Your working memory is the memory you use to remember things in the short term - for example, when you look up a phone number your working memory helps you to remember it long enough to dial it. Working memory is also used as a "scratchpad" for tasks such as mental calculation. By understanding how working memory works we may be able to boost the amount of information we can store in our working memory. This page is about how we might do this, with a focus on remembering numbers.

Scientific research has demonstrated that when learning a list of items in memory, the length of the words matters. For example it is easier to remember the list "cat, dog, fish, elk, cow, eel, horse" than the list "elephant, monkey, buffalo, zebra, hamster, tiger, kangaroo", because the words in the first list are shorter. You can think of the short term memory for sounds - the "phonological loop", as being like a tape recording just a few seconds in length. Longer words take up more "space" in this recording.

One common measure of working memory is the "digit span", the number of digits in a number you can remember when presented quickly. Most people score about seven on this test.

However, because of the word length effect, some numbers take up more "space" in working memory than others. So the digit "Seven" takes up more space than the digit "Six" because it is a longer word. This also means that digit span is affected by the language you speak. Chinese speakers score on average higher than English speakers on digit span tests, other things being equal, because the Chinese words for digits are all one syllable words that can be said very quickly. The shorter words also give an advantage in mental calculation - because Chinese speakers can hold more numbers in their head at once, they get superior math scores on mental calculation tasks, other things being equal. (See this paper or these lecture notes for more on the science behind this).

We can use this to develop "mind performance hacks" to increase digit span and mental calculation ability. For a very simple hack, the theory suggests that learning to say "sev" rather than "seven" when memorising numbers could improve your performance on these tasks.

For a more advanced hack, we could use a system such as the MajorSystem to translate numbers into letters (note that here we are using the Major System to boost short term memory, rather than using it to code up words for long term memory as would be more usual). Using the major system, we could code up numbers as follows:

We could then represent two digit numbers by one syllable words - e.g. 23 could be "nam" - n for 2, m for 3, and the vowel "a" inserted to make it readable. By cramming two digits into a one syllable words, theory suggests that the working memory could be roughly doubled with this method.


I developed and tried the above system exploiting the Major System. Using it I do find a longer digit span, although not quite doubling it.

Also possible would be to try using this system while doing mental calculations, although this would be a lot more effort (relearning all the multiplication tables, for example, to get fluent in using it). Potentially though, it could result in significantly better mental calculation performance.

-- ThufirHawat, August 2008

See also

The techniques above are about using your working memory more efficiently, not about increasing its capacity. There is some evidence that it is possible to train working memory - see BrainTrainingGames for more information.