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.
Baby brains
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 unnece
ssary 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?
Bugs Bunny and Prince Charles
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 participants were given a number of questionnaires to complete which were then taken away by a researcher and supposedly input into a computer. The researcher then returned to give the participant feedback, and told every one of them that they had well-coordinated eye movements and visual exploration skills, which the researchers claimed must have been formed right after birth. Participants were also falsely told that these superb visual skills were probably due to their having been born in hospitals which hung coloured mobiles above the cribs of newborns.
This was, of course, an elaborate lie. It was false feedback that the experimenters had predetermined, to give them an excuse to try to dig into the participant’s infancy memory banks. The participants were then told that in order to confirm that they had indeed had this experience with a coloured mobile, they would be hypnotically age-regressed to the day after birth, and subsequently questioned about what they remembered.
Age regression is a process in which an individual is said to mentally return to an earlier stage of life, giving them better access to memories formed at that time. It is a psychoanalytic concept that originates in notions posited by Sigmund Freud. It has also been discredited by numerous empirical studies – it just doesn’t work reliably as a memory aid.22 In other words, the researchers lied about both the premise of their study, that it was about visual skills, and the effectiveness of their supposed memory retrieval tools.
Yet, despite using these discredited memory retrieval techniques in their research, Cheryl and Melissa Burgess found that participants seemed to recall a high number of details about the time they had supposedly been regressed to. In fact, 51 per cent of participants claimed to be able to remember the coloured mobile they had been told about. And, much like Ruth from the beginning of the chapter, many participants who did not remember the mobile recalled other things such as doctors, nurses, bright lights, cribs and masks.
What was shocking was that almost all the participants who had these pseudo-recollections claimed that they were real memories as opposed to fantasies. The researchers had successfully generated false memories of an event that they had made up, from an age when the brain is physically incapable of forming such long-term memories. That meant that participants had been led to confabulate an entire memory out of thin air – they had generated impossible childhood memories.
Another researcher who wanted to get participants to believe the impossible was Kathryn Braun at Harvard Business School. In 2002, Braun and her colleagues23 conducted an elegant and very simple study that subtly manipulated an experience that many North American children share – a trip to a Disney resort. In what was an interesting crossover exercise between memory research and business, the team wanted to know whether an advertisement could induce a partial false memory.
In their first study, the team asked participants who had previously been to a Disney resort as a child to read an advert that suggested they must have shaken hands with Mickey Mouse when they were there. As the researchers had predicted, those who had read the advert were more confident that they had indeed personally shaken hands with Mickey Mouse than those who had not read the advert. In the second study, the team asked different participants to read a different advert for a Disney resort, this time one that suggested they had shaken hands with Bugs Bunny. Again, the advert increased confidence that the event had actually occurred.
While technically the former experiment could not rule out the possibility of having drawn on real memories, the latter seems more definitely to have convinced participants of an impossible event; Bugs Bunny is a Warner Bros character, so he would have had no place at a Disney resort. It seems that even something as subtle as brief exposure to advertising can manipulate our precious childhood recollections.
This research was important in demonstrating that we can manipulate or confabulate small moments in our lives that are linked to real events, such as a trip to Disneyland. To many, however, this seems a rather mundane snapshot – a false memory for a relatively trivial situation. The question then becomes: Can we do the same with more complex or serious events?
This was the exact question that psychological scientist Deryn Strange asked. She wanted to know whether we can implant false memories of complex events, including absurdly impossible events. Working at a research lab in New Zealand in 2006, Strange and her colleagues24 conducted an experiment with six- and ten-year-old children as participants. The children were given four images: two photos depicting actual events that they had experienced and two showing doctored photos of events they had not experienced. What Strange wanted to know was whether the plausibility of an event affected the likelihood of the children accepting it as true. She therefore gave the children both a ‘plausible’ doctored photo of them on a hot-air balloon ride, and an ‘impossible’ doctored photo of them having tea with Prince Charles.
After interviewing the children about the events three times over the course of three weeks, Strange found that a large number of them, 31 per cent of the six-year-olds and 10 per cent of the ten-year-olds, came to accept the false events as true and generated elaborate details about their experiences. While age seemed to matter – with younger children being more susceptible to generating false memories than older children – plausibility did not. Children came to believe that they had had tea with Prince Charles at the same rate as they came to believe that they had gone on a hot-air balloon ride.
It seems that we can generate convincing memories of false childhood events, even impossible ones, with very little effort indeed.
An idiot whispering like a drunken man
We are beginning to see ways in which memory can be treacherous and wrong. However, anecdotal evidence clearly shows that we are not always fooled – sometimes we realise that our memories cannot be true. When he created the False Memory Archive, artist and Wellcome Trust Engagement Fellow A. R. Hopwood asked the public to anonymously submit a ‘false’ or ‘non-believed’ memor
y. (He went on to work closely with a number of psychologists to develop a series of art works in response to research into false memory for an exhibition that toured the UK from 2013–14.) Here is an example of a false memory reported in the archive:25 ‘I was born in 1979 in Australia, and in 1980 we moved back to the UK to Coventry in the West Midlands, and I grew up there. I have a memory of sitting in a pram beside the construction site of the new Coventry Cathedral, and it’s about half built, with scaffolding everywhere. My mum is there, wearing a long green dress.’
There is nothing particularly unusual about this story. It all sounds plausible enough. There are a number of important details mentioned, including a visual memory of what the mother was wearing. It is also terribly mundane, which makes it feel like an unusual event to have made up or imagined. This image of normality, however, is shattered when the rememberer goes on to say: ‘The new cathedral was built between 1951 and completed in 1962, 17 years before I was born.’
This particular rememberer reportedly first questioned the memory when they returned to the cathedral, which reminded them of the memory. They then decided to check its accuracy. They suggested that the reason for the false memory was probably that they knew that the main cathedral, along with much of the rest of Coventry, was destroyed during World War II. They would therefore also know that it had to be rebuilt, and that this would most likely have included scaffolding. Together this made it easy to create an image, an impossible false memory, in which all these elements featured together.
The Memory Illusion Page 3