Documents visual comfort 3 results

This study investigated the differences between conditions of full face-piece respirator wear and no respirator wear over 9 h on subject ability to detect stimuli dispersed throughout the visual field. Signal detection was assessed at the beginning of each trial and after 1, 3, 5, 7 and 9 h of testing in six male and three female subjects by measuring response times to 32 randomly presented stimulus lights located within a perimeter designed specifically for this purpose. Average reaction time increased with greater peripheralization of the light signals within each experimental condition. Group mean reaction time for each peripheral ring of stimuli (12, 38, 64 and 90) showed that impairments were significantly greater for the respirator wear condition compared with the control condition at all peripheral stimulus locations. For the unmasked condition, female subjects demonstrated significantly faster response times than males at peripheral stimulus locations of 12 (p < 0.002), 64 ( p < 0.001), and 90 (p < 0.01). However, respirator wear resulted in comparable response times between sexes for each peripheral stimulus ring with the exception of stimuli located 12 from the perimeter's centre. No progressive effect of respirator wear on signal detection capability over the duration of the test was observed, suggesting that the degradation of signal detection capability caused by full face-piece respirator wear occurs immediately and persists throughout the period of wear. The findings of this study emphasize that decreased operational effectiveness in situations requiring full face-piece respirator wear should be expected.

"This study investigates the changes in monitor placement, caused by the transition from cathode ray tube (CRT) to liquid crystal displays (LCDs), and discusses possible effects on the resulting viewing distance and the compensating workers' postures. The comparison between 148 workplaces equipped with CRT and 115 equipped with LCD monitors, revealed that the LCD monitors are positioned closer to the rear side of desks, augmenting the mean distance of the screen from the front edge of the desk by nearly 10 cm. The above finding suggests that the mean effective viewing distance may have also increased by the same amount. Considering data on monitors' types, specifications and operating systems' default character size, the study also suggests that in LCD monitors, the augmented viewing distance often exceeds the recommended angular height for comfortable reading while in a comfortable sitting posture. With the aid of a cybernetic model and the above empirical findings, we attempt to explain how the increase of the available effective space in front of the worker offered by LCD monitors may result in the adoption of adverse postures to improve the screen's legibility."