Abstract
Visual detection of life rafts in the sea presents a difficult task which might be aided by use of appropriate sunglasses designed to reduce glare and atmospheric attenuation while enhancing target-to-background contrast. To evaluate this possibility, target acquisition performance associated with the following types of sunglass lenses was compared with that of the unaided eye: Hazemaster, Oakley Doc, Cosmetan and N-15.
A circular 1:1000 scale terrain model was used to simulate an air-sea rescue operation under conditions of relatively low daylight illumination. Observers searched for targets while making simulated banking turns. Performance measures were response time and number of targets found. Results showed the Oakley Doc to be the best and the Cosmetan to be the worst of the lens alternatives. However, no filter was found to be superior to the unaided eye. The data agree with recent target acquisition studies in showing no advantage for yellow sunglass lenses. The results are also consistent with the assumption that supposed enhancement properties of colored lenses may well be offset by losses in light transmission associated with their use.
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