Productivity, accuracy and viewing distance increase as font size increases during computer tasks, according to a small study published in Optometry & Vision Science. The findings may be useful for setting the font sizes for computers and for training office workers.
The researchers found that 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, which is above the high end of ISO recommendations (International Organisation for Standardisation, 1992, 2011).
The study involved 27 participants and evaluated 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). Nineteen participants were aged 18 to 35 and eight participants were aged 55 to 65. Older participants wore progressive lenses for presbyopia.
The monitor location was fixed but participants were able to change their posture and move the chair. They were asked to perform visual tasks that required similar visual skills to common tasks such as internet use, data entry, or word processing.
The researchers found that for each 1-mm increase in font size, there was a mean productivity gain of three correct clicks/min and an improvement in accuracy of 2 per cent. Font size increase also led to an 8 per cent reduction in perceived task difficulty. The study authors noted a trend for this effect to be more pronounced in the younger than in the older group.
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.
“This study demonstrates that productivity is improved when using a large font size (3.6 mm) compared with smaller font sizes (1.8 mm or 2.2 mm) under natural viewing conditions for computer users performing visually demanding tasks,” the authors concluded. “The presence of glare led subjects to lean forward and reduce their viewing distance.”