Page - 1524 - in Book of Full Papers - Symposium Hydro Engineering

stop. In commuter traffic, most signals will be at “caution” aspect, and given the frequency of signals (spaced 1 km apart), most drivers will face two signals per minute. Given the tendency for the attentional system to automate highly repetitive behavior, many drivers lose focus on the reasons for carrying out this repetitive task, and act in reflex whenever the buzzer sounds. The end result is that drivers often hear the buzzer and press the button reflexively without actively thinking about train speed and location. 3.2.2. Perception Perception relates to how we interpret information from our senses. A particular problem is that people are often required to interpret information rather than receive it directly. The interpretation of the information is a source of error and hence risk. 3.2.3. Memory People’s short-term memory has a limited capacity. Tests have shown that we can typically hold only seven individual items at a time in our memories. 3.2.4. Logical Reasoning Humans are not always good at logical reasoning. During the Three-Mile Island nuclear accident, two valves which should have been open were blocked shut. The operators incorrectly deduced that they were in fact open because of an illogical assumption about the instrument panel. 3.2.5. Situation Context Having identified individual failings in human beings, we should also recognize that our performance in any particular situation is greatly affected by the context we are working in. If we are tired, we will not perform so well and may also work poorly within teams. We will all have seen people who perform badly when trying to answer a question on a TV quiz show, the answer to which they know but cannot recall under the pressure of the situation. 1524