Auswirkungen von Umgebungsbeleuchtung auf die Lesbarkeit von negativ polarisierten mobilen Webseiten – eine Eyetracking-Studie

Abstract

Since Apple introduced dark mode, also known as negative polarity, in 2019, it has become increasingly popular. Digital displays are generally optimized for office ambient illumination and prefer positive polarity to reduce reflections from ambient illumination, which is helpful in bright environments but reduces usability in dark environments. Most studies on the readability of negative polarity focus on non-neuroscientific measurement methods under bright ambient illumination and compared to positive polarity, while mobile websites, which are primarily used in dark ambient illumination, receive less attention in research. Therefore, the aim of this study is to investigate the effects of ambient illumination on the readability of negatively polarized mobile websites. In addition to defining relevant terms in this work, a literature review was conducted to identify the research gap and the current state of research on readability. To investigate the effect of ambient illumination on readability, a research design consisting of an eye-trackingbased laboratory experiment was used. Hence, a suitable stimulus and appropriate framework conditions were developed. Moreover, a questionnaire was used to assess participants’ usage and attitude towards dark mode as well as their perceived cognitive load. The questionnaire revealed that all participants were familiar with the dark mode, the majority uses it regularly, especially in dark environments, and appreciate it for its ability to reduce eye strain, followed by its aesthetic design. Most of the participants also accesses websites on mobile devices. Both ambient illuminations resulted in a slightly increased cognitive load. Eye-tracking data revealed no significant effects of ambient illumination on the measured variables of readability. While dark ambient illumination showed better readability in terms of fixation count and fixation duration, bright ambient illumination was better in terms of saccade count, saccade amplitude and reading duration. In terms of theoretical average values, readability was given in both ambient illuminations. Overall, dark ambient illumination showed a slightly lower cognitive load, whereas bright ambient illumination performed minimally better in terms of readability. The differences were minor and therefore not considered meaningful.

Date of Award	2025
Original language	German (Austria)
Awarding Institution	Johannes Kepler University Linz
Supervisor	Dietmar Nedbal (Supervisor)