ABSTRACT
During the Second World War it had become clear that people were severely limited in their ability to act on multiple signals arriving on different channels. Pilots had to try to monitor several sources of concurrent information, which might include the numerous visual displays inside the cockpit, the visual environment outside the plane and auditory messages coming in over the radio. Ground staff confronted difficulties when guiding air traffic into busy aerodromes and radar operators suffered from problems in maintaining vigilance. Psychology had little to say about these problems at the time, but researchers were motivated to try to discover more about the limitations of human performance.
