Cybernetic models are applied prescriptively in design and descriptively as explanatory devices. Their prescriptive use savours of engineering. They are employed in the specification of controllers and regulators for industrial plants, navigation, and so on. The most interesting developments have occurred in the area of predictive, adaptive, and optimizing controllers, usually able to deal with randomly perturbed environments. On the other hand, cybernetic models are widely used in determining the proper relationship between a man and a machine , for example, in the design of vehicle-control systems. Another field of application is teaching and training. Here, training is literally interpreted as the control of a human learning process and insofar as an adequate model exists, the training instructor may be partially or wholly replaced by a suitable machine. In operational research, cybernetic models are used to specify stockholding schemes, process and assembly programming, and inventory control. They are also used in a normative fashion; for example the management of a business enterprise is often modeled as a game-like decision and control process.
Descriptive applications are legion. At a neuro physiological level, cybernetic models have been used to explain many aspects of the working of a brain. Five areas are of special importance: models for simplified neural networks, chiefly representing perceptual processes; statistical models for the complex oscillations and regulations of real neural activity; models relating algorithms or plans (cited earlier) to the conditioning process; models for the mechanisms responsible for maintaining and directing attention; and models for the detailed changes that occur at the synaptic junctions between neurons.
Outside the brain, cybernetic principles are widely used to elucidate the control of bodily functions (autonomic processes, hormone-mediated regulatory systems, muscular control, and so on).A surprisingly large amount of molecular biology and bio-chemistry also rests upon models depicting the organization of enzyme systems and the hierarchical control of enzyme synthesis. This type of explanation promises to have further utility in relating genetically coded instructions to the cellular economy. Cybernetic models have been used in embryology since the early 1950s, and some of the original schemes have now been formulated in a detailed mathematical fashion.
Within psychology, it is possible to explain several classes of behaviour and cognition in terms of hierarchies of control systems. The previously stated notions of planning and learning are pertinent to this field. At a macroscopic level, cybernetic ideas are applied to interpersonal interactions such as conversations, the communicative behaviour of small groups, and the homeostatic processes maintaining the status quo in social systems. Indeed, one of the first essays in this direction took place in the context of social anthropology where cybernetic ideas are becoming of greater importance. Somewhat similar developments have occurred in the animal domain; ethnologists use cybernetics freely, especially in dealing with population density control systems and the regulation of reproduction