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3.2. HUMANS AS INDIVIDUALS Human beings are very complex and no two of us are alike. The variability in our capabilities is marked and yet most tasks assume they are being undertaken by a standardised, competent person. In reality each of us is more or less competent from one day to another. In addition, we tend to over-estimate our own competence usually thinking we are above average. This phenomenon has been given the name “illusory superiority”. In a recent survey, rating how good a car driver they were, most people gave themselves a score of seven out of ten having been told that average was five. In another study 32% of employees in a software company ranked themselves above 19 out of 20 of their colleagues. It is interesting to note that a common reason given for introducing computers and artificial intelligence into financial processes, is that the computers make better decisions than humans. In respect of human errors, industrial psychologists sometimes use the terms “slips”, “lapses” and mistakes. The general definition being that:  A slip is a failure to undertake the task correctly. It could be performing the task too soon or late. Or it could mean omitting to perform a step.  A lapse is a failure to carry out an action, perhaps one task in a series of tasks. For example the omission of steps in maintenance has been cited as a substantial cause of nuclear power plant incidents.  A mistake involves doing something wrong that we believe to be right (there is still the problem of a deliberate error or (violation”). These tend to be of two categories knowledge based or rules based. Such human slips, lapses and mistakes come about for lots of reasons. 3.2.1. Attention People have a limited attention span which has been estimated to be about twenty minutes before fatigue sets in and errors are more likely to occur. Regular tasks become habit forming so that when repeated often enough they become automatic responses rather than reasoned decisions. By way of an example, in a historic study of automatic train protection on the UK network the following was observed in respect of train driver behavior: The automatic warning system installed on passenger trains in the UK is an example of a system that was not designed with the limitations of human attention in mind. It is a device fitted in the train cab, based on the new obsolete mechanical system of signaling that used to signal either STOP or PROCEED. It sounds a bell when a clear (green) signal is passed and a buzzer when caution or danger is signaled. If the buzzer is not acknowledged by a press of the button, then the train begins to automatically 1523