The Effect of Spectrally Selective Filters on Visual Search Performance.
NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA AIRCRAFT AND CREW SYSTEMS TECHNOLOGY DIRECTORATE
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The effect of five spectrally selective filters on the performance of an acuity dependent visual search task was evaluated. The filters were A a neutral density filter control condition B a 5200A green interference filter C a 3215-250 red filter D a neodymium visor and E a holographic filter. The observers were presented with five blocks of ten slides per filter. Each slide projected a 6 by 6 deg field of 900 ten min of arc letter Os which contained a single Landolt C. The observers were required to search the field and report the orientation of the opening in the C. The opening in the C, which subtended 2.64 min of arc, required an acuity of 0.39 for detection. Response time, error rate, accommodative accuracy, and the number of fixations and their duration were recorded for each slide presentation. The results demonstrate that filter type had no effect on any of the response measures. During the first three trial blocks the observers appeared to optimize their search strategies, after which they began to revert to their initial performance levels. Although this effect was not supported statistically, this trend indicates that initially search proficiency increases with practice after which it is offset by fatigue. keywords Visual searching, Visual acuity, Accommodation, Fixation, Human performance.
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