In both field and flight experiments, bias errors in the perceived sizes and distances of objects visible on the periscope’s viewing screen were discovered and quantified. Although it was speculated at the time that the misjudgments might be associated with the accommodation of the eyes to the near distance of the screen, that possibility was not pursued experimentally until practical
optometers became available in the 1970s. The strong dependence of the apparent size and distance of objects on the distance at which the eyes are focused has implications for the design of both real and virtual imaging displays.
Integrated displays. In parallel with the flight-by-periscope experiments
and the concurrent transfer-of-training studies – to be discussed later – the lab undertook a program for the National Research Council to develop the optimum display of bearing and range information to be provided by the Civil Aviation Administration’s new VORDME radio navigation facilities. Williams had advanced the notion of the integrated presentation of flight information, which led to his conception of map displays on which the airplane’s position and heading are plotted automatically.