The Validity of Subjective Reports of Visual Discomfort

Many surveys comparing users of visual display units with non-users have evaluated discomfort with a single questionnaire, designed to determine the occurrence of various symptoms. These in reality elicit the person's opinion or recollection of their discomfort rather than its actual frequency or severity. To examine the validity of this measure for intergroup comparisons, we administered a questionnaire of this type and then determined the incidence of a number of symptoms over a working week. We examined four different work groups and found that, after subjects had been matched for their questionnaire report, there were significant differences in the amount of discomfort reported. This between-groups difference in reporting behavior may account for some reports that VDU users suffer more discomfort than do non-users.