Article 1How to improve long-term memoryWe know how to form long-lasting memories, but how do we look afterthem? And what if they go missing?By Ed CookeThe Guardian, Sunday 15 January 2012Memories are constantly in flux, decaying as soon as they have begun toform. Although you cant count memories, if you could, youd soondiscover that more than half of what we experience is inaccessible tomemory within a single hour. For this reason, when learning, it is best tocontinuously and cyclically review information as you go.Optimal revisionDuring 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 thefew certainties of neuroscience: namely, that all memories growcontinuously weaker, but that the rate of "decay" lessens each time youreview the information.Ebbinghaus found that the ideal time to review a memory is just before youare about to forget it. Furthermore, because your memory gets strongerwith each review, the times at which you should review the information
increase exponentially. In other words, you should first review after a fewseconds, then after a few minutes, then an hour, a few hours, a day, a fewdays, a week, a month, three months, a year, three years, and so on. This isknown as spaced repetition, and is a very effective way of learning.The "forgetting curve" helps to explain why we so often remember nothingshortly after cramming intensely for an exam. Because all the learningtakes place in a week or so and is not subsequently reviewed, it begins tobe forgotten after only a month.Continuous testingAnother important way to keep your memories healthy is to practiseretrieving them. Actively testing yourself is a significantly better way tostrengthen your memory than just passively reviewing the information"contained" within it.This is actually quite counter-intuitive – youd think that being remindedthat Buzz Aldrin was the second man on the moon would be a moreeffective way of strengthening that memory than by being asked thequestion: "Who was the second man on the moon?". But science hasrepeatedly shown that "active retrieval" is a more effective way to boostyour 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 ahill, then being reminded of it is like being dropped by helicopter on top ofthe hill. You enjoy the view, and it feels like youve accomplishedsomething, but if youd climbed to the top yourself, youd have a better ideaof how to get there next time. In other words, when you are tested for amemory, you actively re-create or rediscover it in a way that positivelyreinforces that memory.Theres an interesting correlate of this that takes place during sleep. Recentstudies in neuroscience suggest the brain takes advantage of this "offline"period to repeat, and so select, what should be remembered in the longterm. Principally, the brain seeks patterns that exist across differentmemories that have formed in the recent past. As a result, it is often veryhelpful to review information you wish to remember just before you fallasleep. In the morning, what seemed complex and cloudy can appearsurprisingly lucid.
The danger of getting information wrongAn interesting side effect of how practice reinforces memory is that, whenyou 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 rememberBob Dylans name. Maybe six or seven times Id try but fail to recall it.Each time, Id think it would never happen again. But, sure enough, thenext time I had to remember his name, Id again fail to find the memory.In the end, I had to perform emergency surgery on the association andimagine him bobbing up and down in a dill salad, croaking away in hisinimitable style. This absurd image acted as a temporary crutch or scaffold,and in time my broken memory gradually healed. Now the name BobDylan comes to mind without a problem whenever I need it.How to find a missing memoryThis brings us to the question: how do you find a memory that is resistingbeing recalled? Weve all experienced the frustration of setting outconfidently to find a familiar memory – the name of an actor or title of abook, 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 theres nothing remotely shameful orsurprising about "failures" of recall. The sum of our memory is an almostinfinitely complex and chaotic web of connections: superimposing,jostling, crisscrossing, intermixing, competing; like a jungle, or compostheap, or mad, overcrowded house party. Its a miracle that we can recallanything at all.When we do find ourselves floundering, however, there are a number ofways we can go about increasing our chances of locating a lost memory. Asweve seen, a memory is never an isolated unit of information. There willalways be plenty of implicit context or "components" to the memory: thetime of day, weather, persons present and so on. Think of these as routesinto memory; they are ways of causing the full memory to become activeand coercing your brain into reproducing the whole story.By searching the fringes of the memory, you will increase the likelihood ofrecalling the nugget of information in the centre that you seek.