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Knowledge and Memory

Summer Term in school inevitably means our thoughts turn to exams.  Over the coming weeks, many of our pupils will reach the pinnacle of their acquired knowledge to date on different topics and subjects and I have been talking to them about the fascinating ways that our brains commit that knowledge to our memories. 

As a scientist, I am particularly interested in how much more we now understand about the structure of memory. The process of making memories and retaining knowledge depends on the brain's neuroplasticity and its ability to reorganise itself throughout a lifetime by breaking and forming new connections between its billions of cells. When you learn something new, a group of neurons activate in a part of the brain called the hippocampus - like a pattern of light bulbs turning on.

The hippocampus has to store many new patterns every day and, when pupils are revising, this increases hugely. When something has been learnt and committed to memory the right trigger, such as an exam question, should cause the right pattern to be recalled. Pathways between neurons can be strengthened over time and simple repetition – retrieving a memory over and over again – is the best way to consolidate the pattern. At the time of learning a particular piece of information, memory retention is 100%. This drops rapidly to 40% within the first few days but the declination of memory retention then slows down.  The ‘forgetting curve’ (a concept discovered by a German psychologist, Hermann Ebbinghaus, in the 1800s) is exponential because memory loss is significant within the first few days of learning but the rate of memory loss decreases and the rate of forgetting is much slower from then on.

Science tells us that the ideal time to revise what you've learned is just before you're about to forget it. And because memories get stronger the more you retrieve them, you should wait longer each time: after a few minutes, then a few hours, then a day, then a few days. This is a technique known as ‘spaced repetition’. Ebbinghaus also discovered a phenomenon called ‘overlearning’ during his study on the forgetting curve. The basic idea is that, if you practice something more than would usually be required to memorise it, an effect of overlearning takes place. Overlearned information is stored much more strongly and therefore the effect of the forgetting curve for overlearned information is shallower. These concepts explain why we forget things so quickly after a week of cramming for an exam. Because the exponential curve of memory retrieval does not continue, the process reverses and everything is forgotten within a few weeks.

All of this explains why revision needs to be a repeated activity over a period of weeks and can’t be successfully achieved in an all-night cramming session! It is also why most of our Fourth Form who study Latin currently know much more than I do because it is such a long time since I chose to remember any of the Latin I learnt.

Reflecting on the complexities of memory and recall made me think about the way that knowledge becomes increasingly personal as we grow older. For example, I know that Revd. Moloney, our Chaplain and a teacher of Religious Studies, knows far more than I do about the works of different philosophers and about theology. And I know far more about immunology, genetics and microbiology than Revd. Moloney. But I am also fairly confident that, had he studied Biology in the depth and for as long as I did, he could know as much as I do, and vice versa. The difference is simply that we have chosen to know different things and to focus on different areas in our lives and careers. Up until the end of Fourth Form (Year 9), pupils across the UK have lots of shared knowledge because they have followed a very similar curriculum but this begins to change as they move to the next stage of their education with a more selective focus on the subjects in which they are more interested.  At GCSE, A level and in future degree courses, their knowledge will become increasingly personalised to their areas of specialism.   

Revising for exams is hard work; few people actively enjoy the thought of sitting a set of exams.  We can all remember the effort required to revise and there are undoubtedly moments when pupils will find themselves wondering why they need to know ‘all this stuff’ – especially as I’ve just said that they will forget so much of it and that there are bits they will be more interested in remembering than others!  But the effort required makes it all too easy to forget how fortunate we are to be able to learn, to acquire knowledge and to keep doing this throughout our lives. I encourage all our pupils to have perspective and a sense of balance – there is room for fun and enjoyment alongside hard work in Summer Term – but to value the knowledge they are acquiring now because, even if they won’t remember every fact and detail forever, it is building the foundations for their future learning, wisdom and skills. 

Rowena Cole is The Head of St John's School.  Follow her @rowenacole01 and stay in touch with all the news at St John's by following us @StJohnsSurrey