Ground-Referenced Visual Orientation with Imaging Displays

摘要

Among the many findings reported, the following stand out as contributing to our understanding of the performances of pilots. Judgments of size, and by inference the distance, of objects in natural outdoor vistas are strongly dependent on the distance to which the eyes are focused (r approx 0.9); the exact functional relationship is confounded by the grossly progressive psychophysical inequality of units of the dioptric scale. Accommodation to natural vistas depends in a complicated way on the dark focus of the individual, the retinal locus and spatial frequency of visible texture, and the sharpness of focus needed for the desired discrimination of object identity, for example, reading a sign. Individual differences in dark focus range from perhaps 15 D in extremely myopic people to as distant as -4 D in the extremely hyperopic; the more distant the individual's dark focus, the greater the individual's tendency to focus beyond an acuity target to maximize apparent size for the discrimination of detail. Some individuals can be trained more readily than others to control the focal distance of their eyes voluntarily; there is some evidence that such trainability depends in part on the individual's dark focus and that both the selection and training of combat pilots should take such characteristics into account. (Author)