Memory
A surprisingly potent technique can boost your short and long-term recall – and it appears to help everyone from students to Alzheimer’s patients.
BBC Future
- David Robson
When trying to memorise new material, it’s easy
to assume that the more work you put in, the better you will perform.
Yet taking the occasional down time – to do literally nothing – may be
exactly what you need. Just dim the lights, sit back, and enjoy 10-15
minutes of quiet contemplation, and you’ll find that your memory of the
fac
ts you have just learnt is far better than if you had attempted to
use that moment more productively.
Although it’s already well known that we should
pace our studies, new research suggests that we should aim for “minimal
interference” during these breaks – deliberately avoiding any activity
that could tamper with the delicate task of memory formation. So no
running errands, checking your emails, or surfing the web on your
smartphone. You really need to give your brain the chance for a complete
recharge with no distractions.
An excuse to do nothing may seem like a perfect
mnemonic technique for the lazy student, but this discovery may also
offer some relief for people with amnesia and some forms of dementia,
suggesting new ways to release a latent, previously unrecognised,
capacity to learn and remember.
A simple technique could boost our short and long-term memory. Credit: Getty Images.
The remarkable memory-boosting benefits of
undisturbed rest were first documented in 1900 by the German
psychologist Georg Elias Muller and his student Alfons Pilzecker. In one
of their many experiments on memory consolidation,
Muller and Pilzecker first asked their participants to learn a list of
meaningless syllables. Following a short study period, half the group
were immediately given a second list to learn – while the rest were
given a six-minute break before continuing.
When tested one-and-a-half-hours later, the two
groups showed strikingly different patterns of recall. The participants
given the break remembered nearly 50 percent of their list, compared to
an average of 28 percent for the group who had been given no time to
recharge their mental batteries. The finding suggested that our memory
for new information is especially fragile just after it has first been
encoded, making it more susceptible to interference from new
information.
Although a handful of other psychologists
occasionally returned to the finding, it was only in the early 2000s
that the broader implications of it started to become known, with a
pioneering study by Sergio Della Sala at the University of Edinburgh and
Nelson Cowan at the University of Missouri.
We could all do with fewer distractions in our lives. Credit: Getty Images.
The team was interested in discovering whether
reduced interference might improve the memories of people who had
suffered a neurological injury, such as a stroke. Using a similar set-up
to Muller and Pilzecker’s original study, they presented their
participants with lists of 15 words and tested them 10 minutes later. In
some trials, the participants remained busy with some standard
cognitive tests; in others, they were asked to lie in a darkened room
and avoid falling asleep.
The impact of the small intervention was more
profound than anyone might have believed. Although the two most severely
amnesic patients showed no benefit, the others tripled the number of
words they could remember – from 14 to 49 percent, placing them almost
within the range of healthy people with no neurological damage.
The next results were even more impressive. The
participants were asked to listen to some stories and answer questions
an hour later. Without the chance to rest, they could recall just 7
percent of the facts in the story; with the rest, this jumped to 79
percent – an astronomical 11-fold increase in the information they
retained.
Della Sala and Cowan’s former student, Michaela
Dewer at Heriot-Watt University, has now led several follow-up studies,
replicating the finding in many different contexts.
In healthy participants, they have found that these short periods of
rest can also improve our spatial memories, for instance – helping
participants to recall the location of different landmarks in a virtual reality environment. Crucially, this advantage lingers a week after the original learning task,
and it seems to benefit young and old people alike. And besides the
stroke survivors, they have also found similar benefits for people in
the earlier, milder stages of Alzheimer’s disease.
Our memory for new information is especially fragile just after it has been encoded. Credit: Getty Images.
In each case, the researchers simply asked the
participants to sit in a dim, quiet room, without their mobile phones or
similar distractions. “We don’t give them any specific instructions
with regards to what they should or shouldn’t do while resting,” Dewar
says. “But questionnaires completed at the end of our experiments
suggest that most people simply let their minds wander.”
Even then, we should be careful not to exert ourselves too hard as we daydream. In one study,
for instance, participants were asked to imagine a past or future event
during their break, which appeared to reduce their later recall of the
newly learnt material. So it may be safest to avoid any concerted mental
effort during our down time.
The exact mechanism is still unknown, though
some clues come from a growing understanding of memory formation. It is
now well accepted that once memories are initially encoded, they pass
through a period of consolidation that cements them in long-term
storage. This was once thought to happen primarily during sleep, with
heightened communication between the hippocampus – where memories are
first formed – and the cortex, a process that may build and strengthen
the new neural connections that are necessary for later recall.
The brain might use downtime to cement what it has recently learnt. Credit: Getty Images.
This heightened nocturnal activity may be the reason that we often learn things better just before bed. But in line with Dewar’s work, a 2010 study by Lila Davachi
at New York University, found that it was not limited to sleep, and
similar neural activity occurs during periods of wakeful rest, too. In
the study, participants were first asked to memorise pairs of pictures –
matching a face to an object or scene – and then allowed to lie back
and let their minds wander for a short period. Sure enough, she found
increased communication between the hippocampus and areas of the visual
cortex during their rest. Crucially, people who showed a greater
increase in connectivity between these areas were the ones who
remembered more of the task, she says.
Perhaps the brain takes any potential down time
to cement what it has recently learnt – and reducing extra stimulation
at this time may ease that process. It would seem that neurological
damage may render the brain especially vulnerable to that interference
after learning a new memory, which is why the period of rest proved to
be particularly potent for stroke survivors and people with Alzheimer’s
disease.
Other psychologists are excited about the
research. “The effect is quite consistent across studies now in a range
of experiments and memory tasks,” says Aidan Horner
at the University of York. “It’s fascinating.” Horner agrees that it
could potentially offer new ways to help individuals with impairments to
function.
Scheduling regular periods of rest could help us all hold onto new memories. Credit: Getty Images.
Practically speaking, he points out that it may
be difficult to schedule enough periods of rest to increase their
overall daily recall. But he thinks it could still be valuable to help a
patient learn important new information – such as learning the name and
face of a new carer. “Perhaps a short period of wakeful rest after that
would increase the chances that they would remember that person, and
therefore feel more comfortable with them later on.” Dewar tells me that
she is aware of one patient who seems to have benefitted from using a
short rest to learn the name of their grandchild, though she emphasises
that it is only anecdotal evidence.
Thomas Baguley
at Nottingham Trent University in the UK is also cautiously optimistic.
He points out that some Alzheimer’s patients are already advised to
engage in mindfulness techniques to alleviate stress and improve overall
well-being. “Some [of these] interventions may also promote wakeful
rest and it is worth exploring whether they work in part because of
reducing interference,” he says, though it may be difficult to implement
in people with severe dementia, he says.
Beyond the clinical benefits for these patients,
Baguley and Horner both agree that scheduling regular periods of rest,
without distraction, could help us all hold onto new material a little
more firmly. After all, for many students, the 10-30 percent
improvements recorded in these studies could mark the difference between
a grade or two. “I can imagine you could embed these 10-15 minute
breaks within a revision period,” says Horner, “and that might be a
useful way of making small improvements to your ability to remember
later on.”
In the age of information overload, it’s worth
remembering that our smartphones aren’t the only thing that needs a
regular recharge. Our minds clearly do too.
David Robson is a freelance writer based in London. He is @d_a_robson on Twitter.
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