Human Error Fundamentals

Human error can be divided into the general categories of slips and mistakes [143, 144]. Basic to the difference is the concept of intention or desired action. A mistake is an error in the intention, that is, an error that occurs during the planning of an action. A slip, on the other hand, is an error in carrying out the intention. As an example, suppose an operator decides to push button A. If the operator instead pushes button B, then it would be called a slip because the action did not match the intention. If the operator pushed A (carries out the intention correctly), but it turns out that the intention was wrong, that is, button A should not have been pushed, then this is called a mistake. 

One of the difficulties in eliminating planning errors or mistakes is that such errors are often only visible in hindsight. With the information available at the time, the decisions may seem reasonable. In addition, planning errors are a necessary side effect of human problem-solving ability. Completely eliminating mistakes or planning errors (if possible) would also eliminate the need for humans as controllers. 

Planning errors arise from the basic human cognitive ability to solve problems. Human error in one situation is human ingenuity in another. Human problem solving rests on several unique human capabilities, one of which is the ability to create hypotheses and to test them and thus create new solutions to problems not previously considered. These hypotheses, however, may be wrong. Rasmussen has suggested that human error is often simply unsuccessful experiments in an unkind environment, where an unkind environment is defined as one in which it is not possible for the human to correct the effects of inappropriate variations in performance 

A second basic human approach to problem solving is to try solutions that worked in other circumstances for similar problems. Once again, this approach is not always successful but the inapplicability of old solutions or plans (learned procedures) may not be determinable without the benefit of hindsight. 

The ability to use these problem-solving methods provides the advantages of human controllers over automated controllers, but success is not assured. Designers, if they understand the limitations of human problem solving, can provide assistance in the design to avoid common pitfalls and enhance human problem solving. For example, they may provide ways for operators to obtain extra information or to test hypotheses safely. At the same time, there are some additional basic human cognitive characteristics that must be considered. 

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Task analysis is a fundamental methodology in the assessment and reduction of human error. A very wide variety of different task analysis methods exist, and it would be impracticable to describe all these techniques in this chapter. Instead, the intention is to describe representative methodologies applicable to different types of task. Techniques that have actually been applied in the CPI will be emphasized. An extended review of task analysis techniques is available in Kirwan and Ainsworth (1993). 

Accidents are only the tip of the iceberg they materialise out of sudden unsafe situations, which in turn are often caused by undesirable operator behaviour (human error). We have to know much more about these underlying precursors of actual accidents if we aim at more fundamental understanding of the process of accident production. 

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... 

In this introduction, we have presented an overview of the benefits of applying the technique of SFE to the area of food analysis. There are substantially reduced costs derived from use of SFE versus traditional extraction in the areas of solvent purchase costs, solvent disposal costs, reduced labour charges, and even less need to repeat experiments due to reduced human errors in the overall analytical scheme. Moreover, productivity can be improved and the use of environmentally-unfriendly solvents is greatly reduced. In the rest of this chapter we will explore the fundamental principles of SFE in more detail, discuss some of the aspects of current SFE instrumentation, present a number of examples of applying SFE to food samples, and briefly summarise some hints for methods development. 

In April 1986, fundamental flaws in Soviet reactor designs, combined with procedural human error, resulted in a steam explosion and the expulsion of 5% of the ChemobyM (Ukraine, USSR)... 

Assembly work and supervisory monitoring constitute two occupational activities essential to industrial production that represent different work conditions. For example, work on the assembly line of a car factory and process monitoring in a nuclear power plant differ in terms of demands for training and education, physical environments, consequences of human error, and so on. However, they also share a fundamental psychological characteristic in that both are associated with monotony (Johansson, 1991). 

People s unsafe behavior and unsafe state of object is the direct cause of accident, in which the unsafe behavior of the people is the most important reason, because most of the accidents are caused by human error. The key to create a safe atmosphere is to manage people, educate people, inspire people, and let the staff form strong safety awareness in the influence by environment, to achieve fundamental change from want me to be safe to I want security. ... 

It is fundamental for assessing human error in systems analyses to identify and describe the human acts with importance for the event sequence under analysis (qualitative assessment). This corresponds to the task analyses, which are characteristic of ergonomic studies. Firstly, the important actions, the moment in time at which they are required and the time period available for their execution have to be determined. Furthermore, the requirements for the action, the information necessary, respectively available, the possibilities of correction in case of omission or faulty execution must be estabhshed. Additionally, other factors of important influence on human reliabihty such as the state of knowledge on the process in question, ergonomically favourable or disadvantageous layout of the workplace, the tools or the environment are identihed. On the basis of this task analysis reliability data (normally failure probabilities on demand) are assigned to the tasks identified. They stem from existing data collections (cf. Table 9.21). 

There are, therefore, two fundamental design approaches to mitigate the system s vulnerability to human error reduce the probability and/or reduce the severity of the error ... 

Fundamental operational objectives. These objectives are concerned with increasing safety, improving system performance, and reducing human errors. 

Dhillon, B. S., Engineering Usability Fundamentals, Applications, Human Factors, and Human Error, American Scientific Publishers, Stevenson Ranch, California, 2004. 

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. 

Data show that wire strikes have been the most common type of aerial agriculture accident since at least 1985 consistently accounting for about one-third of human factors related accidents. While this statistic alone suggests fundamental shortcomings in methods adopted by the industiy to address the problem in the past, more concerning is the statistic that almost all of the wire strikes involve wires that the pilot knew were there and had previously avoided, but due to a range of well-known human error conditions, such as excessive task load, distraction, fatigue, etc., the pilots failed to avoid the wires. 

Airservices Austraha technicians also undeigo training in HF and the management of human error. This HF training is similar to that outlined in the ICAO Human Factors Training Manual (199S) and incorporates HF fundamentals such as conceptual models of error, cultural and oiganizational factors, human performance, communication, teamwork and environmental issues. 

Why do errors occur The answer to this fundamental question is multifactorial. A host of factors lead to human error. Space does not permit a thorough exposition of the various factors known to contribute to human error, but a number of key factors can be mentioned here. Firstly, humans demonstrate considerable individual variation, in terms of concentration, intelligence, memory, attentiorr, information processing capability and so on This individtral variation in cognitive abilities between different people can also be seen in the same individtral at different times. This intra-individtral variation in cognitive ability can restrlt from several factors, such as fatigue and illness. 

The second new topic is that of competence. Given that most accidents occur because of human error, or safety failures in systems of work, the management of competence is of fundamental importance. 

In any health and safety training undertaken, particular attention should be paid to the human factors aspects of safety performance, in particular the potential for human error associated with personal factors such as attitude, motivation, perception and even personality. One of the fundamental objectives of training is to increase awareness of all concerned to hazards and their individual accountabilities and responsibilities for health and safety. 

On the other hand, some contemporary approaches to HRA such as A Technique for Human Error Analysis ATHEANA (Barriere et al. 2000), the Connectionism Assessment of Human Rehabihty (CAHR) based on Strater (2000) and the Cognitive Rehabihty and Error Analysis Method (CREAM) by HoUnagel (1998) were developed around the principle that the fundamental element is, in fact, the context in which the task is performed, reducing previous emphasis on the task characteristics per se and on a hypothetical inherent human error probabihty. 

The human contribution must also be considered on a much broader basis than simply human error. Physical limitations, natural human tendencies, cognitive limitations, ergonomics, knowledge, skills, and other characteristics of the people part of the accident-producing process must be considered. This is especially true if we are to identify fundamental and permanent improvements to the process so it produces fewer accidents in the futnre. 

None of the actual/potential human errors described in the examples above are subtle problems, nor do they relate to the technical intricacies of the human visual system, information processing etc. Equally no detailed understanding of hnman psychology, physiology or anatomy is needed to address what are essentially ergonomics limitations of the cmdest type. The fact that such fundamental limitations can and do create serious health and safety risks shows clearly that... 

As mentioned above in relation to the pre-emptive approaches to human error management, the additional analysis required is not fundamentally different from that which is often already undertaken. All that is necessary is a framework which ensures that the factors which predispose human error are investigated systematically and comprehensively. Once again, the process is more important than the procedure. 

Despite the above assurance that the process outlined in not significantly different, in principle, to that already adopted in many organisations it will undoubtedly require more time and more systematic approaches to be used routinely. This, in itself, may be a barrier to adopting such an approach however, the fact that it is fundamentally cmcial to routinely identify human error predisposing factors (particularly those which are common and therefore likely to represent latent failures) can be seen clearly by revisiting some of the examples of human error potential given in Chapters 3-8. 

The Safe System approach is a fundamental shift from traditional traffic safety thinking. It reframes the ways in which traffic safety is viewed and managed. Its aim is to support development of a transport system better able to accommodate inevitable human error. The recognition that humans do make, and will continue to make, errors of judgement as road users is one of the core shifts in thinking. 

There is a long history in the United Kingdom (UK) of research, development and successful practical application of safety and reliability technology. There is a continuing prograimne of fundamental research in areas such as software reliability and human error in addition to further development of the general methodology. Much of the development work was carried out by the nuclear industry. 

HRA analyses the relationship between human behavioural tendencies and the work context to provide a better understanding in anticipating human errors, violations and severe system outcomes. This analysis requires a fundamental understanding of ... 

Several methods to quantify human error probability have been reviewed in Section 9.2. These methods suffer from the difficulty associated with any attempt to construct quantitative, predictive models of human behaviour. The qualitative methods on the other hand, require multi-disciplinary teams to carry out an analysis and this is regarded as being resource intensive. The more recent HRA methods have included cognitive aspects of decision making and the time dimension. However, it has not yet captured the fundamental nature of the interaction between actions and machine responses (Cacciabue et al. (1993)). These interactions lie in the mutual dynamic influence of the operator, the plant and the interfaces. 

The HPI principles along with an understanding of human error precursors can be used to enhance the development of the JHA process. If a fundamental attribute of humans is that they can make mistakes and make wrong decisions then it becomes important to ensure that job requirements... 

Fail-safety in crew operations is a subject which has become more prominent in the last decade (refer INT/POL/25/14), under terms such as human factors engineering . The fundamental principle is that if the design is vulnerable to human error, then an accident is bound to happen. 

Irrespective of the model used to predict the human Fabs, there are situations where less accurate predictions can be expected. This could be due to either variability or error in the input data or due to more fundamental problems in the understanding of drug behavior. 

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