There is a question that has been bugging me and maybe it’s something that one of you has thought about so please share your thoughts.
I’m just reading in my students’ thesis that an important assumption in Predictive Coding is that higher hierarchical levels make predictions for lower levels, while in the other direction, from the bottom of the hierarchy upwards, the signals code prediction errors.
The thesis is about autism and pct, a subject for another time. But this predictive coding idea felt powerful. Don’t worry, this question is about PCT
Powers describes how the upward signal is a copy of the perceptual signal. And the downwards signal is a signal from the output function which serves as a reference for the lower control system.
So, if my information is correct, that is a difference between these theories.
But Powers’ model also keeps bugging me. Every level is built from combinations of lower level perceptions, in a many-to-one relationship. A configuration consists of multiple sensations.
But higher up in the hierarchy, the ‘copy of the perceptual signal’ is more difficult. In a program-level perception, what would be the nature of the signal travelling upwards? The program level branches out infinitely, so when do the signals travel upwards to the higher level?
From that perspective, the predictive coding solution starts to make more sense. As I presented at the lastIAPCT conference, I think that principle-level control uses error signals from the lower level as input, and as described above, I can’t think of a way in which the multitude of signals in a program level perception would serve as input for a higher level. So that would fit the ‘error travels upwards’ hypothesis.
Might it be the case that error sent upward is valid all the way through the hierarchy? That would solve some problems I always run into: where do the error signals go? And how does the control system know that a higher level control is needed? Would that make every step higher in the hierarchy a way to control the uncontrolled signals of the level below (the error signals)?
So for example, if you perceive configurations (level 3) that keep on changing, that change is the error that cannot be controlled at lower levels. If those changes (level 4) have a beginning and an end, the event level (level 5) is a way to control those new kinds of signals. If a sequence is split, so that it can’t be controlled as a single sequence, that error can be used at the program level to control the splitting (the choice point). If a program fails, the error (I think we call this emotion) is input for the principle level that tries to take care of that principle in a very new way (reorganization).
I’m curious who else has been thinking about this and what solutions you have found. And if anyone knows how Powers thought about this.