Abstract
The authors sought to establish whether a reduction in human temporal contrast sensitivity (adaptation) occurs as a result of exposure to a low-frequency periodicity, or beat, between two, high-frequency temporally modulated sources. Specifically, the authors were interested in possible adaptation from exposure to low-frequency beats between video display terminals (VDTS) and ambient fluorescent illumination, which, if it occurs, might be an underlying factor in visual fatigue symptoms experienced by some VDT operators. A small-magnitude frequency-dependent adaptation did occur with exposure to a robust beat stimulus produced by a xenon stroboscope and fluorescent luminaire. When a VDT was substituted for the stroboscope, no significant changes in contrast sensitivity occurred, even under laboratory conditions which favoured the possibility of measurable adaptation. We conclude that any temporal adaptation which may occur in the workplace as a result of viewing VDTS under fluorescent light is at insignificantly low levels.
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