The Evolution of the Control Paradigm

By Dag Forssell

The Perceptual Control Theory (PCT) paradigm originates in 1927, when an engineer named Harold Black completed the technical analysis of closed loop control systems. He was working with the negative feedback amplifier, which is a control device. This led to a new engineering discipline and the development of many purposeful machines. Purposeful machines have built-in intent to achieve specified ends by variable means under changing conditions.

The explanation for the phenomenon of control is the first alternative to the linear cause-effect perspective ever proposed in any science.

The first discussion of purposeful machines and people came in 1943 in a paper called: Behavior, Purpose and Teleology by Rosenblueth, Wiener and Bigelow. This paper also argued that purpose belongs in science as a real phenomenon in the present. Purpose does not mean that somehow the future influences the present.

William T. (Bill) Powers developed PCT, beginning in the mid-50's. In 1973 his book called Behavior: the Control of Perception (often referred to as B:CP) was published. It is still the major reference for PCT and discussion on CSGnet.

B:CP spells out a suggestion for a working model of how the human brain and nervous system works. Our brain is a system that controls its own perceptions. This view suggests explanations for many previously mysterious aspects of how people interact with their world.

Perceptual Control Theory has been accepted by independently thinking psychologists, scientists, engineers and others. The result is that an association has been formed (the Control System Group), several books published, this CSGnet set up and that several professors teach PCT in American universities today.

DEMONSTRATING THE PHENOMENON OF CONTROL

Few scientists recognize or understand the phenomenon of control. It is not well understood in important aspects even by many control engineers. Yet the phenomenon of control, when it is recognized and understood, provides a powerful enhancement to scientific perspectives.

It is essential to recognize that control exists and deserves an explanation in order for the discussions on CSGnet to make sense.

Fortunately, a number of computer programs have been developed by Bill Powers and Rick Marken for MS-DOS and Macintosh computers as well as for Java-enabled Web browsers that demonstrate the phenomenon of perceptual control as well as models to explain the phenomenon.