Paul Leiberton asks:
>But isn't there research that would support the idea that th size of the
>item in STM affects the capacity of STM? While 7+/-2 works fine with
>numbers of one syllable, if the numbers given to a subject were longer
>(e.g., 178, 438, etc) what can be retained in STM drops.
>
It is true that we can store fewer large chunks in STM than small chunks -
the capacity of STM will fall near the larger end of the 7+/-2 range when
we are recalling random digits and will fall closer to the lower end when
we are recalling proverbs. But the trade-off between number of chunks
stored and size of chunks is not simple. Moreover, expertise in encoding
can dramatically increase the size of the chunks stored. For example,
Ericsson, Chase, & Faloon (1980) describe a subject who developed an
elaborate chunking strategy (with extensive practice) that enabled him to
increase his digit span from 7 to 79 digits. When given other memory tasks
(e.g., retention of random letters) his memory span was still 7+/-2. So
the concept of a chunk is still viable. With these expert memorizers, I
would even guess that what gets stored in STM is not the content of the
chunk but some sort of code that will enable retrieval of a complex memory
structure from LTM. In a sense, this probably also happens when we store a
word as a chunk. When we store a word in STM we might only store a link to
the LTM structure(s) that allow us to access all the meanings of the word.
Clearly, the question of what a chunk is - that is, what is the _content_
of the chunk that is stored in STM - is a difficult question to answer. Is
it like a zipped file (same content, just compressed?) or is it something
else (like a link to a web site)? I'm not sure this question is answerable
with the kind of data we can now produce. But the phenomenon represented
by the concept of chunking is important enough to warrant retaining the
concept.
Ericsson, K. A., Chase, W. G., & Faloon, S. (1980). Acquisition of a
memory skill. Science, 208, 1181-1182.
Claudia Stanny
________________________________________________________
Claudia J. Stanny, Ph.D. e-mail: [EMAIL PROTECTED]
Department of Psychology Phone: (850) 474 - 3163
University of West Florida FAX: (850) 857 - 6060
Pensacola, FL 32514 - 5751
Web: http://www.uwf.edu/psych/stanny.html
