Concepts of Human Error

Rasmussen, J. (2000) The concept of human error. Is it useful for the design of safe systems in healthcare, in Safety in Medicine (eds C.A. Vincent and B. de Mol), Elsevier, Oxford. 

The concept of human error, whether intentional or unintentional, is defined as (Lorenzo 1990) ... 

System-oriented studies of the normal cognition and behavior of individuals and the work environment are replacing studies that count error as the target for patient safety research. Researcher Jens Rasmussen, noting problems with the concept of human error (for example, the notion is hard to define and is a function of the biases of the observer), believes that error is only an indication of experts exploring the boundaries of acceptable performance in an unkind environment (Rasmussen, 1998, p. 4), and believes (p. 3) that safety depends on the control of work processes to avoid accidental side effects causing harm to people, environment, or investment. ... 

Rasmussen, J. The Concept of Human Error Is It Useful for the Design of Safe Systems [http //www.ipso.asn.au/vol3/psl.pdf] Safety Science Monitor, 1999,5, 1-3. 

In laboratory studies of human behaviour error is commonly used as an index of performance. A common finding in these studies is the marked trade-off between the speed of response and number of errors made. An example of this trade-off is shown in Figure 23.3. It is interesting to note that many of these approaches have been incorporated into concepts of human error as they apply to considerations of safety. 

The concept of human error became part of safety lore when Heinrich noted that as improved equipment and methods were introduced, accidents from purely mechanical or physical causes decreased and (hu)man failure became the predominant cause of injury. This assumption became the second of the five dominoes in the famous Domino model, described as fault of person. This is in good agreement with the philosophical and psychological tradition to treat human error as an individual characteristic or a personality trait. A modern example of that is the zero-risk hypothesis of driving, which proposes that drivers aim to keep their subjectively perceived risk at zero level. 

Certain types of deviations within a man-machine system increase the probability of accidents and/or the expected value of loss due to accidents, thus being valid indicators of the accident risk. The nature of accidents represented by the deviation model is based on systems theory, on the energy exchange model, the multilinear events sequencing approach, and concepts of human errors as discussed in chapter 4. 

The previous sections have presented an extensive description of some of the central concepts from the cognitive modeling perspective. These topics have been dealt with in some depth because they provide a comprehensive basis for the reduction of human error in the CPI. 

Systemic safety management especially prominent after a major organisational disaster, which forces the organisation to take a fundamental look at its entire safety philosophy the appropriate view of human error is the system-induced error concept, which says that many human errors can be... 

Human reliability (HR) and human error (HE) are positive and negative name. The concept of human reliability is drawn from the product... 

To minimize the possibility of human error in any procedure involving a nuclear device, the U.S. Department of Defense has developed the two-person concept. Two or more persons, each capable of undertaking the prescribed task and of detecting an incorrect or unauthorized step in a procedure, are assigned to the task. One person accomplishes the procedural step and the other checks the action to verify it has been done correctly. It is not necessary that both persons have equal knowledge of the task, only that each is able... 

A technique for predicting the potential for human error in an activity. It evalnates quantitatively the contribution of the human error component in the development of an untoward system. Special emphasis is placed on the human component in prodnct degradation. THERP involves the concept of basic error rate that is relatively consistent between tasks requiring similar human performance elements in different situations. Basic error rates are assessed in terms of contributions to specific system faUutes. 

The Human Factors Theory is based on the concept that accidents are the result of human error. Factors that cause human error are ... 

The Concept of defence-in-depth is applied in designing safety systems to achieve functional diversity, i.e. by providing diversely functioning systems that can perform same safety function (e.g. two shutdown systems), multi barriers to prevent release of radioactivity, multi-defence system, using physical separation of systems and components which serve as back-up (in safety functions) to each other, and procuring components for different systems from different suppliers, to the extent possible. Such an approach leads to a design of safety systems which will be tolerant to a wide range of human errors and equipment failures. 

The main goal of this development work is an enhanced safety concept in which functional capability and reliability are ensured by simple and less sensitive safety equipment. In this way the effects of human error are to be diminished, reactor safety is to be improved even further, and capital cost as well as maintenance reduced. 

The investigators work with clients to design and implement customized solutions based on their company strategies, structure and culture to enhance performance and optimize costs. A fundamental concept of ICAM is the acceptance of the inevitability of human error. As stated by Reason (2000), an organization carmot change the human condition, but they can change the conditions imder which humans work, thereby making the system more error tolerant. 

Part 4 is a collection of human factors interventions from the different indnstry modes. It will introdnce the concept that human error is indeed ubicpiitous and therefore, its management should be approached from multiple applications training and development, leadership and supervision, situational awareness, distraction management etc. Novel elements in this part include research on driver distraction, medical team resource management, a new look at situational awareness, rail risk management and fatigue management in the medical field. 

FMS s 2-day intensive medical TRM program introduces team members to the basic concepts of human performance, as used by the aviation industry in its attempts to understand and prevent crew errors, incidents and accidents. Using a variety of actual airline accident and medical incident case studies, program participants will learn about crew resomce management principles, and how CRM training has achieved positive safety results within the international airhne industry. 

Human error is a concept so well-known worldwide that it is often cited but not actually defined. It should be noted that this term is understood as an action that is not intended not desired by a set of rules or an external observer or that led the task or system outside its acceptable limits (Senders Moray 1991). Human error is not connected with the accident, and thus the result, because it is independent (the same error in other circumstances may lead to different results) and can be simultaneously the result of other circumstances causing the error. However, very often it is considered from the point of view of an accident, due to the fact that it is only after the accident that an analysis is performed which reveals the existence of a specific human error. Another limitation of the category of human error is to specify that human error is understood as only such action, which was not purposely intended by the human (and therefore an action done in good faith, not a deliberate violation of the established rules) (Reason 1990). 

Reason [2] indicates that human error is intimately related to the concept of "intent . Error is only a meaningfiil term when lied to intended (plamied) actions that fiiil to achieve the desired goal without the intervention of some chance or unforeseeable agency. Thus, non-intentional, involuntary and spontaneous actions are not errors. Reason identifies two basic types of error sups and mistakes. 

This paper is concerned chiefly with Hazard Analysis and Risk Assessment when PES are used to carry out critical safety functions and the use to these ends of a modified Hazard and Operability (HAZOP) methodology. In order to put the HAZOP in perspective, some other major factors, influences and definitions will be addressed in the first part of the paper, beginning with the concept of Safety Lifecycle, followed by a short discussion of software risks, some case histories and a description of the development of the HAZOP approach to Hazard Analysis, including the increasing awareness of the signifrcance of human error. 

In summary, there can be no doubt that a positive safety culture is important to the delivery of safety improvements (including minimising the impact of human error) and absolutely central to the sustainability of improvements in safety. However, there is equally no doubt that it remains a rather ephemeral and nebulous concept. 

Is there a behavioral safety program Behavior-based safety is a concept that accidents are a result of human error. Behavior-based programs address the cause of the errors (e.g., attitude, environment)... 

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