Off-topic: Magic Number 7 (WAS: Re: XML Editors - Word 2000??)

Dan Brickley Daniel.Brickley at
Fri Jul 2 14:48:24 BST 1999

On Fri, 2 Jul 1999, John E. Simpson wrote:

> At 10:23 AM 7/2/1999 +0100, Philip Nye wrote:
> >Rick Jelliffe wrote:
> ...
> >> 1) you have to remember the name, this is difficult if there are more
> >> than 7 names in frequent use;
> >> 2) if there are more than 7 elements at any one level, there is a
> >> selection 
> >> problem for GUIs: style provides a way to key hierarchy that provides
> >> reinforcing feedback;
> ...
> >Incidentally, where does the magic number 7 come from?
> When I was at AT&T years ago, there was a company legend (possibly
> apocryphal) about the length of US telephone numbers. According to this
> legend, Bell Labs had surveyed large numbers of customers and determined
> that, on average, people could remember 7 "things," plus or minus 3, about
> another "thing."

This has its roots in the paper "The Magical Number Seven, Plus or
Minus Two: Some Limits on our Capacity for Processing Information"
(1956), Psychological Review, by George Miller[1]. As it happens, Miller
has also been instrumental in creating the rather useful WordNet, a
freely available lexical database which I suspect might figure heavily
at some point in subject classification of Web resources for the
so-called Semantic Web. Therefore we're back on-topic again, phew.

[1] see for HTML version
    or see my CGI frontend lashup at if you're interested...

Daniel.Brickley at                  
Institute for Learning and Research Technology
University of Bristol,  Bristol BS8 1TN, UK.   phone:+44(0)117-9287096

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