A laboratory evaluation of a human operator support system

A possible way of supporting a human operator with the supervision of complex industrial processes is to provide him or her with a knowledge-based system that can detect faults in the process and infer their cause(s) and consequences. The effects of the introduction of such an aid cannot be predicted. On the one hand, it may improve the performance of the operator since it provides additional information about causes and consequences of a malfunction. On the other hand, it may worsen the operator's performance since he or she is either mentally underloaded (when all that is left for the operator to do is to follow the advice of the knowledge-based system) or mentally overloaded (because there is one more system which the operator must understand and check). In order to improve our understanding of this point, we constructed a monitoring and diagnosis system for a nuclear power plant simulation and carried out a laboratory evaluation of this system. During the evaluation, we compared the performance of a group of operators using the support system with a control group. The latter had to perform the same task in a model of a normally equipped control room. Results show that the aided operators performed better when they had to diagnose malfunctions caused by multiple failures, and when they had to diagnose malfunctions which they did not practise during their training.