Knowledge-based errors

Reason divided error into slips, or lapses, and mistakes. Slips or lapses involve the correct choice of a method to achieve a task, but a failure to carry it out correctly. Mistakes on the other hand involve a flaw in the plan which means that even if it is carried out correctly, the objective isn t achieved. Slips and lapses are often skill-and rale-based errors, whereas mistakes are often knowledge-based errors. 

Rule and knowledge-based errors are also collectively termed mistakes. They represent intentional actions being incorrectly carried out. Sometimes the error and its evidence are ignored and dismissed due to the operator s belief that they have in fact acted correctly. 

The classification of human error within the FASGEP project takes into account the woric of Rasmussen, specifically the classification of Rule-Based errors, Skill-Based errors, and Knowledge-Based errors. The causal relationships for each of the classifications have been developed into a causal network. A type of graphical probability model is based on this. 

Reason goes further and highlights the likely feilure modes at each level of behaviour. For exanq>le skill-based enors occur due to control-mode fiulures of both inattention and over-attention. Rule-based errors can arise fiom the misapplication of rules or the q>plication of incorrect rules. Knowledge-based errors can arise due to selectivity, biased reviewing and a number of other fiictors. 

Rasmussen [ 8 ] has indicated that experience is the most inqwitant of the attributes in determiiung the number of knowledge-based errors. A good team has been shown [ 9 ] to result in a reduction in the number of errors introduced. Shared e q)erience has therefore been considered to have the highest weight in assigning the probabilities in this distribution (see Figure 3). 

Knowledge-based errors are concerned with performance in novel or new situations. Actions have to be planned on-line and the process is intellectually demanding. The problem solver will only resort to this type of activity when he has run out of rule-based solutions. An example of knowledge-based performance is that of first learning to operate a piece of machinery. The hydraulic controls of a winch provide a good example. Experimentation will help the operator to build a mental model of how the controls can be co-ordinated to achieve the desired movements. Eventually, the operator will adopt a set of rules derived from that mental model. With practice, the task will become skill-based. Training offers the opportunity to miss out the experimentation phase by guiding the trainee to a correct model of situations, based on the experiences of others. 

The method marks a shift away from knowledge based errors in other error analysis tools to better reflect the visual and auditory nature of ATM. 

Dimension Errors based on automatic behaviour Rule-based Knowledge-based errors errors... 

These two examples hint at a few of the reasons for the importance of knowledge-based systems. A medical faciHty may handle hundreds of infectious disease cases a year. Speedy, accurate diagnosis of these cases, aided by a system such as Mycin, may help the medical faciHty handle more patients, more effectively. Likewise, configuring large computer systems composed of many components can be a time-consuming and error-prone task. 

In the case of the CPI, there are relatively few situations where control room workers are likely to face continuous periods of overload. However, when overload does occur it is likely to be associated with situations when the plant is in an unusual or abnormal state for which the workers may not have any rules or procedures available. In these situations, knowledge-based processing (see Section 2.6.2), which needs considerable mental resources, will be required and errors of diagnosis are likely to occur. 

An influential classification of the different types of information processing involved in industrial tasks was developed by J. Rasmussen of the Rise Laboratory in Denmark. This scheme provides a useful framework for identifying the types of error likely to occur in different operational situations, or within different aspects of the same task where different types of information processing demands on the individual may occur. The classification system, known as the skill-, rule-, knowledge-based (SRK) approach is described in a... 

Performance problems may be exacerbated during unfamiliar or novel process events, for example, situations not covered in the emergency procedures or in refresher training. These events require knowledge-based information processing for which people are not very reliable. The types of errors associated with knowledge-based performance have been discussed in Chapter 2. 

The practical implications of this experiment are that when evaluating the effects of shift work due to circadian effects, the type of task being carried out by the worker must be taken into account. For example, skill-based tasks would be expected to exhibit the performance changes characteristic of low memory load tasks, whereas performance variations in knowledge-based tasks would be expected to follow the pattern of high memory load tasks. Performance on rule-based tasks may depend on the degree of frequency of use of the rules, which in turn may determine the memory load. If these results were confirmed by further process plant studies, it would have implications for when different types of operation (involving different levels of memory load) should be scheduled to reduce circadian rhythm effects and minimize errors. 

With this database in hand, a simple question is asked [29] How different is a knowledge-based potential derived from this lattice database compared to the actual energy function used to construct the database If statistical errors are negligible and the knowledge-based method is perfect, the answer is expected to be They are exactly the same. ... 

The following list divides types of unsafe acts into those that are skill-hased, perceptual, and decision or knowledge-based. (Note that this division is different from the skills-rules-model knowledge-based model described earlier.) Examples are given of each type of error that may result in an unsafe act.( )... 

In this thesis the most important implication of this model is the prediction that different types of errors (Skill-, Rule-, or Knowledge-based) imply different types of preventive measures. ... 

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