[From Wayne Hershberger]
Bill Powers:
Bill, your essay on the perceptual basis of HPCT (WTP, 921003) is
marvelous. Since I am way behind on my E-mail I have had to limit
the threads I read and I overlooked this gem originally. Only
after reading and commenting on the later posts by Bruce, Martin
and yourself entitled "percepts" (see below) did I belatedly
discover your 921003 essay. I think I agree with everything you
say (I want to read it several more times to be sure), except one.
The thing that bothers me is your wording of the second sentence
in the following paragraph--which seems to suggest that a
perceptual world passes through the receptors into the brain.
I would prefer something like this: "It is that the world we
experience directly is ALREADY being shaped by the perceptual
processes even as we are experiencing it."
There is, of course, another interpretation of all this, the
one underlying HPCT. It is that the world we experience
directly has ALREADY passed through the sensory inputs by
the time we experience it. It is the direct manifestation of
the brain's way of reading the same world that scientific
instruments read. It is the brain's way of realizing, of
making apparent, the ordering of the universe. Scientific
instruments create a different realization of, we presume,
the same underlying order (WTP, 921003).
Martin: Thanks for posting (920924) the Georgopoulos reference.
Martin, Bruce, and Bill: Regarding the term, percept.
Bruce, I, for one, use the term percept to refer to the
particulars of experience (objective percepts I call objects for
short--as does everyone) essentially as you surmise (92106) a
psychologist might use the term; that is:
conceive : concept :: perceive : percept
This being the case, I take great care to distinguish percepts
from neural signals, just as you recommend, and I try to encourage
others to do likewise (e.g., my post 920915). Hence, from my
perspective, your caveats are well taken.
Further, I believe all four of the terms in your analogy are of
the utmost importance in this regard. Although the expression -
_conceiving perceiving_ appears to be perfectly reasonable, the
expression _conceiving a percept_ (or perceiving a concept) does
not. The expression _conceiving a percept_ is an oxymoron because
a percept conceived is a concept not a percept. Thus, conceptual
models of perception merely assert an equivalence between
perceptual and conceptual realizations. On this point I trust we
are all agreed. However, it is so easy to confuse this
relationship (of a putative equivalence between these two types of
realization) with a putative relationship between the various
parts of our conceptual models of perception, say, between neurons
and photons--or between neural currents and light rays. To call
the neural currents percepts is to virtually guarantee the
confusion. And to call photons constructs, while claiming that
neural impulses are percepts absolutely insures it. So, when I
conceive of vision as a perceptual process involving HPCT, I
continually remind myself that the system is a conceptual
realization from end to end. Further, when I try to imagine
(derive?) how this conceptual model accounts for the fact that my
visual percepts are perceived as external to my body I am reminded
hat the HPCT has an environmental part and that this is not
necessarily a mere coincidence.
Dag Forssell: Congratulations to you and Christine on your
contract; glad to hear (921001) its going well.
Warm regards, Wayne
Wayne A. Hershberger Work: (815) 753-7097
Professor of Psychology
Department of Psychology Home: (815) 758-3747
Northern Illinois University
DeKalb IL 60115 Bitnet: tj0wah1@niu