[From Rick Marken (2003.06.27.1130)]
Bruce Gregory (2003.0627.1217)
This particular fire hydrant has always had trouble understanding how
the control hierarchy 'decides' which perception to control and, in
particular, how it rapidly shifts from controlling one perception to
controlling another without the delays associated with relying on upper
levels in the hierarchy to reset reference levels.
It depends on what you mean by "which perception to control". I think of the
hierarchy as always controlling a large (and basically fixed) set of perceptual
_variables_. The state in which any perceptual variable is maintained is varied
as the means of keeping other, higher level perceptions under control (see my
"Spreadsheet analysis..." paper in _Mind Readings_). So if the question "which
perception is controlled?" means "to which state is a perceptual variable brought
at any particular time?" then this question can be answered in terms the normal
operation of the hierarchy. What perception is controlled depends on the state to
which a perceptual variable is brought in order to maintain control of a higher
level perception. For example, I must change the perceived location of my finger
in order to type a particular letter. The higher level goal (typing "a", say)
determines which perception of finger position I must get.
If, on the other hand, "which perception is controlled?" means "which perceptual
variable is controlled at any time?" then my answer is "I don't believe that we
switch from controlling one perceptual variable to another". I think the PCT model
says that we are always controlling the same set of perceptual variables all the
time (until we learn to perceive new ones or lose old one). Perceptual changes
that seem like changes from one to another perceptual variable could simply be
changes in the states of perceptual variables that are always under control. For
example, changing from controlling for driving to controlling for going into the
house could be conceived of as a change in the state at which each of these
perceptual variables (driving, going in house) is controlled. The driving variable
is set to zero while the going in the house variable is set to maximum. The
changes are being made, presumably, as the means of keeping still higher order
variables, like "going home" under control.
When I look up from
tuning my car radio and see the brake lights of the car in front of me,
how does the perceptual hierarchy know enough to slam on my brakes?
I think you are continuously controlling for (among other things) avoidance of a
collision with the car in front of you when you are driving. The brake lights are
a sudden disturbance to this variable; a disturbance that is handled in whatever
way is appropriate (slamming on the brakes, swerving, etc).
When the traffic is dicey, how does the perceptual hierarchy know that
I can't afford to direct my attention to looking for a cassette to
Attention is a consciousness phenomenon. So the hierarchy is not involved in
allocating attention. Moreover, attention changes don't affect which variables you
are controlling. What you are talking about is a resource allocation problem; your
eyes can't foveate the radio and the cars ahead at the same time. But you need to
control visual variables to control the radio and the car's relationship to
traffic. I think very high levels of the hierarchy (the program level) are
involved in this low level resource allocation. When you drive, you are probably
controlling for a program like "if traffic dicey then keep eyes on road, else
allow eyes to move from road for no more than 5 seconds".
It has always seemed from my lowly position that the hierarchy is
extremely capable but lacking in much sense of what is important at the
It can be made to have as much "sense" as you can imagine it to have, where
"sense" would probably be defined in terms of the program and principle
perceptions controlled by any particular hierarchy.
Richard S. Marken, Ph.D.
Senior Behavioral Scientist
The RAND Corporation
PO Box 2138
1700 Main Street
Santa Monica, CA 90407-2138
Tel: 310-393-0411 x7971