The Magical Number 4: BBS Call for Commentators

Stevan Harnad harnad at
Tue Feb 8 16:00:28 EST 2000

        Below is the abstract of a forthcoming BBS target article


		by Nelson Cowan 

        *** please see also 5 important announcements about new BBS
        policies and address change at the bottom of this message) ***

This article has been accepted for publication in Behavioral and Brain
Sciences (BBS), an international, interdisciplinary journal providing
Open Peer Commentary on important and controversial current research in
the biobehavioral and cognitive sciences.

Commentators must be BBS Associates or nominated by a BBS Associate. To
be considered as a commentator for this article, to suggest other
appropriate commentators, or for information about how to become a BBS
Associate, please reply by EMAIL by March 7th to:

    bbs at

    or write to:

    Behavioral and Brain Sciences
    ECS: New Zepler Building
    University of Southampton
    Highfield, Southampton

If you are not a BBS Associate, please send your CV and the name of a
BBS Associate (there are currently over 10,000 worldwide) who is
familiar with your work. All past BBS authors, referees and
commentators are eligible to become BBS Associates.

To help us put together a balanced list of commentators, please give
some indication of the aspects of the topic on which you would bring
your areas of expertise to bear if you were selected as a commentator.
An electronic draft of the full text is available for inspection
with a WWW browser according to the instructions that follow after the


	Nelson Cowan 
	Department of Psychology 
	University of Missouri 
	210 McAlester Hall 
	Columbia, MO 65211, USA 
	CowanN at 

    KEYWORDS: attention, enumeration, information chunks, memory
    capacity, processing capacity, processing channels, serial recall,
    short-term memory, storage capacity, verbal recall, working memory

    ABSTRACT: Miller (1956) summarized evidence that people can
    remember about 7 chunks in short-term memory (STM) tasks. However,
    that number was meant more as a rough estimate and a rhetorical
    device than as a real capacity limit. Others have since suggested
    that there is a more precise capacity limit, but that it is only 3
    to 5 chunks. The present target article brings together a wide
    variety of data on capacity limits suggesting that the smaller
    capacity limit is real. Capacity limits will be useful in analyses
    of information processing only if the boundary conditions for
    observing them can be carefully described. Four basic conditions in
    which chunks can be identified and capacity limits can accordingly
    be observed are: (1) when information overload limits chunks to
    individual stimulus items, (2) when other steps are taken
    specifically to block the recoding of stimulus items into larger
    chunks, (3) in performance discontinuities caused by the capacity
    limit, and (4) in various indirect effects of the capacity limit.
    Under these conditions, rehearsal and long-term memory cannot be
    used to combine stimulus items into chunks of an unknown size; nor
    can storage mechanisms that are not capacity-limited, such as
    sensory memory, allow the capacity-limited storage mechanism to be
    refilled during recall. A single, central capacity limit averaging
    about 4 chunks is implicated along with other, non-capacity-limited
    sources. The pure STM capacity limit expressed in chunks is
    distinguished from compound STM limits obtained when the number of
    separately held chunks is unclear. Reasons why pure capacity
    estimates fall within a narrow range are discussed and a capacity
    limit for the focus of attention is proposed.


To help you decide whether you would be an appropriate commentator for
this article, an electronic draft is retrievable from the World Wide
Web or by anonymous ftp from the US or UK BBS Archive.
Ftp instructions follow below. Please do not prepare a commentary on
this draft. Just let us know, after having inspected it, what relevant
expertise you feel you would bring to bear on what aspect of the

The URLs you can use to get to the BBS Archive:



(1) There have been some very important developments in the 
    area of Web archiving of scientific papers very recently.
    Please see:

American Scientist:
Chronicle of Higher Education:

(2) All authors in the biobehavioral and cognitive sciences are
    strongly encouraged to archive all their papers (on their
    Home-Servers as well as) on CogPrints:

    It is extremely simple to do so and will make all of our papers
    available to all of us everywhere at no cost to anyone.

(3) BBS has a new policy of accepting submissions electronically.

    Authors can specify whether they would like their submissions
    archived publicly during refereeing in the BBS under-refereeing
    Archive, or in a referees-only, non-public archive.

    Upon acceptance, preprints of final drafts are moved to the
    public BBS Archive:

(4) BBS has expanded its annual page quota and is now appearing
    bimonthly, so the service of Open Peer Commentary can now be be
    offered to more target articles. The BBS refereeing procedure is
    also going to be considerably faster with the new electronic
    submission and processing procedures. Authors are invited to submit
    papers to:

    Email:   bbs at



(5) Call for Book Nominations for BBS Multiple Book Review

    In the past, Behavioral and Brain Sciences (BBS) journal had only
    been able to do 1-2 BBS multiple book treatments per year, because
    of our limited annual page quota. BBS's new expanded page quota
    will make it possible for us to increase the number of books we
    treat per year, so this is an excellent time for BBS Associates and
    biobehavioral/cognitive scientists in general to nominate books you
    would like to see accorded BBS multiple book review.

    (Authors may self-nominate, but books can only be selected on the
    basis of multiple nominations.) It would be very helpful if you
    indicated in what way a BBS Multiple Book Review of the book(s) you
    nominate would be useful to the field (and of course a rich list of
    potential reviewers would be the best evidence of its potential

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