[From Rick Marken (2000.02.11.0930)]
Dan Palmer (2000.02.11) --
Well, what I've been doing is reading PCT and ecological
psychology concurrently. I'd appreciate someone's general
take on ecological psychology from a PCT perspective...
My general take is that ecological psychology and PCT have
little in common. The main difference is modeling:
ecological psychologists are _not_ interested in modeling
the perceptual process and PCT psychologist are. This lack
of interest in modeling shows up in the last sentence of
your quote from (Gibson, 1979):
"... The eye-head-brain-body system registers the
invariants in the structure of ambient light"
Gibson has no model of this "registration" process. Indeed,
he seems to be opposed to even developing a model. Gibson
basically says a model is unnecessary because we can
understand perception by learning what "invariants" are
out there in the environment. Once we have discovered
these "invariants" (like, x/y, the ratio of the height (x)
to the width (y) of a rectangle, which remains invariant
under various transformations of the rectangle -- size,
location, etc) then we know what the system must be
"detecting" in order to be knowing what's "really" going
on out there, beyond its varying sensory experience. We
don't need to know _how_ these invariants are detected;
just that they "are" detected. It's a rather "behaviorist"
and "realist" approach to understanding perception.
One important aspect of perception that Gibson ignores is
the fact that we _are_ able to perceive (and control) many
"variants" -- perceptual variables that _would_ change
but are prevented from doing so (if they are under
control) by the actions of the organism.
I say all this, by the way, as a one-time fan of Gibson. I
once thought that Gibson's ecological psychology and Powers'
PCT could be reconciled; that was back in 1978 or so when I
used Gibson's "Senses considered..." book as a text for a
course in perception that I was teaching. I no longer
believe that Gibson and Powers can be reconciled.
Ecological psychologists have made some very interesting
_observations_ of perceptual phenomena; but I don't think
their theory is very helpful -- mainly because it is
not a _working_ model.
Also, are there any published comparisons of the two
theories that anyone can recommend?
There was a discussion of Gibson and PCT a long time
ago on CSGNet (back in the early 1990s). Marc Abrams
has been cataloging and (I think) indexing all the
CSG posts going back to the very beginning of CSGNet
(in 1990, I think). Maybe when Marc has finished you
will be able to get access to this discussion by
entering a keyword, like "Gibson" and getting a
list of all the CSGNet posts on the topic.
Marc, if you're listening, maybe you could report on
the status of your archiving project?
Best
Rick
···
--
Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates mailto: rmarken@earthlink.net
http://home.earthlink.net/~rmarken