Seven plus or minus two

 

Professor George Miller’s research into short term memory concluded that people can retain seven plus or minus two items of information in working memory at any given time. Miller's research also showed that by organising items of information into larger chunks the capacity of short term memory could be increased.

Persecuted by the number seven

My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals. This number assumes a number of disguises, being sometimes a little bigger and sometimes a little smaller, but never changing so much as to be unrecognisable. The persistence with which this number plagues me is far more than a random accident. There is, to quote a famous senator, a design behind it, some pattern governing its appearances.  Either there really is something unusual about the number or else I am suffering from delusions of persecution.

Professor George Miller, Psychological Review, 1956

The limitations of short term memory

The results of Miller's research into working memory and the limited capacity of the short term storage process are well documented. His findings conclude that around seven items of information can be held in the short-term storage process of working memory. To handle more information than that, the information must be 'chunked up'. Individual words can be concatenated into sentences or even stories; thus more than seven words can be held in working memory.

Think inside the box

Miller discovered that an organised chunk of information functions as one item, and that a person could hold around seven chunks of information in working memory at the same time. Think of it as a seven boxes or containers in memory each capable of holding one chunk of information.

Miller understood this simple insight had profound implications. If items can be organised as chunks in memory, then memory capacity can be substantially increased by grouping things. To prove this, try holding the following sequence of 10 numbers in memory.

2 5 1 0 6 6 1 6 0 3

Although the ten items exceed the capacity of working memory you may recognise two historically significant dates within the sequence, 1066 (The Battle of Hastings) and 1603 (The Union of the Crowns). By grouping the digits that make the dates into 2 chunks you reduce ten items into four chunks that are easily held within working memory.

• 2
• 5
• 1066
• 1603

A man just beginning to learn radio-telegraphic code hears each dit and dah as a separate chunk. Soon he is able to organize these sounds into letters and then he can deal with the letters as chunks. Then the letters organize themselves as words, which are still larger chunks, and he begins to hear whole phrases. I do not mean that each step is a discrete process, or that plateaus must appear in his learning curve, for surely the levels of organization are achieved at different rates and overlap each other during the learning process. I am simply pointing to the obvious fact that the dits and dahs are organized by learning into patterns and that as these larger chunks emerge the amount of message that the operator can remember increases correspondingly. In the terms I am proposing to use, the operator learns to increase the bits per chunk.

Professor George Miller, Psychological Review, 1956

Seven Plus or Minus Two and other NLP Presuppositions form part of our NLP Practitioner Training Course.