Notes that consistent behavior patterns are created by variable acts and generally repeat only because detailed acts change. It is proposed that the accepted explanation that “cues” cause the changes is unsupported by evidence and is incapable of dealing with novel situations. The apparent purposefulness of variations of behavioral acts can be accepted in the framework of a control-system model of behavior. A control system, properly organized for its environment, will produce whatever output is required in order to achieve a constant sensed result, even in the presence of unpredictable disturbances. A control-system model of the brain provides a physical explanation for the existence of goals or purposes, and shows that behavior is the control of input rather than output. When a systematic investigation has discovered the controlled quantities, the related stimulus-response laws become trivially predictable and variability of behavior all but disappears. Within this model, behavior itself is seen as self-determined in a specific and highly significant sense that casts doubt on the ultimate feasibility of operant conditioning of human beings by other human beings.

Excerpt: It may be that Piaget has for several decades suffered an extreme of misunderstanding of his position – or it may be that in his direct approach to the growth of perceptual organization, he has been applying new principles without having organized them into an “official” statement. The subject of this chapter is another approach that has converged to the same general conclusions from a totally different starting point: cybernetics. In this case the epistemological principles have emerged in an explicit form simply as a consequence of following out the logic of a behavioral model. The model on which I have been working is an offshoot of cybernetics using almost the oldest and least sophisticated of cybernetic concepts: feedback of behavioral outputs to sensory inputs, through the environment. Through a rigorous, and some might say obsessive, application of a simple control-system unit of behavioral organization, I have constructed what seems on first inspection to be a purely hardware model of how behavior works, the kind of model that would make any engineer feel secure.

Excerpt: It is clearly a bit naive to consider trying to write the input-output transfer function for any middling-to¬-complex behavior. In order to make the problem simple enough to handle one must focus on very low- level definitions of input and output, with no guar-antee that the observed function is not contaminated. One can only hope that while the subject is tracking the target he does not change his mind about the importance of speed and accuracy, and does not start thinking about lunch, and is not reminded of some similar and unpleasant situation, and does not want to ruin the experiment. What we need is some way to find the right defini¬tions of input and output, definitions we can be rea¬sonably sure are appropriate to the behaving system and not gratuitous embellishments, scientistic irrele¬vancies or inappropriate anthropomorphisms. I think that we have such a way in a control-system model of behavior.

The book develops the basic ideas of Perceptual Control Theory (PCT) through a series of 13 computer demonstrations. The basic phenomenon of perceptual control is illustrated through interactive demonstrations including real-time manipulations of block diagrams, tracking experiments with a model automatically analysed and matched to user-generated data, and illustrations of reorganization theory which show how control systems can become organized through a biased random walk method of adaptation. This can be viewed as a companion volume to the author’s first book, Behavior: the control of perception, published 35 years ago. Ernst von Glasersfeld was one of the first, over 30 years ago, to recognize the compatibility between PCT and his radical constructivism

Key words: cybernetics