Modelling the human process controller

In many industrial tasks a complex, interactive process must be controlled by a human operator in real-time, with or without the aid of a computer. In order to allocate functions between man and machine at the design stage, a model of human behavior and performance in such tasks is required. Progress towards such a model is analyzed. Real-world studies usually use very complex processes but are designed to study specific problems rather than operator models. Laboratory studies of generally much simpler systems have produced only small effects of major system variables such as displayed information. The problem of performance criteria which are both valid and sensitive remains unsolved, and analysis of verbal protocols has been the major tool used so far in modelling. A loose, heirarchical goal-directed operator model, such as proposed by Bainbridge (1974), is supported by studies from a variety of industries and laboratories.