The aim of this study is to test how differences in exposure to complex tasks change the capacity for situational assessment. Amongst drivers, pilots and electricity controllers, the capacity to assess and respond effectively to changes in the operational environment are critical in sustaining performance and ensuring the safety and security of the public. Establishing the nature of this relationship will enable, for the first time, objective measures of cognitive skill decay. In evaluating cognitive skill decay more accurately, we will provide a cost-effective, easily administered tool, enabling practitioners to identify and address areas of development and providing data to anticipate when cognitive skill decay is most likely to occur.