Perceptual Control Theory

Perceptual Control Theory (PCT) is a systems model for the regulation of actions based on negative feedback loops as used in engineering control theory (Powers, 1973; Robertson, & Powers, 1998). An everyday example of an engineering control system is the cruise control in your car. By way of illustration, the speed limit is 70 mph, so you set the cruise control at 70 mph. The cruise control now has a reference value and must regulate the actions of the car so that its performance conforms to the reference value. The cruise control monitors the speed of the car, i.e., the controlled variable, as indicated by a signal from the speedometer, and compares this monitored value to the reference value that has been set. If the car encounters a hill, i.e., a disturbance, sufficient to cause the car to slow down, there will be a difference between the monitored speed and the reference value. This discrepancy generates what is called an error signal. The cruise control then initiates actions to regulate the speed of your car, e.g., increasing the flow of fuel to the engine. As long as the signal to the cruise control from the speedometer corresponds to the reference value set, the control system simply continues to monitor and initiates no actions.