1. Article 1
How to improve long-term memory
We know how to form long-lasting memories, but how do we look after
them? And what if they go missing?
By Ed Cooke
The Guardian, Sunday 15 January 2012
Memories are constantly in flux, decaying as soon as they have begun to
form. Although you can't count memories, if you could, you'd soon
discover that more than half of what we experience is inaccessible to
memory within a single hour. For this reason, when learning, it is best to
continuously and cyclically review information as you go.
Optimal revision
During the 19th century, Hermann Ebbinghaus, a German psychologist,
spent more than 15 years learning random strings of nonsense syllables,
and testing himself on their recall. What he found has become one of the
few certainties of neuroscience: namely, that all memories grow
continuously weaker, but that the rate of "decay" lessens each time you
review the information.
Ebbinghaus found that the ideal time to review a memory is just before you
are about to forget it. Furthermore, because your memory gets stronger
with each review, the times at which you should review the information

2. increase exponentially. In other words, you should first review after a few
seconds, then after a few minutes, then an hour, a few hours, a day, a few
days, a week, a month, three months, a year, three years, and so on. This is
known as spaced repetition, and is a very effective way of learning.
The "forgetting curve" helps to explain why we so often remember nothing
shortly after cramming intensely for an exam. Because all the learning
takes place in a week or so and is not subsequently reviewed, it begins to
be forgotten after only a month.
Continuous testing
Another important way to keep your memories healthy is to practise
retrieving them. Actively testing yourself is a significantly better way to
strengthen your memory than just passively reviewing the information
"contained" within it.
This is actually quite counter-intuitive – you'd think that being reminded
that Buzz Aldrin was the second man on the moon would be a more
effective way of strengthening that memory than by being asked the
question: "Who was the second man on the moon?". But science has
repeatedly shown that "active retrieval" is a more effective way to boost
your memory power than pure revision.
One way of understanding this is to consider how memories are, in a sense,
movements that your mind makes. If recalling a memory is like climbing a
hill, then being reminded of it is like being dropped by helicopter on top of
the hill. You enjoy the view, and it feels like you've accomplished
something, but if you'd climbed to the top yourself, you'd have a better idea
of how to get there next time. In other words, when you are tested for a
memory, you actively re-create or rediscover it in a way that positively
reinforces that memory.
There's an interesting correlate of this that takes place during sleep. Recent
studies in neuroscience suggest the brain takes advantage of this "offline"
period to repeat, and so select, what should be remembered in the long
term. Principally, the brain seeks patterns that exist across different
memories that have formed in the recent past. As a result, it is often very
helpful to review information you wish to remember just before you fall
asleep. In the morning, what seemed complex and cloudy can appear
surprisingly lucid.

3. The danger of getting information wrong
An interesting side effect of how practice reinforces memory is that, when
you get a test wrong, you are in some ways strengthening the wrong answer
– you are rehearsing failure, which can be dangerous …
I recall once getting into the bizarre habit of not being able to remember
Bob Dylan's name. Maybe six or seven times I'd try but fail to recall it.
Each time, I'd think it would never happen again. But, sure enough, the
next time I had to remember his name, I'd again fail to find the memory.
In the end, I had to perform emergency surgery on the association and
imagine him bobbing up and down in a dill salad, croaking away in his
inimitable style. This absurd image acted as a temporary crutch or scaffold,
and in time my broken memory gradually healed. Now the name Bob
Dylan comes to mind without a problem whenever I need it.
How to find a missing memory
This brings us to the question: how do you find a memory that is resisting
being recalled? We've all experienced the frustration of setting out
confidently to find a familiar memory – the name of an actor or title of a
book, for example – only to wind up empty-headed and confused.
Intriguingly, this often happens with information that we know we know.
The first thing to realise is that there's nothing remotely shameful or
surprising about "failures" of recall. The sum of our memory is an almost
infinitely complex and chaotic web of connections: superimposing,
jostling, crisscrossing, intermixing, competing; like a jungle, or compost
heap, or mad, overcrowded house party. It's a miracle that we can recall
anything at all.
When we do find ourselves floundering, however, there are a number of
ways we can go about increasing our chances of locating a lost memory. As
we've seen, a memory is never an isolated unit of information. There will
always be plenty of implicit context or "components" to the memory: the
time of day, weather, persons present and so on. Think of these as routes
into memory; they are ways of causing the full memory to become active
and coercing your brain into reproducing the whole story.
By searching the fringes of the memory, you will increase the likelihood of
recalling the nugget of information in the centre that you seek.