The effects of type of knowledge upon human problem solving in a process control task

The question of what the operator of a dynamic system needs to know was investigated in an experiment using PLANT, a simulation of a generic dynamic production process. Knowledge of PLANT was manipulated via different types of instruction, so that four different groups were created: (1) minimal instructions only; (2) minimal instructions and guidelines for operation (procedures); (3) minimal instructions and dynamic relationships (principles), and (4) minimal instructions and procedures and principles. Subjects controlled PLANT in a variety of situations that required maintaining production while also diagnosing familiar and unfamiliar failures. Despite the fact that these manipulations resulted in differences in subjects' knowledge, as assessed via a written test at the end of the experiment, instructions had no effect on achievement of the primary goal of production or on subjects' ability to diagnose unfamiliar failures. However, those groups receiving procedures controlled the system in a more stable manner. Possible reasons for the failure to find an effect are presented, and the implications of these results for operator training and aiding are discussed.