Good decisions are based on knowledge supplemented by written information and procedures, analysis of observed symptoms, performance indications, etc. It can be dangerous to believe that existing knowledge and prior experience will be sufficient in every situation, as will be shown in the section entitled ‘Information Processing Limitations’. Once a decision has been made, an appropriate action can be carried out. Our senses receive feedback from an action and its result. This helps to improve knowledge and refine future judgement by learning from experience.