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From: quinn@unix.cis.pitt.edu (Clark  Quinn)
Newsgroups: comp.cog-eng
Subject: Re: Difference between a metaphor and a mental model? (Long)
Keywords: mental models, metaphors
Message-ID: <20080@unix.cis.pitt.edu>
Date: 18 Oct 89 19:43:10 GMT
References: <31966@ucbvax.BERKELEY.EDU> <786@cogsci.ucsd.EDU>
Reply-To: quinn@unix.cis.pitt.edu (Clark  Quinn)
Organization: Univ. of Pittsburgh, Comp & Info Services
Lines: 91


Don Norman's response to Thom Gillespie's question about metaphors and
mental models raises some more questions (as intended).  While I
basically agree with Don's characterization of metaphor (although I
really think we are talking about analogy), I want to paint mental
models in a slightly different way (there, a metaphor).  First, I am
going to discuss what I think the distinction is, and then discuss each
in greater detail.  

The confusion between metaphor and model lies in that both consist of
using a representation, easier to operate in, to solve problems or
understand information in a new or unfamiliar domain.  In the case of
metaphor, the representation that is manipulable is a familiar domain
which is used to apply to a different domain.  Models are a simplified,
conceptual representation of the domain, removed from many of the real
world attributes.  The simplified representation allows prediction and
inference about the domain.  Unfortunately, metaphors can serve as a
mental model.  This is unfortunate both because it confuses the issue
("don't tell me that a mental model is a bunch of metaphors"), and that
people tend to misuse metaphors as a result of thinking they are
models.  

As I mentioned in the beginning, Don's description of metaphor struck
me more as a description of analogy (of course, analogy was the topic
of my dissertation).  What is the difference between analogy and
metaphor?  I never have had a suitable explanation of the distinction.
I have reverted to lumping them together, but if pressed I back up and
leave metaphor to linguistic purposes and use analogy for problem-solving.
I have this intuitive feeling that metaphors are softer and squishier
than analogies (that metaphors only account for some of the relevant
features of a domain, and analogies are more comprehensive), but the
lines blur enough for me to consider them roughly equivalent.  So, when
I say metaphor, I mean analogy.  If you feel different, *please* tell
me why!

In analogy, when we need to understand something new, or we want to
solve an unfamiliar problem, we must fall back on what we know.
Typically, we access a domain that seems similar and try to extend the
relationships from the known domain to the new.  Teachers may also
provide us with analogies to help us.  Psychological evidence (Ratterman 
& Gentner, 1987; Gick & Holyoak, 1980, 1983; Quinn, 1989) suggests
that we use given analogies reasonably well, but don't come up with
them ourselves with any reasonable efficiency.  

Models, typically, are explanatory conceptual models that underlie the
operation of observed phenomena.  While an analogy can serve as a
mental model (such as flow in water explaining flow in circuits) they
often break down in extreme cases (current through a constriction
increases while current in a resistor is consistent with the current of
the entire circuit).  Models typically are the physical laws that are
operating to produce phenomena (like atomic structure predicting
elemental properties).  There is some evidence that people reason 
effectively, given good models (Keiras & Bovair, 1983), but the evidence 
also suggests that people do reason with models (Clement, 1988), incomplete 
and sketchy ones if necessary (Norman, 1983).

This is, I hope, a slightly more precise distinction between models and
metaphors (analogies).  I don't share Don's disenchantment with mental
models, but perhaps that is because I'm now working on mental models
for science understanding (can you say "vested interest"?). -- Clark

Clark N. Quinn
Learning Research and Development Center
University of Pittsburgh
Pittsburgh, PA 15260
(412) 624-9581
quinn@unix.cis.pitt.edu

Ratterman, M.J., & Gentner, D.E.(1987) "Analogy and similarity: determinants
of accessibility and inferential soundness."  Proceedings of the Ninth
Annual Cognitive Science Society Conference.

Gick, M.L., & Holyoak, K.J.(1980) "Analogical problem solving."  Cognitive
Psychology.

Gick, M.L., & Holyoak, K.J.(1983) "Schema induction and analogical transfer."  
Cognitive Psychology.

Quinn, C.N. (1989) "Analogical process performance and training."  Unpublished
Doctoral Dissertation.

Keiras, D.E., & Bovair, S. (1983). "The role of a mental model in learning to
operate a device."  TR 13.  University of Arizona.  

Clement, J.  (To appear) "Learning via model construction and criticism: 
protocol evidence on sources of creativity in science."  In J. Glover, R.
Ronning, & C. Reynolds "Handbook of creativity: assessment, theory, and
research.  New York, NY: Plenum.

Norman, D.A. (1983)  "Some observations on mental models."  In D.E.
Gentner & A.L. Stevens "Mental Models".