any one time, and we can only do so for about 30 seconds.
A concept that often comes up in discussions of short-term memory is that of ‘working memory’. This term generally refers to a larger theoretical construct that has to do with how we flexibly keep information in mind while we do things like problem-solving – short-term memory is generally considered a type of working memory. Conceptual differences between these terms and the way they are used are often incredibly important for researchers, but for the sake of this discussion, I’m going to use them interchangeably.
Christian Tamnes and his fellow researchers at the University of Oslo in Norway6 examined the maturation of working memory in people between the ages of 8 and 22. In a paper they published in 2013 they found that changes in specific parts of the brain were related to improvements in working memory. In particular, they showed that maturation of the so-called fronto-parietal network in the brain was responsible for short-term memory development. The research showed that short-term memory is closely related to our ability to use our higher level thinking (frontal lobe) in harmony with our senses and language (parietal lobe), and that this ability improves with age. The more the relationship between these parts of the brain develops, the better we become at keeping items in short-term memory.
That sounds very neuroscience-heavy, so let me break it down. Our brain is divided into four major sections. The parietal lobe, which sits right at the top of the brain, is responsible for integrating sensory information and language, which is necessary for short-term memory. The frontal lobe is the section that sits at the front of the brain, behind the forehead. This part of the brain is responsible for higher cognitive functions such as thinking, planning and reasoning. The prefrontal cortex, the very front part of the frontal lobe, is assigned particular credit for complex thinking, and is associated with abilities such as planning complex behaviour and decision-making.
The prefrontal cortex is a part of the brain that used to be severed in some individuals who presented with severe mental illness, in a procedure known as a prefrontal lobotomy. These crude interventions, which were essentially completed by shoving an ice pick through the patient’s eye socket and into the brain, were known to severely affect the patient’s personality and intellect. This was considered justified at the time because it was thought to diminish the symptoms of their illnesses. Perhaps this was the case, but only in the sense that the operation typically made those who underwent it into zombies with virtually no personality whatsoever. Prefrontal lobotomies were conducted on many thousands of patients in the US, the UK, the Nordic countries, Japan, the Soviet Union and Germany, among others. The technique was first reported by Egas Moniz in 1936 – he surprisingly received a Nobel Prize for its discovery7 – but was generally abandoned in 1967, when psychiatrist Walter Freeman killed one of his patients.8
Who would have guessed we need such a big network to store such a seemingly small amount of information? Of course, as discussed in Chapter 2, in order to perform even small memory tasks we need to be able to do a tremendous number of things at once – we need to be able to perceive many things simultaneously and sort through them, and we need to be able to integrate that information into our existing memory schemas so that we can understand what it is we are seeing or remembering.
Bringing the discussion back to our early childhood memories, infants and children have been shown to have some short-term memory capability, albeit less than adults, and their memory strategy generally seems to be different – not so much in terms of the basic capacity of short-term memory (although there has been some debate about this over the years) but more in terms of how they approach their environment.
We’ve already mentioned that short-term memory can hold a certain number of items at any one time. And an item means different things at different times. Let’s take a phone number again. While you could try to remember each number individually, seven-five-three-eight-nine-six-zero, it’s easier for you to chunk the numbers together: seventy-five, thirty-eight, ninety-six, zero. By doing that you have just diminished the number of items from seven to four, making it considerably easier to keep the number in your short-term memory.
The use of the technical term ‘chunking’ for grouping things together when performing a task was coined by George Miller,9 the same man who brought us the paper on the magical number seven. The word is really referring to our ability to apply higher level cognitive processes (hence the importance of the prefrontal cortex) to what we consider a unit in our environment. By using our amazing ability to connect things, our brains can actively or passively organise information into pieces.
For example, if I say ‘Starbucks’ to you, you know that I mean a multibillion-dollar behemoth of a corporation that started in Seattle. Or, you know, coffee and free wi-fi. What this means is that you already have a representation of ‘Starbucks’ and what this concept entails in your brain. Thus, in memory processing terms, this counts as one unit of information, rather than the countless different items that you would have to hold in your short-term memory if I just gave you the isolated concepts associated with Starbucks; green, mermaid, coffee, wi-fi, comfy chairs, baristas, venti, grande, tall, latte, muffins, frappuccinos, America, misspelled names on cups … you get the idea.
The same goes for the rest of our world. The more we can group ideas or concepts together into chunks, the more impressive our working memory becomes. This is one of the abilities that improves as we get older; as we come to have more experience interacting with and interpreting the world around us, we get significantly better at chunking.
This means that we are better at holding things in working memory in adulthood than in childhood, and we are better in childhood than in infancy, since in our early years we are less able to process stimuli simultaneously, never mind to consolidate them into more permanent memories that can later be accessed in adulthood.
But what about long-term memory? First of all, while short-term memory is indeed very short-term, I should clarify that long-term memory is not necessarily very long-term. What memory researchers mean by ‘long-term’ is often anything that is kept in the memory for longer than 30 seconds (although, once again, researchers argue about this). However, the term also encompasses memories that we have until we die – including our episodic memories of events and our semantic memories of factual information. And the research on the kinds of long-term episodic memories that last days, years, or even a lifetime has come up with some fascinating results.
Early childhood recollection is one of the most researched areas in the world of memory science. Researchers generally agree that the magic age at which we can begin to form memories that last into adulthood is 3.5 years of age, although some, such as Qi Wang of Cornell University,10 argue this figure is likely to depend on the individual and can be anywhere between 2 and 5 years of age.
Why? Because in addition to necessary brain structures being underdeveloped, before the age of three everything is new, exciting and unfamiliar. We don’t know what is important, and we don’t have the structure – and the language – to make sense of the world, never mind the cognitive resources necessary to process it. Because young children and infants don’t properly understand or discriminate they don’t have any framework for understanding what they should be trying to remember and what they should be forgetting.
This results in a lack of the ability to form early childhood memories that last into adulthood, a phenomenon called childhood amnesia (or infantile amnesia). It is a phenomenon we have known about since 1893 when psychologist Caroline Miles first coined the term.11 In her research she found that most people’s earliest memories were between the ages of two and four. Our understanding of what this means and why it is the case has become significantly more refined since then, but her age estimate was pretty spot on. This is particularly amazing since the notion of false memories, inaccurate pseudo-memories of entire events that never happened, was not to be properly researched or understood for another 70-odd years – when researchers like Elizabeth Loftus came around and revolutionised how we think about memory malleability.
I am not saying that young children do not have memories – they do. Just not memories that generally last into adulthood. From the time we are newborns we can remember simple shapes and colour combinations for up to a day. They are even influenced by the kind of emotion these shapes are paired with; in a 2014 study, Ross Flom and his colleagues in Utah showed five-month-old babies geometric shapes – squares, triangles, circles – at the same time as exposing them to human faces that were either smiling, neutral or angry. This meant that they associated, say, circle with happy, or square with neutral. When tested shortly after exposure, infants were best at remembering the ‘happy’ shapes. The next day, however, they were best able to remember the shapes that were shown alongside a neutral face. How do we test babies’ memories? We measure how long infants look at things. Infants have a preference for new objects, which means that if they remember an object they are going to spend less time looking at it. The results of this study mean that not only can infants remember things for at least a day, which of course counts as long-term memory, but their brains also process and store information about the emotion that was attached to an experience.
From the ability to remember things for a day as an infant, memory capability then increases quite quickly, as two-year-old children can remember some of the events they experience up to a year later. This is why my two-year-old niece may remember who I am if there is a relatively short time between visits, but has trouble remembering me if I don’t see her for a year. It explains why we have all experienced this kind of scenario: ‘Remember Auntie Julia?’ … ‘No?’ … ‘She gave you that beanie baby when you were little!’ Sympathetic look in my direction.
We know that parts of the brain responsible for long-term memory, including part of the frontal lobe and the hippocampus, begin to grow at around eight or nine months,12 so before this it is impossible for infants to have any memories that exceed about 30 seconds. According to Harvard professor Jerome Kagan, one clue that children start to develop memory at about nine months is that this is typically when they become less willing to leave their parents. Being able to miss their mothers is taken as a sign that the infants have a memory of their mother having just been present, and notice when she leaves. According to an interview Kagan gave in 2014 to ABC News: ‘If you’re five months old, it’s out of sight, out of mind. You’re less likely to cry because you just forgot that your mother was ever there, so it’s not as frightening.’13
But whether these memories last into later years is a different question, one that has been addressed by Eunhui Lie and Nora Newcombe at Temple University in Philadelphia. In research they published in 1999,14 they tested the ability of 11-year-olds to recognise pictures of former classmates from their preschool years. Each child was shown a series of pictures of 3- and 4-year-old children, among which were some images of children they had gone to school with 7 years earlier. Most of the children did not recognise any of their former classmates. And if 11-year-olds have a problem with this task, what hope do adults have 20, 30 or 60 years later? Unless we went to school with the same children into our later years, or remained friends with them into adulthood, it seems likely that we would also be hard-pressed to remember any. And yet, we will have spent years with those children. These are not lost memories of short encounters with strangers. No, these are lost memories of years of interactions with the same individuals.
Luckily, long-term memory capabilities develop quickly as we age, both in duration and complexity, as we increasingly understand how the world around us works and what we should consider important. The basic foundations of long-term autobiographical memory are established within the first few years of life, but the main structures involved in memory (the hippocampus and related cognitive structures) actually continue to mature well into early adulthood. This finding has contributed to the notion of an ‘extended adolescence’ that lasts all the way to the age of 25, since the brain continues substantial maturation until at least this age.
So we can come to appreciate the reality and necessity of childhood amnesia when we realise that baby brains are just half-baked, unfinished. Not ready for playing in the big memory league.
So big, yet so undeveloped – cute squirmy babies with proportionally giant heads hold a world of potential. Fatty brains that need to become fatter (your brain is actually about 60 per cent fat), which are the most complex structures in the known universe, and which contain the makings of who we will become.
As just mentioned, in our first years of life our brains undergo absolutely massive physical changes. Wanting to know exactly what these changes look like, a team led by Rebecca Knickmeyer at the University of North Carolina used high-tech neuroimaging to take a peek into the brains of 98 children,15 a number of whom they were able to follow from the ages of two to four weeks right through to two years. In this research, published in 2008, they placed the children into what is known as a structural MRI – a magnetic resonance imaging machine – which can produce a 3D image of the physical structures of the brain. It’s really the stuff of science fiction and I would encourage anyone who is eligible to participate in local neuroimaging research – find a local research centre and you may get the chance to look into your own brain. I have done it myself and, of course, I immediately made the resulting image my Facebook profile picture. I have been told I have sexy ventricles.
Back to baby brains. What the researchers found was astonishing. Baby brains increased in total volume by 101 per cent in the first year, and by an extra 15 per cent in the second. That means they more than doubled in size. Broken down by when the MRIs were taken, the baby brain at two to four weeks of age is only about 36 per cent of the final adult volume, 72 per cent at one year of age, and 83 per cent of the final adult volume by two years. If we extend this developmental timeline beyond this initial study, according to another study by Verne Caviness and a team at Harvard Medical School,16 by the age of 9 the brain reaches about 95 per cent of the adult volume, and it is not until about the age of 13 that our brains reach their full adult size. This increase in brain size coincides quite nicely with the ages at which we start to be able to remember more.
But while tiny baby brains undergo rapid growth, they also face massive neuronal (brain cell) pruning. Pruning means that individual neurons disappear. This process begins almost from birth, and finishes by the time we hit puberty. According to Maja Abitz17 and her team, adults actually have whopping 41 per cent fewer neurons than newborn babies in important parts of the brain that play a role in memory and thinking, such as the mediodorsal nucleus of the thalamus. If you were to see this pruning process without knowing what was going on, you would almost certainly assume with devastation that the poor human you were observing was about to die a horrible brain death – all those beautiful, galaxy-like, neurons just disappearing forever. But, rest assured, things are meant to happen this way: with great brain growth comes great pruning. It is the process whereby our brain becomes more efficient. Our brains grow, and optimise. Grow, and optimise. Grow, and optimise. So, while the overall volume and size increase, the number of neurons actually decreases, to make way for only the most important and lasting information.
As brains lose neurons but grow in size, they also seem to change the way they make connections between neurons. As described in Chapter 3, neurons are the cells in our brain that process and transmit information through electrical and chemical signals. The connections between them, known as synapses, are often thought to be a reflection of learning processes such as those that allow our working memories to chunk information. Synaptogenesis – the formation of synapses – creates the kind of connections that allow us to form a physical web between associated concepts, as with the Starbucks, green, coffee, barista and wi-fi.
According to research done on this phenomenon by neuroscientist Peter Huttenlocher18 from the University of Chicago, there is an overproduction of synaptic connections in infancy, followed by persistence of high levels of synaptic density into late childhood or adolescence. This is followed by synaptic pruning, a process that normally ends around mid-adolescence. This means that we start off in life with many neurons and making an incredible number of connections, which we then retain into childhood. However, as we enter late childhood, our brains start to become better at knowing which connections we need to keep and which are superfluous. From there on until mid-adolescence our brains undergo a sort of spring-cleaning. Sure, when you were five years old you could list all of the dinosaurs, but did you really need all that information? Probably not, says your brain, and erases the connections and neurons responsible for much of this knowledge.
Pruning unnecessary synapses is a crucial step in the learning process, as in addition to forming meaningful connections between related concepts in the brain, we need to be able to get rid of inappropriate ones. We prune any potential networks between Starbucks and unrelated concepts such as, say, yellow, flowers and unicorns. This maximises our efficiency when we are trying to remember what Starbucks is, and our ability to apply this knowledge quickly when needed.
As we grow, the intricate web of unnecessary connections between neurons simultaneously proliferates and is pruned down, so that it can more easily be navigated. We grow a tremendous number of neurons, with many possible connections, then get rid of those neurons and synaptic connections that are used the least in what researchers Gal Chechik19 and colleagues from Tel-Aviv University call optimal ‘minimal-value’ deletion. Essentially we go from a cluttered brain to an elegant brain that is optimised for our particular environment, according to our individual learning, biology and circumstances.
So, due to structural insufficiencies, as well as organisational and linguistic deficits, memories of early childhood events cannot last into adulthood. But we have yet to really explore why we often think we can remember those years anyway. It is intuitively easy to understand how having insufficient brain capabilities mean that we can forget things that actually happened, but how can we seem to remember things that didn’t happen? Why, in the example from the beginning of this chapter, was Ruth so convinced she could remember being born? She had vivid, detailed, multisensory ‘recollections’. She described things she heard in the womb, her emotions and the physical pain she experienced during birth, the doctors and the hospital room in which she found herself. How is this possible?
To explain this, let’s turn to a very clever series of studies on infant mobiles. It is the mid-1990s. We are in Canada’s capital city, Ottawa. Psychological scientist Nicholas Spanos is sitting with his research team. They decide to embark on the task of demonstrating that it is possible to generate early memories of things that are not just unlikely, but impossible. After some discussion, they submit ethics for a study that will go on to rock the foundations of the scientific understanding of memory, and prove that false memories of early childhood events can be easily generated in most people. Tragically, on 6 June 1994 Spanos was involved in a fatal plane crash and so never finished the work himself.20 However, it was continued by his collaborators, Cheryl and Melissa Burgess, and in 1999 they published the results.
In the study,21