The Truth About Memory
When you ask Alex Mullen, the 23-year-old winner of the World Memory Championships, how victory felt, he laughs at himself a bit. Because nobody’s memory is perfect, right?
Mullen had only begun learning to train his memory three years earlier, after seeing a TED talk by the author Joshua Foer, which discussed groups of enthusiasts known as memory athletes who performed amazing feats, such as memorising thousands of random numbers or hundreds of names in just a few minutes.
What Foer had found, to his surprise, was that these people weren’t savants or freaks. They all swore they had perfectly ordinary memories until they started to train them.
That was an appealing message to Mullen, a medical student at the University of Mississippi, who was looking for ways to get a better handle on the huge volume of information he needed to recall. And when he began training, he got hooked on the rapid improvement in his memory and focus.
On the final day of the three day competition in December, where competitors test their minds by memorising numbers, names and faces, historic dates, words and cards in marathon hour-long sessions and quick sprints, Mullen was in second place. He’d set a new world record for memorising 3029 numbers in order over an hour.
One high-pressure round was left: a race to memorise the order of a deck of cards. “It’s the fastest and riskiest and scariest event,” Mullen says. A decade ago, beating 30 seconds was dubbed the “four-minute mile of memory”. Mullen needed 23 seconds or less to win. He made it in 21.5 seconds.
So how did he feel? “You know,” he says, speaking to me from his home in Mississippi. “It’s kind of ironic, but I sort of forget.”
The puzzle of memory is that on different occasions it can either restore the past to us in vivid detail or draw an embarrassing blank. Arts of memory like those Mullen uses were commonplace from the ancient Greeks to the Renaissance until thye became displaced by a machine, the printing press, which propelled the Reformation in Europe and left memory arts seeming like a relic of the medieval past.
In the midst of a second information revolution, scientists are increasingly discovering that memory’s power lies in processes that don’t resemble a machine at all: its strength is in the ability to forget as well as to remember. In the process, they are finding new insights, and validating ancient ones, about how we learn, remember and create.
“The most common misunderstanding is the idea that memory works like a video recorder or a photograph – maybe not an entirely accurate one, but that memory is basically a recording of what’s out there and a reproduction of that experience,” says Daniel Schacter, professor of psychology at Harvard University.
He and many other researchers have found that remembering is a much more active process of construction. The difficulty is not so much in storing information –getting knowledge into memory – but getting it out again when we need it.
Schacter calls failures like these, like when something’s on the tip of your tongue, “blocking”. It’s a familiar feeling for those of us who’ve ever forgotten a name; Schacter says when this happens to you, it’s likely that it was someone you don’t deal with very often.
“Studies have shown that the names we tend to block on are the names of people we are somewhat familiar with, but we haven’t encountered recently or haven’t encountered frequently. There may be not as strong a link between a face and a name for those faces that we block on,” he says.
We’re less likely to get stuck trying to recall something that comes to mind regularly, and the reason why may be embedded in the structure of the brain. “If you think about if briefly and superficially, what could be easier than putting something into something and taking it out again later?” says Michael Rugg, professor of behavioural and brain sciences at the University of Texas in Dallas. “It’s not like that – it’s a phenomenally difficult scientific question.”
Rugg says the standard model of memory – in a simplified form – is that the brain stores experiences and information by adjusting the connection strength of the synapses between neurons. If two neurons are activated at the same time, their connection grows stronger. Then the next time one neuron is activated, it’s more likely the other one will be too.
That has two implications: memory is flexible, meaning that it doesn’t need precisely the same trigger to recall a fact or experience every time; and reactivating a memory is likely to strengthen the synapse connections and make it easier to recall in future.
It’s this last fact that has attracted intense interest from cognitive psychologists. And although it seems like a simple, common-sense idea, the implications of a memory that is strengthened by this effort of retrieval overturn some popular and long-held notions about how we learn.
Robert Bjork, professor of psychology at UCLA, calls his lab the “Learning and Forgetting Lab”. It’s a measure of how important he regards both processes in the way our brain learns what is important for it to retain.
“You know, if I ask you what’s your current phone number or your address,” he says, “You don’t want to do what a lot of computer routines would do and give out a whole load of numbers and then have some sort of decision process on which one is current. When we stop using something like a phone number, the old one remains there but becomes inaccessible, which means it doesn’t interfere. Forgetting is adaptive, not just a weakness.”
When we remember something – a phone number, the capital of Bolivia – we don’t just reveal something what’s in our mind, we make it more retrievable in future. And things that are in competition with it – outdated numbers, last year’s test answers – become harder to recall.
The recommendation for teachers, then, is both familiar and a little surprising: if you want students to remember something, test them often. The attempt to recall the information signals its importance and relevance, and makes it easier to retrieve each time.
As a strategy this is familiar, because tests are a part of every teacher’s repertoire. But it’s surprising because we think the purpose of tests is assessment, when they turn out to be one of our most effective tools for learning.
“Testing has kind of got this bad name because people think of it in its assessment sense. There’s all these expressions, teaching to the test, a derogatory term,” says Bjork. “That’s been so unfortunate because quizzes and low-stakes testing are crucial to optimise learning. Testing has to be thought of in a pedagogical sense as well. In fact, in talking to some audiences I’ve intentionally used the term ‘retrieval practice’ to avoid getting into issues of, aren’t we testing our students too much?”
In 1978 researchers compared one group of students which had repeatedly studied material – cramming – with another which practiced retrieval. In an immediate test, the crammers did better. But two days later, they had forgotten half of what they learned, while the ones who practiced retrieval had only forgotten 13 per cent.
The testing effect appears in the real world of schools as well as in lab tests. In 2006, Columbia Middle School in Illinois agreed to host an experiment by Henry Roediger, a professor of psychology at the University of Washington in St Louis, who compiled his insights into memory and education into a book, _Make It Stick: The Science of Successful Learning._
For a year and a half, students followed the social studies curriculum – equivalent to history and geography – with additional ungraded quizzes for a third of the material, extra revision opportunities for another third of the material, and the rest taught as normal. At the end, students achieved a full grade level higher on the material that they had been quizzed on. But in the material where they just relearned the facts, there was no improvement.
These ideas have been known as far back as Aristotle and Francis Bacon, who recommended testing yourself over re-reading as the way to learn something by heart. Yet they come as a surprise to most students and many teachers. Robert Bjork surveyed 500 college students in 2007: “Overwhelmingly they were not studying in any ideal way, not incorporating these principles.” Re-reading and highlighting are the most common study practices.
As it turns out, this illuminates another principle about memory: we’re bad at understanding how well we know something. We prefer study strategies that promote a short-term feeling of mastery, when in fact our immediate performance doesn’t say much about our long-term learning. Fortunately, testing fulfils three functions: it reveals what we didn’t know, it reinforces what we’ve learned, and it makes us more likely to fill in the gaps next time.
Robert Bjork calls it “desirable difficulties”: the counter-intuitive notion that we’re learning best when we don’t feel like the material is that familiar. It’s better to space out tests than to cram in repeated re-readings of the textbook in one long session. It’s better for teachers to interleave different topics, returning to them from time to time, instead of dealing with them in blocks and moving on.
It’s better to ask students to generate their own answers with essays or a few sentences rather than using multiple choice tests (although multiple choice testing is still effective). It’s better to vary the conditions of practice to prevent learning become rote, and tied to one context – change the format of the test, or even the room you study in can help.
“If you take very seriously this evidence on spacing, variation, retrieval practice, introducing contextual interference, interleaving rather than blocking, your course will be dramatically different than a normal course,” says Bjork. “It will look haphazard in certain respects. It really will change it. And the reactions of your students won’t be immediately positive. You’re doing something that will slow their gains, and people do interpret their current performance as learning.”
William Emeny, head of maths at Wyvern College in Hampshire, is one teacher who’s taken on this challenge. Inspired by the evidence from psychology, he analysed the results of 240 students over the course of their GCSE studies. He realised that in year 9 up to December of year 11, students were effectively getting blocked practice: learning a topic then moving on to the next.
But over the course of year 11, they would take a practice paper every week, testing them on material from the whole three years, effectively introducing spaced retrieval and interleaving. The schools data showed a clear effect: students made more than twice the rate progress in the final six months, with spaced and interleaved practice, as they did in the previous two and a half years. That fact inspired a commitment to introduced spaced learning earlier.
As Bjork predicted, students are slow to realise the improvement. “I have had to be adaptive with strategies for student engagement – they like short, quick wins rather than the struggle for effortful retrieval!” said Emeny in an email discussing his approach with memory researchers. “The most effective strategy I have found so far is explicitly educating students about your research.”
Teachers who upend the curriculum to focus on memory also face objections that memorising isn’t the same as learning. In fact, rather than rote learning, which resembles the superficial fluency that students achieve from repeated study of material without testing, effective retrieval depends on deep understanding.
The key to building a strong memory is connecting knowledge with prior learning, being able to reproduce it in new contexts, and making it relevant and meaningful – all things which are components of good learning. (When students ask, “why do we need to know this?” and “will it be on the test?” they understand their process of learning accurately. Relevance matters to memory and if people are told they won’t be tested on information, or that it can be looked up on their internet later, their recall automatically gets worse.)
James Paterson teaches psychology at LVS Ascot in Berkshire. He’s also the two-times Welsh memory championship and, as he puts it, the Goran Ivanišević of the UK-wide competition (he’s a repeated runner-up).
He uses memory techniques with his students, but he also uses his own experience as a cautionary tale. Part-way through his university course, having newly become a memory master, he used his powers for evil: “Playing sport, going down the pub and thinking I had it in the bag because I was an expert memoriser.”
He struggled in exams, because he’d failed to pick up the analysis and connections he needed for good essays. Now, as a teacher, he uses the techniques of memory athletes to help students reinforce their understanding of complex concepts.
Memory athletes usually rely on two techniques: making abstract knowledge seem more relevant by connecting it to images of people and objects that we already remember, and organising the information in mental spaces called memory palaces.
“All mammals are very good spatial navigators,” says Henry Roediger. “What we’re probably doing is hooking in a very old evolutionary ability in that we remember spaces very well.” The hippocampus is sometimes referred to as the brain’s indexing system for memory, but it’s also responsible for spatial navigation.
At Paterson’s old school near Oxford, colleagues would take students on field trips to the Bodleian while he would sign them out to go to Starbucks. But in reality, it was a trip to a memory palace. There students would break down one of their revision topics and assign key facts and concepts to locations in the café, repeating the system for more than thirty essay topics in different places. (These days he uses locations on the school site.)
Perhaps the most powerful effect, Patterson says, is giving students the confidence that they can organise and retrieve all the information they need, freeing them to think in exams. “That stress-reducing quality is almost the biggest factor of all,” he says.
One reason it’s a mistake to see memory as opposed to higher-order thinking is that the link between recall and creativity is a powerful one: psychologists have found that the same brain regions involved in memory are also responsible for imagining the future. Test subjects who practice recalling detailed memories subsequently perform better at creative tasks, for instance.
“One of my old mentors had as his catchphrase, ‘Memory is the bridge from our past to our future’. It’s not our bridge from the past to the present,” says Michael Rugg. “We don’t have memories so when we’re 60, 70 years old we can sit on our porches and cheer ourselves up thinking of how happy our lives used to be. Memory exists, like all behaviour, to make us more adaptive in the future.”
Tips to remember:
1. Good input matters – there’s no substitute for paying attention
2. Make information memorable by connecting it to prior knowledge, elaborate on it, translate it to different contexts
3. It’s better for students to generate answers themselves than be told something
4. We’re bad at predicting what we’ll remember, but testing later tells us what we really know
5. Create desirable difficulties by spacing out tests and interleaving topics
6. Most students prefer bad study techniques: highlighting passages, repeated reading, cramming the same topic for hours