The effects of age, illumination, and anti-glare treatments on visual task performance and perceived image quality with VDTs

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Virginia Polytechnic Institute and State University


This dissertation investigated the effects of age on performance and image quality rating while varying screen surface treatment, ambient lighting, and character resolution. Five age groups were included, ranging from 18 to 69 years of age. The study used a factorial design to vary seven surface treatments which either reduced glare, enhanced contrast, or both; three lighting conditions, dark, diffuse, and specular; and two character resolutions, high and low, subtending visual angles of 16.1 arcmin. and 32.2 arcmin. respectively. Performance was measured using both a speed of reading task and a search task. In addition, subjects rated the image quality of displayed characters within each filter, lighting, resolution condition using a list of nine adjectives.

Results showed performance times to increase with age. The older age groups (40-49, 50-59, 60-69) performed better with the quarterwave filter, which enhanced contrast and reduced glare, and most poorly with the filters with the harshest etch (Gloss25) and the lowest transmission (31%). Performance was significantly slower for specular and dark lighting. A finding consistent with previous research indicated that extremely high luminance contrast degrades performance with low room illumination. Finally, for all conditions in which resolution was a factor performance was fastest and ratings were highest with the low resolution characters.