How Good Is Your Short-Term Memory?
Take the Test

Short-term memory can be defined as the ability to remember an insubstantial amount of information for a short period of time. An example of this is when someone is given a phone number and is forced to memorize it because there is no way to write it down.

Short-term memory should be distinguished from working memory. Working memory refers to the structures and processes used for temporarily storing and manipulating information, and plays a major role in the processes of thinking. Short-term memory, on the other hand, does not entail the manipulation or organization of material held in memory.

Test your short-term memory using the test in the box:

Digit span is a classic short-term memory task, in that it involves holding a small amount of material for a short period of time.

The most obvious fact about digit span is that it is limited to about six or seven digits for most people, although some people can manage up to ten or more, whereas others have difficulty recalling more than four or five.

What sets this limit?

Memory span measures require two things: (1) remembering what the items are; and (2) remembering the order in which they were presented. In the case of the digits one to nine, we already know the items very well, so the test becomes principally one of memory for order. If, however, I were to present to you with a sequence of digits in an unfamiliar language, Finnish for example, your span would be much less. You would of course have much more to remember, as you would need to recall the order of the sounds comprising the Finnish digits, as well the order of the digits.

Suppose I were to use words, but not digits. Would that matter? Provided I use the same word repeatedly, you would soon become familiar with the set, and would do reasonably well. However, if I were to use a different set of words on each trial it would become somewhat harder as you would again need to remember both what the items were and their order, although this would be easier than for the unfamiliar Finnish digits.

Let’s move to letters

Test yourself on the next sequence by reading each letter out loud, then close your eyes and try to repeat the letters in the order they are written.

CTAIILTCSFRO

Now try the next sequence.

FRACTOLISTIC

I assume you found the second sequence easier, even though it used exactly the same letters as the first. The reason is that the order of the letters in the second sequence allowed you to break it up into pronounceable word-like subgroups or chunks. In a classic paper, George Miller (1956) suggested that memory capacity is limited not by the number of items to be recalled, but by the number of chunks. The first sequence comprised twelve apparently unrelated letters, making it hard to reduce the number of chunks much below twelve, whereas the second could be pronounced as a string of four syllables that, together, made a sequence that, although meaningless, could plausibly be an English word.

Is your digit span rather lower than you might have hoped?

Don’t worry!

The good news is that everyone can take steps to improve their memory, and with time and practice most people can gain the ability to memorize seemingly impossible amounts of information. Thanks to modern neuroscience, we now know that the brain can reorganize itself and change in response to cognitive exercise, just like a muscle responds to physical exercise.