After we have recognised coherent information from the stimuli reaching our senses, we must decide upon a course of action. In other words, decision-making occurs. Decision making is the generation of alternative courses of action based on available information, knowledge, prior experience, expectation, context, goals etc., and selecting one preferred option. It is also described as thinking, problem solving and judgement. This may range from deciding to do nothing, to deciding to act immediately in a very specific manner. A fire alarm bell, for instance, may trigger a well-trained sequence of actions without further thought – for example an evacuation. Alternatively, an unfamiliar siren may require further information to be gathered before an appropriate course of action can be initiated. We are not usually fully aware of the processes and information that we use to make a decision. However, tools can be used to assist us in the process of making a decision. For instance, in aircraft maintenance engineering, many documents and procedures are available to guide the basic decision making skills of the individual.