Reading on screens: Constraints on the visual system
The mass digitization of books is changing the way information is created, disseminated and displayed and the question of interest for psychologists is to know what are the effects of digital devices on reading behaviors. The paper will present two potential sources of disruption in reading: 1) visual fatigue may be induced by backlit displays (television, computer screens, tablets, etc.), 2) comprehension may decrease with some modes of reading (Spritz mode) present on small displays. For visual fatigue, the paper will present two experiments in which participants performed a longitudinal study comparing prolonged reading with two last generation e-readers (LCD, E-ink) and paper book. Results from both objective (Blinks per second) and subjective (Visual Fatigue Scale) measures suggested that reading on the LCD (Kindle Fire HD) triggers higher visual fatigue with respect to both the E-ink (Kindle Paperwhite) and the paper book. The absence of differences between E-ink and paper suggests that, concerning visual fatigue, the E-ink is indeed very similar to the paper. For comprehension, we compared traditional reading (i.e. left-to-right, top-to-bottom) with a rapid serial visual presentation (RSVP) application (named Spritz) that is available on smartphones. This reading mode has received a lot of media attention. RSVP consists of displaying in sequential order one or more words at a time, thus minimizing saccades and eye blinks. According to Spritz’s developers, the elimination of saccades should reduce visual fatigue and improve comprehension. In this study, we had people read on a computer screen a selected part of a book either with Spritz or in the traditional way. Results seem to contradict these claims. The fact that Spritz suppresses parafoveal processing and regressions (i.e. rereadings of words) negatively affected literal comprehension. Furthermore, the important reduction of eye blinks observed for Spritz might contribute to the increase of visual fatigue.