Dear Bill and
Fellow CSGers,
I’m
getting ready to update and finalize my PowerPoint presentation,
“Perceptual Control Theory and the Evolution of Culture”, which I
showed at last year’s CSG conference.[i] (Tentatively,
the new title will be “PCT and Culture Acquisition”.)
I want to be
able to state forthrightly, at the very start, that PCT is the only
comprehensive neuroscience-based theory which can plausibly explain how
behavior works. In other words, PCT is the only theory which can
explain how the nervous system actually mediates between its genetic,
ontogenetic, epigenetic, cultural, and experiential inputs and its muscular
(and glandular) outputs.[ii]
Casting about
for a definitive source to test that hypothesis, I undertook to read Steven
Pinker’s How the Mind Works[iii] – hereinafter
HTMW. Perhaps there I would find an alternative to PCT which meets those
criteria.
HTMW is a marvelous piece of work, pulling
together all of cognitive neuroscience[iv] and creatively
integrating it. Its thesis is that the evolutionary function of the human mind
is to figure out what is going on in the environment and decide what to do
about it. In summary: “The mind is a neural computer, fitted by natural
selection with combinatorial algorithms for causal and probabilistic reasoning
about plants, animals, objects, and people.”[524] The mind-as-computer
consists of multiple modules, operating in parallel among, and within,
themselves.
Behavior is
goal-directed: “Our minds explain other people’s behavior by their
beliefs and desires because other people’s behavior is in fact caused by
their beliefs and desires. The behaviorists were wrong, and everyone
intuitively knows it.” [329]
“Computationally
speaking, representations trigger goal states, which in turn trigger
information-gathering, problem-solving, and behavior-selecting demons that
calculate how to attain, shun, or modify the charged situation.”[v][143]
Our
penultimate goals are acquired through natural selection: “Though the
process of natural selection itself has no goal, it evolved entities that (like
the automobile) are highly organized to bring about certain goals and subgoals.
To reverse-engineer the mind, we must sort them out and identify the ultimate
goal in its design. Was the human mind ultimately designed to create beauty? To
discover truth? To love and to work? To harmonize with nature? …The logic
of natural selection gives the answer. The ultimate goal that the mind was
designed to attain is maximizing the number of copies of the genes that created
it.” [43]
Behavior is
organized hierarchically, at least on the input side: “The ability of
objects to attract reference frames to themselves helps to solve one of the
great problems in vision, the next problem we face as we continue our climb
from the retina to abstract thought.”[268 – emphasis added]
“The
brain is also ready for the second computational demand of an imagery system,
information flowing down from memory instead of up from the eyes. The fiber
pathways to the visual areas of the brain are two-way. They carry as much
information down from the higher, conceptual levels as up from the lower,
sensory levels. No one knows what these top-down connections are for, but they
could be there to download memory images into visual maps.”[287]
HTMW evinces some understanding of
control, but only at the bottom of the hierarchy: “This transfer of skill
must tap into a level of representation for motor control that specifies a
geometric trajectory, not the muscle contractions or limb movements that
accomplish it. The trajectory would be translated into actual motions by
lower-level control programs for each appendage.”[87]
So: HTMW
seems pretty good on the input side; in fact, I think there are some things we
could learn from it about Input Functions or, as I would call them, Inference
Engines.
But: How
is action caused by beliefs and desires? How do those “behavior-selecting
demons” work? After a mind figures out what is going on in the
environment and what to do about it, what neural mechanisms does it use
to convey its conclusions to the motor-control-geometric-trajectory modules?
I think HTMW
leaves a very big gap here. Even ignoring the drawback of not having each input
level tied to output, I have to conclude that Pinker is not giving us a
comprehensive neuroscience theory of behavior. Apparently cognitive
neuroscience just doesn’t do that.
The idea that
activity might be goal-directed at every level simply hasn’t occurred to
the cognitivists.
So my
proposition still stands: Perceptual Control Theory is the only comprehensive
neuroscience-based theory of behavior and, therefore, the only comprehensive
naturalistic theory of behavior.
I’m
still looking for disconfirmation of that proposition.
Any ideas?
Regards,
Ted
···
[i] To see the Beta
version, go to tedcloak.com to see how to download it in various formats.
[ii] And
that therefore, since neuroscience is the only possible route for reducing
behavior to the basic forces of nature, PCT is the only comprehensive naturalistic
theory of behavior.
I can mention two other theories that are
comprehensive, but not based on neuroscience:
·
Behaviorism (learning theory) abjures
neuroscience altogether, except perhaps for a quick nod to Watson’s
reflex arc.
·
Freud
started out as a neuroscientist and made assumptions accordingly, but his
followers have never tried to tie his concepts back into modern ideas about
nervous system activity, to my knowledge.
[iii] Pinker, Steven 1997.
How the mind works . New York: W.W. Norton. 566 pages.
[iv] As of the
mid-nineties. I think that should be adequate.
[v] That statement could
be mapped onto a statement about PCT, perhaps, but it’s the only one I
found that could. There’s no indication of what a behavior-selecting
demon might actually do, except the one cited below.