RE: Data storage, data exchange, data manipulation

[Eric Bohlman <ebohlman@earthlink.net>]

6/29/01 6:33:00 PM, Joshua Allen <joshuaa@microsoft.com> wrote:

>Yeah, depends on what you mean by "understand".  There is the old rule
>of thumb that people can't keep a list of more than 7 things in mind at
>a time, yet we routinely have databases with millions of rows, and lists
>on this mailing list can be as large as 80 greek words at a time.

A very widely misunderstood rule of thumb.  What's true is that most people can hold at most 7 items 
in *working memory* at any time.  When you have a list in front of you and you're reading it, though, 
you generally need to keep at most *one* item of it in working memory; it does *not* follow that 
lists with more than 7 items are difficult to deal with.  So, for example, it's nonsense to say that 
a listbox or menu shouldn't show more than 7 entries at a time, because none of the items displayed 
have to be held in working memory.  OTOH, if the listbox only displayed one entry at a time, *then* 
you'd have concerns with working memory because in going through the list, you'd have to store all 
the items except the one currently being displayed in working memory.