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Responses Biases with Virtual Imaging Displays.

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Final rept.,

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The head-up display was developed to provide the pilot simultaneous viewing of flight information and the outside environment. The HUD optics were collimated so that the symbols appear at optical infinity as does the distant terrain. Operationally, about 30 percent of pilots experience an increased tendency toward spatial disorientation when using a HUD. Two experiments were conducted at NADC to determine whether HUD symbols do fact allow the eyes to focus at optical infinity. And, if not, what is the direction and amount of refocusing necessary to see both the real world and HUD symbols clearly Results showed that the HUD produces undesirable inward focusing shifts when it is used. When simultaneously using the HUD and viewing distant real-world targets, eye focus is not the same as focus to the real-world targets alone. Also, when using the HUD in clouds, focus is not the same as when using the HUD superposed over distant terrain. Collimated HUD symbols were found to be weak visual stimuli that do not draw eye focus much beyond the resting distance, or dark focus. In general, the HUD allows focus to lapse toward the individuals own particular dark focus. Previous research indicates that when focus shifts occur, the apparent size and distance of real-world objects also change. Judgments of the aircrafts position in space can be erroneous. These judgments are critical in tasks such as terrain following, target bombing, and final landing approach. Because individual differences in focusing are large, redesigning the HUD to incorporate manual optical adjustments may be desirable. Using manual adjustment, the optics can be optimized for each pilot. Pilot accommodation training is another consideration. Further experiments are needed to determine the best redesign and training solutions.

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  • Non-Radio Communications

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