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This study evaluated the utility of a binary classification task in assessing the neurotoxic effects of elemental mercury. Twenty-six mercury cell chlor-alkali workers were tested on two occasions. This reaction-time paradigm provided reliable, stage-specific measures of cognitive functioning. In the two stages studied, processing times were found to increase significantly with increasing levels of exposure to mercury. The stage-specific nature of the measures used permits the inference that mercury has a locus of effect in the central nervous system.

To establish a minimum luminance level, a psychophysical procedure was used to establish the 95% correctness threshold for 95% of older drivers (ages ranged from 45 to 67). The correctness threshold and subject response times were obtained over eight letter luminance levels, four letter sizes, and three contrast ratios. The results showed that letters must be at least 0.64 cm high (at an 81.3–cm viewing distance) in order to be visible to 95% of the older drivers when letter luminance is set at 1.71 cd/m2. Response times declined as letter size, contrast ratio, and letter luminance increased beyond their threshold values. Although older drivers' visual acuity losses may be compensated by the use of corrective lenses, their losses in brightness and contrast sensitivity simply mean that they need about 10 times as much light as younger drivers.

Many workers perform manual assembly tasks or use hand tools while the hands are postured above the shoulders or to the side of the body. Experiments were conducted to study the sensitivity of speed-accuracy movement performance to a wide range of hand locations around the shoulder under various levels of hand loads, ratios of work to rest, and task durations. Subjects performed a spatially constrained stylus-to-hole Fitts reciprocal movement task designed to simulate high-incentive manual assembly operations while providing basic information regarding changes in human move and positioning capabilities. Significant decrements in movement performance occurred when hands were postured above shoulder level. Move and positioning times increased 15.3% and 26.5%, respectively, with elevation of the hand from −15 to 60 deg respective to shoulder level. Posturally based decrements in movement capability were unrelated to differences in subject strength capability found among test postures. The consequences of elevated arm postures on human move and positioning capability are presented along with workplace design and methods recommendations for job designers facing work-height decisions in manual assembly environments.