Ever since 28 March 1979, the day of the accident in the nuclear power plant on Three Mile Island, accident investigation and risk assessment have focused on the human factor, most notably in the form of "human error". Countless books and papers have been written about how to identify, classify, eliminate, prevent, and compensate for "human error". This preoccupation with failure is near universal and can be found in all fields of application.
One consequence of this preoccupation has been a bias towards the study of human performance failures, leading to a neglect of normal or "error-free" performance. The unspoken assumption is that failures and successes have different origins and that there therefore is little to be gained from studying the latter. Resilience engineering argues that this assumption is false and that safety cannot be attained only by eliminating risks and failures. The alternative is to understand why things go right, and to find ways to support and amplify that.
This presentation will describe a single principle for human performance that can be used to understand both why things go right and why they sometimes go wrong. The principle reflects the common trait that people in their work naturally adjust what they do to match the conditions – what has happened, what happens, and what may happen. This can be understood by proposing that it is normal for people in work situations to adjust their performance by means of an efficiency-thoroughness trade-off (ETTO) – usually by sacrificing thoroughness for efficiency. The trade-off can be due to a lack of time, lack of resources, company pressures, overload of information and work, etc. The ability of people mutually to adjust their performance is the reason why things go right. Yet in some cases the adjustments may combine in an unforeseen way and lead to adverse outcomes. These outcomes are nevertheless due to the very same processes that produce successes, rather than to errors and malfunctions. The ETTO principle not only obviates the need for specialised theories and models of failure and "human error", but also offers a viable alternative that can support more effective approaches to socio-technical system design and management.
Erik Hollnagel (PhD, psychology) is Professor and Industrial Safety Chair at École des Mines de Paris (France), Professor Emeritus at University of Linköping (Sweden), and Visiting Professor at the Norwegian University of Science and Technology (NTNU) in Trondheim (Norway). He has since 1971 worked at universities, research centres, and industries in several countries and with problems from several domains, including nuclear power generation, aerospace and aviation, air traffic management, software engineering, healthcare, and land-based traffic.
His professional interests include industrial safety, resilience engineering, accident investigation, cognitive systems engineering and cognitive ergonomics.
He has published more than 250 papers and authored or edited 13 books, some of the most recent titles being "Resilience Engineering Perspectives: Remaining Sensitive to the Possibility of Failure" (Ashgate, 2008), "Resilience Engineering: Concepts and Precepts" (Ashgate, 2006), "Joint Cognitive Systems: Foundations of Cognitive Systems Engineering" (Taylor & Francis, 2005) and "Barriers and Accident Prevention" (Ashgate, 2004). Erik Hollnagel is, together with Pietro C. Cacciabue, Editor-in-Chief of the international journal of Cognition, Technology & Work.