摘要 :
An appropriately designed parallax (two-station) range allows a mariner to accurately determine a range line--the correct path to steer his vessel--at greater distances. Less expensive alternatives to parallax ranges are desirable...
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An appropriately designed parallax (two-station) range allows a mariner to accurately determine a range line--the correct path to steer his vessel--at greater distances. Less expensive alternatives to parallax ranges are desirable, and many ideas, principally single-station ranges, have been proposed. However, the mariners' abilities to establish range lines with them have not been measured. The present work has quantified the navigational sensitivity afforded by parallax ranges and three different types of single-station range display systems. The single-station ranges used (a) temporal characteristics, (b) spatial representation, or (c) color changes of the signal to represent changes in lateral position. Range systems were simulated either opto-mechanically or on a high resolution computer display system. The mariners' ability to determine both lateral position in a channel and direction of motion across a channel was assessed psychophysically for each range system.
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We evaluated the effectiveness as an aid to navigation a single-station beacon which was white when viewed from the centerline of a channel and became increasingly red or green when viewed from off center to the right and left. Fi...
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We evaluated the effectiveness as an aid to navigation a single-station beacon which was white when viewed from the centerline of a channel and became increasingly red or green when viewed from off center to the right and left. First we measured the observers' ability to determine whether a light was white, reddish, or greenish. A wide range of colors, from 575 nm to 585 nm, were judged to be white, making it difficult to specify a beacon that would adequately signal center of channel. Second, we measured the ability of the observers to detect a change in color for slowly changing stimuli. There were seven just noticeable differences in the range of color investigated. This would provide a sensitivity of 21.8 m (71.4 ft) over a 152 m (500 ft) wide channel. Measurements were taken with and without a 'white' reference light. Under no condition did the reference light improve performance. For changing stimuli, however, those that were brighter or larger provided better sensitivity than those that were small or dim.
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A double blind study was made to determine the effect of hypoxia on the rate of dark adaptation. The visual thresholds of 10 subjects were measured as they breathed either 21% O2 or 12% O2 for 10 minutes in daylight followed by 50...
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A double blind study was made to determine the effect of hypoxia on the rate of dark adaptation. The visual thresholds of 10 subjects were measured as they breathed either 21% O2 or 12% O2 for 10 minutes in daylight followed by 50 minutes in the dark. The subjects were exposed to the two gases in counterbalanced order on separate days. Reducing the oxygen level to 12% delayed the course of dark adaptation without changing the final scotopic threshold. Keywords: Dark adaptation; Hypoxia. (jhd)
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摘要 :
Ten subjects performed a color matching task with ten sets of seven colors, adapted from sets recommended in the literature. The color sets covered a wide range in color difference values (delta-E* in CIELUV, 1976). Performance wi...
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Ten subjects performed a color matching task with ten sets of seven colors, adapted from sets recommended in the literature. The color sets covered a wide range in color difference values (delta-E* in CIELUV, 1976). Performance with some color sets was significantly better than that with others on a task where color discrimination was important and the colors needed to be discriminated quickly and accurately. Effectiveness of a color set did not depend on the inclusion of any particular colors; rather, the relationships among colors proved to be important. The larger the color difference value between the two most perceptually similar members of a set, the shorter the reaction time and the fewer the errors on the color matching task. (Author)
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This report summarizes the results of two studies conducted in sonar trainers at Naval Submarine School comparing red and blue ambient illumination in sonar control rooms. In one, a subjective assessment of blue, white, and red wa...
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This report summarizes the results of two studies conducted in sonar trainers at Naval Submarine School comparing red and blue ambient illumination in sonar control rooms. In one, a subjective assessment of blue, white, and red was made in the SSBN Sonar Operational Trainer; in the other, detection ranges were measured on the 21B64A/AN/BQQ-5A trainer under red and blue light. The sonar crews of two submarines voiced strong preferences for blue light while those of a third preferred red. Detection ranges did not change with the color of the illumination. (Author)
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A field study of the ability of subjects to judge depressions in the snow was conducted at a cross-country ski area. Many pairs of depressions were made in the snow and each subject was asked to judge which depression in each pair...
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A field study of the ability of subjects to judge depressions in the snow was conducted at a cross-country ski area. Many pairs of depressions were made in the snow and each subject was asked to judge which depression in each pair was deeper. The percentage of correct judgments was significantly greater on an overcast day with yellow goggles than with luminance-matched neutral goggles. (Author)
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Luminance thresholds were measured for the water-immersed eye as a function of adaptation level, viewing distance, and turbidity of the water, and compared to standard adaptation curves. In water, thresholds varied as a function o...
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Luminance thresholds were measured for the water-immersed eye as a function of adaptation level, viewing distance, and turbidity of the water, and compared to standard adaptation curves. In water, thresholds varied as a function of initial adaptation level, and the rate of adaptation paralleled that for the eye in air. However, thresholds were about 1 - 2 log units higher for the water-immersed eye than for the eye in air at all adaptation levels. (Author)
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The curvature distortion perceived under water was measured in three dimensions before and after 15 min of adaptation to the underwater environment. Subjects initially perceived distortions in all three dimensions. After 15 min un...
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The curvature distortion perceived under water was measured in three dimensions before and after 15 min of adaptation to the underwater environment. Subjects initially perceived distortions in all three dimensions. After 15 min under water, they exhibited significant adaptation to the curvature distortion in all dimensions. The type of task performed while in the water did not significantly affect the amount of adaptation. The results are compared with those of previous experiments which have reported evidence of counteradaptation when more than one kind of adaptation is measured simultaneously. (Author)
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One of the major factors limiting man's ability to work at depth is the occurrence of nitrogen narcosis. Other related problems include oxygen toxicity, decompression trauma and carbon dioxide retention. The effects of these three...
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One of the major factors limiting man's ability to work at depth is the occurrence of nitrogen narcosis. Other related problems include oxygen toxicity, decompression trauma and carbon dioxide retention. The effects of these three stresses on man's functioning can be investigated using several methods. Two of these methods, one electrophysiological and the other behavioral, have been successfully used to differentiate the effect of nitrogen narcosis and the effect of pressure per se. NISAT I was designed to assess the effect of an extended dive on functioning. In this dive Navy divers were exposed to approximately 200FSW for seven consecutive day. The breathing mixture contained oxygen levels comparable to those of normal air. This paper presents the results of the electrophysiological recordings (both electroencephalograms and visual evoked potentials) made during this dive and the results of a combined electrophysiological/reaction time measure. Decrements were found in the brain's response to repetitively presented light flashes. Similar changes are typically found in short term dives to the same depth. The variability of the response to fast flash rates and the speed of the response to slow flash rates also increased during the dive. The results are discussed as reflecting the operation of at least two different effects, one a deficit in the ability to process incoming sensory information, and the second a more general brain dysfunction.
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摘要 :
In order to assess individual differences in susceptibility to nitrogen narcosis, a group of 16 men made repeated air dives to approximately 200 ft in a pressure chamber. The visual evoked response of the men at depth revealed sev...
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In order to assess individual differences in susceptibility to nitrogen narcosis, a group of 16 men made repeated air dives to approximately 200 ft in a pressure chamber. The visual evoked response of the men at depth revealed several decrements: in the response to a slow rate of stimulation, there was a highly significant reduction in a component around 160 msec; in the response to a rapid rate of stimulation, marked losses in amplitude and increases in variability were found. The latter changes were related to diving experience while the former were not. No significant changes were found in alpha or theta activity in the EEG. (Author)
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