Bulldozer00's Blog

In William T. Powers’ classic and ground-breaking book “Behavior: The Control Of Perception“, Mr. Powers derives a theoretical model of the human nervous system as a stacked, nine-level hierarchical control system that collides with the standard behaviorist stimulus-response model of behavior. As the book title conveys, his ultimate heretical conclusion is that behavior controls perception; not vice-versa.

The figure below shows a model of a control system building block. The controller’s job is to minimize the error between a “reference signal” (that originates from  “somewhere” outside of the controller) and some feature in the external environment that can be “disturbed” from the status quo by other, unknown forces in the environment.

Notice that the comparator is one level removed from physical reality via the transformational input and output functions. An input function converts a physical effect into a simplified neural current representation and an output function does the opposite. Afterall, everything we sense and every action we perform is ultimately due to neural currents circulating through us and being interpreted as something important to us.

So, what are the nine levels in Mr. Powers’ hierarchy, and what is the controlled quantity modeled by the reference signal at each level? BD00 is glad you asked:

Starting at the bottom level, the controlled variables get more and more abstract as we move upward in the hierarchy. Mr. Powers’ hierarchy ends at 9 levels only because he doesn’t know where to go after “concepts“.

So, who/what provides the “reference signal” at the highest level in the hierarchy? God? What quantity is it intended to control? Self-esteem? Survival? Is there a “top” at all, or does the hierarchy extend on to infinity; driven by evolutionary forces? The ultimate question is “who’s controlling the controller?“.

This post doesn’t come close to serving justice to Mr. Powers’ work. His logical, compelling, and novel derivation of the model from the ground up is fascinating to follow. Of course, I’m a layman but it’s hard to find any holes/faults in his treatise, especially in the lower, more concrete levels of the hierarchy.

Note: Thanks once again to William L. Livingston for steering me toward William T. Powers. His uncanny ability to discover and integrate the work of obscure, “ignored”, intellectual powerhouses like Mr. Powers into his own work is amazing.