Three experiments were conducted in which positive and negative contrast on visual display terminals were directly compared. Operator tasks included visual search and reading, with accuracy and timeliness of response measured. In all cases where significant differences exist, better performance was obtained with negative contrast (dark characters or symbols on a lighter background). The increases in performance range from a low of 2.0 percent to a high of 31.6 percent. Based on the above results, we believe that there are significant advantages in visual task performance obtained from the selection of negative contrast displays.Current standards that require negative contrast appear to be justified, while future revisions of ANSVHFS 100-1 988 and other standards should seriously consider incorporating negative contrast as a recommendation or requirement.

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The performance and comfort of aircrew using stereoscopic displays viewed at a near distance over long periods of time are now important operational factors to consider with the introduction of aerial refueling tankers using remote vision system technology. Due to concern that the current U.S. Air Force vision standards and test procedures may not be adequate for accurately identifying aircrew medically fit to operate this new technology for long mission durations, we investigated performance with the use of a simulated remote vision system and the ability of different vision tests to predict performance and reported discomfort. The results showed that the use of stereoscopic cameras generally improved performance but that individuals with poorer vision test scores performed more poorly and reported greater levels of discomfort. In general, newly developed computer-based vision tests were more predictive of both performance and reported discomfort than standard optometric tests.

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