Working Memory

Bill Skaggs skaggs at bns.pitt.edu
Mon Jun 12 12:29:07 EST 2000

"John H." <johnhkm at netsprintXXXX.net.au> writes:

> [[12/06/00 15:37
> I have been reading a bit about working memory lately but I still haven't
> found a formal definition of the same. From what I can gather working memory
> is defined as the ability to hold a number of elements simultaneously as
> elements for attention. I wonder about this simultaneous bit, but can anyone
> help me here? Is working memory solely regarded as that which can be held
> simultaneously, or does the concept allow consideration for movements into
> and our working memory over given time spans?
> Does a formal definition exist? If so, where can I find it?

The crucial factor is not simultaneity but duration of usefulness.  As
defined by Honig, who I believe was the first to use the term
extensively, "working memory" is contrasted with "reference memory".
Working memory is memory whose usefulness is limited to a specific
period of time, whereas reference memory is useful indefinitely.  A
classic animal behavior task involving both types of memory is
retrieving food reward on an eight-arm radial maze, where only four of
the arms are ever baited (the same four arms on every trial).
Remembering which four arms are baited is reference memory;
remembering which arms have already been visited on the current trial
is working memory.

Note that in some tasks, working memory can last for a substantial
period of time.  When I leave my car at the airport, for example, my
memory of the parking location is working memory, even if I need to
retain it for a week, because once I've retrieved the car, the memory
no longer serves any purpose.

Note also that the distinction between working and reference memory is
defined in terms of the way the memory contributes to a task, not in
terms of the brain mechanism by which the memory is encoded.  Olton,
who popularized the notion of working memory, theorized that there is
in fact a physiological distinction between them, but it's an
empirical question rather than a matter of definition.

	-- Bill

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