Darwin-L Message Log 6:39 (February 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.

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<6:39>From Robert.Richardson@UC.Edu  Tue Feb  8 17:13:12 1994

Date: Tue, 08 Feb 1994 18:10:45 -0500 (EST)
From: "Bob Richardson, University of Cincinnati" <Robert.Richardson@UC.Edu>
Subject: quinarianism
To: darwin-l@ukanaix.cc.ukans.edu

Regarding Peter Stevens' earlier posting in which he said:

>The title of G. A. Miller's article in Psychol. Rev. 63: 81-
>97. 1956 says it all:  "The magical number seven, plus or
>minus two: some limits on our capacity for processing
>information."

The title may not quite say it all.  Miller's proposal was important and
interesting; however, it is limited in crucial ways and unclear in others, and
both should make us cautious about applying it quickly.

First, Miller's limitation to (roughly) seven chunks is intended to apply only
to short term memory.  At the time, that would mean that it applies to a system
in which the information decays in roughly 15 seconds.  Long term memory would
not have been subject to similar limitations. (The model of memory on which it
is based is also problematic.)  We all routinely hold more than seven digits in
long term memory.

Secondly, the critical notion of what counts as a "chunk" is not cleanly
characterized.  For example, a digit such as "5" is a chunk, but so is a letter
such as "A" or a word such as "George".  The consequence of this variability is
that what can be stored over the short term is variable itself, depending
critically on how it is represented.  Miller found one subject that could
remember up to 40 binary digits using clever schemes of recoding.  The familiar
mnemonics for Geological eras are an example which is familiar to many readers
of this list.

There is not likely to be any simple and straightforward application of
Miller's rule to biological problems.

Robert C. Richardson
Richards@UCBEH.san.uc.edu
Richards@UCBEH.bitnet

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