Despite the date, I think this 10-year-old cautionary note posted by
Bill P. March 20, 2004 that I recovered in my quick scan of the
ECACS Forum is worth noting when people get hung up on the literal
word of B:CP or others of Bill’s writings:
···
"When you
actually start making a model work, you find that you have to
things demanded by the problem and you can’t slavishly follow
the simple PCT diagram. Even in the Little Man, which first
saw the light in the late '80s or early '90s, I had to ignore
the levels as I had defined them in order to make the model
match what was known about the spinal control systems.
Obviously the model still belongs to the PCT family, but its
details were dictated mainly by nature, not by the theory. I
think that will continue to be the story."
MT: Despite the date, I think this 10-year-old cautionary note posted by Bill P. March 20, 2004 that I recovered in my quick scan of the ECACS Forum is worth noting when people get hung up on the literal word of B:CP or others of Bill’s writings:
···
“When you actually start making a model work, you find that you have to things demanded by the problem and you can’t slavishly follow the simple PCT diagram. Even in the Little Man, which first saw the light in the late '80s or early '90s, I had to ignore the levels as I had defined them in order to make the model match what was known about the spinal control systems. Obviously the model still belongs to the PCT family, but its details were dictated mainly by nature, not by the theory. I think that will continue to be the story.”
Thanks, Martin, that’s something well worth keeping in mind.
When Bill developed his perceptual hierarchy, he was trying to create a system capable of self-organizing. The bottom-level control systems might be present at birth, along with the reorganizing system, but in its effort to keep intrinsic variables within survivable limits, the reorganizing system would act first to tune those bottom-level control systems. Once these were functional, second-level systems would emerge (during further reorganization) to control new perceptions (constructed from lower-level perceptual signals) by manipulating the reference signals of the first-level systems. Once the second-level systems were working reasonably well, this would set the stage for the emergence of level-systems, and so on up the hierarchy. It’s an elegant solution to the problem of how control systems might emerge through the individual’s interactions with the environment. It also enforces a logical necessity if these systems are to work properly as a hierarchy, which is that higher-level systems should act to set references of systems at the next lower level and not vice versa.
To fill out this hierarchical model, Bill needed to specify what kind of perception would emerge at each level. The hierarchy he proposed was based partly on anatomical/physiological evidence (especially at the lowest level), but for the most part was based on introspection and logical considerations. Bill repeatedly warned that these levels were speculative, and increasingly so as one ascended the hierarchy. They were not to be taken as fixed and immutable, but as proposals to be subjected to scientific testing and modified as necessary to agree with the results of those tests.
MT: Despite the date, I think this 10-year-old cautionary note posted by Bill P. March 20, 2004 that I recovered in my quick scan of the ECACS Forum is worth noting when people get hung up on the literal word of B:CP or others of Bill’s writings:
“When you actually start making a model work, you find that you have to things demanded by the problem and you can’t slavishly follow the simple PCT diagram. …”
BA: Thanks, Martin, that’s something well worth keeping in mind…
BA: Bill repeatedly warned that these levels were speculative, and increasingly so as one ascended the hierarchy. They were not to be taken as fixed and immutable, but as proposals to be subjected to scientific testing and modified as necessary to agree with the results of those tests.
RM: Exactly. The hierarchy and the levels of perceptual control that make it up were proposed as a framework for research (and clearly described as such in the paper “A cybernetic model for research…” reprinted on pp. 167-220 of LCS I). I have never restricted myself to considering the proposed levels of perceptual control when I develop control models of behavior. When it’s a hierarchical model, like my two handed coordination model (http://www.mindreadings.com/Coordination.html) I just have the model control perceptions at each level that seem to “make sense” in terms of what the controller has to do in the task.
RM: I have done research that directly tests Bill’s proposals about the levels (eg. Marken, R. S., Khatib, Z. and Mansell, W. (2013) Motor Control as the
Control of Perception, Perceptual and
Motor Skills, 117, 236-247). But much more is needed. Once we know a lot more about the nature of the perceptual control hierarchy – and whether it even is a hierarchy – then I presume that we will be able to start incorporating this knowledge into our control models of performance in specific tasks.
Best regards
Rick
–
Richard S. Marken PhD www.mindreadings.com
It is difficult to get a man to understand something, when his salary depends upon his not understanding it. – Upton Sinclair