a system is provided for testing and enhancing the alertness of operators who monitor video surveillance imagery . alertness is tested by displaying any of a variety of visual elements on top of or near the video imagery , and receiving input from human operators in response to the visual elements , via one or more input devices . the system further allows for economic management of human operators by transmitting imagery from many video sources to any number of operators . video feeds are automatically switched , via software , away from an operator who wishes to take a break or has poor alertness . in this fashion , the system maximizes operator vigilance while also maximizing workflow for all available operators .