Glare is a very common source of image degradation on computer displays. Reading is one of the most common tasks performed with computers. Reading is also a task that is very sensitive to image degradation. The aim of this study was to assess the effect of different glare conditions on eye movements when reading.
In a balanced repeated-measurement experiment, 16 subjects (age: 20-35) read texts under four controlled lighting conditions: Overhead light (no glare), Desk luminary (peripheral glare), Window behind (indirect glare), Window in front (direct glare). The subjects read three texts under each condition: First a short standardized text from the Swedish version of the International Reading Speed Texts (IReST)(Trauzettel-Klosinski et al., 2012 ), secondly a longer newspaper text, and finally an additional IReST text to compare against the first. The texts were read on a Tobii T120 eye tracker.
The results show that glare does have a negative effect on reading performance. The more adverse the lighting condition was, the slower the reading speed became. The decrease was primarily a result of increased fixation durations. Both window conditions (i.e. direct and indirect glare) increased the fixation durations significantly (p < .05). This study shows that even moderate glare conditions can have an impact on reading. Even the worst condition in the experiment fell well within recommended luminance levels for workplace environments (SIS, 2011).
Trauzettel-Klosinski, S., Dietz, K., and the IReST study group (2012). Standardized Assessment of Reading Performance: The New International Reading Speed Texts (IReST). In press.
SIS (2011). Light and lighting - Lighting of work places - Part 1: Indoor work place. SS-EN 12464-1. Swedish Standards Institute.