How Much Can You Remember?

seven-magic-number.png

Monday, 7.14pm

Sheffield, U.K.

Without memory, there is no culture. Without memory, there would be no civilization, no society, no future. – Elie Wiesel

It’s easy to sit staring at a blank screen waiting for the perfect line with which to start your piece. Experienced writers will tell you that you just need to start writing, put anything down because the first thing you need to do is get your mind moving.

John McPhee in his book Draft No. 4 and the essay of the same name writes about a hypothetical writer struggling with the start, blocked from beginning. He suggests starting the piece with “Dear Mother” and then writing about how frustrated you are, whinge all you like, and once you’ve done a bit of that you start writing about your topic and some of the words are relevant. And then later you go through your work and cut out everything that is irrelevant or whinging and keep what’s important.

I think that’s good advice but really you don’t have to just complain. On any large project there’s lots of ancillary material, the stuff that sits around the edges of the actual product of your creative work. That “stuff” is important – no one creates something perfect the first time. It’s the accumulation of all that stuff that eventually helps you create something useful. We don’t often get to see that part of a writer’s process because a finished, printed, perfect book hides all of that.

I was wondering about this as I went about researching my latest project. A single idea might require you to read five or six papers before you start to get a feel for the shape and size of the idea and what it’s trying to get across. Some days you have something to say. Other days you’re just reading and figuring things out. So should you just wait until you have something to write or should you just get on and do something – have that daily practice and eventually, from the mass of what you do, extract the bits that might make sense in a packaged form?

I think that’s a sensible approach and lines up with “literate” methods of creation which I’ve described previously. So I’m going to keep doing that – mixing thinking about the topic and the state of my studies with content that might make its way into a package and hope that works.

Now, back to the actual focus of this post, which is one of memory. What is memory anyway?

Any discussion of memory will probably start with George Miller’s famous 1956 paper “The magical number seven, plus or minus two: some limits on our capacity for processing information” one of the most cited papers in cognitive and psychological science. Miller described a set of experiments that seemed to show there are limits to how much we can remember, and suggested that the upper limit was around seven.

That clearly doesn’t mean that we can only hold seven things in memory. You hold many faces, many names, many types of data and information in your memory. You probably know thousands of words in your preferred language. You’ve learned that over time, however, and repeated and rehearsed that information in such a way that it’s in long-term memory and you can access it at will. Miller talks specifically about one-dimensional data and the capacity of the brain to process that kind of information.

For example, if you listen to a number of tones and are asked to then remember them and label them you’ll do fine if you hear three tones, ok if it’s four, but once you get to five to seven different tones it’s much more likely that you’ll get confused. Performance drops off rapidly if you’re asked to remember more than seven.

Miller wrote at a time when communications systems were being developed and so the nascent theories of communications technology played a part in the research. You might think that tone identification is a rather pointless exercise, but it becomes less so when you think about morse code. That’s a tonal system with two tones – a long and short one. You might be able to reduce the length of messages by using three tones but at the cost of increasing confusion and the changes of losing the message because you can’t transcribe it correctly.

One way to think about the issue is shown in the diagram. You have an input signal and an output signal. In the middle you have the potential for variation in the input and variation in the output. You could make mistakes in sending the message as when you press the wrong tone for your morse code character or you could make a mistake in taking it down. The extent to which the input variance and the output variance are correlated is determined by the overlap. If you have a poor sender and a poor listener their overlap will be low, with errors in sending and receiving. Conversely, with two expert operators you have a high chance of getting the message across. I remember speaking once to an amateur radio enthusiast who talked proudly about how a listener from across the world had commented on “how sweet his morse code was.”

Miller’s paper is over half a century old and later work has not really done much to build on those insights. It’s likely that seven is an optimistic number and the actual number of things we can hold is closer to three or four (Cowan, 1998), when you remove the ability to rehearse (repeat to remember) or to carry out long-term memorisation.

What we’re not interested in, however, is how much you can remember mentally but how to use note taking to help you remember more and that requires understanding the concept of dimensions a little more clearly. Let’s look at that in the next post.

Cheers,

Karthik Suresh

References

Cowan, N. 1998, “Visual and auditory working memory capacity”, Trends in cognitive sciences, vol. 2, no. 3, pp. 77-77.

Miller, G.A. 1956, “The magical number seven, plus or minus two: some limits on our capacity for processing information”, Psychological review, vol. 63, no. 2, pp. 81-97.

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