Cognitive and conceptual errors

The purpose of this paper is to provide an understanding of the nature of cognitive and conceptual errors, to describe their underlying causes and to show how this knowledge can be applied to predicting and reducing such errors. Cognitive errors are essentially concerned with failures of high level human functions such as diagnosis, problem solving or decision making. As the level of automation has increased in nuclear power operations, the role of the operator and operating team has increasingly become that of a high level supervisory controller, who is required to manage situations that cannot be handled by the automatic protective systems. The operator will also be involved in monitoring the state of the system in order to make early detections of situations which would ultimately lead to the system tripping, resulting in loss of production. In many cases the operator can intervene to reduce the incidence of such trips by taking appropriate compensatory actions. The approach of increasing the level of automation and relying on the operator to intervene in unusual situations increases the importance of a systematic consideration of cognitive errors. The distinction between the cognitive and the traditional approach to human error is described. An overview is provided of a number of models that have been used to explain cognitive errors. Finally the application of these approaches to the prevention of cognitive errors, the prediction of these errors in probabilistic safety analysis, and the use of the models to enhance the evaluation of incident root causes is described