This book includes all of the papers presented at the NATO Symposium on Human Detection and Diagnosis of System Failures held at Roskilde, Denmark on August 4-8, 1980. The Symposium was sponsored by the Scientific Affairs Division of NATO and the Rise National Laboratory of Denmark. The goal of the Symposium was to continue the tradition initiated by the NATO Symposium on Monitoring Behavior and Supervisory Control held in Berchtesgaden, F .R. Germany in 1976 and the NATO Symposium on Theory and Measurement of Mental Workload held in Mati, Greece in 1977. To this end, a group of 85 psychologists and engineers coming from industry, government, and academia convened to discuss, and to generate a state-of-the-art consensus of the problems and solutions associated with the human IS ability to cope with the increasing scale of consequences of failures within complex technical systems. The Introduction of this volume reviews their findings. The Symposium was organized to include brief formal presentations of papers sent to participants about two months in advance of the meeting, and considerable discussion both during plenary sessions and within more specialized workshops. Summaries of the discussions and workshop reports appear in this volume.