A Comparison of Seven Visual Fatigue Assessment Techniques In Three Data-Acquisition VDT Tasks

Abstract

We compared 7 methods of measuring visual fatigue--accommodation power, visual acuity, pupil diameter, critical fusion frequency (CFF), eye movement velocity, subjective rating of visual fatigue, and task performance--for their sensitivity to visual load. In the experiment, 10 participants performed a monitoring task at 2 viewing distances, read articles under 2 levels of screen contrast, and tracked visual targets at 2 different speeds. The same measurement techniques, excluding pupil diameter and eye movement velocity, were compared by extending the task time from 20 to 60 min with the same VDT tasks to test for possible improvement in sensitivity. The results indicated that sensitivities of accommodation power, visual acuity, and CFF were greatly improved by a longer task period, but these 3 measurement techniques did not distinguish among tasks. Pupil diameter, eye movement velocity, and subjective rating of visual fatigue were sensitive in differentiating tracking from reading and monitoring tasks. Eye movement velocity and subjective rating were sensitive to the changes in target velocity of the tracking task. Although task performance was not directly comparable to other measurement techniques, it helped to ensure that participants maintained the same performance level by devoting more resources to the high-load conditions. Actual or potential applications of this research include using some of these assessment techniques for the design of adaptive displays.

Visual Fatigue and Performances for the 40-min Mixed Visual Work with a Projected Screen

“…Iwasaki and Akiya [16] confirmed that the decrease in CFF reflects a decline in retina or optic nerve activity. Because of high sensitivity and convenience, a change in CFF is considered as an important index with which to measure physiological visual fatigue [17,18].…”

Evaluating visual cues for window switching on large screens

“…To estimate awareness, we occasionally introduced changes to content in non-active windows when cues were displayed. Since objective measures of visual fatigue are costly to obtain, vary widely and are sensitive to many factors such as task period [8], we instead rely on subjective user feedback. Since it is infeasible to evaluate the full factorial design with 160 combinations, we restricted our first study to the nine basic cues.…”

Effects of virtual lighting on visual performance and eye fatigue

“…They provided a good method for capturing these differences in visual performance depending on the luminance contrast in different VDT tasks, including a tracking task and reading (Chi & Lin, 1998). It is important to note here that the Chi and Lin study is comparing two different luminance levels on the VDT.…”

“…However, some empirical studies describing the impact of luminance ratios on performance (Kokoschka & Haubner, 1985) have compared a screen (VDT) luminance level with one off-screen somewhere in the immediate surrounding area. A comparison of seven visual fatigue assessment techniques in different VDT tasks showed that the subjective measure using a Likert scale was one of the most sensitive in differentiating differences in eye fatigue (Chi & Lin, 1998). Participants rated their level of severity of discomfort on a 5-point scale describing, for example, to what extent their eyes feel tired.…”