How Does Memory Work?
The biggest challenge in learning any new subject is to remember what you have learnt and hopefully retain the new information for long term. It doesn’t matter how old you are, memory fails all of us from time to time. Unless you belong to the “fortunate” group of hyperthymestics who possess an amazing autobiographic memory which enables them to remember everything they have experienced in vivid details.
On the other hand, who wishes to have that kind of memory anyway. I am sure you don’t want to remember all your past mistakes, humiliation, and traumatic events in great details forever.
But if you want to take on a learning activity of any nature, a good memory can serve you well. And I believe that you do have a decent memory whether you choose to believe it or not.
Think about it, to be able to fluently use your native language in speaking or writing, you have already remembered thousands of words or expressions. The fact that your language proficiency hasn’t diminished with time is good enough to prove that your memory is indeed doing a good job.
However, you may argue that all your language development happened in the past when your memory was still sharp. After a certain age, your memory somehow got “rusty”. And I am sure you are not the only one feeling like that.
Contrary to this popular belief towards memory, new research has found that human memory does not decline as sharply as once thought. An average person’s mental capacity can continue to improve well into the 70s. So if you are way short of being 70 years old, believe me, you do have a good memory to learn anything you wish.
Of course, forgetting is just part of the reasons for being human. Why some pieces of information such as people’s names or the whereabouts of your keys are lost has nothing to do with a defective brain, rather it is because the information was only stored in your short term memory.
Just like what its name suggests, by its very nature, such memory does not last forever. Moreover, your short-term memory can only hold around seven bits of information. So as the new information comes in, the old one is simply replaced.
Because of its transient character of your short term memory, it is obviously not the best option to store your knowledge. Therefore, the holy-grail of learning has to be your long term memory.
Your long term memory has such an amazing capacity to store information. So vast that it dwarfs even the latest hard-drive with the highest storage capacity. But how does certain information ends up there is still a mystery and no one knows for sure. One of the clues we do have is that repetition seems to play an important role in transferring information into your long term memory.
By repetition, I don’t mean that you have to keep reading a new word for thousands of times non-stop in order to remember it for good. That is in fact the least effective way for retaining new information, but the most effective way to invite boredom and destroy motivation for learning.
Instead, the spaced repetition technique is often recommended which is essentially revisiting previously learned material at increasing intervals of time between each revision session. This means once you have learnt the material, you revise it in one hour, then at the end of the day, then have another go on the following day, a week later, then 2 weeks, then one month and so on and so forth.
This technique was designed to overcome the transient nature of memory, first described by a German psychologist named Hermann Ebbinghaus who subsequently hypothesised the idea of the forgetting curve. A typical graph of the forgetting curve may look something like this.
The forgetting curve visually illustrates what happens to newly learned information when no attempt is made to retain it. As you can see, nearly half of the new information can be forgotten in a matter of hours. By the end of the month, only a small fraction of the original memory remains. And this does not even account for the potential interference from similar materials you are subsequently exposed to.
To counter the diminishing effect of the memory, frequent review of the material is necessary. This brings out the next question. Just how often should you review the material?
This depends on the material and how strong the initial memory is. The stronger and more “impactful” the first impression is, the less frequently do you need to review the information.
Memory technique such as mnemonics can certainly strengthen the initial memory, and I will elaborate on the subject of mnemonics in another post.
But an event like the disappearance of MH370 or 9/11 can often leave a lasting effect on the witness’s memory without any further review of the event. Obviously, not all learning material can be as dramatic as those impactful events. When it comes to memorising vocabulary, there has been suggestions that as many as 12 revisions are required for each word spaced out over a period of 12 months.
This may sound like a mammoth task scheduling revision sessions for thousands of words. Luckily, nowadays many computer programs have built-in algorithms to automatically schedule review sessions for you.
One of these programs on the Mac is Mental Case which I have used extensively. It is certainly very handy when it comes to exam preparation. It is basically a flashcard program which automatically schedule revision based on the spaced repetition principle. If you own a mac or MacBook, give Mental Case a try and you will find it very useful in your study.