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Feedback Functions

In PCT, a "feedback function" is all of the "stuff" in the environment that connects a control system's actions to variables the system must affect in order to control its own perceptions. Sometimes a feedback function is short and direct, such as when the contractions of muscles in a person's arm pull on parts of his skeleton and move parts of his arm so that he sees his hand in front of his face, a result that he intended to produce.

For a person who controls her perceptions of where her car is on the road, the feedback function allows movements of her hands and arms to affect variables that result in her seeing the hood of the car in the place she intends to see it, relative to her perception of the road. Her feedback function includes the car's steering wheel, all of the linkages between the steering wheel and the devices that affect the angle of  the car's wheels relative to the car's chassis, the car's wheels and tires, and other things we can ignore for now. In a way, the driver's own muscles "amplify" her very small neural error signals and create forces that she applies to the steering wheel. Various mechanical and hydraulic systems further amplify the forces she applies to the steering wheel and turn them into changes in the position of an object, the car, that is massive, compared to the incredibly weak neural error signals that "drive" the driver's actions.

You probably noticed that, in PCT, the way we use the word "feedback" is very different from the way traditional behavioral scientists use the word. There, people talk about feedback as something that one person "gives" to another, or that a person "receives" from the environment. In that usage, "feedback" is identical to "knowledge of results."

On Ed Ford's web site, in the section called,  Section on PCT, my document titled  Book One, Chapter 31, contains descriptions of the feedback functions for two students and a teacher, when the three of them interact in a classroom.

When you read about PCT, be sure to keep in mind the technical definition of "feedback."