Servo Mechanisms

Servo-mechanisms are divided into two general types:

1. where the target, goal, or "answer" is known, and the objective is to reach it or accomplish it
2. where the target or "answer" is not known and the objective is to discover or locate it

The human brain and nervous system operates in both ways. An example of the first type is the self-guided torpedo, or the interceptor missile. The target or goal is known an enemy ship or plane. The objective is to reach it. Such machines must "know" the target they are shooting for. They must have some sort of propulsion system which propels them forward in the general direction of the target. They must be equipped with "sense organs" (radar, sonar, heat perceptors, etc.) which bring information from the target. These "sense organs" keep the machine informed when it is on the correct course (positive feedback) and when it commits an error and gets off course (negative feedback). The machine does not react or respond to positive feedback. It is doing the correct thing already and "just keeps on doing what it is doing." There must be a corrective device, however, which will respond to negative feedback. When negative feedback informs the mechanism that it is off the beam" too far to the right, the corrective mechanism automatically causes the rudder to move so that it will steer the machine back to the left. If it “over-corrects” and heads too far to the left, this mistake is made known through negative feedback, and the corrective device moves the rudder so it will steer the machine back to the right. The torpedo accomplishes its goal by going forward, making errors, and continually correcting them. By a series of zigzags it literally “gropes” its way to the goal.

Dr. Norbert Wiener, who pioneered in the development of goal-seeking mechanisms in World War II, believes that something very similar to the foregoing happens in the human nervous system whenever you perform any purposeful activity-even in such a simple goal-seeking situation as picking up a package of cigarettes from a table. We are able to accomplish the goal of picking up the cigarettes because of an automatic mechanism, and not by "will" and forebrain thinking alone. All that the forebrain does is to select the goal, trigger it into action by desire, and feed information to the automatic mechanism so that your hand continually corrects its course.