Charles Burnette asked:
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Although your distinctions address visceral, behavioral and reflective design,
your explanations of the terms visceral, behavioral and reflective seems to map
to McLean's physiological model of brain stem, limbic system, and neocortex and
even to the evolutionary model of brain development to some degree. Do your
distinctions have physiological correlates or should they be understood simply
as useful categories for thinking about design that are based on other kinds of
evidence or arguments? Also, since visceral and reflective thought also mediate
behavior where do you draw your lines or your fuzzy limits.
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In our theory, the visceral and behavioral levels take in sensory input and
control the muscles (motor system). But the reflective layer cannot directly
control behavior. The mechanism by which it exerts its control is by biasing.
See:

Norman, D. A., & Shallice, T. (1986). Attention to action: Willed and automatic
control of behavior. In R. J. Davidson & G. E. Schwartz & D. Shapiro (Eds.),
Consciousness and self regulation: Advances in research, Vol. IV. New York:
Plenum Press.

The division of the brain into three rough levels is a popular pursuit in
neuroscience, started by MacLean in 1973.

MacLean, P. D. (1990). The triune brain in evolution: Plenum Press.

MacLean, P. D., & Kral, V. A. (1973). A triune concept of the brain and
behaviour. Toronto: University of Toronto Press.

The pursuit is popular both among proponents and opponents. (Science thrives on
controversy.) Our model differs from MacLean's, if only because a tremendous
amount has been learned since his time. Our model is based on considerable
evidence from the neurosciences. The scientific version of our theory is:

Ortony, A., Norman, D. A., & Revelle, W. (In press). The role of affect and
proto-affect in effective functioning. In J.-M. Fellous & M. A. Arbib (Eds.),
Who Needs Emotions? The Brain Meets the Machine. New York: Oxford University
Press.

The work in the paper was then applied to design in:

Norman, D. A. (2004). Emotional Design: Why We Love (or Hate) Everyday Things.
New York: Basic Books.

The paper came first -- but given the vagaries of scientific publishing, with
its extensive review process (and waiting for all the other contributors to get
their papers to the book editor, I managed to write my book and get it published
before our scientific paper was published (I am supposed to get the final
revision in within a week, except that the editor (Fellous) hasn't yet sent me
his comments, and then the book gets published in early 2005. maybe. This will
be the third major revision of the paper.)

I can send the Ortony, Norman, & Revelle paper to anyone who requests it. (The
pdf version of the paper is 320 Kbytes, which is why I am not simply attaching
it.)

Don

Donald A. Norman
Nielsen Norman Group http://www.nngroup.com
[log in to unmask] http://www.jnd.org

Prof. Computer Science and Psychology
Northwestern University, [log in to unmask]