Continuing the discussion from PCT vs Free Energy (Specification versus Prediction):

I think the term that best describes input functions is “perceptual functions”. The perceptual functions in PCT are assumed to be neural networks that act as *mathematical functions* that take afferent neural signals as inputs and produce a single afferent signal as output.

I think what is really needed is to figure out what it is about these perceptual functions that gets reorganized when reorganization occurs. You talk about reorganizing “input functions” quite a bit when you talk about reorganization but it’s never been clear to me what it is about these functions that you think is being reorganized. I see three possibilities:

- The inputs to the function
- The parameters of the function
- The nature of the function itself

I think 1) and 2) are physiologically feasible, can be accomplished in a reasonably short time and that the effectiveness of both has been demonstrated in Bill Powers’ simulation of reorganization that was rewritten in Java by Mark Smith.

I think 3) may be physiologically possible but I don’t believe it could be accomplished in a reasonably short time – especially if the nature of the function that needs to be constructed is particularly complex. I also know of no model of reorganization where reorganization of the perceptual functions involves changing the nature of the function itself.

In Bill’s model of reorganization of the perceptual functions, all the perceptual functions that are reorganized are of the same type. They are linear functions of the form:

p = a.1 * x.1 + a.2 * x.2…+ a.n * x.n.

The reorganization involves random change of the parameters of this function (the a.i’s), which is type 2) reorganization. When a parameter goes to 0 it reorganization has functionally removed the corresponding input (the corresponding x.i), which is type 1) reorganization.

It seems to me that 3)-type reorganization of perceptual functions is inconsistent with the current version of the PCT model, which posits that there are about 10 different ways in which all humans perceive the world. This implies that humans have about 10 different types of perceptual functions. A considerable amount of research is needed to test whether or not this conjecture is true. But if it is, it suggests that all people come into the world with the *same 10 types of perceptual functions* “built in”. It seems highly unlikely that these *same 10 types* of perceptual functions would be built by everyone from scratch by random reorganization.

It also seems unlikely that reorganization could regularly come up with a completely new perceptual function type as a way of solving control problems. Such a change would result in a completely new way of experiencing the world. But may it could. I’d be interested in seeing any relevant data on this.

I think it would be worthwhile to try to figure out how to determine which of these three different possible ways of reorganizing perceptual functions is going on in any particular learning situation.