Movement Coordination — Movement Patterns

The subtitle of this book contains the word behavior. The study of human behavior is a huge field of research. Under the concept of behavior we may subsume simple movements up to highly complex behavior, such as dealing with other humans or with specific situations. The intention of my approach is to be as operational as possible and to study those experimental phenomena that can be treated in a quantitative manner. This is why I shall choose in this and the following chapters movement coordination. In the spirit of synergetics, I shall be concerned with qualitative changes (that can be measured quantitatively!). It should be noted, however, that qualitative changes can be observed in quite a number of different kinds of human behavior. To take a most striking example, let us think of cases studied in psychiatry. Here in the case of schizophrenia we find well-defined transitions between normal behavior and psychotic episodes. The same is true for transitions between depressions and manic episodes. The most striking feature of these phenomena is the existence of well-defined behavioral patterns; for instance, we can readily distinguish between a normal and a psychotic state of a person, though there are a variety of manifestations of, say, schizophrenia. At any rate we may state that behavioral patterns are quite clearly defined and coherent within themselves. It appears as if the behavior of a person is governed by — what I would like to call — a single order parameter. This picture may be oversimplified, but the main issue of this chapter is to demonstrate that such well-defined transitions occur in movement coordination, and my claim is that from here on we may extrapolate to far more complicated kinds of behavior and transitions between them. In a way the problem will be not so much to model these more complicated transitions, but to develop adequate means to quantify human behavior in complex circumstances. We shall elucidate this kind of problem from a different point of view in Chap. 17, where we shall deal with decision making, which may again be considered as a certain kind of human behavior. Studies of the circumstances under which transitions between behavioral patterns occur are, of course, of practical importance in many respects. Let us again take psychosis as an example. Can one predict when such an event will happen or are there any indicators that a psychosis is starting? When we take seriously the analogy between movement patterns and more general behavioral patterns, I believe one can claim that such indicators exist.