7 Clusters

Unlike long term memory, the relatively small amount of information that humans are able to save in
short-term memory shows easily definable limitations.

A psychologist by the name of George A. Miller noticed a trend among his experiments on short-
term memory tasks and he came up with “the magic number 7 plus or minus 2.” He found that the
amount of data that one is able to store within short-term memory is finite, and more specifically, is
thought to be limited to about 9 to 5 clusters (7 on average).  This basically means that most people
can store about 7 symbols at a time without creating the memorial associations related to long term

If you spend just a few seconds trying to memorize 7 symbols and then look away, you should be
able to recall the numbers as long as you continue to rehearse them.   Some people can remember
more symbols than others, however, very few people can hold upwards of 10 symbols in their short
term memory alone.

Telephone numbers and license plates are both numbers that people are often pressured to
memorize quickly. This is part of the reason why in most countries throughout the world they both
normally contain few more than 7 symbols.

Try it yourself:

Read this number out loud and try to memorize the sequence in only two seconds:     3749284
…not so hard huh?

Now try this one:  

…quite a bit more difficult right?
Organization for the Advancement of   
Interdisciplinary Learning