More Devil's Bibliogrphy

[From Rick Marken (930120.0900)]

No collection of misconceptions about PCT (and general feedback control)
would be complete without a quote or two from:

Fowler, C. and Turvey, M. T. (1978) Skill acquisition: An event approach
with special reference to searching for the optimum of a function of
several variables. In G. Stelmach (Ed.) Information processing in motor
control and learning (pp. 1-39) New York: Academic Press

An entire section of this article is dedicated to Powers HPCT
model of behavior. It starts on p. 26 and runs to p. 31. Their
efforts to show the limitations of the HPCT model are detailed,
quantitative and completely wrong. Despite numerous demonstrations
of the fallacies and misconceptions in the Fowler/Turvey paper
(as well as letters to Turvey -- the main "bad gut -- see below)
explaining these problems) there has never been any reply from
Fowler/Turvey and certainly never an apology for this terribly
mischevious "trashing" of HPCT.

Here are a couple of quotes from the end of the section describing
(incorrectly) HPCT.

" Quantitative knowledge of results must rarely be informative in
a hierarchical closed-loop system because, typically, there is a
one to many mapping between an error signal and the conditions that
may have provoked it. We can conclude from that, perhaps, that the
actor/pereciver is not appropriately characterized as a hierarchy
of control systems at least when he is performing tasks in which
he must exploit the abstract information putatively extracted by
the superordinate levels of the system". p 31

This statement is the typical mixture of some correct statements
and some incorrect assertions that is the hobgoblin of PCT
reviews. Yes, there is a one to many mapping of error to
outputs in a hierarchy of control systems, but this problem
is solved on the input side of the hierarchy -- when there are
several higher order systems.

"The closed-loop model of Powers characterizes the actor as an
inflexible general-purpose device". p 31

No comment necessary -- Oh. All right. Can everyone say "re-
organization".

An interesting followup to this catastrophic article (from an
HPCT perspective -- maybe an accurate report would have allowed
the PCT revolution to start in the early 1980s) is that Carol
Fowler was the Editor at JEP who handled the review of my 1986
Hierarchical Control paper which was EXTREMELY critical of the
Fowler/Turvey article. Yet, Ms. Fowler was not only fair in
the review process -- she was largely responsible for arguing
for it's acceptance (since there were some disagreements between
the reviewers about its merit). So, although Carol Fowler happens
to be the first author of one of the most notorious anti-PCT
articles ever published, I would have to class her as one of the
"good guys" -- if not in terms of understanding PCT, certainly in
terms of scientific integrity. I think she must have been a student
of Turvey's at the time the article was written -- and under his
apparently strong "trendy science" spell (I've never met him but
I hear he talks a pretty convincing line of BS).

And, yes, it's true -- I AM a nice guy; though not nearly as nice as
Greg and Ray are for saying it.

Best

Rick

I think she must have been a student
of Turvey's at the time the article was written -- and under his
apparently strong "trendy science" spell (I've never met him but
I hear he talks a pretty convincing line of BS).

I believe that they've married since then. I've also experienced a
poor "response rate" from her/them (i.e., answering letters).

O----------------------------------------------------------------------------->

Cliff Joslyn, Cybernetician at Large, 327 Spring St #2 Portland ME 04102 USA
Systems Science, SUNY Binghamton NASA Goddard Space Flight Center
cjoslyn@bingsuns.cc.binghamton.edu joslyn@kong.gsfc.nasa.gov

V All the world is biscuit shaped. . .