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Effect of font size and glare on computer tasks in young and older adults.

Ko-P; Mohapatra-A; Bailey-IL; Sheedy-J; Rempel-DM
Optom Vis Sci 2014 Jun; 91(6):682-689
PURPOSE: At a fixed viewing distance (VD), reading speed increases with print size. It is not known if this holds for computer tasks when postures are not constrained. Reflective glare on a monitor may reduce productivity. The effects of both may be modified by age. We evaluated effects of age, font size, and glare on performance for visually demanding text-based tasks on a computer. METHODS: Nineteen young (18 to 35 years old) and eight older (55 to 65 years old wearing progressive lenses that correct for presbyopia) subjects participated in a study with two trial factors: font size (1.78, 2.23, and 3.56 mm) and glare (produced by bright light-emitting diode task light reflective off a matte liquid crystal display monitor). The monitor location was fixed but subjects were allowed to change their posture and move the chair. Subjects performed visual tasks that required similar visual skills to common tasks such as Internet use, data entry, or word processing. RESULTS: Productivity, accuracy, and VD increased as font size increased. For each 1-mm increase in font size, there was a mean productivity gain of 3 correct clicks/min and an improvement in accuracy of 2%. Font size increase also led to lowered perceived task difficulty. Adding reflective glare on the monitor surface led to a reduced VD but had no effect on productivity or accuracy. With visual corrections for presbyopia, age had no effect on these relationships. CONCLUSIONS: Productivity is improved when the font is increased from 1.78 or 2.23 to 3.56 mm for text-based computer tasks. The largest font size corresponds to a visual angle of font of 23.4 arcmin. This visual angle of font is above the high end of ISO recommendations (International Organization for Standardization, 1992, 2011). The findings may be useful for setting the font sizes for computers and for training office workers.
Visual-fields; Visual-motor-performance; Visual-motility; Optic-system; Optical-analysis; Video-display-terminals; Office-workers; Computer-equipment; Ergonomics; Age-groups; Task-performance; Eye-movement; Eyesight; Monitors; Eye-glasses; Physiology; Humans; Electronic-equipment; Author Keywords: video display terminal; electronic display; character size; viewing distance; visual angle of font; visual acuity reserve; office ergonomics; usability; productivity
David M. Rempel, Ergonomics Graduate Program, University of California Berkeley, UC Richmond Field Station, 1301 S 46th Street, Bldg 163, Richmond, CA 94804
Publication Date
Document Type
Journal Article
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Fiscal Year
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Identifying No.
Grant-Number-T42-OH-008429; M072014
Issue of Publication
Source Name
Optometry and Vision Science
Performing Organization
University of California, Berkeley