In 1943 the Royal Air Force asked for laboratory studies that might determine the optimum length of time radio operators in antisubmarine patrols should be kept at watch. This request was made because of evidence that during patrols numbers of potential U-boat contacts were being missed. This report records visual and auditory vigilance tests, in which the conditions under which men actually operated during watch to detect signals indicating presence of enemy underwater craft were simulated.
Auditory vigilance tests were also devised and apparatus designed to provide a test simulating the duties of Asdic (sonar) operators. Asdic equipment detects presence of submerged submarines by providing an auditory signal representing the echo reflected by underwater objects.
In all the tests the conclusions were that subjects miss more signals after working one-half hour and that the decline can be prevented by alternation of this duty with other work at one-half-hour intervals.