Binocular Coordination in Reading When Changing Background Brightness

Contradicting results concerning binocular coordination in reading have been reported: Liversedge et al. (2006) reported a dominance of uncrossed fixations, whereas Nuthmann and Kliegl (2009) observed more crossed fixations in reading. Based on both earlier and continuing studies, we conducted a reading experiment involving varying brightness of background and font. Calibration was performed using Gabor patches presented on grey background. During the experimental session, text had to be read either on dark, bright, or grey background. The data corroborates former results that showed a predominance of uncrossed fixations when reading on dark background, as well as those showing a predominance of crossed fixations, when reading on bright background. Besides these systematic shifts, the new results show an increase in unsystematic variability when changing the overall brightness from calibration to test. The origins of the effects need to be clarified in future research.