Human action, the goal-directed interaction of the person with the environment, has long been a problem area for psychologists seeking to model human behaviour and for philosophers seeking to understand the interaction of body and mind. Nowadays it is a major problem area in studies of where one seeks to mimic human action. Perhaps the major area of application of studies of human action, however, is in clinical medicine where the pathology of action in geriatric cases, or where brain injury leads to similar malfunction, is of increasing importance. However, none of these fields yet offers any overall solution to the problem of understanding, modelling, synthesizing and correcting action. There are deep problems in the philosophical foundations, the psychological studies, the artificial intelligence simulation and the clinical treatment of action in all its varied forms. Our main argument is that the problem of understanding action is a tractable but extremely complex one, and involving many closely interacting levels of discourse. The main objective of our current work is to provide a clear, methodological framework for the study of action (Gaines & Kohout, 1976). In our opinion lack of a well-defined methodological framework for analysis of action and its pathology has been a major impediment to both experimental and studies in neuroand behavioural sciences. The human, even in apparently simple actions, brings into play a complex hierarchical system. The action of a muscle can be understood only in the context of the overall tonus, the preceeding and succeeding behaviour, the intent for the overall movement, and so on. No combination of psychological and physiological observation is currently adequate to monitor all relevant detail. One has doubts that this may ever be so. We certainly need far more structural contexts in which to work than those provided by naieve experimental empiricism or behaviourism. It is also reasonable to doubt the possibily of having anything rather than ad hoc, piecemeal models of the many interacting components of the overall hierarchical system. There is a profound question as to what extent we can comprehend or model such complexity. However, I shall aim to show that this is a similar question that was faced by, for example, a chemist in coming to comprehend the structure of a natural material. Even though inhomogenous and complex, with local peculiarities, it is potentially understandable in terms of regular and simple phenomena in complex inter-relationships. The key formal structure or rather theoretical framework for analysis of action (Kohout & Gaines, 1976) is closely related to a generalization of a model of dynamic protection in multi-access computer systems (Kohout & Gaines, 1975). The important 397