Summary of key facts about working memory

1. Working memory is what we can keep active in the mind while we perform mental operations.
2. There are only a limited number of chunks of information we can keep in working memory at one time (between 4 and 10). When new ones are added, old ones are pushed out.
3. The size of the chunks is not limited. In fact, sometimes making them bigger makes it easier, particularly, if we increase their size by making them more meaningful to us.

What is working memory and why it matters for good performance

Working memory is the small mental buffer you use to keep things on top of mind so that you can do something with them. You need working memory when you do mental calculations, compare ideas, recognise faces, drive a car, or when you write a sentence. Without it, we would be too slow at doing any of these things.

There are many things we don’t know for certain about working memory but we are sure, it is very limited. It can only hold about 7 discrete items at once (some people say it’s even less but definitely no more than 10).

A good simple example is writing down a phone number someone is dictating to you. Unless you focus, you can usually only do it a few digits at a time and nobody can do a whole 10 digit phone number. Just remembering each digit individually and then writing them down one by one is impossible without some mental tricks. And it’s these sort of tricks that we can learn from.

The very simplest mental trick is to chunk the numbers. So instead of putting 2 3 5 6 7 8 9 1 9 3 6 into your working memory buffer one by one, you can do 2356 7789 1936. Now you only have three chunks in working memory. This is easier but the chunks don’t mean anything, so it will still be a challenge. So instead, you can decide to chunk the numbers in a way that has some meaning. 23 (how old your cousin is) 5677 (a house number) 89 (number of a road you travel on) 1936 (date in history). All of a sudden, it’s much easier to quickly put the numbers into your working memory and keep them there. (The world record holder can use this approach to memorise 514 digits in 5 minutes.)

So what we did was:

1. Create chunks
2. Make the chunks bigger and richer by adding meaning

This seems like a paradox. If working memory is limited, how can we make it easier to think when we put more in? That is the second thing we are sure about when it comes to working memory. Even though the number of chunks we can keep in it is limited, the size of the chunks is not. Chunks, by the way, is the technical term in the research, so we will use this here, as well.

Working memory in practice

How does this work in practice? We use working memory for much more than just writing down phone numbers. It is involved in everything we do. Working memory is fundamental to speaking, reading and writing. Here is another example. Take this English sentence:

Books are often very expensive.

It probably took you less than a second to read and understand. (Assuming you are a native speaker who does not have dyslexia or some other difficulty that slows down processing.)

Let’s take a similar sentence in another language. Let’s say Czech. You probably don’t speak Czech but, it should be very easy to translate, if I give you all the words first.

Here is an alphabetical list of the four words that will appear in the sentence.