The concept of human error has a prominent place in the history of human factors. When there is a failure in a system where the human is a component, a strong tendency exists to blame the human. The easier way is to conclude that the system failed because the human made an error. This is a predisposition often shared by engineers, marketing people, juries in courts, and, unfortunately, sometimes people whose work is concerned with safety. Even today, when an airplane crashes, it is not uncommon to hear the news media focusing on the question or issue "What did the pilot do wrong?"
It is not my intent to imply that humans do not make errors, nor that it is inappropriate to consider human error in a work context. But, clearly, there are more productive approaches to dealing with system failures than focusing blame on the human component. In recent years, our team has conducted extensive theoretical and empirical research and experimentation on human error. Error is taken as a generic term that encompasses all those occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency." (Reason, 2004).
We recently had an opportunity to work on a project with a Fotune 500 company to stratify the data contained in a database related to safety incidents and accidents. The vast majority of the reports examined attributed fault to the person who was injured. "He or she was not paying attention" and "Human Error" were the most common phrases. Usually, there was little or no effort to consider the role of other potential factors such as the equipment being used, the environment in which it happened, the task that was being carried out, or how these aspects of the system fit or did not fit the person. Here again, there is often a tendency to assume the primary fault for an accident and injury lies with the employee.
There are a couple of key points to be noted about this definition and the perspective it offers about the concept of error. First, the notion that an error has occurred is based on the failure to achieve an outcome or goal. Second, the concept of intention is central to this entire perspective or theoretical framework regarding human error. Intention in this context consists of two elements: (1) an end-state to be attained (the goal), and (2) a means (the actions) by which the end-state is to be achieved.
When dealing with human error we should distinguish between three levels of performance (Rasmussen, 1983): skill-based, rule-based and knowledge-based. Skill-based - At this level people carry out routine, highly-practiced tasks in what can be characterized as a largely automatic fashion.